KEY CONCEPT New species can arise when populations are isolated.

Speciation - the development of two or more species from one existing species Species - a group of organisms with the ability to interbreed and produce fertile offspring in the natural environment.

Ex. There are 18 Different species of Penguins

Speciation can result when members of a population become isolated from one another Speciation is the creation of 2 different species from 1. Populations become genetically isolated when there is no gene flow between them due to some type of separation. Gene flow is the exchange of genes between populations through sexual reproduction.

Processes that result in Reproductive Isolation which keep individuals from producing offspring Physical Physiological Behavioral processes

Causes of Speciation - How new species are created Geographic isolation of populations Can lead to Reproductive isolation of population New Species (unable to breed when together)

Types of Isolating Mechanisms that prevent Reproduction

Geographic Isolation Members of a population may become isolated from one another by geographic boundaries like mountains, rivers or even oceans

Geographic Isolation can lead to Reproductive Isolation

Mechanical Isolation- type of reproductive isolation due inability to physically mate Reproduction cannot occur because “parts” don’t fit

Temporal Isolation – type of reproductive isolation due to reproducing at different times

Behavioral Isolation – reproductive isolation due to differences in mating or courtship behavior even though they are able to physically interbreed

Different mating rituals Different species of bowerbird build and decorate their bowers in different colors in order to woo females. The Satin bowerbird (left) builds a channel between upright sticks, and decorates with bright blue objects The MacGregor’s Bowerbird (right) builds a tall tower of sticks and decorates with bits of charcoal.

Ecological Isolation – reproductive isolation due to living in different parts of the habitat (microhabitats) and rarely come in contact with each other Notaden bennettii (dark frog) lives underground and only emerges after heavy rains Litoria rubella (light frog) lives in trees and does not burrow underground.

Speciation - the development of two or more species from one existing species The isolation of populations can lead to new species being formed.

See Google Classroom to review “Mechanisms of Evolution”