The role of toe "spikes" for a Mediterranean sprinter lizard (Acanthodactylus schreiberi).

Methods

Summary

First we’ll perform samplings from three different populations. We will target, a sufficient number, of adult (males) and juvenile individuals, with intact tails. After the transportation of the individuals at the laboratory, we will let them for two days before any further handling in order to acclimatize.

Before trials, we will let the lizards to thermoregulate at their preferred temperature in a specific design terrarium, for one hour, in order to be able to perform on their highest level. The specific terrarium has a heating lamp on the one end and ice bags on the other on order to create a thermal gradient.

Each lizard will perform five trials with one hour of thermoregulation breaks between them, on three substrate types (sand, dirt, dirt/rock). Before trials we will record morphometric measurements for each individual (SVL, tail length, weight, fore limbs length, hind limbs length, fore toepad length, hind toepad length and largest toe length on hind limb).

All trials will be recorded at 240fps frame rate. The trial recordings will be used in order to measure maximum speed (based on the number of frames needed to cover 20cm) and maximum instant acceleration (based on the displacement of snout’s position among frames) for each individual. In the video given in lab notes, we give the methodology we used in a previous study and so we will use the same approach for the current study.

Also we are going to take measurements of fringe-related characteristics (length of the three longest fringes, number of fringes on the longest toe), from at least ten individuals from each population. These measurements will be used in order to search for differences among populations and also to find if there is a correlation between these characteristics and the length of their longest toe.

Next we will perform the appropriate statistical analyses for each case (i.e ANOVA, multiple regressions), in order to answer our question on the relation of fringes and sprint performance, on different substrate types and also if there is any morphological or physiological “spike” related adaptation for the populations living in different habitat types.