Species definintion

Biological Definition, Ernst Mayr definition

“Species are groups of actually or potentally interbreeding natural population which are reproductively isolated from other such groups”

Morpholoical species definition

Most useful for this class; if two indiviuals resemble each other morpholically then they are the same species

Evolutionary species definition

They have the same evolutionary trajectory; used by the endangered species act

Are species real

The boundries we use to define species are human made

allopatric speciation

Requires panmictic popluations; A Vicariance event divides the population; indpended evolution occures in each population; once the barriar goes away the two can no longer breed; EX: California rabbits and navada rabbits

Sympatric speciation

Speciation with out a physcal barrier; Can be caused by reproductive isolation (Lake Barombi Mbo); Sexual selection (hawaii fruit flys); or polyplody in pacman frogs

Rate of speciation

Was thought to be slow but is fast; in Lake victoria 500 cichlids speciated over 12,000 years from a monophyletic group;

Prezygotic isolating mechanisms

Keeps them apart before they mate

Behavioral isolation

A prezygotic mechanism; a behaviroal mechanism prevent mating, EX; mating dance

Ecological isolation

Prezygotic; they rarely meet each other despite living in the same geographic area

Temporal isolating

prezygotic; reproduce at different times

Morphlogical isolation / mechanical isolation

prezygotic; Reproductive structures are physcally incompatible

Gametic isolation

Prezygotic; Egg and sperm can not meet

Post zygotic mechanism

After fertilziation

Zygote mortality

post zygotic; Fertilization occurs but the zygote never produces viable offpsring

Hybrid mortality

post zygotic; A hybrid begins developing but dies before it reaches reproductive maturity

Hybrid Sterility

postzygotic; Hybrids are sterile and unabe to produce offspring