speciation Flashcards
what is the biological species concept
species are groups of natural populations that can interbreed
does speciation happen fast
no its slow so its hard to differentiate species
what is speciation
when one species becomes 2
it doesn’t always happen when evolution occurs
what is the critical process in forming a new species
the segregation of the gene pools
the ancestor gene pool becoming 2 separate pools
what makes speciation faster/easier
interruption of gene flow (someone new joining my group) No gene flow=faster speciation
what is allopatric (geographic) speciation
when it becomes 2 species because of a geographic barrier,
a barrier could have formed or some members might have crossed a barrier doing founder effect
If environment is different they will evolve differently or if there are variations of the alleles and then a barrier forms there will be differences
(think of ll is like a mountain between them)
what is sympatric speciation
speciation that happens with no physical barriers
syn= without
what is the cause of sympatric speciation
polyploidy, a duplication of a whole chromosome set
how does polyploidy arise
Autopolyploidy when chromosomes duplicate in a single species (2 2n gametes combine, making a tetraploid person)
allopolydoiy when the chromosomes of 2 different species mix
what happens when autoployoidy occurs
2 2n gametes combine and it makes a tetraploid person which makes them sterile but if its a plant it can still have kids with itself or other tetraploids (same for ppl).
the viable gamete has 3 chromodsomes when its 2 tetraploids have kids
explain Allopolyploidy
when ppl interbreed of different species (hybridize) they can be fertile since each chromosome has pretty much an identical partner for meiosis
prezygotic isolation mechanisms (or barrier)
they happen before fertilization and prevent hybridization spatial/habitat (dont live in same place) temporal isolation (dont mate at same time) behavioural isolation (not attractive) mechanical isolation (not same size/shape of sex organs gametic isolation (sperm and eggs dont attach)
post zygotic isolating mechanisms
they happen after fertilization and reduce fitness of hybrid offsprings by:
hybrid zygote abnormality (kont mature normally)
low hybrid viability (survive less well so have less kids)
hybrid infertility
what are two natural selection mechanisms that happen when a hybrid is not fit
prezygotic isolation mechanisms (or barrier) and post zygotic isolating mechanisms
