SPECIATION Macroevolution Review Microevolution Changes in allele freq

SPECIATION Macroevolution

Review: Microevolution Changes in allele freq. of a population over time.

Review: Microevolution

Macroevolution Speciation: � Formation of a new species

Biological Species Concept A population or group of populations whose members have the potential to interbreed with one another in nature to produce viable, fertile offspring, but who cannot successfully interbreed with members of other species

Definition of a Species Population of interbreeding organisms

Speciation begins with isolation

ISOLATION MECHANISMS AP Biology Ch. 24

Pre-zygotic Isolation Mechanisms

Habitat Isolation Populations are geographically separated.

Behavioral Isolation Populations respond to different mating cues Hyla chrysoscelis Hyla versicolor

Temporal Isolation Populations breed during different times

Mechanical Isolation Populations anatomically prevent reproduction

Gamete Isolation Populations sperm are unable to fertilize different eggs

Post-zygotic Isolation Mechanisms

Hybrid Sterility Hybrid offspring is not fertile

Hybrid Breakdown Hybrid may be fertile but subsequent generations are not

Limitations to BSC Does not account for � Asexually reproducing species: bacteria � Hybrid species: Mule � Fossil species: Trilobite

Speciation in Action http: //www. youtube. com/watch? v=YCo. Ei. LOV 8 jc https: //www. youtube. com/watch? v=8 yv. EDqrc 3 XE

MODES OF SPECIATION Ch 24. 2

Review Universe formed ~13. 8 bya Earth formed ~4. 6 bya Life present ~3. 5 bya Microevolution & Macroevolution � genetic changes within a population � natural selection acts upon phenotypes Diversity of Life on Earth Today

Review Isolation Mechanisms (How) Habitat Isolation Behavioral Isolation Temporal Isolation Mechanical Isolation Gametic Isolation Hybrid Sterility Hybrid Breakdown

Modes of Speciation (Where) Allopatric Speciation: � Speciation Peripatric Speciation � Speciation occurs with small population isolation Parapatric Speciation � Speciation occurs with geographic isolation occurs between adjacent populations Sympatric speciation � Speciation occurs within a population

Allopatric Speciation Ex: Biogeography � Rhacophorinae frogs (310 sp. in India) � Mantellinae frogs (100 sp. in Madagascar) Geology and DNA evidence suggest 88 mya

Peripatric Speciation Ex: Founder Effect � Ursus maritimus & Ursus arctos Geology and DNA suggest 150 tya

Parapatric Speciation • Ex: Ring Species • • Ensatina Salamanders Currently happening http: //www. youtube. com/watch? v=YCo. Ei. LOV 8 jc

Sympatric Speciation Ex: Polyploidy in Plants � 1900, Europeans brought Tragopogon sp. � Tragopogon miscellus is now found! DNA shows tetraploidy (4 N)

Sympatric Speciation Ex: Sympatry in animals � Amphilophus citrinellus & Amphilophus zaliosus Nicaragua Crater Lake formed 10 tya

SPECIATION, PATTERNS & TIME AP Biology Ch 24. 3

Review: Speciation Process of making a species Biological Species Concept: � Populations are no longer capable of interbreeding

Speciation & Time Is speciation a slow process? Fast process? Both?

Speciation & Time Charles Darwin � Phyletic Gradualism: Slower process gradually developing species � Support: Various fossil lineages Variation in large populations Allopatric speciation � Ex: Homo sapiens

Speciation & Time Stephen J. Gould � Punctuated Rapid Equilibrium: process & is followed by long periods of stasis � Support: Various fossil lineages Parapatric speciation Sympatric speciation Adaptive Radiation � Ex: Tyrannosaurus Rex

Speciation & Time Adaptive Radiation: � Presence of new ecological conditions leads to the diversification of many species

Patterns in Speciation Divergent Evolution: � Anagenesis One species evolves into another species � Cladogenesis One species evolves into separate species

Patterns in Speciation Convergent Evolution: � Distantly related species converge on similar structures Bats, Birds, Butterflies wings are analogous structures

Patterns in Speciation Parallel Evolution: � Similar environments produce many similar species

Patterns in Speciation Coevolution? � Probably incorrectly applied to interspecific competition

Speciation Misconceptions Evolution is not goal oriented! � There is no primary body plan for any species Natural Selection must work with current body plan Ex: 6 wings on birds would be awesome � Adaptations Ex: are often compromises Seal flippers instead of legs