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Mattsson et al lbwo pva v2
1. A Stochastic Population Viability Analysis for Rare Large-bodied Woodpeckers… with Implications for the Ivory-billed Woodpecker B. J. Mattsson, R. S. Mordecai, M. J. Conroy, J. T. Peterson, R. J. Cooper, & H. Christensen Warnell School of Forestry & Natural Resources University of Georgia, Athens
18. Results: Years to Extinction 95 th 75 th 50 th 25 th 5 th 200 iterations
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24. Allee Effect Exposed ♀ Constant Positive feedback: Improved mate finding t = t + 1 t ? 100? END Female i Nads t+1 = Nads t + Njvs t Juvenile produced? P(jvs ) Adult survives? B(ads ) START: Year = t Tally no. adults ( Nads t ) Tally no. juveniles produced ( Njvs t )
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29. A New, Demographic Robustness Paradigm? Moderate-high demographic rates ensure persistence of small populations despite moderate environmental stochasticity and Allee effect
If there was one word to describe the model we developed, it would be “simple”.
We have number of initial adults on X and predicted extinction rate on Y Each line represents one combination of input values that resulted in population persistence When survival and fecundity were at least intermediate, populations were likely to persist despite an initial population size of 5. Otherwise, populations were unlikely to persist.
We again have number of initial adults on X and predicted extinction rate on Y {Each line represents a combination of input values that resulted in population persistence} In contrast with life history variation where there was no Allee effect, here when initial population size dropped from 30 to 17, persistence became unlikely. This was only true, however, when survival was at least intermediate. When survival was low, even larger populations were unlikely to persist.
![Not-So-Large-Bodied Outline ,[object Object],[object Object],[object Object],[object Object],[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)