CONSERVATON BIOLOGY Lecture07 – Spring 2014 Althoff - reference Chapters 11-12

1. CONSERVATON BIOLOGYLecture07 – Spring 2014 Althoff - reference Chapters 11-12 ISLAND BIOGEOGRAPHY

2. Equilibrium Theories of Diversity • Attempt to explain diversity patterns observed in natural ecosystem • Some patterns noted: 1) species richness increases dramatically from high latitudes toward the equator 2) within latitudinal belts, diversity appears to be correlated with temperature, ecosystem productivity, topographic heterogeneity within a region, and structural complexity of local habitats 3) ___________________ exhibit species impoverishment

3. Equilibrium Theories of Diversity…con’t • Everywhere, higher diversity is associated with greater ecological variety • How do we explain these patterns of diversity? 1) the ultimate source of diversity is __________ (the production of new species by the splitting of evolving lineages) 2) Species _________ (i.e., go extinct)—most species that have ever existed have disappeared 3) If Speciation Extinction….Species increase If Speciation Extinction….Species decrease 4) Diversity might achieve a ________________

4. Consider “steady-state” of species richness…. • Can examine this on a more localized level/scale (so do not think global scale for now) • Best illustrated by examining patterns of diversity on oceanic islands • Robert MacArthur and E.O. Wilson: EQUILIBRIUM THEORY OF ISLAND BIOGEOGRAPHY 1963 Evolution 17:373-387 (technical paper) 1967 Theory of Island Biogeography (book) ETIB

5. Equilibrium Theory of Island Biogeography • = the number of species on an island balances regional processes governing ____________against local processes governing ______________.

7. Immigration

8. IMMIGRATION “Curve” • As species fill an island, the ____________ of new species ______ Why? • As new species arrive, fewer are left on the _________________ • Those “left” on the mainland that haven’t colonized have ___________________ • Once all species from mainland have colonized, immigration rate ____________

9. Immigration EXTINCTION

10. EXTINCTION “Curve” • As species fill UP the island, the ______ at which they become _______________ Why? • Main reason: ______________________ ______________ increases as species accumulate

11. Other FACTORS to consider... • ____________________________ • ____________________________ • ____________________________ • ____________________________ ___________ • ____________________________

12. Who is most likely to colonize?

13. vs.

14. Small vs. Large Islands • Small islands support fewer species than larger islands….. if ______________ from the mainland

15. vs.

16. Near vs. Far Islands • Islands near the mainland have more species than those farther away…. for ____________ islands

18. ___________________________ – in general…but same result over time

19. ETIB • Describes a ____________ and __________________________. • Example, if a disaster exterminated part of an island’s biota, new colonists would—over time—restore diversity to pre-disturbance equilibrium

20. Test of ETIB • Simberloff and Wilson (1970) • They first counted all arthropod species present on each of 4 small mangrove islands in Florida Bay • Then they removed entire arthropod fauna by fumigating the islands with methyl bromide • Islands were resampled at regular intervals for a year

21. Note A Note B No. of species present Note C months

22. Simberloff and Wilson study • Note A: islands closer to sources of colonists recovered more species faster than more distant islands • Note B: at the end of the year, species richness had leveled off, suggesting that an equilibrium had been reached • Note C: the new equilibrium numbers of species were similar to the numbers of species before defaunation

23. The Real World... • True Islands • “Habitat” Islands a) altitude barriers b) vegetation/habitat barriers c) disturbance RESULT: __________________

24. Relevance to Conservation Biology? • Should guide our thinking about understanding how areas might be recolonized—or efforts that need to be made to “_________” recolonization (i.e., human transport, corridors, etc.) • Should guide our thinking about ________ ________: big vs. small, one vs. many, near vs. far, etc.