Preprint Article Version 1 NOT YET PEER-REVIEWED

Estimating Density and Temperature Dependence of Juvenile Vital Rates Using a Hidden Markov Model

Current address: University of California, Los Angeles, CA 90095, USA
Version 1 : Received: 16 December 2016 / Approved: 18 December 2016 / Online: 18 December 2016 (09:33:13 CET)

How to cite: McElderry, R. Estimating Density and Temperature Dependence of Juvenile Vital Rates Using a Hidden Markov Model. Preprints 2016, 2016120092 (doi: 10.20944/preprints201612.0092.v1). McElderry, R. Estimating Density and Temperature Dependence of Juvenile Vital Rates Using a Hidden Markov Model. Preprints 2016, 2016120092 (doi: 10.20944/preprints201612.0092.v1).

Abstract

Organisms in the wild have cryptic life stages that are sensitive to changing environmental conditions and can be difficult to survey. In this study, I used mark-recapture methods to repeatedly survey Anaea aidea (Nymphalidae) caterpillars in nature, then modeled caterpillar demography as a hidden Markov process to assess if temporal variability in temperature and density influence the survival and growth of A. aidea over time. Individual encounter histories result from the joint likelihood of being alive and observed in a particular stage, and I included hidden states by separating demography and observations into parallel and independent processes. I constructed a demographic matrix containing the probabilities of all possible fates for each stage, including hidden states, e.g., eggs and pupae. I observed both dead and live caterpillars with high probability. Peak caterpillar abundance attracted multiple predators, and survival of fifth instars declined as per capita predation rate increased through spring. A time lag between predator and prey abundance was likely the cause of improved fifth instar survival estimated at high density. Growth rates showed an increase with temperature, but the most likely model did not include temperature. This work illustrates how state-space models can include unobservable stages and hidden state processes to evaluate how environmental factors influence vital rates of cryptic life stages in the wild.

Subject Areas

Anaea aidea; caterpillar demography; multi-state mark-recapture; state-space model; stage-structured matrix

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