Getting a Tail Up on Conservation?

Lizards are an important indicator species for understanding the condition of specific ecosystems. Their body weight is a crucial index for evaluating species health, but lizards are seldom weighed, perhaps due in part to the recurring problem of spontaneous tail loss when lizards are in stress.

Now ecological researchers have a better way of evaluating these lizards. Dr. Shai Meiri of Tel Aviv University's Department of Zoology has developed an improved tool for translating lizard body lengths to weights. Dr. Meiri's new equations calculate this valuable morphological feature to estimate the weight of a lizard species in a variety of different ecosystems.

“Body shape and body size are hugely important for the understanding of multiple ecological phenomena, but there is a need for a common metric to compare a multitude of different species,” he says.

Building a lizard data bank

In a study published recently in the Journal of Zoology, Dr. Meiri evaluated hundreds of lizard species: long-bodied, legless species as well as stout, long-legged species; some that sit and wait for prey, others that are active foragers. Based on empirical evidence, such as well-established behavioral traits, he built a statistical model that could predict weights of lizards in a reliable, standardized manner, for use in the field or at the lab.

For the study, Dr. Meiri looked at a large sample of lizards — 900 species in 28 different families — and generated a dataset of lizard weights, using this dataset to develop formulae that derive body weights from the most commonly used size index for lizards (the length of the head and body, or “snout–vent length”). He then applied a species-level evolutionary hypothesis to examine the ecological factors that affect variation in weight–length relationships between different species.

Predicting post-disaster damage to the environment

How can this standardized metric protect our environment? “It can help answer how lizard species may react if there were major shifts in the availability of food due to climactic changes,” he says.

In the future, zoologists will be able to use Dr. Meiri's method to better predict which communities of animals will shrink, grow or adapt to changing conditions, even after massive environmental disasters like the recent Gulf of Mexico oil spill.