Macroecological and biogeographical patterns of limb reduction in the world's skinks

Marco Camaiti*, Alistair R. Evans, Christy A. Hipsley, Mark N. Hutchinson, Shai Meiri, Rodolfo de Oliveira Anderson, Alex Slavenko, David G. Chapple

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Aim: Limb reduction is a dramatic evolutionary transition, yet whether it is achieved in similar trajectories across clades, and its environmental drivers, remain unclear. We investigate the macroevolutionary and biogeographical patterns of limb reduction in skinks, where limb reduction occurred more often than in any other tetrapod clade, and test their associations with substrate categories using a global database. We test for habitat associations of body shapes in a group of Australian skinks using quantitative habitat data. Location: Global (Scincidae), Australia (Sphenomorphinae). Taxon: Skinks, Australian Sphenomorphinae. Materials and Methods: We use morphological data to explore the patterns of limb reduction in the world's skinks, investigating how body proportions differ across skink clades and subfamilies. We examine the relationships between body shape and substrate (coarsely classified). Further, we investigate the relationships between body shape and high-resolution soil and climate properties extracted from each species' distribution for Australian sphenomorphines. Results: Relationships between limb lengths and trunk elongation show idiosyncratic patterns across skink clades. Presacral vertebrae numbers positively correlate with trunk elongation in all taxa, except Glaphyromorphus. Skinks from sandy habitats show greater disparity between forelimb and hindlimb lengths than all other substrate categories. In sphenomorphines, shorter limbs and elongated trunks correlate with colder, more humid microhabitats and richer soils; high limb disparity correlates with hot, arid microhabitats and sandy, poor substrates. Main Conclusions: The evolutionary trajectories of limb reduction in skinks are clade-specific and sometimes unique. Selection for specific limb proportions and body sizes in limb-reduced forms changes across substrates. On poor, sandy substrates of arid environments, body shapes with longer hindlimbs may be more efficient for locomotion in a granular fluid (i.e. sand) and exploit the air–substrate interface than complete limblessness. On richer, more humid substrates, such morphology is rare, indicating that navigating cluttered substrates selects for more equal and shorter limb lengths.

Original languageEnglish
Pages (from-to)428-440
Number of pages13
JournalJournal of Biogeography
Volume50
Issue number2
DOIs
StatePublished - Feb 2023

Funding

FundersFunder number
Australian University Librarians
Equity Trustees Charitable Foundation
Monash-Museums Victoria Robert Blackwood
Monash‐Museums Victoria Robert Blackwood
Wiley - Monash University
Holsworth Wildlife Research Endowment
Australian Research CouncilLP170100012, FT200100108, DE180100629
Monash University
Ecological Society of Australia

    Keywords

    • Australian Sphenomorphinae
    • biogeography
    • ecomorphology
    • limb reduction
    • macroecology
    • morphological evolution
    • skinks

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