Natural history of monitor lizards (family Varanidae) with evidence from phylogeny, ecology, life history and morphology

The causes of variation in life histories are a central theme in evolutionary biology. In this thesis, hypotheses regarding variation in morphology and life histories are tested using phylogenetic relationships among monitor lizards (genus Varanus). Monitor lizards (Family Varanidae) are a group of 50 species that possess variation in morphology, life-history traits, and ecology. The phylogeny for 37 species of monitor lizards and their closest outgroups are inferred from mitochondrial DNA sequence data. The influence of allometry on life-history traits is explored to understand the relationship between variation in life-history traits and in body size. Trade-offs between life-history traits are tested to see if variation in these traits coevolves independent of body size. It is predicted that a trade-off between clutch number and hatchling size should be found among monitor species. Morphological variation independent of size (shape) should be related with habitat use (ecomorphology). Then, in turn, it is predicted that similarities in morphology and ecology should lead to predictable life-history strategies. The use of phylogeny is crucial to conduct rigorous tests of these hypotheses and to understand how different traits evolved in relationship to each other, the environment and common ancestry through the history of the lineage. Understanding the relationship between life-history variation and morphology, specifically body size, in monitor lizards will greatly enhance our knowledge of life-history evolution.