BIO 200 Lecture Notes - Lecture 30: Species Richness, Temperate Climate, Circular Reasoning
18 Dec 2018
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Document Summary
Latitudinal gradient in species diversity: a bit on species richness, what is lat gradient, hypotheses for cause of gradient. Latitudinal gradient in species diversity: species richness- # species present. More area= more rich bc bigger space means more habitats. Heterogeneous habitats= more niche (diversity: evenness- relative abundance of each species (kinda like distribution) Lat gradient in species diversity: #species peaks around equator (27-28n) and sorta bell curves out toward poles but why: climate stability- more seasons (disturbances) in temperate zone so tropics more diverse bc more stable. Tropics stable in temp but not in precipitation: inc competition- tighter niche packing in tropics meaning indiv survive in narrower niches aka more specialist. Circular reasoningpredation can"t be cause of more diversity; predators are part of diversity: inc energy- eco hypothesis; stable temps in tropics mean more solar energy. Evidence: richness correlates w annual evapotranspiration (aet) aka measure of heat/energy. Problem: aet correlates but doesn"t cause more diversity; energy isn"t full answer.
