DOI: 10.5061/dryad.hhmgqnknq
title: Extreme events, trophic chain reactions, and shifts in phenotypic selection

description: Demographic consequences of rapid environmental change and extreme
 climatic events (ECEs) can cascade across trophic levels with evolutionary
 implications that have rarely been explored. Here, we show how an ECE in
 high Arctic Svalbard triggered a trophic chain reaction, directly or
 indirectly affecting the demography of both overwintering and migratory
 vertebrates, ultimately inducing a shift in density-dependent phenotypic
 selection in migratory geese. A record-breaking rain-on-snow event and
 ice-locked pastures led to reindeer mass starvation and a population
 crash, followed by a period of low mortality and population recovery. This
 caused lagged, long-lasting reductions in reindeer carrion numbers and
 resultant low abundances of Arctic foxes, a scavenger on reindeer and
 predator of migratory birds. The associated decrease in Arctic fox
 predation of goose offspring allowed for a rapid increase in barnacle
 goose densities. As expected according to r- and K-selection theory, the
 goose body condition (affecting reproduction and post-fledging survival)
 maximising Malthusian fitness increased with this shift in population
 density. Thus, the winter ECE acting on reindeer and their scavenger, the
 Arctic fox, indirectly selected for higher body condition in migratory
 geese. This high Arctic study provides rare empirical evidence of links
 between ECEs, community dynamics and evolution, with implications for our
 understanding of indirect eco-evolutionary impacts of global change.
description: <strong>First dataset <br></strong>
 The first data set includes the data to run the correlative
 analysis, presented in Figure 2 in the article. This was based on time
 series data on Svalbard reindeer abundance, a proxy of Arctic fox
 abundance and abundance data of barnacle geese on high Arctic Svalbard.
 Annual estimates of barnacle goose population size at Ny-Ålesund were
 obtained from the results of an integrated population model. All data are accessible in published articles or
 online. The percentage of occupied dens was used as a proxy of abundance
 of Arctic foxes, based on annual records of known den sites around
 Ny‐Ålesund with pup production during summer (Fuglei et al. 2003) and were obtained from MOSJ (2021). Data of reindeer abundances (population
 counts) were available from Supplementary Information Figure S1 in
 Hansen et al.
 (2019). Data of goose
 abundance (total population size estimated with an integrated population
 model) were obtained from (Layton-Matthews et al. 2019). Please see
 respective publications for details on the data collection
 methods. <br> <strong>Second
 dataset</strong> The second dataset includes
 individual-level data to
 analyse demography-trait relationships (Figure 3) and to model
 eco-evolutionary dynamics (Figure 4). The data includes a unique bird identification
 number, observation year, body mass (g), tarsus length (cm), whether that
 individual survived the following breeding season (I) and the number of
 recruits of both sexes contributed by that individual to the following
 breeding season (B). These data were available over the study period
 1991-1999. Females were caught during the breeding season, more
 specifically during the moulting period when parents raise their
 offspring, and ringed with colour and metal identification rings.
 Recapture data were based on daily observations of ringed individuals
 around Ny-Ålesund. We assessed reproduction based on observations of
 adults with fledged offspring at the beginning of August. The number of
 recruits the following year was based on parentage data where families
 were monitored after capture (and ring marking) to attribute
 parent–offspring relationships (ref 64 in article).
 <strong>We encourage
 persons wishing to use these data in further analyses to contact the data
 owner and curator: </strong><strong>Maarten J.J.E. Loonen (email:
 m.j.j.e.loonen@rug.nl). </strong><br>
description: # Extreme events, trophic chain reactions, and shifts in phenotypic
 selection
 [https://doi.org/10.5061/dryad.hhmgqnknq](https://doi.org/10.5061/dryad.hhmgqnknq) Two datasets are enclosed, the first to perform the correlative analyses (Figure 2), the second to estimate the demography-trait relationships (Figure 3) and estimate density-dependent phenotypic selection (Figure 4). ## First dataset: Correlative analysis Time series data of a proxy of Arctic fox abundance, wild Svalbard reindeer abundance, and barnacle geese abundance data. All data are accessible in published articles or online. The percentage occupied dens was used as a proxy of abundance Arctic foxes, based on annual records of known den sites around Ny‐Ålesund with pup production during summer (Fuglei et al. 2003) and were obtained from MOSJ (2021). Data of reindeer abundances (population counts) were available from Supplementary Information Figure S1 in Hansen et al. (2019). Data of goose abundances (total population size estimated with an integrated population model) were obtained from (Layton-Matthews et al. 2019). Data are presented a PDF with a description of the data and as a .csv file. <br> ## Second dataset: Phenotypic selection Individual-level data used to analysis demography-trait relationships (Figure 3) and to model eco-evolutionary dynamics (Figure 4).Data includes a unique bird identification number, observation year, body mass (g), tarsus length (cm), whether that individual survived the following breeding season (I) and the number of recruits of both sexes contributed by that individual to the following breeding season (B). Data are included as a .csv sfile We encourage persons wishing to use these data in further analyses to contact the data owner and curator: Maarten J.J.E. Loonen Faculty of Arts Arctic and Antarctic studies — Faculty Board A-weg 30 9718 CW Groningen The Netherlands Email: m.j.j.e.loonen@rug.nl