JMIH 2016: The Effect of Incubation Moisture on Desiccation Rate

Corey Cates, a PhD student in the Warner Lab presented his latest
results on desiccation tolerance in Anolis sagrei. Desiccation tolerance
is resistance to water loss and is crucial for lizards especially in dry
habitats. Lizards have parchment-shell eggs that take up water from
the environment during incubation. Corey used two incubation conditions to
test whether desiccation tolerance changes throughout the lifetime of
a lizard and whether incubation moisture has an effect on desiccation
tolerance. His study site consists of four islands within the Tomoka River
in Tomoka State Park, Florida. Two of them
have little vegetation, arid climate and lizards lay their eggs in
dry substrate that consists of shells and rocks. The other two islands
have more vegetation cover, cooler climate and moist dark soil to
incubate the eggs. Corey collected individuals from all
islands and incubated their eggs under dry and wet conditions. He
found that desiccation tolerance is highly plastic: hatchlings that
were incubated under dry conditions show low desiccation rates,

matching rates for naturally incubated individuals.

Experimentally incubated individuals match desiccation rates of individuals sampled in the field

Experimentally incubated individuals match desiccation rates of individuals sampled in the field

He also found that desiccation rates decrease within the lifetime of an individual.

Desiccation rates decrease after releasing hatchlings on experimental islands

Desiccation rates decreased after hatchlings were released on experimental islands

He then released the hatchlings to measure survival. He found that desiccation rates are adaptive: individuals incubated under humid conditions had higher survival on mesic islands, and dry incubated individuals had higher survival on arid islands. Future research will focus on exploring the physiological mechanisms that lead to differences in desiccation tolerance, such as scale number and scale size. He will be continuing complementary research during his dissertation work to further explore the effects of incubation moisture on lizard phenotypes.

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