Feed or fight: Food availability and intraspecific aggression for an island lizard
Like 1 Dislike 0 Published on 23 Sep 2015
Islands are great natural biological laboratories to investigate how organisms can adapt to different selective pressures. This study by Donihue et al (www.colindonihue.com) takes advantage of the different sizes of islands in the Greek Archipelago to investigate how a common lizard, Podarcis erhardii, differs in body size, head shape, and bite force depending the size of the island
The authors hypothesized that strong bites would be an advantage for lizards on small islands. A strong bite could help a lizard to eat relatively hard or large insects, so if food resources were sparse on a small island the lizard might not starve. A harder bite might also help the lizard win fights with the other lizards competing for the same valuable resources (like food, mates, or nesting sites) on a small island where lizard densities are often high.
The authors caught lizards on 11 islands in the Greek Cyclades, and measured the lizards’ body and head size and bite force. They then flushed the lizards' stomachs to see what they were eating and compared the stomach contents to insects caught in traps. Finally, they counted the bite scars and lost toes, which typically result from battles with other lizards.
They found that bite force did increase on small islands and that the competition indicators, i.e., bite scars and lost toes, best predicted the pattern in bite force, as hardness of prey species didn't differ significantly between islands.
To find out more, you can read the article or go to Colin Donihue's website:
http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12550/abstract
www.colindonihue.com