Data from: Body size evolution on islands: are adult size variations in tiger snakes a non-adaptive consequence of selection on birth size?

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).