Speciation Speciation Defined evolution of a new species

Speciation • Defined: evolution of a new species • Species: group of organisms that

Gene Flow • Defined: Movement of alleles from 1 population to another • With

Genetic Drift • Defined: Changes in gene pool due to chance (not natural selection)

Geographic Isolation • Mountains, rivers, canyons, oceans may separate a population – Gene flow

Behavioral Isolation • Although not geographically separated, reproduction is prevented – 1) Different mating

Temporal Isolation • Although not geographically separated, reproduction is prevented – 1) Mate at

• Occurs as a result of End Result: behavioral, Reproductive Isolation geographical, &

Kobe Kuiz • • What is speciation? What leads to speciation? What is gene

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Speciation

Speciation • Defined: evolution of a new species • Species: group of organisms that can interbreed and produce fertile offspring • Factors that lead to evolution – – – Natural Selection Gene flow Mutations Sexual selection Genetic drift

Gene Flow • Defined: Movement of alleles from 1 population to another • With gene flow: – At first: Increases variations in a population (new genes introduced) – Over time: Populations appear more similar (genes mix together) • Without gene flow – No variations exchanged – Organisms adapt to their own environment – New species develop

Genetic Drift • Defined: Changes in gene pool due to chance (not natural selection) • More likely in smaller populations • Ex: Natural disaster – Pre-forest fire (left picture): Blue is more advantageous – Post-forest fire (right picture): Due to more red survivors, red has the advantage to reproduce – Survival unrelated to adaptations

Geographic Isolation • Mountains, rivers, canyons, oceans may separate a population – Gene flow stopped • Each population adapts to its isolated environment • Over time, genetic differences prevent reproduction (new species)

Behavioral Isolation • Although not geographically separated, reproduction is prevented – 1) Different mating rituals – 2) Use of pheromones • No gene flow: differing populations unable to reproduce

Temporal Isolation • Although not geographically separated, reproduction is prevented – 1) Mate at different seasons – 2) Some nocturnal • No gene flow: differing populations unable to reproduce

• Occurs as a result of End Result: behavioral, Reproductive Isolation geographical, & temporal isolation • No mating = no gene flow • Two groups unable to reproduce – Sex organs don’t match – rituals don’t attract – physically separated • New species created

Kobe Kuiz • • What is speciation? What leads to speciation? What is gene flow? What happens if gene flow is prevented? • How are temporal, behavioral, and geographic isolation different? • How are temporal, behavioral, and geographic isolation similar?