Topic 4C.5 Reproductive Isolation and Speciation

speciation

the formation of new species

hybridisation

the production of offspring as a result of sexual reproduction between individuals from two different species

allopatric speciation

speciation that occurs when populations are physically or geographically separated and there can be no interbreeding or gene flow between the populations

adaptive radiation

a process by which one species develops rapidly resulting in several different species which fill different ecological niches

marsupials

mammals that give birth to very immature young and then protect them in pouches

monotremes

primitive mammals that lay eggs and feed their developing offspring with milk from mammary glands

placental mammals

mammals that provide for the developing fetus during gestation through a placenta

sympatric speciation

speciation that occurs between populations of a species in the same place; they become reproductively separated by mechanical, behavioural or seasonal mechanisms; gene flow continues between populations to some extent as speciation occurs

population bottleneck

the effect of an event or series of events that dramatically reduces the size of a population and causes a severe decrease in the gene pool of the population, resulting in large changes in allele frequencies and a reduction in genetic diversity

founder effect

the loss of genetic variation that occurs when a small number of individuals become isolated, forming a new population with allele frequencies not representative of the original population