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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
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
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This document was uploaded on 01/06/2014.
- Spring '13