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Population DynamicsChapter 10

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Africanized Honeybees

http://www.youtube.com/watch?v=e7fUXw-5T2Q

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Collared Doves

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Rapid Changes in Response to…

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Dispersal in Rivers and Streams

• Stream dwellers have mechanisms to allow them to maintain their stream position.– Streamlined bodies– Bottom-dwelling– Adhesion to surfaces

• Tend to get washed downstream in spates.– Muller hypothesized populations maintained via

dynamic interplay between downstream and upstream dispersal.• Colonization cycle

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Dispersal in Rivers and Streams

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Metapopulations

• A metapopulation is made up of a group of subpopulations living on patches of habitat connected by an exchange of individuals.– Alpine Butterfly - Roland et al.– Lesser Kestrels - Serrano and Tella.

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Patterns of Survival

• Three main methods of estimation:– • Identify individuals born at same time and keep records

from birth.– • Record age at death of individuals.

– • Calculate difference in proportion of individuals in each

age class.• Assumes differences from mortality.

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High Survival Among the Young

• Murie collected Dall Sheep skulls, Ovis dalli.– Major Assumption: Proportion of skulls in each

age class represented typical proportion of individuals dying at that age.• Reasonable given sample size of 608.

– Constructed _________________________.• Discovered bi-modal mortality.

– <1 yr.– 9-13 yrs.

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Survivorship Curves

• : Majority of mortality occurs among older individuals. – Dall Sheep

• : Constant rate of survival throughout lifetime.– American Robins

• : High mortality among young, followed by high survivorship.– Sea Turtles

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Survivorship Curves

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Age Distribution

• Age distribution of a population reflects its history of survival, reproduction, and growth potential.

• Miller published data on age distribution of white oak (Quercus alba).– Determined relationship between age and trunk

diameter.– Age distribution biased towards young trees.• Sufficient reproduction for replacement.

– Stable population

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Age Distribution

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Age Distribution

• Rio Grande Cottonwood populations (Populus deltoides wislizenii) are declining.– Old trees not being replaced.– Reproduction depends on seasonal floods.• Prepare seed bed.• Keep nursery areas moist.

– Because floods are absent, there are now fewer germination areas.

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Rates of Population Change

• : Number of young born per female.

• : Tabulation of birth rates for females of different ages.

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