Details

Autor(en) / Beteiligte

• Cordero, Gerardo A.
• Balk, Michelle L.
• Pérez‐González, César E.
• Solberg, Lisa M.
• Doody, Jeremiah Sean
• Plummer, Michael V.
• Janzen, Fredric J.

Titel

Geographic variation in incubation temperatures promoting viable offspring production in broadly co‐distributed turtles

Ist Teil von

• Journal of experimental zoology. Part A, Ecological and integrative physiology, 2024-06, Vol.341 (5), p.509-524

Ort / Verlag

United States: Wiley Subscription Services, Inc

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• Organisms whose early life stages are environmentally sensitive produce offspring within a relatively narrow range of suitable abiotic conditions. In reptiles, development rate and survival are often maximized if incubation temperatures remain under 31°C, though this upper bound may vary within and among species. We addressed this expectation by comparing responses to egg incubation at 30°C versus 33°C in congeneric turtle species pairs with broad syntopic geographic distributions. In the two softshell turtles (Apalone spp.), the greatest changes in development rate and phenotypic variance were observed in the northernmost population, which had a low survival rate (40%) at 33°C. The presumably suboptimal temperature (33°C) for northern populations otherwise yielded 76%–93% survival rates and fast swimming speeds in more southern populations. Still, in one species, northern hatchlings incubated at 33°C matched the elevated speeds of their southern counterparts, revealing a countergradient response. In northern populations of the two map turtles (Graptemys spp.), survival was also reduced (28%–60%) at 33°C and the development rate (relative to 30°C) increased by up to 75%. Our experiments on divergent taxa with similar nesting ecologies substantiate that the optimal thermal range for offspring production is variable. These findings encourage further work on how population‐ and species‐level differences relate to local adaptation in widely distributed oviparous species. Geographic variation in developmental temperatures was evaluated in North American turtles. Temperatures that were favorable to egg incubation in southern populations negatively impacted offspring survival in northern populations. The hottest temperature resulted in low hatching success while yielding fast hatchlings in some northern populations, suggesting that optimal thermal regimes differ according to trait and population. Research highlights Geographic variation was evaluated in  turtles. High  egg incubation temperatures reduced offspring survival in the north, with a countergradient response in some populations. The optimal thermal regimes likely differ according to trait and population.