Fall 2010 IB Workshop Series sponsored by IB academic advisors What can I do with a B.S. in IB? Thursday, Oct. 27 4:00-5:00pm 162 Noyes Lab Career Center Staff will be on hand to discuss the job search, and job opportunities and ideas for IB majors.

OBJECTIVES Species Diversity at scales above local Regional SD Equilibrium theory + Island Biog. Theory Latitudinal SD Continental SD Global SD

What affects regional species diversity? Area Equilibrium Theories A. Additions = Losses B. Island Biogeography Theory Habitat heterogeneity Suitability of physical conditions Isolation from centers of diversity

Equilibrium theories: diversity reflects a balance between processes that add vs. remove species. ***What processes add species? speciation immigration What processes subtract species? extinction emigration Differences in diversity between communities reflect differences in relative rates of these processes.

*** What is the pattern? What two equilibrium factors may explain it? Figure 1

Equilibrium theory of island biogeography: # species = balance of immigration on a regional scale vs. extinction on local scale. Figure 2

Islands closer to the mainland support more species because of higher immigration rates. Figure 3

Larger islands support more species because of lower extinction rates. Figure 4

Which hypotheses are illustrated in Figure (a) + (b)? Figure 5

Applications of Island Biogeography Theory to: Terrestrial systems mountain tops as islands fragmented remnants as islands Design of nature reserves

Regional-scale patterns of diversity also reflect: Habitat heterogeneity Suitability of physical conditions Isolation from centers of diversity

***What are three patterns in regional species diversity? What factor accounts for each pattern? Figure 7

How do patterns of species richness differ among taxa? Why? Figure 8

What are two patterns of species turnover (beta diversity) at regional scales? Figure 9

What is the major change in longitudinal beta diversity with increasing latitude? Which latitude has more climatic uniformity? Figure 10

Multiple scales of species diversity Local Regional Latitudinal Continental Global

***What is latitudinal gradient in woody species diversity? What explains it? Figure 11

Compare the relationship of climate variables and species richness along latitude. Figure 12

Hypotheses to explain latitudinal gradient in species diversity… Time and stability Heterogeneity in space and time (Vegetation and food complexity) Herbivore and pathogen pressure Competition/niches Disturbance

Multiple scales of species diversity Local Regional Latitudinal Continental Global

How do history + biogeography + climate change influence species diversity?

History of life is gauged by geologic time scale. Cretaceous 150mya Cambrian 600mya --> Permian 286mya

Equilibrium theory in continental communities: balance between speciation and extinction on regional scale Figure 13

***Has diversity been constant? What is role of extinction vs. additions? Figure 14

Catastrophes --> what are consequences - short- and long-term? ***Asteroid impact--> extinctions of what? Figure 15

Multiple scales of species diversity Local Regional Latitudinal Continental Global

Continental drift --> positions of continents change over geologic time. Climate changes too --> influences geography of evolution Figure 16

Continental drift changed routes of dispersal via separation + joining. Figure 17

What explains great variation in species richness over the earth? Figure 18

Wallace: Major zoogeographic regions reflect long-term evolutionary isolation. Figure 19

***How explain same body form in multiple continents? Convergence or divergence? Figure 20

Exchanges of biotas after joining of continents: e.g. The Panama land bridge Figure 21

***What are major changes among regions from Tertiary to present? What accounts for them? What are major differences today? Figure 22

Climate change in N.A. shifted species diversity; Miocene drier with grasslands. Fig Figure 23

***Why did climate change during the Ice Age contribute to Europe’s low species richness? Figure 15 Figure 24

What is relationship between tolerance of low temperature / rainfall and extinction? Figure 25

Oak trees shifted their distributions after end of most recent glacial period. Figure 26

How does ‘dispersal limitation’ explain differences in post-glacial expansion? A,b = small; c,d = large seeded species Figure 27

How does climatic history determine species distributions + community composition? Figure 28

Climate change influences distributions of organisms. How does the historical extent of climate zones help to explain global patterns of species richness? Figure 29

Has diversification been faster in tropics than temperate area? Figure 30

Where does more diversification occur? Why? How does this relate to more species near 0 than at higher latitudes? Figure 31