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Biology 106 2015 > Speciation > Flashcards

Speciation Flashcards

1
Q

selection doesn’t favor traits that are good for the population or the specie as a whole….

A

it only favors traits that are good for individuals

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2
Q

favorable traits

A

increase the fitness of an individual in a given environment

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3
Q

true or false:

individuals don’t evolve, populations do!

A

true

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4
Q

speciation

A

formation of new and distinct species

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5
Q

population

A

an interactive group of individuals of a single specie that occupies the same area at the same time

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6
Q

birds common on campus

A
  • house sparrow (passer domesticus)
  • black phoebe (savoriness nigricans)
  • house finch (carpodaccus maxicanus)
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7
Q

species

A

kind

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8
Q

how does speciation (the process by which one species give rise to another or several new species) happen?

A
  1. morphological species concept
  2. phylogenetic species concept
  3. biological species concept
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9
Q

Morphological Species concept

A

groups of organisms with a similar phenotype (look alike) are members of same species

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10
Q

details on morphological species concept

A
  • many species look similar over large geographic ranges
    - blackbirds in upstate NY look similar those across north america
  • sometimes not all members of same species don’t look alike (males and females may look different from each other)
  • sometimes they look different from they fulfill different ecological roles ( ants- major and minor workers)
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11
Q

cryptic species

A
  • 2 or more distinct species are mostly morphologically indistinguishable
  • dna barcodes identify cryptic species and determine their geographical rages
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12
Q

Phylogenetic species concept

A

smallest group of organisms that shares a common ancestor is a distinct species

  • ex. phylogeny of fruit flies
  • not useful for understanding how species form
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13
Q

biological specie concept

A

species are groups of actually or potentially interbreeding natural populations that can mate and produce fertile offspring

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14
Q

actually

A

live in the same place and actually interbreed

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15
Q

potentially

A

don’t live in same place, but could interbreed

- blackbirds in NY and BC aren’t likely to encounter but are still able to interbreed

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16
Q

details of biological species concept

A
  • most widely used and most mechanistic of the species concepts
  • new species are formed when populations whose members can potentially exchange genes become reproductively isolated from eachother
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17
Q

reproductive barriers

A
  • prezygotic reproductive barrier

- postzygotic reproductive barrier

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18
Q

prezygotic reproductive barrier

A

-act before fertilization to prevent it

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19
Q

postzygotic reproductive barrier

A

act after fertilization to prevent development of viable and or fertile offspring

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20
Q

habitat isolation

A
  • individuals of one population evolve preferences for one habitat, and individuals of another for a different habitat
  • species live and mate in their preferred habitats and may never com into contact during mating season
21
Q

temporal isolation

A

individuals of population evolve to mate during one season and individuals of another to mate during a different season
-ex. 3 species of co-occuring leopard frogs reproductive seasons don’t overlap

22
Q

behavioral isolation

A

when individuals reject or fail to recognize potential mating partners because of their behaviors

  • bredding calls of male gray tree frogs differ among related species
  • calls of sister species differ in frequency
  • females ignore calls made by males of their sister species
23
Q

mechanical isolation

A

when differences in shapes, positions, or sizes of reproductive structures prevents cross-fertilization

  • conspecific snails
    • reproductive parts both on right side of head easy to line up and mate
  • heterospecific snails
    • reproductive parts of one individual on left side and other on right which makes hard to fuck
24
Q

gametic isolation

A

when sperm and eggs in a species-specific manner

-if protein doesn’t bind, then the sperm can’t fertilize the egg

25
Q

reduced hybrid viability/fertility

A

hybrid offspring may have problems developing, surviving, and or reproducing

  • goat and sheep
  • mule
  • both are sterile
26
Q

are hybrids ever fertile?

A

yes but many suffer from:

-hybrid breackdown

27
Q

hybrid breakdown

A

when 2 hybrids mate or when hybrids mate with the parent species, the next generation may not survive/ reproduce

  • rice
    • 1st gen was fine
    • 2nd gen are stunted and sterile
28
Q

allopatric

A

new species form a single species due to geographic isolation

29
Q

sympatric

A

new species evolve from a single species while inhabiting the same geographic region

30
Q

details on allopatric

A
  • common mode of speciation

- speciation occurs when a geographic barrier isolates populations into 2 or more groups

31
Q

geographic barriers

A

mountains, rivers, pond, rising sea level

32
Q

stages of how allopatric speciation proceeds

A
  • 2 populations become geographically separated (barrier gene flow)
  • accumulated genetic differences isolate them reproductively
33
Q

secondary contact

A

occurs when isolated reestablish contact with elimination of a geographic barrier

34
Q

what happens after secondary contact?

A
  • if each population’s gene pool didn’t differentiate enough to be reproductively isolated, the populations will interbreed and may merge
  • if they have differentiated, then they have become separate species
35
Q

sympatric isolation details

A
  • less common mode of speciation

- speciation and reproduction occurs without a geographical isolation

36
Q

sympatric speciation occurs due to:

A
  • habitat preferences (food, light) which may lead to mating in that preferred habitat
  • sexual selection
  • ex. apple maggot fly
  • over time, genetic differences between subpopulations accumulated, leading to speciation without isolation
37
Q

hybridization

A
  • reproductive barriers are often not perfect

- if separated populations reunited before they are fully reproductively isolated, interbreeding can occur

38
Q

hybrid zone

A

regions where hybrids are produced

39
Q

3 possible outcomes of hybridization

A
  • stability
  • fusion
  • reinforcement
40
Q

stability

A

hybrid zones may last for many generations if hybrids continue to be produced

  • ex. hybrid toads are much less fit but zone persists because toads keep on going at it.
  • weak reproductive barriers and lots of gene flow stabilizes production of hybrids
41
Q

fusion

A

2 species may fuse to one species

-with weakened reproductive barriers and continued gene flow, distinct cichlid species are fusing into one

42
Q

reinforcement

A

hybrids are much less fit (lower survival) than members of both parent species
-natural selection reinforces reproductive barriers
-reducing formation of unfit hybrids
favoring breeding within a specie
-in time hybrids are no longer formed and 2 species have completely diverged
-reinforcement occurs only if population is sympatric
-leopard frogs

43
Q

how rapidly does speciation occur in geological time?

A
  • punctuated equilibrium

- gradualism

44
Q

punctuated equilibrium

A

speciation occurs in short bursts, new species appearing suddenly and remaining the same for years (cladogenesis)

45
Q

gradualism

A

speciation proceeds uniformly and by steady, gradual transformation of whole lineages into new species (anagenesis)

46
Q

why do rates of speciation vary?

A
  • usually higher in groups with poor dispersal abilities; in such organisms, even “small” geographic barriers can lead to allopatry
  • rates higher in groups with specialized diets
  • rates higher in animal-pollinated than wind-palliated plants
  • rates are higher in groups that undergo strong sexual selection
47
Q

fusion

A

2 species may fuse to one species

  • some distinct cichlids species in East Africa lakes are fusing
  • pollution makes water murky, hampers female ability to identify males, so hybrids are regularly formed
  • with weakened reproductive barriers and continued gene flow, distinct cichlid species are fusing into one
48
Q

why do rates of speciation vary?

A
  • usually higher in groups with poor dispersal abilities; in such organisms, even “small” geographic barriers can lead to allopatry
  • rates higher in groups with specialized diets
  • rates higher in animal-pollinated than wind-palliated plants
  • rates are higher in groups that undergo strong sexual selection

Biology 106 2015 (9 decks)

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