A database of the morphology, ecology and literature of the world's limb-reduced skinks

Marco Camaiti, Alistair Evans, Christy Anna Hipsley, Mark Norman Hutchinson, Shai Meiri, Rodolfo O. Anderson, Alex Slavenko, David G. Chapple

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Aim
Limb-reduced squamates are a convenient model system to investigate macroevolutionary trends in morphology. Here, we provide morphological, ecological and literature data on all known species of limb-reduced skinks (Scincidae) and their relatives, representing one of the most diverse and widely distributed groups of limb-reduced squamates.

Location
Global.

Taxon
Skinks (Reptilia, Squamata: Scincidae). Limb-reduced forms.

Methods
Morphological data were sourced from the primary literature, spanning a period of over 150 years. Linear body measurements were averaged across all values in the literature, preserving proportionality to body length. For digits and presacral vertebrae, we used maximum recorded counts. Ecological and biogeographical data were sourced from habitat assessments in the primary literature, online databases and field guides. Literature data were sorted according to type of study. To exemplify the applicability of the database, we used Markov-chain ordered models to estimate the evolutionary frequency of limb reduction and loss in skinks.

Results
We find evidence of limb reduction and loss in a total of 394 species worldwide, representing ~23% of all skink species, and ~30% of genera. The distribution of limb-reduced and limbless forms differs from that of fully limbed forms, as they are present in all biogeographic realms with the almost complete exclusion of the Americas. We estimate that limb reduction evolved more than 50 times in skinks, and that loss of at least one limb pair evolved at least 24 times.

Main conclusions
The dataset captures a broad spectrum of morphological and ecological variation in a large, globally distributed taxonomic group. It establishes a widely applicable definition of limb reduction based on limb proportions as a reference for future studies. Such an extensive collection of morphological and ecological data can pave the way for investigations of dramatic morphological transitions and their ecological drivers at a global and local scale.
Original languageEnglish
Pages (from-to)1397-1406
Number of pages10
JournalJournal of Biogeography
Volume49
Issue number7
DOIs
Publication statusPublished - Jul 2022

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