• Julia RIley

Developmental Plasticity in Reptiles: A Database and Review

A Painted Turtle (Chrysemys picta) hatchling basking outside its nest cavity amongst some dried eggshells after emergence. In the Reptile Developmental (RepDevo) Database 32% of the studies have focused on 6 species, one of which is the Painted Turtle (N = 15 papers). The other species are: the Common Snapping Turtle (Chelydra serpentina; N = 24), Eastern Three-Lined Skink (Bassiana duperreyi; N = 19), Leopard Gecko (Eublepharis macularius; N = 15), Red-Eared Slider (Trachemys scripta; N = 14), and Eastern Fence Lizard (Sceloporus undulatus; N = 10).

Over the past months I have been working at the University of New South Wales, first as a postdoctoral research associate supported by Lisa Schwanz and then as an Endeavour Postdoctoral Fellow with Daniel Noble. I was so lucky to be able to work with them both, as well as other amazing colleagues, on a topic that fascinates me: developmental plasticity in reptiles. It is well known that the environment during development affects reptile morphology, physiology, and behaviour, which often can have fitness implications. Our research specifically focused on how the environmental temperature experienced by embryos can affect phenotypic variation in reptiles.

Recently the major aspect of our research program was published in Scientific Data – a large effort was put towards compiling a comprehensive database of thermal plasticity in reptiles. We felt that, although there is substantial empirical literature detailing experimental manipulations of embryonic thermal environments, summarizing and interpreting patterns at a comparative level has been difficult because of a lack of collated, accessible data. The RepDevo database we assembled can be downloaded online here. Our aim is to create a freely-accessible database that can be updated as new studies and data emerge. In fact, if you have data or are publishing a study on thermal plasticity in reptiles, you can submit your findings to the database! Currently, the RepDevo database contains nearly 10,000 phenotypic estimates from 155 species of reptile, collected from 300 studies manipulating incubation temperature (published between 1974–2016). The data encompass various morphological, physiological, behavioural and performance traits along with growth rates, developmental timing, sex ratios, and survival (e.g., hatching success). We hope that this resource is a helpful repository for data on thermal plasticity of reptile embryos that can be used to test overarching theories in this field.

A summary of the taxa present within the RepDevo Database

A summary of the phenotypic traits within the RepDevo Database and how the taxa are represented within each trait

Using the database, a meta-analysis was performed, which was published in Biological Reviews, to quantify the general trends that exist and the magnitude of the impact incubation temperature has on reptile phenotype. Overall there was a large effect of incubation temperature on numerous traits, which is evidence of the crucial role incubation temperature has on reptile phenotype. We then systematically reviewed the research contained within our RepDevo Database, to qualitatively assess the major findings within this field over the past 50 years. We identified key research themes associated with thermal developmental plasticity, important gaps in empirical research, and demonstrated how future progress can be made through targeted empirical, meta-analytic, and comparative work. The potential for future comparative work is immense. There are over 300 studies summarised in the RepDevo database, which provide a unique opportunity to test the generality of theory and to reveal gaps in our current knowledge. We hope others within this field will be as excited about this new resource as we are, and that it will generate much productive research in the future!

A summary of the increase in studies with constant versus fluctuating, more natural, incubation temperatures over time

The global distribution of reptile thermal effects within the RepDevo Database

Article References:

Noble DN, Stenhouse V, Riley JL, Warner DA, While GM, Du W-G, Uller T, and Schwanz LE. 2018. Towards a comprehensive database of thermal developmental plasticity in reptiles. Scientific Data, 5: 180138.

Noble DW, Stenhouse V, and Schwanz LE. 2018. Developmental temperatures and phenotypic plasticity in reptiles: a systematic review and meta‐analysis. Biological Reviews, 93: 72-97.

While GM, Noble DWA, Uller T, Warner DA, Riley JL, Du W-G, and Schwanz LE. 2018. Patterns of developmental plasticity in response to incubation temperature in reptiles. Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, doi: 10.1002/jez.2181