Speciation Flashcards
What is the biological species concept?
A species is a group of actually or potentially interbreeding natural populations that are reproducing isolated form others
What is the morphological species concept?
A species is a group of organisms that have similar physical traits
What is the phylogenetic species concept?
A species is a group of oganisms that shares a common ancestor and can be distringuished from other organisms by particular traits
What are the pros and cons for the biological s.c.?
PROS: simple, based in HW concepts
CONS: doesn’t apply to all organisms, don’t always have mating data, complex mating systems
What are the pros and cons for the morphological s.c.?
PROS: good for groups where data is limited
CONS: similarity and difference in appearance can be misleading (convergent evolution)
What are the pros and cons for the phylogenetic s.c.?
PROS: includes historical/evolutionary context, applies to all organisms
CONS: requires modern genetic data and tools
What is polyploidy?
Having more than two sets of chromosomes (3n)
How does polyploidy influence reproductive isolation and speciation?
Polyploids are usually sterile due to their odd number of chromosomes, but in some instances can mate with other polyploids
How does speciation occur through allopatry through vicariance?
A physical/geological barrier separates a population into two roughly even halves and if it comes back together it will be to different to interbreed
How does speciation occur through allopatry through the founder effect?
A small group branches off and comes back to different to join the pre-existing population
How does speciation occur through parapatry?
A group has selective pressures within a populaion leading to changes (usually on the edge of the population)
How does speciation occur through sympatry?
Two populations diverge within each other usually caused by a mutation that increases in frequency through the population
What is evolutionary radiation?
Occurs when rapid speciation results in a burst of new species from a single ancestor
What is adaptive radiation?
Occurs when this radiation results in species adapted to a particular environment and filling different ecological niches
(EX: honey creeper bill specialization in Hawaii)
What is gametic isolation?
Sperm can’t fertilize egg
What is behavioral isolation?
Don’t recognize other mates
What is mechanical isolation?
Physically different in sex organs
What is habitat isolation?
Occupt different habitats or different parts of the same habitat
What is temporal isolation?
Different breeding times (season)
What is reduced hybrid inviability?
Hybrid offspring don’t complete development of have low survivorship
What is reduced hybrid fertility?
Hybrid offspring are viable, but sterile
What is hybrid breakdown?
Hybrid offspring are viable and fertile, but subsequent offspring are inviable/sterile
What is a post-zygotic barrier?
Prevent a hybrid zygote from developing into a viable fertile adult
What is a pre-zygotic barrier?
Prevent mating or prevent fertilization
