WEEK 9: SPECIATION Flashcards
what is speciation?
when different types of animals undergo independent divergence
/the evolutionary process by which populations evolve to become distinct species.
what is the problem with observing speciation?
too fast to observe in fossil records but too slow to observe if it occurred in real time.
what is linnaen classification?
where all species have a name conforming to a binomial or trinomial system.
in terms of how species form, what is allopatic?
barrier forms in group
change during isolation
new distinct species after equilibration of new range
in terms of how species form, what is peripatic?
new niche entered
niche in isolation
in terms of how species form, what is parapatric?
new niche entered but it is not completely cut off from big group- its adjacent.
evolutionary pressures cause change
what is an example of a ring species
herrings (around the western world)
herring gull (uk) and lesser black-blacked gull (Scandinavia) are incompatible
in terms of how species form, what is sympatric?
when two groups of the same species live in the same geographic location, but they evolve differently until they can no longer interbreed and are considered different species
what is the difference between pre-zygotic and post-zygotic barriers?
pre-zygotic is preventing transfer of gametes to members of another species
post-zygotic is reduced survival or reproductive rates of hybrid zygotes
give an example of pre-zygotic barrier
limited dispersal (ie) in humans over uk
give an example of post-zygotic barrier
fly’s male genitals cant always fit in female and eject sperm successfully
why don’t hybrids always work?
survival lower due to developmental problems
survive but infertile
