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Biology 1B - evolution Flashcards

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1
Q

describe how comparative anatomy provided evidence leading Darwin and Wallace to propose the theory of evolution by natural selection

A
  • observations of homologous structures (similar structures with different functions) suggested common ancestry
  • observations of analogous structures (different structures with similar function e.g. wings on birds and insects)
  • vestigial structures - reduced structures with no apparent function today
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2
Q

describe how taxonomy provided evidence leading Darwin and Wallace to propose the theory of evolution by natural selection

A
  • the classification of organisms revealed patterns of similarity and hierarchy, reflecting shared ancestry and divergence over time
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3
Q

what is the Linnaean system

A

part of taxonomy
a system that grouped species in ways that aligned with evolutionary relationships

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4
Q

describe how geology provided evidence leading Darwin and Wallace to propose the theory of evolution by natural selection

A
  • fossil record provided evidence of gradual changes in species over time and transformations from simple to more complex forms
  • extinct fossils also hint that the dynamic of nature of life and its adaptation to changing environments
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5
Q

what view of geology influenced Darwin and Wallace to propose the theory of evolution by natural selection

A

uniformitarianism (Charles Lyell) - the same processes we see today also acted in the past

influenced Darwin by suggesting that earths features changed slowing over long periods, giving enough time for gradual evolution

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6
Q

describe how biogeography provided evidence leading Darwin and Wallace to propose the theory of evolution by natural selection

A
  • the geographical distribution of species supported the idea of common descent, and different in different areas even if they occupy the same niche
  • for instance similar species found on island sand nearby continents e.g. Darwin’s finches in the Galapagos islands
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7
Q

what are the two theories of evolution proposed by Darwin and Wallace

A

1) the living organisms we see today are all related by descent (common ancestry)

2) the means by which evolution occurs is a process of natural selection

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8
Q

explain the basis of natural selection

A
  • organisms differ from one another
  • these differences are heritable
  • many more organisms are born than survive and reproduce
  • therefore, any variation makes one offspring more successful than another will have a greater chance of being passed to the next generation
  • “survival of the fittest”
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9
Q

use insecticide application to explain how evolution/ natural selection works

A
  • population of insects with variation
  • some have chromosome with gene conferring resistance to insecticide
  • subject to insecticide
  • only ones with gene survive and reproduce
  • population develop resistance to insecticide
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10
Q

what are some puzzles in evolution

A

1) how do we get complexity and perfect adaption from random chance
- evolution cant see into a future (once something has evolved a certain way cant unevolve/ correct its mistakes)
- evolution is like a safe cracker, trying different mutations until it finds an advantageous one

2) how do we get novelty
- changes in developmental timing
- gene and genome duplications

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11
Q

what are 5 mechanisms that cause evolution
(basis of genetic variation in populations)

A

natural selection
non-random mating
genetic drift
gene flow
mutation

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12
Q

what 3 conditions must be fulfilled for natural selection
and the outcome

A

variation
differential success
inheritance

if all 3 conditions are fulfilled then change over time will occur and the most successful variant will increase in frequency at the expense of less successful variants

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13
Q

what is an example of evidence of natural selection that influenced Darwin

A

different colour morphs of the annulet moth were observed each matching the habitat it was found in
these variations pointed to survival of the fittest

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14
Q

what is kin selection

A

key concept in evolutionary biology that relates to natural selection

natural selection focuses on self interest of an individual promoting their own genes, not survival for the good of thew species - selection acts on individuals not groups, but animals cooperate because helping individuals sharing the same genes also promotes their genes

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15
Q

what is punctuated equilibrium

A

key concept in evolutionary biology relating to natural selection

examples of both gradualism (Darwin) where steady accumulation of small changes over long periods and no change over time (stasis)
as well as fast changes in the wild and lab

mixture of slow and fast changes is punctuated equilibrium

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16
Q

what is the definition of natural selection

A

non-random survival of random variation

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17
Q

what does speed of evolution depend on

A

how strict the selection criteria is
(strong/ weak selection)

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18
Q

how does non random mating cause evolution

A

certain mating preferences (e.g. sexual selection) can influence allele combinations and genetic variation within populations

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19
Q

what are the two scenarios in which genetic drift occurs in nature

A

1) The founder effect - a small group establishes a new population with a different gene pool and allele frequencies due to small size

2) The bottleneck effect - a small fraction of the population survives that is no longer representative of the original population
can by caused by natural disaster etc. and can lead to low genetic diversity

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20
Q

what is genetic drift

A

mechanism of evolution that involves random changes in frequency of alleles within a population overtime

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21
Q

what is gene flow

A

any movement of individuals and/or the genetic material they carry, from one population to another
e.g. migration
increases genetic diversity and decreases differences between populations

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22
Q

does evolution lead to perfection

A

evolution doesn’t necessarily lead to perfection

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23
Q

for what reasons does evolution not necessarily lead to perfection

A

Accidental Toolkit
Existing Variation
Compromise
Historical Constraints

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24
Q

how does “accidental toolkit” explain how evolution doesn’t necessarily lead to perfection

A

mutations arise by chance and provide tools for natural selection to act on, but are not designed for perfection

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25
how does existing variation explain how evolution doesn't necessarily lead to perfection
evolution works through variation already present in the population, it cannot create them from scratch
26
how does compromise explain how evolution doesn't necessarily lead to perfection
adaptations involve trade offs where beneficial traits come at a cost, balances competing demands
27
how do historical constraints explain how evolution doesn't necessarily lead to perfection
constrained to organisms ancestry, new traits must involve modifying existing structures
28
what is sexual selection
specific type of natural selection where individuals with certain traits are more successful in attracting mates and reproducing
29
what does heterozygote mean
having two different versions of a gene, one inherited from each parent
30
what are mutations a source of
variation they are a mechanism of evolution
31
what can cause mutations
copying errors environmental factors (radiation) jumping genes
32
what can mutations lead to
incorrect: DNA sequence chromosome structure number of chromosomes
33
what can the consequences of mutations be
harmful (mostly) neutral beneficial (rarely)
34
what is sexual reproduction a source of
variation when the combinations of genes are re-combined and re-shuffled every generation
35
explain continuous variation
all these sources of variation can yield continuous distributions of traits within a population but only the genetic component counts for evolution
36
what is as polygenic trait
characteristic influenced by multiple genes E.g. height (influenced by multiple genes and environment)
37
what do phenotypes incorporate
nature and nurture, but only nature accounts for evolution
38
how is variation maintained
the selection - variation paradox
39
explain the selection - variation paradox
selection depends on variation favours mean over tail (stabilising selection) but selection theoretically causes a loss of variation and it requires variation to ensure populations can evolve and survive highlights the delicate balance
40
how is the selection -variation paradox adressed
addressed by exploring mechanisms that maintain genetic diversity ( different kinds of selection such as balancing, oscillating, disruptive, frequency dependant)
41
what is the red queen hypothesis
there is always pressure to evolve counter adaptations and hence exposed to directional selection
42
what are different types of selection
directional selection disruptive selection frequency dependant selection
43
what is directional selection
type of natural selection where one extreme of a trait is favoured over the other or the average
44
what is an example of directional selection
Darwin's finches on Galapagos deep beak favoured when dry narrow beak favoured when wet
45
what is disruptive selection
when selection favours the two tails over the mean
46
what is frequency dependant selection
when a phenotype is only favoured when it is either rare or common
47
what is the hardy-Weinberg principle
concept in population genetics. provides mathematical framework to show how allele frequencies in a population remain constant between generations if there is no selection
48
what does the rate of evolution depend on
both the heritability of traits and the strength of selection
49
what is anagenesis
a pattern of evolutionary change when one species evolves continuously over time into a distinctly different one
50
what is cladogenesis
a pattern of evolution the splitting of a lineage into two or more distinct species branching occurs due to reproductive isolation
51
what is a species
a group of organisms that can reproduce with one another in nature and produce fertile offspring
52
what are prezygotic and postzygotic barriers
mechanisms of reproductive isolation that prevent different species from breeding and producing fertile offspring
53
describe prezygotic barriers
prevent fertilisation from occurring, occur before formation of zygote
54
what are examples of prezygotic barriers
1)habitat isolation - populations don't meet 2) behavioural isolation - little/no sexual attraction between males and females 3) temporal isolation - mating/ flowing occurs at different seasons or times of day 4) mechanical isolation - structural differences in reproductive organs make mating impossible
55
what are postzygotic barriers
occur after fertilisation and prevent hybrid offspring from surviving or reproducing
56
what are some examples of post zygotic barriers
1) reduced hybrid viability - hybrid zygotes fail to develop or reach sexual maturity 2) reduced hybrid viability - hybrid fail to produce functional gametes 3) hybrid breakdown - offspring of hybrids have reduced viability or fertility
57
what is speciation
the process through which new species arise in nature
58
what is allopatric speciation
when speciation occurs in geographically isolated areas
59
what is sympatric speciation
speciation occurs in the same area genetic isolation without geographic isolation (time, microhabitat, behaviour)
60
describe allopatric separation
populations become geographically isolated and can no longer interbreed populations diverge to the point where they are no longer able to interbreed even when back together due to adaptation of different environments or genetic drift
61
what is founder event speciation
the process where a small number of individuals from a large population establish a new population in a geographically isolated area, leading to speciation
62
how can sympatric speciation occur
1) instantaneous evolution - rapid genetic or phenotypic changes that lead to the emergence of new species in e very short time frame, more commonly observed in certain plants 2) divergent selection - occurs when natural selection favours different traits in different parts of the population, over time leads to genetic and phenotypic divergence, potentially causing speciation (e.g. speciation)
63
what is auto polyploidy
where an organism has multiple sets of chromosomes that originate entirely from a single species occurs due to error in cell division causes the duplication of the entire organism
64
how does auto polyploidy lead to speciation
because the new plant cannot breed with its parent due to mismatch in chromosome number
65
what is allopolyploidy
when an organism has multiple sets of chromosomes that originate from two different species happens through hybridization the hybrid undergoes chromosome doubling, creating a viable organism with a stable genome
66
what has allopolyploidy been important for
crop evolution E.g. wheat
67
what are morphospecies
species defined by physical characteristics such as shape size or colour
68
what are biological
species defined by the ability to interbreed and produce viable offspring
69
what is the species problem
refers to the complexity in defining and delineating species due to overlapping concepts and limitations

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