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)
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
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)
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
5
Q
How do species form?
A
- allopatric
- peripatric
- sympatric
- parapatric
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
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
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
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
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)
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)