Estimating postnatal dispersal: tracking the unseen dispersers

Publication Type:Journal Article
Year of Publication:2005
Authors:Johnson, DM, Horvitz, CC

Postnatal dispersal, defined as dispersal from the natal patch soon after reaching maturity, is common in a variety of insect species. Postnatal dispersal may increase connections among subpopulations and, thus, significantly affect local population dynamics in metapopulation and source-sink contexts. Yet most mark-recapture studies,of insects miss the postnatal dispersal phase because it comes soon after eclosion. Cephaloleia fenestrata (Chrysomelidae) is a specialist herbivore of the rolled leaves of Pleiostachya pruinosa (Marantaceae, common name "prayer plant"). Some P. pruinosa patches were flooded prior to the onset of this study, extirpating the majority of C. fenestrata in the flood zone and providing a natural experiment and an opportunity to observe recolonization dynamics. We built a spatially explicit population projection matrix model to simulate spatial population dynamics of C. fenestrata. The model was a poor fit to the empirical data. Adding postnatal dispersal to the model resulted in a much better model fit. This study suggests that 81% of C. fenestrata disperse from the natal site soon after eclosion. Model simulations indicated that postnatal dispersal increases the mean population size in the flood zone more than six-fold and the standard deviation more than three-fold. Herein we present an implicit method of estimating postnatal dispersal when marking animals before the postnatal dispersal phase is problematic.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith