Feed or fight: Food availability and intraspecific aggression for an island lizard
Islands are great natural biological laboratories to investigate how organisms can adapt to different selective pressures. This study by Donihue et al …
My name is Colin Donihue and I'm a field ecologist
at Yale University.
My team and I recently published a study in Functional Ecology
focusing on a wall lizard in the Greek Archipelago.
Lizard traits can change depending on conditions
like if predators are present or if food is
abundant or scarce.The question we asked for
this study was whether lizard bite forces
changed across islands of different sizes.
We suspected it would change because bite
force is related to what a lizard can eat
and how well it can fend off other lizards.
We predicted that on small islands lizards
would have a stronger bite force because a
stronger bite force could enable them to eat
harder diet items like snails when food is
less abundant or the harder bite force could
help that lizard defend its territory better
against other lizards.
The perfect place to answer this question was in the Greek Cyclades
because of the wide range in island sizes
and the abundance of the local wall lizard, Podarcis erhardii.
All summer my team and
I took a ferry and kayaked from island to
island catching lizards. Over the summer we
caught several hundred lizards and looked
at their diets and quantified the levels of
lizard-on-lizard aggression between populations.
After analyzing all the data, we found that
lizards on small islands did have stronger
bites than lizards on large islands and second
that these lizards were using their bites
more to ward off other lizards than to gain access to harder food.
This research gives us new insight into not just how
lizards differ from place to place but also why.
This finding is important because it gives us new information on how the context around a species,
in this case, the abundance of food or the density of competitors,
affects a functionally important ecological trait: bite force.