Lectures6-7_4pp

Net reproductive rate r0 average number of offspring

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Unformatted text preview: rage number of offspring produced by an individual during its entire lifetime! R0 = the product of survival and fecundity, summed over all age classes = ! lxmx! R0 = 1(0) + (0.8)(0.2) + (0.6)(0.3) + (0.4)(1) + (0.4)(0.6) + (0.2)(0.2) + (0)(0) = 1.02! ! Not all individuals are equal in their effect on future population growth:! ! The value of an individual to pop. growth varies by age:! #-young individuals have a lifetime left, but some probability of #not surviving to reproduce at all! #-older individuals have less life left, but are assured of #reproducing if they have made it that far.! What does it mean to have R0 > 1 ? R0 < 1? R0 = 1? ! R0>1 means each individual is leaving more than 1 offspring before he die, population is increasing. r can be estimated using R0 as: ln (R0 / Generation Time) (but we aren t going to do this…)! What you need to know to determine reproductive value:! (1)  Age-specific survivorship! If Type III survivorship: young individuals worth little (most die)! ! If Type I survivorship: young individuals worth much, as they have high prob of survival and a lifetime of reproduction.! reproductive value - the expected reproduction of an individual from their current age onward! Application of reproductive value: Which is a more effective conservation strategy?! 1. Help hatchlings survive the first year of life ( Headstarting )! 1 of 100 survives (2)  Age-specific fecundity! !Age of first reproduction: (determines how long an individual must survive before having any reproductive value)! ! How does fecundity change with age?! ! WHO CARES? ! Reproductive value tells you which age classes most influence future population growth.! 2. Protect adults by requiring fishing net to have escapes for adult turtles (TED)! turtles...
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This document was uploaded on 01/06/2014.

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