Speciation Flashcards

1
Q

Definition of speciation?

A
  • forms bridge between evolution of populations and taxonomic diversity
  • diversity of organisms is consequence of cladogenesis (where they form and diverge, tree splits off)
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2
Q

What is linnaean classification?

A
  • all species have a name conforming to binomial/trinomial system
  • groups of similar sorts are a genus, within the genus there’s species, within that there could be subspecies
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3
Q

What’s the biological species concept?

A
  • species is a group of individuals fully fertile inter se
  • barred from interbreeding with other similar groups by its physiological properties (whether they can breed together and provide fertile offspring)
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4
Q

What’s the phylogenetic species concept?

A
  • irreducible cluster of organisms that’s diagnosably distinct from other clusters
  • within which there’s a parental pattern of ancestry and descent
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5
Q

How do species form?

A
  • allopatric
  • peripatric
  • sympatric
  • parapatric
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6
Q

What is the allopatric way of forming species?

A
  • original population but barrier emerges which splits poopulation in 2
  • evolve in reproductive isolation from each other
  • when they come into contact again they’re distinct species and unable to breed with each other
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7
Q

What is the peripatric way of forming species?

A
  • from original population a new niche enters
  • that niche becomes isolated and the speciation occurs within that area
  • closely related species in isolated, nearby but unconnected area
  • like allopatric but one population is smaller, there’s limited pool of genetic variability
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8
Q

What is the sympatric way of forming species?

A
  • occurs when species overlap with one another
  • evolution of new species within same habitat due to reproductive isolation
  • caused by life cycle becoming interrupted at some point
  • likely to occur through pre-zygotic or post-zygotic barriers
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9
Q

What is the parapatric way of forming species?

A
  • new niche enters original population but doesn’t become isolated or separated, connected partially at least
  • within the niche different selective pressures act on them
  • leads to them becoming reproductively isolated and distinct from founder population
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10
Q

What are pre-zygotic barriers?

A
  • prevent/reduce likelihood of transfer of gametes to members of another species
  • stop them from being able to breed
  • ecological isolation (physical barriers)
  • behavioural isolation
  • pre-mating barriers (limited dispersal that prevent them from mixing and isolating behaviours that one sex won’t respond to)
  • post-mating pre-zygotic barriers (if they can breed there’s barriers that prevent zygote from forming) (due to morphology they can’t link gametes or they can’t penetrate egg resulting in gamete isolation)
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11
Q

What are post-zygotic barriers?

A
  • consist of reduced survival or reproductive rates of hybrid zygotes
  • hybrid unviability (hybrids have lower survival rates, mortality is intrinsic)
  • hybrid sterility (survival to maturity but can’t produce viable gametes so are infertile)
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