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evolution > Macroevolution > Flashcards

Macroevolution Flashcards

1
Q

Biological species concept

A

a population or group of population in nature whose individual members can interbreed to produce viable, fertile offspring that can also interbreed

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2
Q

example of biological species concept

A

Grey’s zebra (endangered) and plains zebra (widespread) are different species- can’t interbreed

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3
Q

speciation occurs when..

A

population become isolated over time

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3
Q

speciation

A

when some members of a sexually reproducing population change so much that they are no longer able to reproduce

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4
Q

speciation causes formation…

A

of new species from existing species

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5
Q

what’s the most common form of speciation?

A

allopatric speciation

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6
Q

allopatric speciation occurs when…

A

populations of a species are geographically isolated

Can no longer exchange genetic information

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6
Q

in allopatric speciation, over many generation the populations…

A

gradually become less and less alike

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7
Q

in allopatric speciation, eventually two populations evolve…

A

some sort of reproductive isolating mechanism

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8
Q

What is a form of allopatric speciation?

A

Adaptive radiation

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8
Q

example of allopatric speciation

A

the isthmus of Panama arose some 3 million years ago, populations of snapping shrimp have diverged into seperate species

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9
Q

Sympatric speciation occurs….

A

gradually or suddenly

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9
Q

In plants sympatric speciation occurs mostly because of…

A

chromosomal changes

ex. Polyploidy

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9
Q

How does sympatric speciation evolve?

A

new species evolves from within a large population

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9
Q

In animals sympatric speciation occurs because of…

A

non-random mating, ex, Squirrels mate at sunset and sunrise results in 2 new species

Ex. Diane Dodd maltose vs starch flies

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10
Q

where does sympatric speciation occur?

A

occurs in species in within the same geographical area

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11
Q

how does adaptive radiation occur?

A

When members of a single species occupy a variety of distinct niches within with different environmental conditions

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12
Q

what does adaptive radiation describe?

A

describes the rapid evolutionary diversification of a single ancestral line

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13
Q

example of adaptive radiation

A

beak types in finches of the Galapagos Islands

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14
Q

In adaptive radiation, members evolve…

A

different morphological features (adaptations) in response to the different selection pressures

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15
Q

What are pre-zygotic isolating mechanisms?

A

barriers that either impede mating between species or prevent fertilization

16
Q

What are the 5 pre-zygotic isolating mechanisms

A

behaviour, habitat, temporal (timing) , mechanical, gametes

17
Q

examples of behavior

A

bird songs, courtship rituals of elk, insect pheromones

certain groups of birds will only respond to species-specific mating calls

17
Q

Behaviour

A

any special signals or behaviours that are species specific

prevent interbreeding with closely related species

18
Q

Habitat

A

two species may live in the same general region but different habitats

rarely encounter each other

19
Q

example of temporal (timing)

A

three tropical orchid species time lapse between weather stimulus and flowering is 8,9, and 10 days respectively

19
Q

Temporal (timing)

A

two species may occupy the same habitat but mate or flower at different times of day, seasons or years

20
Q

examples of habitats

A

common garter snake found near water whereas northwest garter snake found in open areas (like meadows)

21
Q

another example of temporal

A

frogs will live same pond but breed during different seasons (spring vs summer)

22
Q

Mechanical

A

closely related species may attempt to mate but fail to achieve fertilization between they are anatomically incompatible

23
Q

example of mechanical

A

genitalia specificity in insects

certain breeds of dog are morphologically incapable of mating due to size

24
Q

Gametes

A

egg and sperm meet but rarely fuse to form a zygote

25
Q

example of gametes

A

sperm of one species cannot survive in the environment of the female reproductive tract of another species

26
Q

what are post-zygotic isolating mechanisms?

A

barriers the prevent hybrid zygotes from developing into viable fertile individuals

27
Q

what are the three post-zygotic isolating mechanisms?

A

hybrid inviability, hybrid sterility, hybrid breakdown

28
Q

what is hybrid inviability?

A

embryo dies in early development before birth

genetic incompatibility prevents normal mitosis after fusion

29
Q

example of hybrid inviability

A

sheep and goats

30
Q

what is hybrid sterility?

A

hybrid offspring is sterile

meiosis fails to produce normal gametes in the hybrid because chromosomes of the tow different species differ in number of structure

31
Q

example of hybrid sterility

A

mule offspring between female horse and male donkey n

32
Q

examples of hybrid breakdown

A

hybrids between the cotton species Gossypium barbadense, G.hirsytum and G.tomentosu

The offspring of hybrid copepods have less potential for survival or reproduction

32
Q

what is hybrid breakdown?

A

Hybrids can mate with each other but produce either weak or sterile offspring in the next generation

33
Q

where does hybrid breakdown occur?

A

in plants

34
Q

Divergent evolution

A

common ancestor

diverge to produce homologous structures

species appearance becomes more different over time

species are closely related (share genetic homology)

35
Q

example of divergent evolution

A

pentadactyl limb structure (vertebrates)

36
Q

convergent evolution

A

different ancestor

converge to produce analogous structures

species appearance becomes more similar over time

species are unrelated (genetically different)

37
Q

2 models of speciation

A

phyletic gradualism

punctuated equilibrium

37
Q

example of convergent evolution

A

wings in insects, birds and bats

38
Q

what is phyletic gradualism?

A

speciation occurs uniformly

steady and gradual transformation of whole lineages

39
Q

What is punctuated equilibrium?

A

species remain stable for long periods before undergoing abrupt and rapid changes (speciation)

39
Q

example of phyletic gradualism

A

fossil record of horse shows many intermediate forms connecting ancestral to modern species

39
Q

In punctuated equilibrium, speciation is seen as…

A

periodic process (big changes occur suddenly followed by long periods of no change)

40
Q

punctuated equliibrium is supported by…

A

general lack of transitional fossils (such absences could be because fossilization conditions are rare)

evolution (6 decks)

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