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Darwinian Evolution Flashcards

(48 cards)

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1
Q

Evolution

A

Gradual change at the genetic level of populations over the course of several generations

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2
Q

Specation

A

Occurs when new species arise from common ancestors via descent with modification

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3
Q

Darwinian evolutoin

A

Charles Darwin’s theory of evolution and the chromosomal theory of inheritance guide biological research to this day

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4
Q

Origins of Darwinian Evolutionary Theory

A

Early Greek philosophers recognized fossils as evidence for extinct life

Evolutionary thinking was considered rebellious for most of history

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5
Q

Principles of Darwinian Evolution

A

Perpetual change
Common descent
Multiplication of species
Gradualism
Natural selection

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6
Q

Perpetual change

A

The living world is neither constant nor perpetually cycling but is always changing

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7
Q

Fossil record

A

Shows the hereditary continuity throughout the history of life

Fossils can also show environmental changes

Trends in fossil diversity are produced by varying rates of species formation vs extinction over time

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7
Q

Common descent

A

All organisms share a common ancestor

The last universal common ancestor likely existed over 4 billion years ago

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8
Q

Phylogeny

A

Evolutionary history of organisms

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9
Q

Homologies

A

Characters or character states that share the same evolutionary origin

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10
Q

Homologies show common descent

A

Homologies were inherited from an corresponding character fo an ancestor with some modifications

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11
Q

Nested hierarchy

A

Groups withing roups supports a history of phylogenetic bracketing

Species cluster into groups within groups based on suites of similar homologies

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12
Q

Ontogeny

A

Development of an organism through its entire life

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13
Q

Ontogeny recapitulates phylogeny

A

Early developmental features are more widely shared across taxa compared to later ones

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14
Q

Changes in the timing of developmental events and physical location of structures in the body plan

A

Explain the emergence of new homologies

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15
Q

Heterochrony

A

Change in timing of developmental events

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16
Q

Heterotrophy

A

Change in physical location of a developmental process

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17
Q

Multiplication of species

A

Genetic variation within a species provides the material from which new species arise

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18
Q

Speciation

A

Formation of new species from an existing species

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19
Q

No definitive consensus on what a species is

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A

Multiple species concepts exist

20
Q

Reproductive barriers

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A

Biological features that prevent interbreeding between species

21
Q

Prezygotic

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A

impair fertilization

22
Q

Postzygotic

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A

impair development, survival, or reproductive capability

23
Q

Evolutoin of reproductive barrires

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A

Geographic isolation followed by divergence

24
Allopatric populations
Populations of one species occupying separate geographic areas Cannot interbreed because of geographic separation, but can if the barriers are removed
25
Allopatric speciation
Occurs when the separated populations evolve independently and develop reproductive barriers
26
Populations can be separated by 2 means:
Vicariance Founder event
27
Vicariance
Geological or climate change separates populations
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Founder event
Small number of individuals disperse to a distant region with no members of that species
29
Sympatric speciation
Occurs when individuals within a species specialize to occupy different niches within the same habitat Ex. cichlid fish in the African Great Lakes
30
Adaptive radiation
Evolution of several ecologically diverse species from a common ancestor Many different species can arise within a short period of geological time
31
Adaptive radiation can be seen in lakes and young island
Volcanic islands initially lack life but are slowly colonized Ex. Galapagos finches
32
Gradualism
Large phenotypic differences between species only occur through the accumulation of smaller changes over time
33
Populational gradualism
States that new traits are established in a population by increasing their frequency
34
Phenotypic gradualism
New traits are produced over small incremental changes over hundreds to thousands of generations
35
Phenotypic gradualism is controversial
Not all changes in phenotype are small Ex. Dwarfing in dogs and sheep
36
Punctuated equilibrium
Phenotypic evolution is concentrated in short events of branching speciation followed by longer intervals of morphological stability Both punctuated and gradual evolution are seen in the fossil record
37
Natural selection
Major process by which evolution occurs in Darwi's theory Explains the origin of adaptation
38
Darwin developed the theory of natural selection based on
5 observations and 3 inferences he drew from them
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Observation 1
Organisms have great potential fertility All populations produced large numbers of gametes and offspring each generation Population increase exponentially
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Observation 2
Natural populations mostly remain constant in size Natural populations fluctuate ins ize across generations and sometimes go extinct No natural populations show continued exponential growth
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Observation 3
Natural resources are limited The exponential growth of a natural population would require unlimited resources to provide food and habitat Resources are finite
42
Observation 4
Populations show variation among organisms No two individuals are exactly the same even within populations
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Observation 5
Some variation is heritable Offspring resemble their parents Darwin at the time did not understand the mechanism of inheritance
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Inference 1
Members of a population undergo a continuing struggle to exist Overpopulation leads to a more severe struggle for food, space, and shelter Only a small part of individuals ruvive each generation
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Inference 2
Varying organisms show differential survival and reproduction favoring advantageous traits Traits that confer an advantage to survival allow organisms to live longer and pass those traits onto their offspring
46
Inference 3
Over many generations, natural selection generates new adaptations and new species Propagation of favorable traits transforms species Natural selection leads to speciation
47

Darwinian Evolution (3 decks)

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