The present study aimed to understand how Anatolian ground squirrels, Spermophilus xanthoprymnus (Bennett, 1835), have responded to global climate changes through the Late Quaternary glacial–interglacial cycles. Accordingly, ecological niche modelling was used, together with molecular phylogeography. Using species occurrence data compiled from field observations and relevant sources and the maximum entropy machine learning algorithm in MAXENT, an ecological niche model was developed to predict the potential geographical distribution of S. xanthoprymnus under reconstructed past (the Last Interglacial, approximately 130 000–116 000 years ago and the Last Glacial Maximum, 21 000 years ago) and present (1950–2000) bioclimatic conditions. In addition, using cytochrome b mitochondrial DNA sequences deposited in GenBank and the Bayesian skyline plot in BEAST, demographic events (population fluctuations) were further assessed over the history of Anatolian ground squirrels. Combined ecological niche modelling and molecular phylogeography revealed that S. xanthoprymnus, itself also a temperate (mid‐latitude) species, has responded to global climate changes through the Late Quaternary glacial–interglacial cycles in a fashion converse to that of most temperate (mid‐latitude) species: its range expanded rather than contracted during the glacial periods and contracted rather than expanded during the interglacial periods. In other words, Anatolian ground squirrels have been in refugia during the interglacial periods, suggesting that the classical paradigm of glacial range contraction and interglacial range expansion for temperate species may not be as general as previously assumed. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 19–32.

No abstract

A phylogenetic comparative analysis of geographic variation in body size of an obligately hibernating marmotine species (Anatolian ground squirrels, Spermophilus xanthoprymnus) is presented in relation to environmental variables that pertain to four principal hypotheses (heat conservation, heat dissipation, primary productivity, and seasonality hypotheses). Adult Anatolian ground squirrels (78 males and 90 females) were collected from ten geographic localities in Anatolia for use in morphometric analyses. First, the study tested whether significant variation in body size occurs over the geographic range of S. xanthoprymnus. Then, to understand the possible cause(s) of the observed pattern of geographic variation in body size of Anatolian ground squirrels, four hypotheses were tested, separately and simultaneously, using a phylogenetic comparative method. Overall, food availability (primary productivity hypothesis) and, especially in males, over-winter fasting endurance (seasonality hypothesis) are likely the primary underlying mechanisms generating the observed pattern of increasing body size towards colder, more seasonal environments, with higher summer precipitation and productivity (or a Bergmannian size pattern).

Predictable empirical patterns of variation in body size along spatial and environmental gradients have been documented within many species of mammals. Four main hypotheses, heat conservation, heat dissipation, primary productivity and seasonality, have been proposed to explain these patterns of variation in body size. In this study, we reported an analysis of geographic variation in body size of Richardson's ground squirrels Urocitellus richardsonii, a North American hibernating, burrowing mammal. Firstly, we evaluated whether a Bergmannian size pattern was exhibited by Richardson's ground squirrels. Secondly, we used an information‐theoretic approach to test which of the four main hypotheses best explain(s) geographic variation in body size of Richardson's ground squirrels or to assess whether, as proposed by McNab's ‘resource rule’ or Huston and Wolverton's ‘eNPP rule’, the primary productivity hypothesis is the only explanation. Richardson's ground squirrels exhibited a pattern of increasing body size towards the colder areas, that is, more productive and seasonal central Alberta and foothills of the southern Alberta Rocky Mountains, indicative of a Bergmannian size pattern. Plant productivity and seasonality in plant productivity were likely the primary underlying factors generating the observed pattern of geographic variation in body size. Thus, our results supported primary productivity and seasonality hypotheses. From these results, we see that McNab's ‘resource rule’ or Huston and Wolverton's ‘eNPP rule’ (i.e. spatial variation in food availability) is an explanation for a Bergmannian size pattern in Richardson's ground squirrels, but not the only explanation.

No abstract