Speciation Flashcards
Speciation
- origin of new species
- results in two of more descendant species
biological species
group of populations which can interbreed but are reproductively isolated from other such groups
isolating mechanisms
pre-zygotic barriers
post-zygotic barriers
Pre- zygotic barriers
- barriers to successful mating and fertilization
- habitat, temporal, behavioral, mechanical, gametic
Post- zygotic barriers
- fertilization occurs but hybrids are inviable or infertile or -breakdown after only a few generations
- one reciprocal cross is fertile, but the other isn’t
allopatric speciation
-interruptions of gene flow are due to geographical separation.
sympatric speciation
some interruptions of gene flow occur without geographical separation
-increase in # of chromosomes
autopolyploidy
meiotic error where they produce gametes with all (unreduced) chromosomes
-become isolated from parent species
allopolyploidy
mess up chromosomal segregation at meiosis
-most common
convergent evolution
traits in two or more organisms appear to be similar, but they evolved independently in each lineage
homology
same or similar relation. common ancestry
homoplasy
characteristic shred by a set of species but not present in a common ancestor
anisogamy
post zygotic care often much higher among females
vicariant speciation
speciation due to geographical disturbances
