Fundamentals of Evolutionary Biology Flashcards

Question

What is an example of inbreeding in pedigree dogs?

Answer 1

The gene pool of 10,000 pugs is only made up of 50 individuals, leading to high levels of inbreeding.

Answer 2

The Hapsburg Jaw and polydactyly - Examples of inbreeding in European royals

Answer 3

Increased homozygosity - Preferential mating with individuals with similar characteristics - Increased likelihood that offspring receive identical alleles from both parents at these loci. Change in Allele Frequencies - Can lead to the development of subpopulations.

Answer 4

somatic cells.

Answer 5

Mosaicism and tumors

Answer 6

Germline cell mutations

Answer 7

Mutations are a random process - Influenced by environmental effects but still ultimately random

Answer 8

- DNA polymerase infidelity - Base substitutions - Chromosomal abnormalities - Errors in repairing double-strand breaks in DNA.

Answer 9

Have the potential to change the amino acid sequence of a protein - Have a more significant impact on the organism

Answer 10

Poisson distribution suggests mutations arise independently

Answer 11

Supports the idea that mutations are random - Results show mutations not directed by external factors

Answer 12

Weak - While mutation is not the main driver of evolution, it provides the raw material on which evolution can act

Answer 13

Mixing of non-homologous chromosomes occurs. - Independent assortment. Mixing of homologous chromosomes occurs. - Crossing over.

Answer 14

Results in the random segregation of maternal and paternal chromosomes into gametes. - During meiosis

Answer 15

Homologous chromosomes pair up and exchange segments of DNA - Forming chiasmata (point at which paired chromosomes remain in contact during the first metaphase of meiosis)

Answer 16

- Leads to the production of recombinant chromosomes and increasing genetic diversity

Answer 17

Outcome different each time - stochastic - Can drift in any direction by chance

Answer 18

More stable allele frequency (less effect).

Answer 19

Reduces genetic diversity - Sooner or later due to random sampling, alleles will be lost from the population

Answer 20

Much more severe between generations in small populations

Answer 21

Caused by variation in random sampling of gametes in finite populations - Leads to loss of variation Random process (Stochastic) - cannot predict allele freq change with certainty - Unlike natural selection/mutation pressure

Answer 22

- Number of individuals in a population who contribute offspring to the next generation - Reflects the genetic diversity of a population. Often differs from the actual population size due to factors such as: - Unequal sex ratios - Variation in offspring number - Population structure.

Answer 23

The total number of individuals in a population - not all individuals contribute equally to the gene pool

Answer 24

Theoretical population in which Mating is random - All individuals equally likely to have offspring - Number of offspring doesn’t vary more than by chance - Number of breeding individuals remains same each generation - Equal numbers of males and females involved in breeding

Answer 25

Smaller - This is where the effective population size (Ne) comes in

Answer 26

Effective population size (Ne) is the size of an idealized population that would experience the same rate of genetic drift as the actual population - not all individuals in a population contribute equally to the gene pool - provides a more accurate estimate of the potential for genetic drift to occur

Answer 27

Reflects historical small population

Answer 28

Not all individuals in a population contribute equally to the gene pool - leading to a difference between N and Ne Factors - variation in reproductive success - fluctuations in population size - differences in male and female contribution to the next generation affect Ne

Answer 29

- Can lead to an uneven contribution to the gene pool Some individuals may have more offspring than others - leading to a larger genetic contribution

Answer 30

- Random fluctuations in the number of offspring can lead to deviations from the idealized population assumptions used to calculate Ne.

Answer 31

- Population bottlenecks, expansions, or fluctuations can cause changes in Ne. - Historical population events can have long-term effects on Ne Populations that fluctuate consistently - Will have a low Ne

Answer 32

When male and female contribution to the next generation is not equal - effective population size (Ne) can be much smaller than census population size (N) - leading to a greater impact of genetic drift and reducing genetic diversity.

Answer 33

Individuals of different ages can have different contributions to the gene pool - Age-structured populations can have a larger difference between N and Ne

Answer 34

Ensure more equal male contribution to the next generation - Unequal male and female contribution can have a negative impact on genetic diversity and effective population size - By controlling mating, zoos can increase genetic diversity and maintain a healthy population

Answer 35

Population is severely reduced in size, resulting in a loss of genetic diversity - Can occur naturally or as a result of human impacts, such as habitat destruction or overhunting - Population bottlenecks can have significant long-term consequences for genetic diversity and the viability of a population

Answer 36

Cheetahs experienced a population bottleneck around 10,000 years ago at the end of the last glaciation period - This bottleneck severely reduced their population size and genetic diversity - Today, cheetah populations still have low genetic diversity due to this historical event, as well as recent human impacts

Answer 37

Can have massive consequences for genetic diversity - Genetic drift can have a greater impact on a small population - Reduced genetic diversity can take thousands of generations to restore.

Answer 38

Ne is closer to the pre-expansion population size during a population expansion

Answer 39

Northern elephant seals experienced a population bottleneck due to human hunting in the 1890s - Drastically reduced their genetic diversity.

Answer 40

Loss of genetic diversity that occurs when a new small population is formed from a larger population

Answer 41

Small population is extracted from a larger population - Results in a random sample that may be skewed - Can lead to a loss of genetic diversity and vulnerability to genetic drift in the small population

Answer 42

Amish population - The Amish people were founded by ~200 German colonists - Genetically isolated - Founders had a recessive deleterious autosomal allele underlying a form of dwarfism, and polydactyl of the hands, short stature, and congenital heart malformation - 12.3% of the Amish population are now heterozygotes for this gene

Answer 43

- pattern of variation of genetic traits within and between populations

Answer 44

Analyzing the genetic makeup of individuals within populations and how they cluster with closely related individuals

Answer 45

Gene flow is the transfer of genetic information from one population to another - can counteract the effect of random genetic drift - homogenizing allele frequencies between populations and reducing genetic differentiation

Answer 46

Measure of the extent of genetic population structure - Based on the inbreeding coefficient f

Answer 47

The probability of identity by descent of two alleles drawn from a population

Answer 48

FST compares the probability of identity by descent of two alleles drawn from a subpopulation - to drawing two alleles from a total population comprised of multiple subpopulations.

Answer 49

Proportion of individuals that are heterozygous

Answer 50

Proportion of individuals that are expected to be heterozygous based on Hardy-Weinberg (i.e. 2pq).

Answer 51

The fractional reduction in heterozygosity of an inbreeding population relative to a randomly mating population with the same allele frequencies

Answer 52

Fis is often used to refer to F, where I represents individual and S represents subpopulation - measures the proportionate reduction of heterozygosity due to mating of related individuals within a subpopulation.

Answer 53

ST - represents the proportionate reduction in heterozygosity of subpopulations relative to the heterozygosity of the total combined population IT - represents the proportionate reduction in heterozygosity of inbred organisms relative to the total population.

Answer 54

Fst - used measure in population genetics to quantify genetic differentiation between populations Fit - inclusive measure of inbreeding and represents the proportionate reduction in heterozygosity of inbred organisms relative to the total population

Answer 55

High Fst value indicates that allele frequencies are different between populations - there is significant genetic differentiation between populations

Answer 56

- Gene flow, or movement of individuals between populations, tends to decrease FST - size and distance between populations can also affect FST, with smaller and closer populations having lower values.

Answer 57

Genetic markers used to determine genetic population structure - Variation in enzymes encoded by different alleles detected through electrophoresis - Often used in the past, but now being replaced by more powerful DNA-based markers

Answer 58

- Sequence data - Mitochondrial DNA - Autosomal markers - Microsatellites - Allozymes

Answer 59

Microsatellites are simple sequence repeats that are often used to estimate genetic diversity - Scored based on the length of repeated units

Answer 60

- Arise because of a DNA slippage mechanism in replication - Easily misalign, leading to an increase or decrease in the number of repeats

Answer 61

- Mitochondrial DNA is a type of genetic marker that is maternally inherited - often used to study population genetics and evolutionary biology

Answer 62

a method of determining the genetic makeup of an organism by analyzing its entire or a portion of its DNA sequence

Answer 63

Allozymes are variant forms of enzymes that are used as genetic markers

Answer 64

- DNA located on the autosomes - Non-sex chromosomes in the genome

Answer 65

- Very variable with high mutation rate - Easy to amplify even from small amounts of degraded DNA - Suitable for use with a wide range of organisms, including museum specimens

Answer 66

Genetic markers that represent a single base change in DNA sequence that occurs at a specific position in the genome

Answer 67

Human populations are not that genetically diverse - Findings suggest that the concept of 'race' is not a valid biological concept, and has no scientific basis - Suggests that personalized medicine based on individual genetic differences is a more reliable than medicine based on racial or ethnic categories

Answer 68

Assumes a set of populations - each with infinite size and no genetic drift - connected by gene flow with migrants at the same rate (m) regardless of distance

Answer 69

Most species have some geographic structure and are composed of many sub-populations (demes) - in which genetic drift and natural selection can operate differently - leading to non-random breeding patterns

Answer 70

Increases genetic diversity - by introducing new alleles - can decrease genetic differentiation between populations by homogenising allele frequencies through migration

Answer 71

Species often have many sub-populations

Answer 72

Demes tend toward the total population average over time - gene flow homogenizes allele frequencies across populations

Answer 73

FST is a measure of population differentiation due to genetic drift

Answer 74

Migration homogenizes allele frequencies, thus reducing FST, while genetic drift skews allele frequencies, thus increasing FST.

Answer 75

Parameter used to estimate the number of migrants per generation in a population - product of the effective population size (Ne) and the migration rate (m) - represents the number of individuals per generation that move between populations due to migration - May not be true for wild populations

Answer 76

Interplay between genetic drift and mutation

Answer 77

Evolutionary process where organism becomes better able to survive in an environment - From natural selection acting on heritable characteristics

Answer 78

Ability of one genotype to produce more than one phenotype - Response to different environmental conditions

Answer 79

Phenotypic plasticity

Answer 80

Immobile - high need to meet environment

Answer 81

- High rate of population growth - Heritable traits - Variation in these traits among individuals of species - Some of these traits must affect fitness

Answer 82

Individuals with one extreme of a trait have higher fitness than individuals with the other extreme - It can occur when environmental conditions change, or when a new predator or prey is introduced

Answer 83

Individuals with intermediate values of a trait have higher fitness than those with extreme values - Can occur when environmental conditions are stable or when extremes are disadvantageous.

Answer 84

Individuals with extreme traits have higher fitness than those with similar traits - It can occur when environmental conditions are variable or when there are different niches to be filled

Answer 85

Variations in DNA sequences that occur within a population

Answer 86

Individuals with two copies of the same allele have higher fitness than those with two different alleles

Answer 87

Individuals with two different alleles have higher fitness than those with two copies of the same allele

Answer 88

Homozygotes for the Hb-S allele have a severe form of sickle cell anemia, which can be life-threatening.

Answer 89

Heterozygotes for the Hb-S allele have some protection against malaria and do not develop sickle cell anemia

Answer 90

Provides some protection against malaria - mutation in the beta-globin gene that codes for hemoglobin

Answer 91

Mode of natural selection in which multiple alleles are maintained in a population due to - Heterozygote advantage - Frequency-dependent selection

Answer 92

Number of offspring an individual produces

Answer 93

Absolute fitness of a genotype divided by the absolute fitness of the genotype with the fitness

Answer 94

Amount by which the fitness of a genotype differs from that of a reference genotype

Answer 95

Manipulate environment or apply selective pressures - Study how natural selection affects the frequency of alleles or genotypes in a population

Answer 96

Drives genotype frequencies away from Hardy-Weinberg equilibrium

Answer 97

- process of forming homozygous individuals carrying two copies of the recessive carbonaria allele is slow

Answer 98

Heterozygous genotype has a higher fitness than either of the homozygous genotypes - Maintains genetic diversity in a population

Answer 99

Heterozygous genotype has a lower fitness than either of the homozygous genotypes - can lead to an unstable equilibrium, depending on where the equilibrium lies

Answer 100

Fixation is the process in population genetics by which a particular allele reaches a frequency of 100% and becomes the only allele present at a given locus in the population - means that all individuals in the population are homozygous for that allele

Answer 101

study of how quantitative traits are inherited and evolve

Answer 102

Vary continuously - Height, blood pressure, plumage colour, wing length - Many sexual selection traits - Not usually single gene

Answer 103

Language - Genetic capacity to learn language but entirely dependent on environment Flamingo colour - Genetic capacity to pick up colour

Answer 104

Capacity of an organism (genotype) to develop any of several phenotypic states depending on the environment - Can be morphological, behavioural, life history (investment in early or late reproduction) - Some traits more plastic than other

Answer 105

Reared in presence of predators gain defensive structures

Answer 106

Shallow vs deep phenotypes Deep - larger and rounder Shallow - more streamlined

Answer 107

Deep body phenotype - Provides them with a fitness advantage in high predation environments - More adaptive escape response - Attain higher swimming speed, acceleration, and turning rates - Less vulnerable to predation by pike

Answer 108

Shallow and streamlined body shape phenotype - phenotype allows them to more efficiently - provides fitness advantage by enhancing their competitive ability - compete for limited resources - food and breeding sites

Answer 109

Gape size of pike limits their ability to eat deep phenotype crucian carp - smaller pike cannot prey on these fish - advantage for deep phenotype

Answer 110

Ground finch Geospiza fortis - Not actually a finch Major drought 1977 - Only large seeds available - Only birds with large beaks could survive - Large beaks were selected for

Answer 111

Crossbills - Seeds from hemlock or lodgepole - small or big - Small bill depth can access hemlock, large can access lodgepole - Intermediate doesn’t get shit

Answer 112

Birthweight in human infants - Favours individuals with trait values near population mean - Lowest infant mortality around norm

Answer 113

Study of different traits at same time Stripedness - camo Reversal - escape behaviour - High striping and few reversals led to high survival rates due to effective camouflage - High stripey individuals with many reversals had low survival rates - poor camouflage - Low strip snakes with many reversals had high survival rates, effective escape behaviour can compensate for a less effective camouflage strategy

Answer 114

Orange guppies - more vulnerable to predation - more attractive to females (because if they survive while very orange they are more attractive?) A positive selection gradient would indicate that males with more intense orange coloration have higher reproductive success - Guppies would become more orange

Answer 115

Selection for milk production in cows lead to decreased fecundity - ability to produce offspring or reproductive cells

Answer 116

Certain traits are correlated at the genetic level - Same regions of the genome are associated with variation in multiple traits - Eg. long arms with long legs - Partially heritable Traits can evolve while not under direct selection - Natural selection operating on one trait can affect another

Answer 117

Single locus affects more than one trait - This can result in seemingly unrelated traits being genetically correlated because they are both affected by the same gene

Answer 118

Non-random association between alleles at different loci - can result in seemingly unrelated traits being genetically correlated - both affected by loci that are physically close to each other on the genome

Answer 119

No light - Lost eyes - Sensory cells now respond to vibrations Pax6 gene - Controls eyesight, enhanced senses and other genetic factors - Genetic correlations

Answer 120

Species or group of organisms that is distributed worldwide - occurring in many different geographic regions

Answer 121

Species or group of organisms that is restricted to a particular geographic region or habitat and is not naturally found anywhere else

Answer 122

Species or group of organisms that has non-continuous distribution - isolated populations that are separated by large geographic distances.

Answer 123

Distribution in which a formerly continuous population - becomes separated by a physical or environmental barrier - mountain range, river, or sea - leading to the development of distinct, geographically isolated populations

Answer 124

Separates two distinct distinct modern terrestrial faunas - Corresponds to a deepwater separation between continental plates - Same latitude, similar geology, area of coast line etc - very similar general environments - Two completely different communities of fauna

Answer 125

Mexican plateau and tropical low-lands - geographical barrier of the Isthmus of Panama

Answer 126

Himalayan Mountains

Answer 127

Sahara and Arabian desert

Answer 128

- Fruit flies - Brown rat - Common rock dove - House dust mite - Commensal organisms (follow humans)

Answer 129

Fossa and lemurs (Madagascar)

Answer 130

- Marsupials (Australasia and the Americas) - Alligators (North America and China) - Araucaria pine (South America and Australasia)

Answer 131

Looked at more than vertebrates - Mostly corroborated Wallace’s realms - Finer separation - Australasian realm split into Australian and Oceanian

Answer 132

- Range expansion through favourable habitat - Jump dispersal across unfavourable habitat

Answer 133

Corridors only certain organisms can cross

Answer 134

- Passive - sweepstakes - eg. rafting, Wind, storms

Answer 135

- Isthmus of Panama - Links central and South American - Land bridge

Answer 136

1883 Krakatoa eruption killed all life - 50 years later repopulated forest from Java and Sumatra

Answer 137

Seeds, spores, small animals - Prevailing winds will disperse organisms in particular directions

Answer 138

Seeds, plankton, larvae etc

Answer 139

- Extinction - Does not occur at same time in all places

Answer 140

Leads to divergence and speciation

Answer 141

A taxon that persists as a remnant of what was once a diverse and widespread population

Answer 142

Past environmental changes - Climate fluctuations, geological events, or human activities that have created isolated or marginal habitats - Subset of population is confined to available hospitable area - broader population either shrinks or evolves divergently

Answer 143

Previously thought lemurs arose by vicariance - Split from Gondwana Molecular phylogenies - Many species too young to have arisen by vicariance - Waif dispersal from Africa

Answer 144

There was no exchange of organisms in or out after the first 10 million years - Caenozoic - Isolation led to the evolution of unique and diverse mammalian faunas in South America

Answer 145

Dispersal events of Marsupials, xenarthrans, and native ungulates - From South America - During Caenozoic

Answer 146

- Human hunting and climate change - End of Pleistocene

Answer 147

Climate change

Answer 148

Domain Kingdom Phylum Class Order Family Genus Species King Phillip Came Over For Good Spaghetti Thank me later

Answer 149

Hypothesising relationships among organisms based on uniquely shared characters/traits

Answer 150

Assumptions: - (Inherited) characters change/are acquired over time - Any group of organisms related by common descent - Character similarities/differences reflect evolutionary history

Answer 151

Advantages - useful for understanding evolutionary relationships among extinct taxa - many features to choose from Disadvantage - can introduce biases based on subjective decisions about what features to include - some traits may be more susceptible to convergent evolution than others

Answer 152

Shared trait because of common descent - useful character

Answer 153

Similarity of traits not due to common ancestry - Arises through convergent evolution, parallel evolution, or evolutionary reversal - makes it difficult to reconstruct accurate evolutionary relationships among different taxa

Answer 154

Occurs when two or more closely related lineages independently evolve similar traits or features - Similar to convergent evolution

Answer 155

A trait or feature that was lost in an ancestor is subsequently regained in a descendant lineage

Answer 156

Molecular Data very abundant (10s thousands characters) - Objective (?) – computer algorithms Accessibility - Expensive (becoming cheaper) Morphological Data - hundreds of characters Subjective - human interpretation Accessibility - Labour intensive

Answer 157

Molecular fossil data unusable beyond 5mya

Answer 158

Rooted - one taxon acts as outgroup to all others - single common ancestor considered - length of each branch indicating the amount of evolutionary change that has occurred

Answer 159

Branch lengths represent the amount of evolutionary change that has occured

Answer 160

All tips equidistant from root - Branch lengths represent absolute time or some other measure of evolutionary time - assume a constant rate of evolution over time

Answer 161

Unrooted - no assumptions about ancestry - does not have a root node - branching pattern represents only the relative similarities and differences among the organisms - not used for evolutionary history

Answer 162

Genes from same ancestor

Answer 163

Genes separated by speciation events

Answer 164

Genes separated by gene duplication

Answer 165

Misalignment and unequal crossing over

Answer 166

Duplication followed by loss of genes

Answer 167

Paralogs can independently acquire mutations after gene duplication To help understand For example, imagine a gene duplication event that produces two paralogs, A and B. Over time, mutations accumulate in each paralog independently, resulting in differences in their DNA sequences. If we compare the sequences of paralog A from two different species, we might conclude that they are orthologs (i.e. genes that diverged through speciation events). However, if we compare the sequences of paralogs A and B within the same species, we will see that they are more similar to each other than to the A orthologs from other species. I still dont understand

Answer 168

The movement of genetic material between different species or clades

Answer 169

Makes evolutionary relationships between organisms more complex - resulting in network instead of a simple tree

Answer 170

Mostly between closely related bacteria but can be in eukaryotes and distant clades

Answer 171

Ancestral gene copies fail to coalesce into a common ancestral copy until deeper than previous speciation events

Answer 172

All copies of the gene present in the current population are derived from a single ancestral copy that existed in the past

Answer 173

When a speciation event occurs, the ancestral population splits into two or more daughter populations - each may carry a slightly different set of gene copies. - Over time, the genes in each population will diverge due to mutation and drift, and new alleles will arise. - As a result, the gene tree may not match the species tree, because of the differences in the sorting of alleles between populations. NOIDEA WHATHISMEANSSO CONFUSED SEND HELP IF YOU CAN

Answer 174

- Seeks to find the simplest explanation requiring the fewest assumptions. - It suggests that the tree topology that requires the fewest character changes should be preferred

Answer 175

Often loads of possible trees that can be supported through this method - Especially when dealing with many taxa - For example, with just six taxa, there can be 945 possible trees to support through parsimony

Answer 176

Measure characters and use them to infer the relationships among organisms - ultimately resulting in a phylogeny

Answer 177

Find the best-fitting phylogenetic tree - involve sub-sampling and applying algorithms to obtain an approximate answer to phylogenetic inference - algorithm always climbs up and looks for local optima in the imaginary tree-length landscape - aim is to hit the biggest peak, through random start points and comparing optima - samples trees randomly to find most likely to be optimal - Possible to get multiple most parsimonious trees

Answer 178

Used to overcome the limitations of computationally intensive methods such as exhaustive search algorithms - which are not practical for large datasets

Answer 179

Summarise multiple trees as a consensus tree - shows the uncertainty of the contested divergences

Answer 180

Inferring phylogenetic trees based on the principle of finding the tree that maximizes the probability of the observed data given an evolutionary model

Answer 181

Maximum likelihood, like parsimony, aims to find the tree with the fewest evolutionary changes. - Maximum likelihood uses evolutionary models to guide toward the most probable tree - Parsimony only counts the number of changes

Answer 182

Mutation rates and differences in rates between sites and genes

Answer 183

- Bootstrap analysis - Run maximum likelihood analysis on each dataset - Construct consensus tree from the resulting trees to determine the support for each branch

Answer 184

Shows if and which species have a disproportionate influence on the tree - provides a measure of statistical support for each branch of the tree

Answer 185

Method for inferring the probability of a hypothesis tree given the data - Calculating the posterior probability of the hypothesis tree given the data - the prior probability of the tree - the probability of data given the tree

Answer 186

Allows incorporation of a prior knowledge and provides a way to calibrate certainty - often used in combination with other methods for more accurate results

Answer 187

Distant taxa may appear to be closely related due to the high number of mutations they have accumulated - Leading to incorrect placement on the tree

Answer 188

By looking for homology - Likelihood can help distinguish true relationships from artificial ones caused by long branches

Answer 189

Estimate the time of divergence between two species based on the assumption that mutations accumulate in DNA sequences at a relatively constant rate - May be different between molecules

Answer 190

Comparing the amount of sequence divergence between closely related species whose divergence times are known from the fossil record

Answer 191

- Variation in mutation rates among genes and lineages

Answer 192

Morphologically (almost) identical but are incapable of producing fertile hybrids - can only be identified by genetic, behavioral, or ecological factors Examples - Eg. mosquitos - 6 species but only some transmit malaria - Eg yeast - budding yeast identical but you can only use S. cerevisiae to bake bread

Answer 193

Only applicable to sexually reproducing organisms Asexual organisms given binomial names - considered taxonomic species but not biological species Does not apply to fossils Intermediate cases - Reproductive barrier incomplete

Answer 194

- Eg hybridisation zone of carrion and hooded crows - Eg broad sympatric hybridisation of gray oak and gambel’s oak

Answer 195

Difficult to determine if they are capable of interbreeding due to physical barriers

Answer 196

Based on evolutionary history - descended from a common ancestor and who all possess a combination of certain defining, or derived, traits

Answer 197

A basal cluster of organisms that is diagnosable distinct from other such clusters and within which there is a parental pattern of ancestry and descent (PSC1) The smallest exclusive monophyletic group of common ancestry (PSC2)

Answer 198

- Behavioural isolation - Ecological Isolation

Answer 199

Serve to identify individual of same species - Vary in chemical structures, chirality and ratios Eg European Corn Borer (Moth) - Females from different races produce different blends of the cis and trans isomers of the same pheromones

Answer 200

Mainly mammals and insects

Answer 201

Differences in the behaviour of individuals of different species during courtship and mate selection Variation in secondary sexual characters - Eg. Such as the brightly coloured plumage of male hummingbirds - used to attract mates of the same species while repelling potential mates of different species Use of different acoustic signals in green lacewings - Distinguish between members of different species during courtship

Answer 202

Inability of a species to use another species’ environment

Answer 203

Occupy same space but reproductively isolated due to different niches Eg. Goldenrod plants - Adapted to specific soil moisture

Answer 204

Species adapted to two largely allopatric habitats

Answer 205

Mating seasons Mating time and activity (morning vs evening)

Answer 206

Temporal isolation - Different life cycle lengths - Living in same area - 13 year vs 17 year - Alternate species opportunity to mate once every 221 years

Answer 207

Microspatial - Host specific insects - They mate where they feed - Different species different host

Answer 208

Macro-spatial - one species prefers loamy soils - other prefers sandy soils Temporal - reach sexual maturity in autumn - spring field crickets reach sexual maturity in spring

Answer 209

Temporal - One species of drosophila breeds in the morning, another in the evening

Answer 210

Morphological disparity adapted for different pollinators Eg. figs and fig wasps - Nearly all 750 fig species pollinated by different wasps Eg bees vs hummingbirds - flowers shaped for ease of their pollinators

Answer 211

- Mechanical isolation - Copulatory behavioural isolation - Gametic isolation

Answer 212

Structural incompatibility of reproductive organs between two species - Not very common among animals

Answer 213

Eg. Japanese Carabid beetles Males from other species with different shape and size genitalia - Can cause tearing of female reproductive organs - Sometimes fatal Creates a strong selective pressure for females to only mate with males of the same species

Answer 214

More common in plants Flowers have specific shapes - incompatible with some pollinators Some flowers have deep floral tubes - can only be reached by pollinators with long proboscises

Answer 215

Behaviour of individual during copulation insufficient to allow normal fertilisation - Failure of sperm transfer despite compatibility between genitals

Answer 216

Eg drosophila - Females terminate copulation before transfer if tactile stimulation incorrect

Answer 217

- prevents the fusion of gametes from alternate species - prevent fertilization between individuals

Answer 218

Caused by intrinsic factors such as differences in gamete size or shape

Answer 219

Involves active selection of conspecific (same species) gametes over heterospecific (different) gametes

Answer 220

Females inseminated by both conspecific and heterospecific sperm Produce few hybrid offspring - Conspecific gametes were favoured - some progeny were hybrids

Answer 221

If hybrid zygote formed - Hybrid inviability - Hybrid sterility

Answer 222

Zygote dies due to genetic incompatibilities

Answer 223

Zygote survives, unable to produce viable progeny - Very wasteful evolutionarily

Answer 224

Hybrid does not find appropriate niche Heliconius butterflies - exhibit a range of mimicry rings - which serve as a defense against predators Hybridization between different mimicry rings - results in non-mimetic hybrids - these have lower fitness due to increased predator mortality

Answer 225

Ecological Post-zygotic barrier - hybrids of two species outcompeted Two taxons - mountain and basin - Hybrid hopeless in basin (out competed by both mountain and basin taxons) - Hybrid fitness in mountain is alright but outcompeted by mountain taxon

Answer 226

Cannot obtain mates Eg. lacewing - Courtship song - Hybrid has intermediate song - discriminated against by females of both species

Answer 227

Can appear/disappear as environmental conditions change Eg. Sagebrush hybrid outcompetes parent species in specific soils

Answer 228

Eg Mus musculus musculus and M.m. domesticus (mouse sub species) - Hybrid more prone to parasites (extrinsic) due to reduced genetic resistance (intrinsic)

Answer 229

When reproductive isolation is incomplete - the heterogametic sex (the sex with different sex chromosomes) shows the strongest degree of reproductive isolation (most likely to be unviable)

Answer 230

Rule applies when the sex chromosomes are different between the two species - such as in mammals (where females are XX and males are XY) - Lepidoptera (where females are ZW and males are ZZ) - birds (where females are also ZW and males are ZZ)

Answer 231

When two different species interbreed, the genes on their chromosomes may be incompatible - fitness of hybrid offspring on one allele is dominant over the other For example - consider two genes A and B, with two alleles each (A1, A2, B1, and B2) A1 is incompatible with B2 B2 is dominant over B1. In this case - heterozygous individuals with A2B2 will be fit because they have one compatible allele and one dominant B2 allele. Heterozygous individuals with A1B2 will be affected because they have one incompatible A1 allele and one dominant B2 allele.

Answer 232

Whether males or females are more affected by the incompatibilities depends on which sex is heterogametic (has different sex chromosomes) and which allele is dominant In birds and Lepidoptera - where the XY is the female, an incompatible gene on the X chromosome will affect heterogametic males (XY) more than homogametic females (XX). In mammals, where the XY is the male - an incompatible gene on the X chromosome will affect heterogametic females (XX) more than homogametic males (XY).

Answer 233

- heterogametic sex has a greater proportion of genes that are unique to its sex chromosome - makes it more susceptible to the negative effects of genetic incompatibilities.

Answer 234

Refers to the accumulation of genetic differences over time between populations or species - Lack of recombination/problems in meiosis due to differences in the sequence of homologous chromosomes - Can make it difficult for them to match up during fertilization - Strength of isolation increases with genetic distance

Answer 235

Refers to chromosomal rearrangements - Prevents annealing of parental homologues in meiosis

Answer 236

translocations, fissions, inversions, deletions, and duplications leading aneuploidy

Answer 237

- Negative epistatic interactions (improper binding) between two or more genes that can result in reduced fitness or sterility in hybrids - Incompatibilities between genomes that lead to disharmonious interactions - Causing reduced fitness or sterility in the hybrid offspring

Answer 238

Arises if one population evolves the A1B0 genotype and the other evolves the A0B1 genotype - allowing formation of unfit A1B1 hybrids if the populations were to come into contact

Answer 239

Two species live in the same geographic range, there is a higher probability of encountering and attempting to mate with each other - evolved stronger prezygotic isolation mechanisms to prevent hybridization and maintain genetic differentiation

Answer 240

- When two similar species that coexist in the same geographic area - evolve different traits that allow them to use different resources or occupy different ecological niches

Answer 241

- Natural selection strengthens reproductive barriers between two closely related species - Reduces chance of interbreeding and the production of hybrid offspring

Answer 242

Evolution of traits that further promote the divergence between two sympatric species

Answer 243

- When the two species are sympatric - Brown morphs are more prevalent and preferred by females - Reducing chance of hybridisation

Answer 244

Reduction of gene flow to 0 - physical (geographic) barrier extrinsic to the organism - due do geological or climate events - divergence without hybridisation events

Answer 245

- Divergence of large populations - Allopatrically

Answer 246

Emergence of the Isthmus of Panama in Pliocene - Divided snapping shrimp populations to pacific and Caribbean - Now in labs only 1% interspecific pairs can mate

Answer 247

- Secondary hybrid zone forms - Hybrids with low fitness

Answer 248

Natural selection - ecological selection - sexual selection Dobzhansky-Muller incompatibilities Genetic drift

Answer 249

Georgia and New York populations feed on maple Ontario population feeds on Willow - Greater RI between Ontario and New York despite close geographic proximity - Sexual isolation more pronounced between ecologically divergent population

Answer 250

Two ecomorphs - benthic (large, big mouth, big prey) - limnetic (small, feeds on plankton) Found in different Canadian lakes - Females preferentially mate same ecomorph, whether from same or different lake - reproductive isolation has evolved between the two morphs

Answer 251

Isolation by female preference for phenotypic traits of conspecific males - Eg. birds of paradise, hummingbirds

Answer 252

Bottlenecked population that has experienced severe reduction in size

Answer 253

Small subset of individuals survives and reproduces - Reduction in genetic diversity - Increase in the frequency of certain alleles

Answer 254

Divergence of small population from large ancestral population - Founder effect - Genetic drift acts strongly on small populations Invasion of novel habitat - strong selection

Answer 255

Eg. paradise kingfisher variation in New Guinea - Several different species on small islands

Answer 256

Divergence of spatially distinct population - some gene flow (0

Answer 257

Eg A. odoratum - grass species - Grass evolved to tolerate heavy metals near mines - Populations under strong selection pressure for metal tolerance diverged from neighbouring populations growing on uncontaminated toil - Increased self fertilisation to avoid dilution of tolerance genes

Answer 258

Divergence between a single, initially randomly mating, population (m=0.5) - Speciation despite high gene flow

Answer 259

Insect sympatric speciation when shifting host/adapting to new plant host - Same species but beginning to develop new niche

Answer 260

- Host/Habitat-shift speciation - Polyploid/Hybrid speciation

Answer 261

- Powerful disruptive selection imposed by two ecological niches - Association between ecological niche and mate choice - Leads to the development of reproductive isolation

Answer 262

Sibling species each inhabits different host Apple vs Hawthorne - choice of host Conclusions - Host preference must have genetic basis - Genetic based trade-off in fitness associated with colonising and adapting to new plant host (alleles suitable for one host may be selected against in the other) - The two plants have different fruiting time (favouring alleles optimising time for mating)

Answer 263

Occurred due to divergent selection pressures imposed by differences in soil preference - Resulted in differences in the timing of reproduction and flowering season between the two species - Over time, this reproductive isolation occurred Despite no lack of physical barrier

Answer 264

Cytological change (cellular change brings reproductive barrier) Polyploids are post-zygotically isolated from their diploid progenitors - Ie. 4n breeding with 2n gives 3n - unpaired chromosome - unviable Instantaneous speciation by a single genetic event (autopolyploidy and allopolyploidy)

Answer 265

Fusion of two 2n gametes of same species

Answer 266

Fusion of two 2n gametes from two closely related species

Answer 267

Some recombinant offspring produced by hybrids of two species are fertile but reproductively isolated from parent species Eg Helianthus - Hybridisation between H. petiolaris and H. annus gave 3 other Helianthus species

Answer 268

- Time required for complete RI (Reproductive Isolation) from start of process

Answer 269

Time between origin of new species and when that species specialises again (TFS + waiting time until next TFS)

Answer 270

- Polyploid speciation (instantaneous) - Hybrid speciation - Adaptive Radiation (rapid speciation and phenotypic adaptation to exploit unoccupied niches)

Answer 271

Sympatric speciation is fast (Rapid TFS), however it happens rarely (long BSI)!

Answer 272

Smaller population (founder-effect) - under genetic drift and selection - can have rapid TFS

Answer 273

Current and ancestral taxa are likely to occupy similar niches - Better adapted than, and outcompete, other taxa - Eg. if a woodland niche becomes vacated, it's easier for terrestrial mammals and plants to move in than fish

Answer 274

Traits are not lost immediately - Can make it difficult to determine whether the trait is truly adaptive or not - Comparison with other taxa can reveal former use

Answer 275

- Neutral or negative selection pressure replaces positive selection - The trait may persist for some time still (especially if neutral) - Removal may have no positive effect, or even a more deleterious side effect

Answer 276

Human vermiform appendix - Used to be for fermentation - Still is in other organisms

Answer 277

7 cervical vertebrae (few mammals deviate) - Hard to change as vertebrae development occurs early - Would allow increased flexibility and length

Answer 278

Mutation removing constraints allows for adaptive radiation - allowed radiation into new niches

Answer 279

Heart chambers are completely separated - Whales, seals, penguins don’t breath under water - No point sending blood to lungs - But they must Crocodiles, marine iguanas can divert blood away from lungs (due to design of the heart)

Answer 280

Similar due to common descent

Answer 281

Similar due to common selection pressures (convergent evolution)

Answer 282

Dolphins resemble ichthyosaurs - due to convergence - adapted to swimming

Answer 283

Reptiles - lateral undulations - movement pattern limited by constraint of anatomy Mammals - vertebrae articulate around the transverse plane allows for up-and-down movement - due to suckling and breathing constraints

Answer 284

Usually not good for bone fossils

Answer 285

Many features not preserved - Anatomy - Physiology - Behaviour - Colouration - Fur/feathers - Only really get bone

Answer 286

If we have many plausible explanations/hypotheses, accept the simplest until proven wrong - In evolutionary terms, this means the explanation requiring the least amount of evolutionary changes

Answer 287

Ancestral shared state - eg fingers in limbs of tetrapods (present in last common ancestor)

Answer 288

Modification or change to a plesiomorphy

Answer 289

Monophyletic clade that contains all the descendants (extinct and extant) of the last common ancestor of two or more extant taxa

Answer 290

Paraphyletic group that contains the extinct taxa that are more closely related to one crown group than another

Answer 291

Allow us to infer similarities and differences between extant organisms - Traits seen in multiple extant taxa likely plesiomorphies, or ancestral traits, which can help us reconstruct the traits of the last common ancestor of the crown group

Answer 292

Represent extinct organisms that are closely related to a crown group - Provide information about the characteristics of the last common ancestor of a crown group - Allow for the inference of the polarity (direction of evolutionary change) of traits that are uncertain in the crown group

Answer 293

Saurischia and Ornithischia.

Answer 294

Theropoda and Sauropodomorpha

Answer 295

Common feature of extant dinosaurs is that they are all bipedal (birds)

Answer 296

No, many including T-Rex, were bipedal - quadrupedal was evolved later in the group

Answer 297

No, especially basal (early) ones, were also bipedal.

Answer 298

Basal sauropodamorpha may have been facultative bipeds - later ones were more likely obligate quadrupeds

Answer 299

It is close to the transition from bipediality to quadrupediality - Indicating a possible facultative bipedal stance

Answer 300

Look unique traits present in crocodiles and birds - If found, the most parsimonious explanation is that it is plesiomorphic and present in the last common ancestor of archosauria and therefore in Saturnalia

Answer 301

Saturnalia tupiniquim

Answer 302

Crocodiles and Birds

Answer 303

Reptiles and mammals

Answer 304

Consequence of physical/chemical restraints - Eg. blood being red - This is just the colour of haemoglobin Consequence of genetic drift Associated with adaptive trait - Eg. genetically linked through pleiotropy - Could be under neutral selection or even maladaptive, but linked to adaptive trait

Answer 305

Traits that evolve for one function (due to one set of selection pressures) but by chance are later suitable for performing a novel role - Eg Primate (human) grasping Primarily used in eating and locomotion Exaptative uses - Tool use - Became useful for technology

Answer 306

Separates the respiratory tract from the first stage of the digestive tract

Answer 307

Prevent food from entering the respiratory tract during feeding

Answer 308

Structure that extends from the primary palate to the back of the oral cavity

Answer 309

Separate the nasal cavity from the oral cavity - Allowing mammals to breathe while chewing

Answer 310

Early mammals - after the divergence from non-mammalian synapsids (adaptation not present in reptiles)

Answer 311

- Allows infants to suckle while breathing Affects vocal resonance - Forming sounds/articulation

Answer 312

Other animals like crocodiles and dicynodonts that also have a secondary palate - Do not suckle or use speech

Answer 313

Inherent ability of DNA polymerases to occasionally make errors while copying DNA during replication - Leading to mutations in the DNA sequence

Answer 314

Most common type of mutation - Single nucleotide is replaced by another nucleotide

Answer 315

Result from errors during replication, recombination, or repair - Particularly in repetitive regions of the DNA sequence - Leading to frameshift mutations and potentially disrupting protein function

Answer 316

Spontaneous damage or loss of these bases from DNA - Leading to single-strand breaks, crosslinks, or potentially more severe damage if left unrepaired

Answer 317

- Aneuploidy (an abnormal number of chromosomes) - Structural changes (such as translocations, inversions, or deletions)

Answer 318

Chromosomal rearrangements - such as deletions, inversions, or translocations, potentially altering gene expression or disrupting critical gene function

Answer 319

Both upper and lower on I-beams and lower on L-beams - increase the stiffness of the overall structure - making it less likely to bend

Answer 320

Makes the upper jaw stronger, providing a fitness benefit - Particularly important for organisms that handle live prey - Pose a risk of breaking the upper jaw

Answer 321

Complete palette is much stronger than none at all - intermediate phases also increased strength - selection pressure for the evolution of the palette

Answer 322

Constrictor colli - Over time, it migrated out and formed the facial muscles we have today.

Answer 323

Forms the cheeks - Crucial role during chewing - Prevents food from falling outside of the teeth by keeping it in

Answer 324

Orbicularis oris muscle forms the lips and plays a role in keeping food in and suckling - primary selective pressures were likely mastication and suckling rather than facial expressions

Answer 325

Co-evolution involves mutual responses between species - Not just adaptation to an environment - Promotes a diversity of adaptations, with reciprocal responses often being unique and specific to the interacting species

Answer 326

Co-evolution can take the form of predation - Predator exerts strong selection pressure on prey Herbivory - plants develop defences against vegetarian predation - competition between two different species (interspecific)

Answer 327

- Species are evolving reciprocally but cannot evolve away from each other - Ongoing evolutionary arms race

Answer 328

- Indefinite unending escalation (an evolutionary arms race) - Stable genetic equilibrium (such as when plants evolve defenses to reduce, but not completely stop, herbivory) - Cycles/fluctuations in the genetics of both species (common in parasitism) - Possible extinction of both species

Answer 329

- Genetic variation for relevant traits in both the enemy and victim species - Reciprocal effects of these traits on the fitness of individuals - Outcome of enemy-victim interactions being dependent on the characteristics of the involved traits

Answer 330

Predator detecting prey first places selective pressure on vigilance - prompting the prey to develop better detection avoidance techniques - such as camouflage

Answer 331

Gazelles evolve longer legs for speed Cheetah evolves lower bone density to increase its speed These adaptations may reach a constraint where the costs outweigh the benefits - such as the potential speed detriment from having too low a bone density

Answer 332

Passiflora plant takes advantage of the Heliconius butterfly's avoidance of leaves with eggs already on them - Plant produces egg-like buds - mimic the appearance of butterfly eggs - Deters female butterflies from laying their eggs on the plant - Larvae are highly carnivorous and pose a threat to the plant.

Answer 333

Delay in reciprocal response between two co-evolving species - response to an adaptation in one species is not immediate in the other, which can complicate the study of these dynamics

Answer 334

Involves multiple species, with their effects not being independent - For example, a pollinator may interact with multiple plant species, causing changes in all involved species

Answer 335

A species evolves a radical new defense, escaping its enemy - For example, a plant could evolve a chemical defense that makes it inedible to a particular herbivore - Often leads to diversification of the victim species and introduction of new or different enemies, which then diversify in response

Answer 336

Rough-skinned newts have evolved a potent toxin, tetrodotoxin (TTX), as a defense mechanism - When threatened, they exhibit aposematism, an honest signal of toxicity, by exposing their yellow underbelly - Garter snakes, a predator of these newts, have been observed to develop resistance to this toxin, resulting in an ongoing co-evolutionary arms race

Answer 337

Warning signal used by certain poisonous or dangerous animals - involves a conspicuous display - bright coloration or distinctive patterns

Answer 338

a change in one species leads to a shift in another species - often leads to an evolutionary arms race where each species responds to adaptations in the other.

Answer 339

- Producing more TTX reduces the likelihood of being eaten - but energy and resources required for this high TTX production could result in fewer offspring

Answer 340

Developing too much TTX resistance allows them to eat toxic newts - but physiological adaptations required for this resistance may reduce their crawling speed

Answer 341

Evolved a tolerance to the milkweed's chemical defenses - Also developed a strategy to notch the milkweed leaf - Which reduces the plant's latex production

Answer 342

Acquire the plant's toxins and become toxic themselves - Deters predators - Increases butterflies fitness

Answer 343

two or more harmful or distasteful species that share common predators evolve to resemble each other - resemblance enhances their mutual protection - the viceroy butterfly, which is also distasteful, has evolved to mimic the appearance of the toxic monarch butterfly, enhancing the protective effect of their shared warning coloration

Answer 344

viceroy butterflies have evolved to mimic the appearance of monarch butterflies - it's not necessarily considered co-evolution because the evolution of one species (viceroy) does not seem to be causing reciprocal changes in the other species (monarch). - If the monarch butterflies were evolving in response to the viceroys (for instance, to look more dissimilar), it would be a clear case of co-evolution.

Answer 345

Mutualism is a type of beneficial interaction in co-evolution where both species involved benefit from their interactions. Examples include pollination, clownfish and anemones, and acacia plants and acacia ants.

Answer 346

Acacia plants provide accommodation in the form of domatia (hollow thorns) and food bodies for acacia ants. In return, the ants protect the acacia plants from vines, herbivores, and pathogens.

Answer 347

Darwin Hawk Moth and Darwin's Orchid have a tightly coupled mutualistic relationship in pollination. The moth is a specific pollinator of the orchid, and the orchid provides nectar as food for the moth. This relationship is so specific that each has evolved particular traits to facilitate this interaction.

Answer 348

Commensalism is a type of interaction in co-evolution where one species benefits from the relationship and the other species is unaffected or experiences very negligible costs. - Examples include birds nesting in trees and pilot fish foraging on the scraps left by sharks.

Answer 349

Birds benefit from the relationship by having a place to build their nests and live. The trees are largely unaffected by this, although there might be a very minor cost due to the added weight of the nest, but this cost is typically negligible and does not harm the tree

Answer 350

enhances the survival or reproduction of an organism relative to its ancestral state. Essentially, it's a trait that increases an organism's Darwinian fitness.

Answer 351

- complex characteristics in an organism undergoing mutually inter-dependent adjustments in response to the same natural selection pressures The eye - complex organ that has undergone numerous changes and developments over time due to natural selection pressures.

Answer 352

Effects that a gene has on its environment, outside of the individual organism's body - An example is a beaver's lodge - Though the lodge is not a part of the beaver's body, it is a product of the beaver's genes and can impact its fitness.

Answer 353

For the mimicker, resembling a dangerous or unpalatable species can deter predators, increasing their survival. - Can be a fitness cost for the mimicked organism if predators learn that organisms resembling their warning signals can sometimes be harmless or tasty.

Answer 354

Idea that some traits may appear to be adaptive - but are actually by-products of other structural or developmental constraints

Answer 355

- Interaction between the environment, functional morphology, developmental constraints, historical constraints, phylogeny, and time - Investigates how these factors collectively influence the evolution of an organism's form and structure

Answer 356

Limitations on evolutionary change that are imposed by the characteristics of the ancestral species - For example, the panda's "thumb" is a modified wrist bone because development can't just add an extra finger

Answer 357

Nerves in vertebrate eyes - sit on top of the photo sensors, creating a blind spot Whales have a vestigial pelvic girdle Recurrent laryngeal nerve in mammals - loops around the heart to get from the throat to the thorax - was the most efficient path in fish, the ancestors of terrestrial vertebrates

Answer 358

Functional constraints refer to the hard limits imposed by physics and chemistry - organisms have difficulty producing metals because it requires high temperatures Eg limits in oxygen diffusion - Eggs can’t get any bigger - Insects can’t get bigger - tracheal system Eg mechanical limits to size - Bones highly conserved in vertebrates - no strength innovations - Neural transmission speed - too slow if your foot is too far from your CNS

Answer 359

Limitations on evolutionary change imposed by the properties of biological materials and the processes that produce them - For instance, bone, while versatile, is not as strong as carbon fiber

Answer 360

Macroevolution - changes that occur at or above the level of species, such as adaptive radiation, rates of diversification and change, and mass extinctions. Microevolution - on the other hand, involves smaller-scale changes within a population due to mechanisms like mutation, migration, genetic drift, and natural selection.

Answer 361

Evolutionary trends are sustained tendencies for evolutionary change in a particular direction - example of such a trend is Cope's rule, which suggests that organisms tend to get larger over time

Answer 362

Measured using fossils, which can provide evidence for physical changes in species over time - Such as horn swelling in brontotheres or mammalian brain size - Additionally, we can produce phylogenetic trees from the genetics of extant organisms and use these trees to extrapolate back in time - Predicting historical evolutionary events like the onset of bipedal locomotion

Answer 363

Involves reconstructing past events based on current evidence - Extrapolating from existing animal behavior, genotype, and phenotype against their relatedness - Relies on assumptions and can lead to inaccuracies

Answer 364

Mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged

Answer 365

Rates of molecular change can vary between different organisms and even between different gene loci within the same organism - These variations can be due to differences in life history traits, mutation rates, and selection pressures.

Answer 366

Required to convert genetic differences into absolute time - often done by relating the genetic divergence to independently known dates such as fossil records or known geological events

Answer 367

Method used to estimate the age of a species or group of species in phylogenetics - uses known divergence points of species (nodes) to calibrate the molecular clock - nodes often come from the fossil record or paleogeographic events

Answer 368

A relaxed molecular clock model allows rates of molecular evolution to vary among lineages - more realistic model than strict molecular clock models because it accounts for natural variability in mutation rates and selection pressures

Answer 369

Method that uses both node data and genomic phylogeny of modern animals, along with morphological phylogeny of fossils - allows for simultaneous analysis of extinct and extant taxa using genetic sequence data and morphological character data, with defined fossil dates

Answer 370

Can distort molecular clocks as it influences the rate of change in genetic material - Areas of the genome that are under strong selection pressure may evolve at different rates compared to areas that are under weak or no selection pressure

Answer 371

Unique deep-time perspective - Aid in reducing long branch attraction by breaking up long branches - Show the sequence of morphological change - Provide a timescale for evolutionary events - Assist in rooting trees

Answer 372

Fossil records are not complete - Don't have perfect identification methods - Fossil biodiversity might appear artificially low

Answer 373

Refer to changes in biodiversity following a mass extinction event Competitive displacement - Where a species is outcompeted by another Incumbitive replacement - where a species becomes extinct due to bad luck rather than any particular disadvantage

Answer 374

- Coelocanth, a fish with a highly conserved phenotype - Maple leaves - Bivalves Display a very slow accumulation of apomorphies

Answer 375

Unobservable or short-lived changes in organisms that may not be apparent in the phenotype - These changes may have arisen and gone extinct with poor preservation - Thus not leaving substantial evidence in the fossil record

Answer 376

Phylogenetic constraints - Adaptation of a wrist bone instead of developing an extra finger in pandas - Limit evolutionary possibilities based on the organism's evolutionary history Functional constraints - Hard limits posed by physics and chemistry - Limits to size due to oxygen diffusion and mechanical strength Fabricational constraints - Limitations of biological materials - For example, bone not being as strong as carbon fibre

Answer 377

Gradualism is the theory in evolution that suggests changes occur steadily over time, with no sudden leaps - An example of this is the trilobites, which show a gradual and contemporaneous increase in the number of ribs

Answer 378

Idea of rapid evolutionary changes or leaps - An example of this can be seen in horses, which remained around 80/90kg for a long period - Before undergoing a rapid increase in body size and hypsodonty (larger teeth)

Answer 379

Once species appear in the fossil record, they will become stable, showing little net evolutionary change for most of their geological history - This 'stasis' is punctuated by rare instances of branching evolution

Answer 380

Divergent evolution of numerous related lineages within a short period of time to occupy different ecological niches - An example of this is the evolution of Darwin’s finches - Underwent rapid diversification to occupy different niches in the Galapagos islands after a gap in the niches was created

Answer 381

Clades should generally increase in body size over evolutionary time due to advantages that larger size confers in competition and survival Evolution of horses - Maintained stable weight for a long period, suddenly experienced a rapid increase in body size

Answer 382

In the separate freshwater lakes of Africa, Cichlid fish have undergone a unique adaptive radiation - Due to the complete gene isolation in each lake, every species in each lake belongs to a single diverse monophyletic clade per lake - Each group has diversified into a similar range of species morphologies - compelling case of adaptive radiation under similar environments and complete isolation

Answer 383

Individual organisms are distinctly male or female - Each individual produces only one type of gamete - Either sperm or eggs

Answer 384

Form of asexual reproduction in which development of a new individual occurs from an unfertilised egg - It's observed in various animal species including Komodo dragons, aphids, and daphnia

Answer 385

Recombination - Allows for the shuffling and mixing of parental chromosome pairs from generation to generation - Can introduce new gene combinations - Can be beneficial for the survival and adaptation of a species

Answer 386

Form of asexual reproduction, specifically a type of sperm-dependent parthenogenesis. - Copulation occurs and sperm triggers embryogenesis - Does not contribute any genetic material - This is observed in some species of fish

Answer 387

Asexual reproduction in plants - where a new individual develops from a somatic (non-sexual) cell

Answer 388

Individuals produce both male and female gametes - Some species may be one sex when young and mature to the other - Others may be both at the same time - Some can self-fertilise

Answer 389

Recombination - Allows for shuffling of parental chromosome pairs - Promoting genetic diversity from generation to generation

Answer 390

First - Producing males is costly and they don’t really contribute to population growth as only females can bear offspring Second - In sexual reproduction, only 50% of an organism's genes are passed onto offspring - Compared to asexual reproduction where 100% of the genome is passed on

Answer 391

Recombination, a process used in DNA repair, is believed to have evolved around 3 billion years ago. - Sex, which involves recombination to create genetic diversity, likely evolved 1-2 billion years ago - The exact reasons for the evolution of sex are still a subject of research and debate

Answer 392

Includes the energy and resources expended in locating a mate and competing with others for the chance to reproduce - Can involve physical contests, display behaviors, or the risk of predation during the search

Answer 393

Rapid population growth - Every individual can bear offspring Asexual reproduction allows for the passing on of 100% of an individual's genome to their offspring - Ensuring a higher degree of genetic continuity

Answer 394

- Recombination is believed to have evolved approximately 3 billion years ago - Sex probably evolved 1-2 billion years ago

Answer 395

- Energy and time spent finding a mate - Risk of not finding a mate - Potential disease transmission during mating - Increased predation risk during copulation - Higher energy requirements at the cellular level, as meiotic division is more costly than mitosis. - Recombination in sexual reproduction can break up favourable combinations of alleles

Answer 396

Genomes of an asexual population accumulate deleterious mutations in an irreversible manner - Concept highlights the advantage of sexual reproduction - Recombination can shuffle mutations and reinstate the fittest class, effectively 'turning back' the ratchet.

Answer 397

Allowing for the combination of beneficial alleles from different lineages - In sexual reproduction, two favourable mutations do not need to arise in the same lineage - They can come from two different parents and be combined in their offspring - Makes adaptation faster in sexually reproducing species compared to asexually reproducing ones - Where each favourable mutation has to occur in the same lineage

Answer 398

Faster adaptive evolution Prevention of accumulation of deleterious mutations Maintains variety of genetic combinations - Lead to greater diversity and resilience in a population

Answer 399

- Accumulation of harmful mutations (Muller's Ratchet) - Slower pace of adaptive evolution Most asexually reproducing species are relatively short-lived on an evolutionary timescale

Answer 400

Generates greater number of different genotypes that can adapt to a wider range of conditions - In unpredictable environments, sexual reproduction can supply genetic diversity and result in more resilient offspring

Answer 401

Switch between sexual and asexual reproduction depending on environmental conditions Favourable, predictable conditions - Asexual reproduction dominates to quickly produce many offspring Unpredictable Conditions - Sexual reproduction is favoured as it provides genetic diversity - Increasing the chance of survival in varying conditions

Answer 402

Facultative sexual strategy - Shifting between asexual and sexual reproduction based on environmental conditions Reproduce asexually - Near the parent plant, where the environment is predictable and matches the mother's environment. For seed dispersal - Offspring's environment may require different adaptations, strawberries reproduce sexually - Ensures variety of genotypes that can potentially adapt to different conditions

Answer 403

Typically reproduce asexually for rapid population growth - switch to sexual reproduction in response to unfavorable or unpredictable conditions - ensure genetic diversity

Answer 404

In the context of sexual reproduction - making it harder for parasites to adapt to their host - If offspring were clones (asexual reproduction) - parasite perfecting its strategy against one member of the species would then be equipped to overcome any member of the species Through sexual reproduction - offspring have a mix of genes - thus a parasite adapted to infect the parent might not be as successful with the offspring

Answer 405

Explains why sexual reproduction is favored over asexual reproduction - individuals of the same species may inhabit slightly different niches due to individual genetic differences, essentially expanding the ecological "space" a species can occupy - On the other hand, identical clones would have identical niches - limiting the population's adaptability to diverse environments and conditions - suggests that sexual reproduction is beneficial because it can generate a variety of genotypes that can exploit a range of environmental niches.

Answer 406

Fitness of a trait increases as it becomes rarer Can produce a cycle - trait increases until it becomes common enough to cause a reduction in fitness - trait frequency decreases

Answer 407

Fitness of a trait increases as it becomes more common - think this is the wrong way round

Answer 408

Color polymorphisms Cepaea nemoralis snails by negative frequency-dependent selection - predators, the song thrush - forms a search image for the most common morph - resulting in much greater predation pressure on the common than the rare morph

Answer 409

Increased heterozygosity - When individuals of dissimilar characteristics. - There is an increased likelihood of offspring with heterozygous genotypes as the relevant loci. - Maintains population genetic diversity.

Answer 410

Crossing Over: Occurs first - during prophase I of meiosis. - homologous chromosomes pair up and exchange segments of DNA. - chromosomes then contain genetic (alleles) material from both parents Independent Assortment: Later - during metaphase I of meiosis - chromosomes line up at the cell's equator. - homologous pairs of chromosomes (tetrads) align randomly - creates a mix of maternal and paternal chromosomes distributed into gametes.

Fundamentals of Evolutionary Biology Flashcards

(438 cards)