DOI: 10.5061/dryad.14cr5345
title: Data from: Body size evolution on islands: are adult size variations in tiger snakes a non-adaptive consequence of selection on birth size?

description: Mean adult size has been used as the traditional measure of body size to
 explain trends of insular gigantism and dwarfism in a wide array of taxa.
 However, patterns of variation in body size at birth have received
 surprisingly little attention, leaving open the possibility that adult
 body-size differences are nonadaptive consequences of selection acting on
 neonate body size. Here I used an empirical and correlative approach to
 test this hypothesis in a mosaic of 12 island and mainland snake
 populations in Australia. Data collected on 597 adult and 1,084 neonate
 tiger snakes showed that (1) both adult and neonate mean body sizes varied
 strongly across populations; (2) prey diversity and size convincingly
 explained birth-size variations: birth size—notably, gape size—correlated
 with prey size; (3) neonate snout-vent length was significantly correlated
 with neonate gape size; and (4) neonate snout-vent length was
 significantly correlated with adult snout-vent length. Postnatal growth
 rates recorded under common-garden conditions differed across populations
 and were correlated with mean prey size. These data collectively suggest
 that (1) prey size is the main driver for the evolution of body size at
 birth in gape-limited predators, (2) adult size variations may reflect
 selective forces acting on earlier life stages, and (3) adult size
 variations may also reflect resource availability during ontogeny
 (notably, prey diversity).
description: Aubret
 53172Excel file contains 4
 sheets. First sheet titled Adult Tiger snakes contains field data
 collected on Adult Tiger snakes (sex, body mass and snout-vent length).
 Sheet titled Mothers litters and neonates contains laboratory and museum
 data about reproductive output in female tiger snakes for several
 populations. For each female is given birth date, mean litter body mass
 (calculated average body mass for all neonates in a given litter), mean
 litter svl (calculated average snout vent length for all neonates in a
 given litter), and mean litter jaw (calculated average jaw length for all
 neonates in a given litter). Sheet titled Prey contains data collected in
 Museum collection for prey available at each study site. Latin names are
 given with body mass and maximum circumference of each prey item. Sheet
 titled Growth experiment contains experimental data on growth rate and
 food consumption in neonate Tiger snakes from several populations.
 Headings indicate for each mother its population of origin, neonate
 identification number, birth date and morphometrics at birth. Body mass
 and snout vent length are recorded every two months until the end of the
 experiment. Column titled Total growth in body mass indicates the
 difference in body mass between the start and the end of the experiment.
 The two last columns are Total food (total amount of food consumed by each
 neonate over the course of the experiment) and Length of experiment (total
 duration of the experiment). Conversion rates were calculated (column
 titled Increase in body mass per g of food) and daily growth rates in body
 mass (increase in body mass in mg per day). Similar calculation were made
 for snout vent length (increase in svl per g of food; increase in svl in
 mm per day).