What need for speed? Lizards from islands missing predators sprint slower

Here we test the hypothesis that island species that have evolved in predator-poor environments have reduced locomotor abilities. More than 60% of recent recorded extinctions are from islands 1, and island taxa are often susceptible to invasive predators typically because of the loss of ancestral antipredator behaviors. While locomotor abilities are critical for escaping predation, little is known on how the presence of different types of native predators influences these abilities by maintaining selective pressure. To fill this gap, we documented sprint speed in the Aegean wall lizard (Podarcis erhardii) from Aegean islands (Greece) with varying levels of predation pressure. We show that on islands where mammalian predators were present, lizards sprinted fastest. Lizards sprinted at an intermediate speed where predators other than mammals were present, and lizards sprinted slowest on islands where no predators were present. These results indicate that lizards from the lowest-predation ..., Study system
The Cyclades archipelago is a cluster of land-bridge islands located in the central Aegean Sea (Greece). Since the end of the last glacial maximum approximately 18,000 years ago, rising sea levels have fragmented former mainland coastal regions. As Holocene sea level rise separated the area, populations of plants and animals also became increasingly isolated, thus setting the stage for the evolution of locally adapted island phenotypes.
The study area has warm, long, dry summers and mild, rainy winters as is typical of Mediterranean region climates. Humans have inhabited the region for thousands of years, altering the vegetation through agriculture and animal grazing. Today island habitats consist typically of agricultural fields edged by dry-stone walls and embedded in a matrix of spiny, summer-deciduous, low-growing woody vegetation known as phrygana.
The Aegean wall lizard (Podarcis erhardii, Lacertidae) is a medium-sized lizard, typically ranging in size from 48-78 mm f..., The three main files used in the analyses were the Dataset 1,2, and 3 files. These files were used for sprint speed analysis, stamina analysis, and island averages respectively.
However, there is a lot of additional data from video analysis. Every sprint video is available and is labeled as the island name and the number of the video (eg. Amorgos1.mp4) the can be found in the zip file for each location (i.e. Amorgos.zip). Video files were analyzed using the program SAVRA (see the link in the methods below), values from this program were then saved into an Excel file that was labeled with the island name (eg. Amorgos5.xlsx). These files were then used in Matlab to calculate velocity (code is in files: get_quintic_spline_and_max_va.m and run_for_all_the_lizards.m). Using this code we obtained velocity (sprint speed) values, that were then saved into Microsoft word documents (eg. amorgosvalues.docx). These values were then matched to the appropriate video, lizard, and trial. This informati...