DOI: 10.5061/dryad.m905qfv5p
title: Phenological mismatch affects individual fitness and population growth in the winter moth

description: Climate change can severely impact species that depend on temporary
 resources by inducing phenological mismatches between consumer and
 resource seasonal timing. In the winter moth, warmer winters caused eggs
 to hatch before their food source, young oak leaves, became available.
 This phenological mismatch changed the selection on the temperature
 sensitivity of egg development rate. However, we know little about the
 fine-scale fitness consequences of phenological mismatch at the individual
 level and how this mismatch affects population dynamics in the winter
 moth. To determine the fitness consequences of mistimed egg hatching
 relative to timing of oak budburst, we quantified survival and pupation
 weight in a feeding experiment. We found that mismatch greatly increased
 mortality rates of freshly hatched caterpillars, as well as affecting
 caterpillar growth and development time. We then investigated whether
 these individual fitness consequences have population-level impacts by
 estimating the effect of phenological mismatch on population dynamics,
 using our long-term data (1994–2021) on relative winter moth population
 densities at four locations in the Netherlands. We found a significant
 effect of mismatch on population density with higher population growth
 rates in years with a smaller phenological mismatch. Our results indicate
 that climate change-induced phenological mismatch can incur severe
 individual fitness consequences that can impact population density in the
 wild.
description: Field data on winter moths were collected yearly since 1994 in
 four forests around Arnhem, the Netherlands, using simple funnel traps to
 catch adult moths in winter (see [Van Asch et al. 2013, Nat Clim Change]
 for details). Eggs collected from these wild adults were kept in a field
 shed at the Netherlands Institute of Ecology. 
 Deposited field data for the period 1994–2021 include per year:
 number of adult moths collected, with for each moth (individual-based data
 with individual identifier): number of eggs laid, spring seasonal timing
 of their eggs kept in our field shed, and spring seasonal timing of
 budburst of oak trees in the field on which adults were caught.
 Experimental data were collected in a caterpillar feeding
 experiment in the Spring of 2021, using eggs from the long-term field
 monitoring (described above). The experiment consisted of a split-brood
 design, where the timing of hatching of eggs laid by each female was
 manipulated to induce staggered hatching. Caterpillars were then divided
 over different photoperiod treatments (constant photoperiod or naturally
 changing photoperiod) and different phenological mismatch treatments
 (hatching before [0–4 days] or after oak budburst [1–5 days], and then fed
 with oak leaves accordingly).  Deposited experimental
 data include per caterpillar (individual-based data with individual
 identifier): parent origin (Catch area, tree, and date), hatch date, death
 date (if died before pupating), pupation date, pupation weight, date of
 adult emerging, adult weight, and adult sex.