Geographic variation of wing morphology of great fruit- eating bats (Artibeus lituratus): environmental, genetic and spatial correlates of phenotypic differences RICHARD D. STEVENS 1 *, MARY E. JOHNSON 2 and EVE S. MCCULLOCH 3 1 Department of Natural Resources Management and the Museum of Texas Tech University, Lubbock, TX, 79409, USA 2 The Great Basin Institute, 16750 Mt Rose Highway, Reno, NV, 89511, USA 3 Division of Biology, 103 Ackert Hall, Kansas State University, Manhattan, KS, 66506, USA Received 15 December 2015; revised 15 January 2016; accepted for publication 15 January 2016 Responses of species to environmental gradients are important and frequent determinants of geographic phenotypic variation that can drive adaptive processes. Nonetheless, random genetic processes such as drift can also result in geographic variation in phenotypes, and should be evaluated before implicating selection as the process driving phenotypic change. We examined geographic variation in wing morphology of Artibeus lituratus among 18 different sites distributed across interior Atlantic Forest of Paraguay and Argentina. Moreover, we contrasted geographic variation with environmental, spatial, and genetic variation to test hypotheses related to selection and drift and their impacts on wing morphology. For A. lituratus distributed across interior Atlantic Forest, significant differences among sites characterized variation in wing morphology. Geographic variation was significantly related to climatic variables but not spatial or genetic distances. Such a pattern suggests that phenotypic variation is related to selection for particular environmental regimes, and not genetic drift. Four significant dimensions of phenotypic variation were determined. Three dimensions were related to variation among individuals in terms of wing tips, whereas one was related to overall body size. Wing tips are important for manoeuverability during flight and differences among sites likely reflect differences in forest and vegetation structure that must be managed during foraging. Although climate provides good surrogates for environmental variation, it is probably only an indirect cue of selection regimes that determine variation in wing morphology. Future studies should evaluate more direct environmental measures such as vegetation structure when attempting to interpret geographical variation in wing morphology. © 2016 The Linnean Society of London, Biological Journal of the Linnean Society, 2016, 118, 734–744. KEYWORDS: geographical variation – morphometrics – selection – wing morphology. INTRODUCTION For many taxa of plants and animals, especially those with large geographic ranges, there is a com- mon pattern of geographic phenotypic variation related to environmental variables (e.g. latitude) or climatic characteristics (e.g. temperature or precipi- tation) (Masaki, 1967; Barclay, Fullard & Jacobs, 1999; Roff & Mousseau, 2005; Yom-Tov & Geffen, 2006; Jiang et al., 2013; Sun et al., 2013). Environ- mental correlations such as these can provide valu- able insights into the microevolutionary processes responsible for biotic diversification, with natural selection arguably being the most important. For example, when environmental regimes cause differ- ential reproductive success across different pheno- types, and there is geographical variation among sties regarding those environmental regimes, selec- tion can produce phenotype–environment rela- tionships. Nonetheless, a number of different microevolutionary processes can also result in pheno- type–environment relationships (Armbruster & Sch- waegerle, 1996). Other genetic processes unrelated to the environ- ment, such as mutation or genetic drift, can produce menacingly similar geographical patterns (Arm- bruster & Schwaegerle, 1996). Genetic drift can cause a spatial pattern of isolation-by-distance (IBD) *Corresponding author. E-mail: richard.stevens@ttu.edu 734 © 2016 The Linnean Society of London, Biological Journal of the Linnean Society, 2016, 118, 734–744 Biological Journal of the Linnean Society, 2016, 118, 734–744. With 3 figures. Downloaded from https://academic.oup.com/biolinnean/article/118/4/734/2705731 by guest on 06 June 2022