Shape-shifting animals

Congratulations to Sara Ryding, Deakin University for the first chapter of her PhD thesis being published in Trends in Ecology & Evolution on “Shape-shifting: changing animal morphologies as a response to climatic warming”. Link to the paper here or here.

In this review, Sara writes about how animal appendages (ears, feet, limbs, bills, etc) are important morphological indicators of temperature and therefore potential signatures of changing climate.

Appendages have an important, but often undervalued, role in animal thermoregulation as sites of heat exchange.

This thermoregulatory role leads to geographic clines in animal morphology where animals at lower latitudes, in warmer climates, have larger appendages (a pattern known as ‘Allen’s rule’).

In this review, we discuss evidence for animals (mostly evidence in birds and mammals, although the field does extend to other animal taxa) that are shifting their morphologies to have proportionately larger appendages in response to climate change and its associated temperature increases.

A thermal image of a Galapagos sea lion, showing distinctly warm front flippers. Appendages tend to be variable in size and have capacity to vary peripheral blood flow, and thus may serve as sensitive indicators of changing climate.

It has been a real pleasure to work with Sara Ryding on this project. Full credit and thanks go to Sara for all her hard work on this paper. I helped out only a small bit, but she reviewed the field within which my lab has been conducting collaborative research since 2010. Hopefully more research will follow as she navigates the rest of the project us (Drs. Matthew Symonds and Marcel Klaassen and myself). Many late nights and early morning zoom meetings await us all. Many thanks to Deakin University and the Australian Research Council for supporting this project.


Ryding, S, Klaassen, M, Tattersall, GJ, Gardner, JL, and Symonds, MRE. 2021. Shape-shifting: changing animal morphologies as a response to climatic warming. Trends in Ecology & Evolution. DOI:

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