11.5 Speciation Through Isolation Updates: Read 11.3 SQ3R theme: founder effect due Homework: –Quizzes done for week, resume Tuesday –11.5 reading/DRTA due Monday – detailed answers –Beaks lab due Tuesday AAP: Mondays, Tuesdays, Thursdays Keystones: Wednesday 5/18 – Thursday 5/19

11.5 Speciation Through Isolation LEQ: How does a population become isolated? Do Now: founder effect Revisit 4 and 5 from your reading: –Share what you learned from your responses for 4 –Revise 5 if necessary, –Submit for credit Key terms: founder effect

11.5 Speciation Through Isolation Gene pools can change due to chance Gene pool variation and physical variation can change for a number of reasons: –Migration: gain/loss of members –Mortality/births Founder effect is when a small group of a population splits off and forms a new population

11.5 Speciation Through Isolation Chance changes in allele frequencies can lead to major changes in gene pools in a small population Will adaptive traits be present? Can a species evolve?

11.5 Speciation Through Isolation Pair-share and discuss: What type of selection pattern fits the leg-size change of anoles introduced to the island? What type of selection pattern best fits leg length and toepad size in the ecomorphs of anoles? –Twig v. trunk/ground How is variation related to running and climbing ability?

11.5 Speciation Through Isolation Anole ecomorphs illustrate disruptive selection

11.5 Speciation Through Isolation Activity: Selection by Predation

11.5 Speciation Through Isolation

Updates: 11.5 reading/DRTA due Homework: –Quizzes resume Tuesday –Beaks lab due Tuesday –Anole simulation due Wednesday AAP: Mondays, Tuesdays, Thursdays Keystones: Wednesday 5/18 – Thursday 5/19

11.5 Speciation Through Isolation LEQ: How does a population become isolated? Do Now: wordsplash 5 sentences: allele frequency, natural selection, fitness, gene flow, adaptive trait, founder effect, adaptive radiation Key terms: isolation

11.5 Speciation Through Isolation Variation is a characteristic of, but does not define a species

11.5 Speciation Through Isolation Macroevolution: speciation overview Different species cannot (usually) interbreed successfully Speciation can occur when populations can no longer interbreed

11.5 Speciation Through Isolation Reproductive isolation prevents species from interbreeding Mules have reduced hybrid fertility Eastern Gray Treefrogs are hybrids!

11.5 Speciation Through Isolation Pair-share: how do the finches demonstrate how a reproductive barrier evolved and how to maintain it in a species?

11.5 Speciation Through Isolation What type of selection pattern explains dewlap color?

11.5 Speciation Through Isolation Lake Malawi cichlids choose mates based on coloration: –normal light: females mate with same-species males –orange light: females mate with males of the opposite species and produce fertile hybrids! Behavioral isolation reinforces mate preference

11.5 Speciation Through Isolation Courtship behavior can prevent interbreeding –Western Meadowlarks (left) and Eastern Meadowlarks, (right) do not interbreed –Songs and behavior are traits too!

11.5 Speciation Through Isolation Is there a clear moment when speciation actually occurs?

11.5 Speciation Through Isolation

Geographic isolation can isolate populations Geography (allopatry) can limit gene flow between populations as populations re-adapt to their environments

11.5 Speciation Through Isolation

Coywolves: A Hybrid Species what is the relationship between skull size and diet in wolves and coyotes? What adaptations give coywolves an advantage over their parent species? Why do you think animals have adaptations that prevent hybridization? What might happen if hybridization was more common? Speculate: Why is it difficult for hybrid species to emerge in the wild?

11.5 Speciation Through Isolation Reproductive barriers be strengthen over time (reinforcement). Why?

11.5 Speciation Through Isolation Geographical distributions of model for mimicry (yellow) and mimic-only (green)

11.5 Speciation Through Isolation Discussion: “Painting” wings Why does the fruit fly Drosophila biarmipes exhibit wing spots while Drosophila melanogaster does not, even though they share the same “paintbrush” genes? What evolutionary advantage do you think a male fruit fly gains from having wing spots?

11.5 Speciation Through Isolation The isolation of populations can lead to speciation. Populations become isolated when there is no gene flow. –Isolated populations adapt to their own environments. –Genetic differences can add up over generations.

11.5 Speciation Through Isolation Reproductive isolation can occur between isolated populations. –members of different populations cannot mate successfully –final step to becoming separate species Speciation is the rise of two or more species from one existing species.

11.5 Speciation Through Isolation Populations can become isolated in several ways. Behavioral barriers can cause isolation. –called behavioral isolation –includes differences in courtship or mating behaviors

11.5 Speciation Through Isolation Geographic barriers can cause isolation. –called geographic isolation –physical barriers divide population Temporal barriers can cause isolation. –called temporal isolation –timing of reproductive periods prevents mating