evolution - bio

Question 1

Oparin and Haldane hypothesis

Answer 1

• they theorized how life arose

hypothesized:
- that early earth’s atmosphere was likely reducing (gain e-)
- life arose gradually from inorganic building blocks
- these building blocks could form organic compounds from lightning or UV radiation energy

Haldane suggested organic molecules accumulated in the primordial oceans, “prebiotic soup”

other hypotheses suggest tidal pools allowed the formation of polymers
- increased conc of organic monomers + heat may have resulted in dehydration synthesis and polymer formation

Question 2

Miller and Urey Experiment

Answer 2

• wanted to test out Oparin and Haldane hypothesis
• recreated early earth conditions in experiment, sealing chemicals in a flask (ammonia, methane, water, and hydrogen)
• stimulated lightning (energy)
• saw formation of organic molecules (amino acids)

Question 3

RNA world hypothesis

Answer 3

• hypothesized to be first form of genetic material

RNA is versatile:
- can store genetic info
- can catalyze rxns (ribozymes)

building blocks (ribose, sugar, phosphate group, nitrogenous base) are easily synthesized

Question 4

What are protocells?

Answer 4

the earliest precursor to the cell (aka protobionts)
- not yet cells, but thought to eventually evolve to contain self-replicating molecules with metabolic source

Question 5

what was the very first form of life? second?

Answer 5

first anaerobic heterotrophic prokaryotes

makes sense:
- had to be anaerobic (not much oxygen on earth to begin w)
- had to be prokaryotic (basic, lack the more complex organelles later introduced into life)
- heterotrophic (had to consume organic substances to obtain energy, more complex pathways like the sun werent evolved yet)

then, autotrophic prokaryotes
- formed through mutation of heterotrophic prokaryotes
- created their own energy through photosynthesis
- these early autotrophic cells were the first anaerobic photosynthesizers (eg cyanobacteria) - created oxygen as byproduct
*caused oxygen to be released into atmosphere, which is what we have today (going from reducing environment to oxidizing environment), also when oxgen reactive with UV light, it formed the ozone layer

Question 6

endosymbiotic theory

Answer 6

• the origin of eukaryotic cells

hypothesis:
- mitochondria and chloroplast were small individual prokaryotic organisms
- engulfed by other prokaryote, resulted in symbiotic relationship

evidence:
- interior features of mitochondria/chloroplasts resemble prokaryotes
- circular DNA
- independent genome
- prokaryotic-like ribosomes
- replicate independently

Question 7

what is paleontology?

Answer 7

study of fossils, observing large, rapid changes that show evidence of new species

Question 8

what is a homologous vs analagous structure?

Answer 8

Homologous structures:
- anatomical features in species that originate from a common ancestor
- may not have the same function
- similar physiological features “look the same”
- example: forelimbs in vertebrates (shared common tetrapod ancestor)

Analagous structure:
- anatomical features with similar function but do not share a common ancestor
- structure is not fundamentally similar
- evolved similar traits to adapt to similar environments

can be analagous and homologous
ex birds and bats
- homologous at skeletal level (tetrapods)
- analagous at the wing level (different functions of wings)

Question 9

vestigial structures meaning

Answer 9

structues that appear useless now but had some ancestral function

eg wisdom teeth, appendix, whale pelvis/femur bones, etc

Question 10

catastrophism, who proposed the theory and what does it mean?

Answer 10

• george cuvier proposed this thoeyr when he noticed gaps in the fossil record (ie species that would suddenly disappear)

his theory states that earth’s history is shaped by major geologic catastrophe;
- meaning most changes to earth happened via sudden violent large-scale events in a shhort period of time
- examples: meteors, super volcanoes

these events would lead to mass extinctions –> impacting evolution by drastic changes to the ecosystem

Question 11

gradualism/uniformatirianism what does it mean

Answer 11

• the opposing theory to catastrophism, states that changes to earht and its organisms happened via small scale processes, gradually over a very long period

the same processes occur today –> movement of tectonic plates

Question 12

Lamarcks theory

Answer 12

Inheritance of acquired characteristics:

• organisms pass on traits required throughout their lifetime to their offspring
• “use and disuse” (traits that are used build up over time and pass on to offspring, unused ones deteriotate) but this is INCORRECT
• natural transformation of species (offspring become more and more complex each generation, organisms do not become extinct or split into more species, just continued evolving into more complex species) but this is also INCORRECT

Question 13

Darwin-Wallace theory

Answer 13

theory of natural selection
- “survival of the fittest”
- pressure increases fitness, the ability to produce offspring
- the population adapts as a result

descent with modificaiton
- over many generations, populations accumulate changes, eventually leading to entire new species that can branch off from a common ancestor
- reproductively advantageous variations (traits) passed on

individuals DONT involve, populations DO

Question 14

what is neo-darwinism?

Answer 14

the modern understanding of darwins theory, with a genetic understanding

• genetic mutations produce the variations within a population
• advantageous genes are passed on (not phenotypes)

Question 15

intra vs intersexual selection

Answer 15

intra:
- selection within the same sex
- individuals directly compete for mating opportunities w the opposite sex
- usually a male behaviour
examples: males demonstrating strength in battles of dominance

inter:
- individuals of one sex select for traits in the opposite sex
- males or females selecting for traits increases allele frequency of that trait = evolution
- usually a female behaviour
- commonly appearance-based
- example: female peacocks selecting male peacock w nice feathers

Question 16

natural selection is driven by _____________

Answer 16

the inheritance of traits

Question 17

a species is a group of ________ isolated organisms

Answer 17

REPRODUCTIVELY (can interbreed with one another to produce fertile offspring)

Question 18

Which of the following individuals has the highest fitness?

A.
A bird that lays 4 eggs, all of which live to adulthood

B.
A rabbit that produces 12 offspring, with 6 surviving to adulthood

C.
A frog that lays 300 eggs, with 100 surviving to adulthood

D.
A fish that lays 500 eggs, with 200 surviving to adulthood

E.
A bear that has one offspring, which lives to adulthood

Answer 18

D. HIGHEST #

In evolutionary biology, fitness is determined by an organism’s ability to survive and reproduce. The individual that produces the most offspring, with the greatest number surviving to adulthood, has the highest fitness. In this example, the fish has the highest fitness because it produces the most surviving offspring. Environmental pressures, such as predators or harsh conditions, influence whether traits are beneficial, and these traits can increase fitness by helping individuals adapt.

Question 19

gene pool means what?

Answer 19

all the diff copies of alleles within a population

Question 20

What are the 5 mechanisms for changing allele frequencies?

Answer 20

• also the same as the 5 ways that evolution can occur (because they change the allele frequencies)

1. Natural selection
   - increases or decreases allele frequency due to favoring alleles conferring a fitness advantage
2. Gene flow
   - the transfer of alelles between populations when individuals leave (emigration) or enter (immigration) populations
3. Genetic drift
   - random increase or decrease of alelles by CHANCE. the smaller the population, the larger the effect
   - founder effect: occurs when a small group of individuals become isolated from a larger population
   - bottleneck effect: occurs when population undergoes a significant reduction in size due to natural catastrophe
4. Non-random mating
   - individuals choose mates based on their particular traits
   - eg sexual selection, inbreeding
5. Mutations
   - lead to changes in allele frequency

Question 21

genetic drift vs genetic flow

Answer 21

genetic drift:
- happens to one population due to chance (random fluctuation of allele frequencies)
- looking at allele frequencies in the new population

genetic flow:
- active exchange of alleles between populations as a result of migration
- can occur in any population, gene flow requires the movement of individuals b/w populations

Question 22

what are 5 sources of genetic variation

Answer 22

1. mutations
   - introdcues new alleles into a population
   - gene number or position: disrupting, rearranging, or deleting loci of genes
2. sexual reproduction
   - dependent upon unique combination of alleles
   - crossing over (prophase I)
   - independent assortment (each gamete has unique combo of alleles)
   - random fertilization (which sperm/egg fertilizes)
3. diploidy
   - the presence of two copies of each gene
   - preeserves genetic variation
   - also describes how recessive alleles can be carried silently
4. outbreeding
   -mating between indiviudals that genetically unrelated, new alleles introduced into population, increase heterozygotes
   - can contribute to hybrid vigor (heterosis), resulting in higher quality offspring than either parent species (eg mules)

inbreeding:
- closely related indiviudals mate
- this changes GENOTYPE proportions but NOT allele frequency
- more homozygous dominant/recessive, less heterozygotes –> less genetic variation

5. balanced polymorphism
   - two or more alleles in the population are maintained, because each allele can be advantageous in different conditions
   - heterozygous advantage: when heterozygotes have higher fitness than both homozygotes (eg sickle cell anemia)
   - frequency dependent selection: fitness of a particular phenotype varies with how common it is (which alleles are best for survival changes depending on how many other individuals have those same alleles, eg a predator looking for a more common colour allele and the rarer one surviving)

Question 23

what is hybrid vigor?

Answer 23

occurs in outbreeding (mating between indiviudals that genetically unrelated, new alleles introduced into population, increase heterozygotes)

hybrid vigor (heterosis), results in higher quality offspring than either parent species (eg mules)

Question 24

Hardy-Weinberg Equilibrium, what are the conditions for it to occur?

Answer 24

• describes a state of genetic equilibrium within a population
• condition where allele and genotype frequencies do not change from generation to generation
• NO EVOLUTION is occuring

certain requirements must be met, if any are violated it is not in genetic equilibrium and evolution IS OCCURING:
1. no mutations (gene pool remains the same, no changes to alleles or allele frequency)
2. mating is completely random (no sexual selection or inbreeding)
3. no natural selection (no advantage for one phenotype over another)
4. large population size (essentially immune to genetic drift)
5. no gene flow (population is isolated)
*none of the 5 ways to change allele frequency are occuring - OPPOSITE to these

Question 25

Hardy-Weinberg equilibrium equation

Answer 25

p^2 + 2pq + q^2 = 1 - assumes there are only two alleles for every trait possible, the dominant and the recessive allele - p represents allele frequency for the individual dominant allele (what percentage of all the copies of this gene are for the dominant allele) - q represents alelle frequency for the individual recessive allele (what percentage of all the copies of this gene are for the recessive allele) p + q = 1 (only two possibilites, must add to 100%) - p^2 is the frequency of homozygous dominant individuals (AA) - q^2 is the frequency of homozygous recessive alleles (aa) - 2pq is the frequency of heterozygous individuals (Aa) so p^2 + 2pq + q^2 = 1 also makes sense, also genotypes sum to 100%!!!

Question 26

What is reproductive isolation?

Answer 26

when a population is unable to successfully breed (produce fertile, viable offpsring) with a related population, they are reproductively isolated - dependent upon factors that prevent populations interbreeding (geography, behavior, or genetics) biological barriers that prevent interbreeding are called reproductive isolation mechanisms

Question 27

What do pre-zygotic isolation and post-zygotic isolation mean

Answer 27

Both are types of reproductive isolation mechanisms Pre-zygotic isolation mechanisms: - prevent a zygote from forming in the first place 1. habitat isolation (populations dont live near each other) 2. temporal isolation (populations are active and mate at diff times) 3. behavioural isolation (differences in mating behaviours, eg mating calls or courtship rituals) 4. mechanical isolation (reproductive organs are not compatible) 5. gametic isolation (male gamete is unable to fertilize the female gamete) Post-zygotic isolation mechanisms: - zygote does form, but other conditions keep the species separate 1. hybrid inviability (zygote fials to develop properly and dies before reaching reproductive maturity) 2. hybrid sterility (hybrids reach adulthood, but cannot reproduce; sterile) 3. hybrid breakdown (hybrids mate and produce offspring, but those offspring cannot reproduce themselves (future generations are inviable))

Question 28

what are the mechanisms of speciation? allopatric vs sympatric

Answer 28

allopatric speciation (aka "geographic speciation") - physical barrier leads to one population separating into two separate species sympatric speciation - no physical barrier, but still separation into two separate species - can occur when isolation mechanisms prevent interbreeding through either: 1. habitat differentiation (many habitats in same geographical areas, leads to diff pressures, diets, etc --> diff adaptations and genetic differences over time) 2. sexual selection (mating occuring exclusively, can accumulate differences) 3. polyploidy (a condition where an organism has more than 2 sets of chromosomes) - now those with polyploidy are incapable of mating with those that DONT have it, but can still mate with other polyploids

Question 29

what is adaptive radiation?

Answer 29

rapid evolution of many species from a single ancestor - occurs when the ancestral sepcies is introduced to new areas or environmental pressures - new resources available allow species to fill niches within the environment eg darwins finches in galapagos, with different beaks

Question 30

divergent vs convergent evolution vs parallel evolution vs coevolution

Answer 30

divergent: formation of two or more species from a common ancestor, become increasingly diff over time convergent: opposite, unrelated species with no common ancestor independentely evolving similar traits, result of having to adapt to similar environments parallel: two related species (divergent) continue to stay closely related for a long period of time coevolution: two or more species can influence each others evolutionary pathway (eg predator/prey or pollination)

Question 31

what are secondary compounds in survival adaptation?

Answer 31

toxic chemicals produced in plants - discourage would-be herbivores - keeps the population alive examples: - tannins in plants tastes bitter - nicotine from tobacco plant (poisonous to insects)

Question 32

what is cryptic colouration vs aposomatic colouration?

Answer 32

both are survival adaptations cryptic colouration = camouflage (helps blend in) aposomatic colouration = conspicuous colours or patterns that make an animal stand out, warns predators that they are dangerous (posionous, stinging, bad taste, etc)

Question 33

what is mullerian mimicry?

Answer 33

a type of survival adaptation - two or more species resemble another in appearance, share the same defense mechanism - often have common predators, predators also benefit, learning to avoid both - example: viceroy and monarch butterflies, bees and wasps

Question 34

what is bastesian mimicry

Answer 34

- two or more species resemble one another in appearance, but only one is dangerous - non-dangerous animal benefits from the resemblance since predators will still avoid them eg coral snake (venomous) and king snake (non-venomous)