Data from: Hotter nests produce hatchling lizards with lower thermal tolerance

In many regions, the frequency and duration of summer heatwaves is
predicted to increase in future. Hotter summers could result in higher
temperatures inside lizard nests, potentially exposing embryos to
thermally stressful conditions during development. Potentially,
developmentally plastic shifts in thermal tolerance could allow lizards to
adapt to climate warming. To determine how higher nest temperatures affect
the thermal tolerance of hatchling geckos, we incubated eggs of the
rock-dwelling velvet gecko, Amalosia lesueurii, at two fluctuating
temperature regimes to mimic current nest temperatures (mean 23.2°C, range
10–33°C, ‘cold’) and future nest temperatures (mean 27.0°C, range 14–37°C,
‘hot’). Hatchlings from the hot incubation group hatched 27 days earlier
and had a lower critical thermal maximum (CTmax 38.7°C) and a higher
critical thermal minimum (CTmin 6.2°C) than hatchlings from cold
incubation group (40.2 and 5.7°C, respectively). In the field, hatchlings
typically settle under rocks near communal nests. During the hatching
period, rock temperatures ranged from 13 to 59°C, and regularly exceeded
the CTmax of both hot- and cold-incubated hatchlings. Because rock
temperatures were so high, the heat tolerance of lizards had little effect
on their ability to exploit rocks as retreat sites. Instead, the timing of
hatching dictated whether lizards could exploit rocks as retreat sites;
that is, cold-incubated lizards that hatched later encountered less
thermally stressful environments than earlier hatching hot-incubated
lizards. In conclusion, we found no evidence that CTmax can shift upwards
in response to higher incubation temperatures, suggesting that hotter
summers may increase the vulnerability of lizards to climate warming.