Dress for success: Climate pressures predict fur insulation and body size in natural and reintroduced populations of a threatened marsupial

Phenotypic variation in functional traits underpins responses to environmental gradients, influencing thermoregulation, energy balance, and long-term persistence under climate extremes. Climate change is altering these gradients globally, yet in species that have disappeared from much of their range, adaptive phenotypes may have also been lost, potentially limiting population viability following reintroduction to different climates. The greater bilby (Macrotis lagotis) is a threatened Australian marsupial that has undergone severe range contraction since European settlement and has been the focus of subsequent conservation translocations. To test hypotheses of climate-associated morphological divergence, we quantified spatial variation across its historical distribution and in reintroduced populations in traits that are key determinants of heat exchange and thermal buffering: skull size (as a proxy for body size), ear length, and fur morphology (dorsal and ventral hair length, depth, an..., Museum specimens
We measured skull dimensions and ear lengths of bilby specimens housed in the American Museum of Natural History, Australian Museum, Australian National Wildlife Collection, British Natural History Museum, Melbourne Museum, Museum and Art Gallery of the Northern Territory, Queensland Museum, South Australian Museum, and Western Australian Museum. Cranial measurements were taken using digital callipers (resolution = 0.01 mm) by the same observer following methods outlined by Aplin et al. (2010). For this investigation, we measured skull length (occipitonasal length; greatest length of the skull) and skull width (zygomatic width; maximum width across cranium) as proxies for body size (Aplin et al., 2010; Travouillon, 2016; Umbrello, 2018). From this dataset, we identified 106 bilby specimens with location data allowing climatic assessment, of which 98 specimens were adults from naturally occurring populations (Figure 1). Where possible, we measured ear length from the cro..., # Data from: Dress for success: Climate pressures predict fur insulation and body size in natural and reintroduced populations of a threatened marsupial

Dataset DOI: [10.5061/dryad.59zw3r2p5](https://doi.org/10.5061/dryad.59zw3r2p5)

## Description of the data and file structure

We collected data from bilby skulls housed in the American Museum of Natural History, Australian Museum, Australian National Wildlife Collection, British Natural History Museum, Melbourne Museum, Museum and Art Gallery of the Northern Territory, Queensland Museum, South Australian Museum, and Western Australian Museum and bilby fur from the Australian Museum, South Australian Museum, and Western Australian Museum. We also assessed bilby fur at Arid Recovery Reserve and Venus Bay Conservation Park to assess phenotypic divergence from a shared source population. Climate variables (BIO5, BIO6, BIO12, BIO15) were extracted from CHELSA v2.1 climatological rasters (Karger et al., 2017, 2021), representing the 1981–2..., ,