RIM (Reproductive Isolating Mechanism)

Prezygotic

Postzygotic

Geographical: physical barriers separating pop. - unable to breed because of different selection pressures in different environments

Ecological: different 'niches' same geographical location - pop. that are ecologically isolated seldom (rarely) come into contact with each other

Structural/Morphological: differences in external reproductive organs - different organs may not allow for the transfer of gametes (sperm or pollen)

Temporal: breeding behaviour occurs at different/non-overlapping times e.g. daily (differences in timing of mating), seasonal (differences of mating/pollination)

Behavioural: differences in mating behviour, courtship behaviour and activity patterns

Activity patters

Diurnal: day time activity

Noctural: night time activity

Crepuscular: twilight activity (sun is below the horizon)

Gametic: incompatibility of gametes

Egg surface without right chemical receptors

Sperm cannot penetrate surface of egg

Sperm cannot survive in chemical environment of female

Hybrid Inviability: zygote embryo/offspring in inviable - dies early in development

Inviable: unable to survive or develop normally

Hybrid sterility: hybrid reaches maturity but is infertile

Hybrid Breakdown: occurs when hybrid reaches maturity, able to breed but next/subsequent gene. are infertile/reduced reproductive capacity

RIMS act cocurrently resulting in speciation

RIMS may result from or a combination of prezygotic and postzygotic isolating mechanisms