The influence of environmental factors on the morphology of red-backed volesMyodes gapperi(Rodentia, Arvicolinae) in Québec and western Labrador

Abstract

Geographical patterns of morphological variation in small mammals are often associated with environmental factors. The southern red‐backed vole Myodes gapperi is a widespread and abundant small mammal in Canada, occurring in environments as diverse as mixed‐wood forests and taiga. First upper molars and skulls from nine populations of southern red‐backed voles distributed across three ecozones and approximately 10° of latitude were analysed by means of geometric morphometric techniques, and their relationships with environmental variables were examined. A weak, non‐linear trend of size increase towards higher latitudes was observed in voles' skulls. Environmental variables appeared to be important drivers of shape differentiation among populations from the three distinct ecozones analysed. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112, 204–218.

Environment and space as drivers of variation in skull shape in two widely distributed South-American Tayassuidae,Pecari tajacuandTayassu pecari(Mammalia: Cetartiodactyla)

“…Although we did not test it directly, these traits might have evolved as adaptations against competition because differences in bite force and body size are important for niche partitioning between these species in sympatric contexts (Kiltie, ). In fact, we observed crucial differences in the skull shape of these peccaries in colder and drier environments, to the south of the Amazon Basin, where food items might be scarcer and harder to find (Souto‐Lima & Millien, ). Pecari tajacu is characterised by a less specialised morphology, at the cost of reducing bite force (large molars and a lower temporal muscle area), whereas a more conservative morphology and powerful bite force are observed in T. pecari (a large temporal muscle area).…”

“…). We then extracted 22 environmental variables for each site that are important predictors of skull shape variation in mammals (Cáceres et al ., ; Meloro et al ., , b; Souto‐Lima & Millien, ). Nineteen bioclimatic variables were taken with 2.5 arc‐minutes resolution from the WorldClim raster database (Hijmans et al ., ), and other three variables from the Atlas of the Biosphere (average annual relative humidity, net primary productivity and evapotranspiration, https://nelson.wisc.edu/sage/data-and-models/atlas/maps.php), using DIVA‐GIS 7.5 software (http://www.divagis.org/download).…”

“…Furthermore, neutral evolution (e.g. genetic drift, gene flow) might be responsible for morphological variations (Marroig & Cheverud, ; Cardini et al ., ), especially in an historical context of changing environmental conditions (Souto‐Lima & Millien, : 205).…”

“…Geographical variation in morphological traits has been strongly influenced by both environmental and historical factors (Freckleton & Jetz, ). Large numbers of macroenvironmental patterns of morphological variation have been described at both the intraspecific (Cardini, Jansson & Elton, ; Souto‐Lima & Millien, ; Kim et al ., ) and interspecific level (Ashton, Tracy & De Queiroz, ; Cáceres et al ., ; Meloro et al ., ,b; Bubadué et al ., ). Climatic variables (e.g.…”

“…temperature and precipitation) have been suggested to account for the patterns observed through their influence on thermoregulatory mechanisms (Ashton et al ., ; Martinez et al ., ), or on food availability in the environment (Cardini et al ., ). In this respect, morphological variation across the environmental gradient might reflect not only evolutionary adaptations, but also the phenotypic plasticity of species (Peres‐Neto & Magnan, ; Souto‐Lima & Millien, ; Jaffe, Campbell‐Staton & Losos, ). Most life history traits often covary with size (Gould, ), even across large spatial scales (Cáceres et al ., ; Meloro et al ., , b).…”