Species Richness in Ecological Communities Flashcards Preview

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Flashcards in Species Richness in Ecological Communities Deck (11)
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species richness

# of species present in given ecological community


species diversity

variety & relative abundance of species present in ecological community



extent of similarity btwn 2 species based on relative abundance
- types: high or low
- high evenness = more species diversity & richness


patter of theory of island biogeography

(1) large patches of habitat contain more species than do smaller ones
(2) ocean islands have smaller # of species than same size on continent


process of theory of island biogeography

(1) immigration & emigration
(2) island size & isolation


immigration & emigration process of TOIB

(1) immigration decline as island species # increases
(2) competition prevent new species from establishing
(3) extinction rates increase, species richness increase - extinction


island size & isolation process of TOIB

(1) immigration rates higher on large islands, close to mainland
(2) extinction rates highest on small islands far from shore
(3) species richness greater on large & near shore islands


prominent explanations for latitudinal gradient in species diversity

(1) high-productivity hypothesis
(2) energy hypothesis
(3) area & age hypothesis


high-productivity hypothesis

(1) increase speciation rates, decrease extinction rates
(2) increase biomass production -> support more herbivores -> more herbivore predators
(3) higher population -> more intense competition
(4) speciation rates increase as niche differentiation occurs w/in herbivor, parasite, predator & scavenger populations


energy hypothesis

extension of high-productivity hypothesis

(1) some highly productive habitats are species poor
(2) high T, more species diversity - increase productivity
(3) high energy inputs = key to high speciation & low extinction rates


area & age hypothesis

temperate & arctic latitudes covered w/ ice over last 2 million years but tropical regions were not