W09_Lect2_Distribution+of+Diversity

W09_Lect2_Distribution+of+Diversity - Synopsis of good 1on1...

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Synopsis of good 1on1 questions from Monday • If California is such a tough place for plant growth, then why is California an agricultural center? – Irrigation is the key • What are the general principles we need to understand in looking at Biomes? – Climatic controls on distributions; but more for your edification than for specific knowledge. • When are pre-labs due? –9AM One estimate comes from a study of insects in 19 individual trees ( Luehea seemannii ) in Panama Terry Erwin Can you hear me now? True / False Present-day factors determining species distributions: Climate: the abiotic theater Average and annual variation in conditions of temperature and precipitation in a given region over the long-term Climate is a major determinant of the types of plants in an area. Today’s focus: climate Species are not randomly distributed on the face of the Earth Red areas = 1.4 land area but have 44% of vascular plants and 35% of 4 key vertebrate groups (mammals, amphibians, birds, and reptiles) Myers et al. 2000 Nature Biodiversity “hotspots” - places with many species that are endemic (occur in no other regions) Other regions may be “hotspots” for different groups Global Diversity Gradients General patterns in biodiversity: the latitudinal gradient
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Why are the tropics more diverse? A. Ecological hypotheses Higher carrying capacities of populations Higher primary productivity (solar energy) More stable, predictable environments B. Evolutionary hypotheses Higher diversification rates Lower extinction rates (more stable env.s) C. Historical hypotheses More time for evolution Which one is correct? Tree species richness decreases with increasing elevation Stevens 1992, American Naturalist What causes these (and other) patterns ? Which of the following is more diverse? 5 “species”, 20 individuals -16 aqua -1 red -1 ye l low - 1 blue -1 b lack 5 “species”, 20 individuals - 4 aqua -4 red -4 ye l low - 4 blue -4 b
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This note was uploaded on 10/08/2009 for the course BIS 2 taught by Professor Schwartzandkeen during the Spring '09 term at UC Davis.

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W09_Lect2_Distribution+of+Diversity - Synopsis of good 1on1...

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