Dayananda Buddhi, Murray Brad R, Webb Jonathan K
School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia.
School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia
J Exp Biol. 2017 Jun 15;220(Pt 12):2159-2165. doi: 10.1242/jeb.152272.
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, , 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 (CT 38.7°C) and a higher critical thermal minimum (CT 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 CT 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 CT can shift upwards in response to higher incubation temperatures, suggesting that hotter summers may increase the vulnerability of lizards to climate warming.
在许多地区，预计未来夏季热浪的频率和持续时间将会增加。更炎热的夏季可能导致蜥蜴巢穴内温度升高，这有可能使胚胎在发育过程中暴露于热应激环境中。从潜在角度看，热耐受性的发育可塑性变化可能使蜥蜴适应气候变暖。为了确定巢穴温度升高如何影响孵化出的壁虎的热耐受性，我们将岩栖天鹅绒壁虎的卵在两种波动温度条件下进行孵化，以模拟当前巢穴温度（平均23.2°C，范围10 - 33°C，“冷”）和未来巢穴温度（平均27.0°C，范围14 - 37°C，“热”）。与冷孵化组的幼体（分别为40.2°C和5.7°C）相比，热孵化组的幼体提前27天孵化，其临界热最大值较低（CT为38.7°C），临界热最小值较高（CT为6.2°C）。在野外，幼体通常在公共巢穴附近的岩石下栖息。在孵化期，岩石温度范围为13至59°C，经常超过热孵化和冷孵化幼体的CT。由于岩石温度如此之高，蜥蜴的耐热性对它们利用岩石作为避难所的能力影响很小。相反，孵化时间决定了蜥蜴是否能够利用岩石作为避难所；也就是说，晚孵化的冷孵化蜥蜴比早孵化的热孵化蜥蜴遇到的热应激环境更少。总之，我们没有发现证据表明CT会随着孵化温度升高而向上变化，这表明更炎热的夏季可能会增加蜥蜴对气候变暖的脆弱性。
