DOI: 10.5061/dryad.7pvmcvdw2
title: Maximization of fitness by phenological and phenotypic plasticity in range expanding rabbitfish (Siganidae)

description: Global warming is modifying the phenology, life-history traits and
 biogeography of species around the world. Evidence of these effects have
 increased over recent decades; however, we still have a poor understanding
 of the possible outcomes of their interplay across global climatic
 gradients, hindering our ability to accurately predict the consequences of
 climate change in populations and ecosystems. We examined the effect that
 changes in biogeography can have on the life-history traits of two of the
 most successful range-extending fish species in the world: the tropical
 rabbitfishes Siganus fuscescens and Siganus rivulatus. Both species have
 established abundant populations at higher latitudes (poleward) in the
 northern and southern hemispheres and have been identified as important
 ecological engineers with the potential to alter the community structure
 of seaweed forests (Laminariales and Fucales) in temperate regions.
 Life-history trait information from across their global distribution was
 compiled from the published literature and meta-analyses were conducted to
 assess changes in (i) the onset and duration of reproductive periods, (ii)
 fecundity, (iii) size at maturity, (iv) growth rates, (v) maximum body
 sizes and (vi) longevity in populations at the leading edge of range
 expansion in relation to sea surface temperature and primary productivity
 (i.e., a common proxy for nutritional resource levels). Populations at
 highest latitudes had shortened their reproductive periods and reduced
 growth rates, taking longer to reach sexual maturity and maximum sizes,
 but compensated this with higher fecundity per length class and longer
 lifespans than populations in warmer environments. Low primary
 productivity and temperature in the Mediterranean Sea resulted in lower
 growth rates and body sizes for S. rivulatus, but also lower length at
 maturity, leading to increased life-time reproductive output. The results
 suggest that plasticity in the phenology and life-history traits of
 range-expanding species would be important to enhance their fitness in
 high latitude environments, facilitating their persistence and possible
 further poleward expansions. Quantifying the magnitude and direction of
 these responses can improve our understanding and ability to forecast
 species redistributions and its repercussions in the functioning of
 temperate ecosystems. 
description: Quantitative information was
 obtained from the literature using the following two independent search
 criteria in the Web of Science: {*Siganus OR rabbitfish* AND *reproduction
 OR fecundity OR spawning*} and {*Siganus OR rabbitfish* AND *size OR
 length OR growth OR Age OR abundance*}. Publications with useful
 information were then selected, and the references cited within, as well
 as the publications that had cited each of these works, were reviewed in
 turn to obtain more publications that were not detected by the initial
 online searches. <em>Siganus fuscescens</em> and
 <em>Siganus canaliculatus</em> were considered synonyms and
 data from studies of these were pooled (Hsu et al. 2011). Data were extracted from tables and
 scatterplot figures using the software DataThief (Flower et al. 2016). In all cases, length was standardized to fork
 length (FL) using the length-length equations reported in FishBase for
 <em>S. fuscesens</em> (Froese & Pauly 2019), and by Shakman et al. (2008) for <em>S. rivulatus</em>. Information on growth and longevity for both species of rabbitfish was only extracted from studies that reported growth curves based on length-at-age information produced from the analysis of sectioned sagittal otoliths of females and males. In addition, we estimated length-at-age information for populations of S. fuscescens in Western Australia from specimens collected in temperate (Perth) and tropical environments (Pilbara and Kimberley).