Bio%20201%20S12%20Lect%2015%20%28True%29%20v3

If our example was in days not years

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Unformatted text preview: on size: barnacle seAlement Carrying capacity Logistic growth – Testing assumptions –  Early laboratory cultures (Pearl 1927) ‘r’ versus ‘K’ strategies r (‘r selected’; r selec8on)   rapid popula:on growth   high Reproduc:ve output   high dispersal ability   poor compe::ve ability K (‘K selected’; K selec8on)   slow popula:on growth   reproduc:ve output low   dispersal low   good compe:tors, displace others   stable popula:on size at the carrying capacity r = rapid popula:on growth, high Reproduc:ve output - poor compe::ve ability K = slow popula:on growth, low reproduc:ve output - good compe:tors, displace others birth and death rates are usually density dependent •  lower densi:es – higher popula:on growth –  higher birth rates, lower death rates •  higher densi:es – lower popula:on growth –  lower birth rates, higher death rates •  could be due to –  resources –  predators –  diseases •  some factors, e.g. weather and natural disasters have effects that may not depend on popula:on density three density dependent effects on song sparrow popula:ons plus one density independent effect (not shown): harshness of winters popula:on fluctua:ons •  seen in all species to some degree •  but some popula:ons more stable than others –  tend to be species with large, long- lived individuals with low reproduc:ve rates •  e.g. birds and mammals fluctuate less than insects (small, short genera:on :mes, high reproduc:ve rates; highly vulnerable to environmental fluctua:ons) hLp://www.admin.mtu.edu/urel/PressReleases/ feature/wolves/moosewolf successful reproduc8ve years can have long las8ng effects strategy of many tree species: •  reproduce synchronously (all members of a popula:on, great reproduc:ve effort all in one year/season) –  other years, very liLle reproduc:on •  reproduce episodically –  semi- irregular and unpredictably hLp://www.norcalblogs.com/sustainable/acorns1.jpg •  species that depend on these trees (e.g. seed eaters and herbivores) tend to travel around to find the popula:ons in large reproduc:ve years (mast years) Abrahamson, W.G. and Layne, J.N. 2003 Long- Term PaLerns of Acorn Produc:on for Five Oak Species in Xeric Florida Uplands. Ecology 84: 2476- 2492. some generali:es about densi:es •  species that u:lize abundant resources tend to reach higher densi:es than those that u:lize rare or sparse resources –  e.g. herbivores more common than carnivores •  body size correlates strongly with maximum densi:es –  small organisms reach higher densi:es than larger organisms •  highly social species can reach very high densi:es –  humans, social insects •  low densi:es tend to be seen in –  new species (e.g. plant hybrid species) –  species on the verge of ex:nc:on...
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This note was uploaded on 10/02/2013 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.

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