species

geographical trait variation

yellow rumped warblers, only part of range of species get traits, gene flow doesn’t completetly mix within species

yellow rumped warblers

recent divergence, interbreed readily, plumage variation not different species

biological spceis concept

gene flow maintains cohesion of populations, not always aligned with taxonomy, isolation and no interbreeding

species

one or more populations, large collections of populations

populations

group of interbreeding or potentially interbreeding individuals, cohesion maintained by gene flow

phylogenetic species concept

generalization, assign types of phylogenetic trees to minimum evolutionary units, different way of assigning spcies names to groups of organisms, more functional definition encompassing evolutionary history

naming species through pylogenetic concept

are these statistically different enough to be names differ, could avoid issues and ambiguities, doesn’t rest on reproduction isolation

allopatric speciation

major form, populations are geographically separated, warblers taking different parts of North American, diversification of Darwin’s finches and natural selection

Darwins finches

colonization reduced population size, which resulted in a dramatic reduction in gene flow, speciation events occur, allopatric speciation

large beaks

finches with ___, crush large seeds

small beaks

crush small seeds

thin needle like beaks

go for insects, adapted woodpecker like finch

clines

many traits that vary through space, measurable gradient in single characteritic across species range, size, still gene flow

downy woodpecker

cline example, as go north the body size gets larger, thermal management response

bergmanns rule

within clade, larger bodies populations are found in colder climates, larger animals have lower surface area to volume ration, better heat retention

migration selection balance

evolutionary equilibrium where local selection is counteracted by influx of genes from other populations, stable equilibrium where new alleles keep entering population via migration but selection keeps removing them,

ring species

expand into west and east regions, once they merge into same middle of circle they are too different to interbreed, species biological concept

gulls

dont interbreed at and of cycle circle, can hybrid at connecting regions, intermediate s are hard to tell what it is

hybridization

many birds form hybris, but do so rarely

rare hybridization

large geographic regions meet a small area, hybrids are not fit enough to expand, hybrids are only fit exactly where that hybridization occurs, birds don’t recognize their visuals

variations in coloration and behaviors

can cause specieation in birds, don’t recognize their same species

behavioral mechanism dominates in birds

highly visual, intelligrent, social, high capacity for species recognition, prezygotic mechanisms appear to prevail over genetic incompatibiity

flightedness

ecological niche shift to _____

birds have same amount of chromosomes

hyrbids are not sterile like mules

prezygotic mechnaisms

egg and sperm never meet, sympatric but rarely meet due to different habitats or times, incompatible anatomy or behavior, gametes never fuse

postzygotic mechanisms

hybrid inviability, genetic incompatibility, hyrbid sterility and breakdown

hyrbid inviability

hybrid was made, but will die, sterile will not make sperm to be fertile

genetic incompatibility

dominance effects (one species alleles ccause suppression of essentional function), epistatsis (mess up expression of genes through genetic contol mechanisms), chromosomal incompatibility (chromosomes don’t line up together for cell division)

sex determination

reverse between mammals and birds, females carry sex determinant

hyrbid zones

central texas with titmice, where hybridizaiton occurs, various reasons why cannot expand (time, bad space beyond region)

unstable hyrbid zones

hybrid zone moves, townsend warbler takes over and displaces, hyrbidize, but then towndsend dominate and push them out

hyrbid escape

southern scua is a hybrid of two species, hybrids went to southern hemisphere, gene flow cut off, turned into own species