Category: Reproduction

Global lizard trait database

29/8/2018

In a recent publication in Global Ecology and Biogeograpy, I present a vast dataset of over 20 body size, ecological, thermal biology, geographic, phylogenetic and life history traits for global lizards.

Over the past 12 years I have been collecting trait data on lizards to complement GARD’s geographic data and allow asking interesting ecological, evolutionary and biogeographic questions – as well as, hopefully, informing conservation decisions. To this end I've now published geographical, morphological, ecological, physiological and life history data for the 6,657 known species of lizards. In the data paper I present descriptive statistics regarding these traits and point to avenues for future research using the dataset.

Scincus scincus (Photo: Simon Jamison)

I hope these data will facilitate more study into the biology of these most fascinating of creatures, and that the database publication will encourage others to add yet more data and to correct errors I surely have made when assembling them.

Author: Shai Meiri

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Island life only works if you’re easy-going – uncovering predictions of the island syndrome for lizard clutch size variation

18/9/2017

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In a recent publication in the Journal of Biogeography we show that Insular lizards with variable clutch sizes follow the predictions of the island syndrome, while lizards with fixed clutches do not.

Life-histories of insular species are hypothesized to slow down, a phenomenon known as the "island syndrome". Insular individuals are thus expected to lay smaller clutches of larger eggs compared with individuals belonging to closely related mainland species. Most lizards have variable clutch sizes and can lay any number between one egg and a species-specific maximum, which can be well over 50 eggs. Many lizards, such as geckos and anoles, however, lay invariant small clutches of one or two eggs, and may thus be unable to manifest some aspects of the island syndrome. We tested whether insular species with either variable or invariant clutch sizes respond to insularity differently by analyzing egg, clutch, hatchling and female sizes and brood frequencies of 2,511 lizard species.

Mediodactylus kotschyi (photo Rachel Schwarz)

Pafilis & Rachel, Kalogria region NW Peloponnes (photo Shai Meiri)

We found that insular species with variable clutch sizes lay smaller clutches of larger eggs, from which larger hatchlings emerge, compared with mainland species, as expected by the island syndrome. Lizards with invariant clutch sizes, however, lay smaller clutches on islands and increase clutch frequency, compared with mainland species, perhaps because of limitations set by the female body cavity and pelvic opening. This may result from lower seasonality of tropical islands, leading to a greater spread of reproductive effort, or as a result from fluctuations in population densities caused by tropical storms. Our results also emphasize the importance of taking differences in life-history traits into account while studying lizard reproductive traits on large phylogenetic scales.

Kampana islet (photo: Rachel Schwarz)

Author: Rachel Schwarz

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Global lizard trait database

Island life only works if you’re easy-going – uncovering predictions of the island syndrome for lizard clutch size variation

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