Discussion 7 Island biogeography During the Anthropocene Island

Discussion 7 Island biogeography During the Anthropocene

Island Biogeography Extinction, species capacity, & colonization Colonization rate

Good hypothesis - Must be testable!

Is island biogeography testable? - Difficult at large scales - Requires long time range

Human-mediated colonization of Anoles * Colonization primarily mirrors isolation

Hypotheses • Exotic anoles have mostly established on impoverished banks • Increased colonizations have diminished the past signal of speciation on bank richness • Effect of island area has strengthened while effect of Isolation has weakened

Q: Explain why the authors think exotic anoles are more likely to established on impoverished banks

Species Have exotic anoles colonized islands with fewer than expected native species? Area Impoverished

Has increased colonization obscured the past effect of speciation on anole biogeography? • Island isolation and Phylogenetic diversity • Low immigration species descend from fewer colonisers closely related • Predicted: More phylogenetically diverse than expected • Island area and speciation rate Orderly Disorderly Describe theoretical relationship of island isolation to phylogenetic diversity. What is the predicted effect of increased colonization on phylogenetic diversity? Describe the process.

Has increased colonization obscured the past effect of speciation on anole biogeography? Negative phylogenetic diversity-isolation relationships are expected, where the most isolated islands contain small numbers of closely related species – phylogenetic diversity is low Composition on isolated islands

• Island area and speciation rate Species richness • Minimum area threshold required for speciation • Area < threshold negligible speciation • Area > threshold positive relationship • Prediction: small islands would act like big islands Past Present Describe theoretical relationships of island Area and to speciation rate. What is the predicted effect of increased colonization on speciation rate? Describe the process. Area Speciation rate Has increased colonization obscured the past effect of speciation on anole biogeography? Area

Based on the anole distributions, what can you infer about the Islands Cuba, Hispaniola and Puerto Rico, in comparison to Bonaire, Blanquilla and St. Lucia?

a m u xim M Variation after Variation before Area Species Richness Does area now explain more of the variation in anole richness than isolation? Isolation Prediction: More variation explained Prediction: Less variation explained by island area by island isolation

Does area now explain more of the variation in anole richness than isolation? Isolation Less variation explained by isolation Present Speciation rate Past Isolation

• Smaller islands smaller populations reduced shipping higher isolation • Strengthens effect of island area Q: The US embargo on Cuba (est. 1960) ended in 2014 and may decrease economic isolation. Based on the results of this paper, what would be the biogeographic and ecological consequences for anole lizards in Cuba? Species Richness Economic Isolation