Island Biology

The genetic and phenotypic basis of thermal adaptation

I am currently in collaboration with Professor Jonathon Losos, Dr Mike Logan, and PhD student Lauren Neel working on a large-scale transplant study in Exuma, Bahamas. Using the Brown Anole, Anolis sagrei, as our study system, we aim to identify the genetic basis of thermal adaptation and the phenotypes associated with this.

In 2017 we collected the lizards from mainland Exuma and ran morphology and physiology analyses on them. Morphology measurements included head, body and limb measurements using digital callipers, weighing the lizard, scanning their dorsal and ventral surfaces, and taking photos of the lizard’s dewlap. Physiology measurements included measuring their metabolic rate, panting threshold, upper voluntary temperature, and their critical thermal minimum temperatures. We then transplanted 20 males and 20 females to 17 different experimental islands in Exuma. These islands differ thermally and structurally.

One of our thermally hot islands- photo taken by Dr. Mike Logan
One of our thermally cooler islands- photo taken by Dr. Mike Logan

Our sandy island, also likely to be another thermally hot islands- photo taken by Dr. Mike Logan

This year (2018) we randomly assigned locations for 30 Operative Temperature Models (OTM’s) to be placed on each of the 17 islands. These will provide us with an indication of the temperatures available. Once an individual was caught from one of the experimental islands, we measured their body temperature using a digital thermometer, the location where the lizard was caught (using GPS coordinates), the height the lizard was perched and the width of the perch.  We also noted the substrate the lizard was perched on and whether the lizard was basking. Once brought back to the lab, physiological and morphological variables were measured along with their thermal preference.  Lizards were released back to the islands they were caught from 3 days later. From this data we will be able to identify variation in morphology and physiology due to the transplant of A. sagrei to the islands.

Additionally, PhD student Lauren Neel is constructing 3D thermal landscapes using aerial imagery, macro-climate data and biophysical modelling. From this we will be able to make predictions about how thermal physiology is expected to differ between islands.

From the wet tropics to the dry deserts