Speciation and Macroevolution Flashcards
Unit 3
Divergence
if gene flow ends, isolated populations can diverge, which can lead to speciation
morphological species concept
organisms that look the same are the same species
biological species concept
organisms that reproduce together represent the same species
phylogenetic species concept
organisms that share evolutionary history are the same species
ecological species concept
organisms that occupy the same ecological niche are the same species
monophyletic group
an ancestral population and all descendants
synapomorphy
shared, derived trait unique to a monophyletic group (black dashes on a phylogeny)
prezygotic barriers
1) habitat isolation
2) behavioral isolation
3) temporal isolation
4) mechanical isolation
5) gametic isolation
postzygotic barriers
1) hybrid inviability
2) hybrid sterility
3) hybrid breakdown
habitat isolation
species occupy different habitats in the same geographic range
behavioral isolation
sexual selection
temporal isolation
mating at different times
mechanical isolation
1) incompatible genital organs
gametic isolation
1) sperm of one species may not survive the environment of female in a closely related species
2) molecular recognition on the surface of eggs (proteins coating the eggs)
hybrid inviability
hybrid embryos die when genetic regulation fails during embryonic development
hybrid sterility
problems during meiosis cause abnormal gametes, sterile offspring
hybrid breakdown
inability of second generation hybrid to reproduce because of some defect
allopatric speciation
geographic separation of populations restricts gene flow
sympatric speciation
new species arise within the range of the parent populations
ring species
provide examples of what seem to be stages in the gradual divergence of new species from common ancestors
adaptive radiation
evolution of many diversely-adapted species from a common ancestor is called an adaptive radiation
endemic species
species found nowhere else in the world
polyploidy
extra sets of chromosomes
Hugo de Vries
produced a tetraploid primrose species from a diploid primrose species and they could not interbreed
three types hybrid zones
1) reinforcement
2) fusion
3) stability
reinforcement (hybrid zone)
strengthening of reproductive barriers
fusion (hybrid zone)
weakening of reproductive barriers
stability (hybrid zone)
continued production of hybrids
hybrid vigor
hybrid has improved traits
gradualism
continuous evolution over a long period of time
punctuated equillibrium
long periods of stasis punctuated by period of rapid speciation
