DOI: 10.5061/dryad.nk98sf7z8
title: Data from: The costs of living on the coast: reduction in body size and size-specific reproductive output in coastal populations of a widespread amphibian

description: Body size is a critical component of organismal biology. Body size is
 known to be influenced by a plethora of environmental conditions, among
 which exposure to large-scale variations of salinity has been
 comparatively overlooked. Yet, exposure to salinity is known to affect
 energetic allocation toward growth and reproduction. In this study, we
 investigated the morphological differences between inland and coastal
 individuals of spined toads (Bufo spinosus) in Western France. 
 We measured adult morphology both outside and during the reproductive
 season on 190 individuals, and assessed reproduction in pairs originating
 from inland (N=20) and coastal (N=30) environments. Overall, we found that
 adult coastal toads were smaller and lighter than inland individuals.
 Reproductive correlates of these differences included lower fecundity and
 smaller egg size (but higher egg density) in coastal females.
 Interestingly, these differences were not allometric correlates of body
 size, as coastal females invested proportionally less in all components of
 reproduction (fecundity, egg size and egg protection). These results
 suggest altered resource allocation to growth and reproduction in coastal
 amphibians, which may be related to the marked spatial gradient of
 salinity (measured in reproductive ponds) and the associated costs of
 osmoregulation (higher osmolality in coastal individuals), for which local
 adaptation and higher tolerance to salinity remains to be tested.
description: The dataset is related to the article “The costs
 of living on the coast: reduction in body size and size-specific
 reproductive output in coastal populations of a widespread amphibian”.
 This article was meant to compare coastal and inland individuals of the
 species <em>Bufo spinosus</em>. These individuals were
 captured either during reproduction (50 amplectant pairs [amplexus], each
 constituted of one male [M] and one female [F], captured in ponds, from
 16/02/2022 to 02/03/2022), or outside reproduction (90 individuals
 captured on roads, from 08/09/2022 to 15/10/2022). We provided two
 datasets, each one corresponding to one period of capture. These datasets
 allow us to determine differences in investment during reproduction, but
 also in morphology, between coastal and inland populations. Precise
 locations can be given on demand but were not included in the dataset as
 some captures were performed in natural reserves. Site (coastal or inland)
 is indicated, as well as date of capture. Individuals or amplectant pairs
 are identified by a letter corresponding to the site of capture (C for
 coastal and M for inland) as well as a number corresponding to their order
 of capture.  During
 reproduction, for each amplexus (constituted of one male and one female),
 we assessed time to laying (time between capture and laying), egg strings’
 length (mm), eggs’ diameter (mm), eggs’ density (number of eggs/mm) and
 number of eggs (all determined using the ImageJ software), size of both
 males and females (SVL: Snout-Vent-Length, given in mm), and calculated
 the size difference between a male and female in the same amplexus (both
 absolute and given in percentage), the initial (at capture) and final
 (after egg laying) of males and females, and the difference in mass
 between capture and egg laying (both absolute and given in
 percentage).  Outside
 reproduction, we captured 45 males (M) and 45 females (F) independently
 (these individuals were opportunistically captured on roads in either
 coastal or inland locations), and computed their size (SVL:
 Snout-Vent-Length, given in mm) and mass (given in
 g).