A test of the Resource's and Bergmann's rules in a widely distributed small carnivore from southern South America, Conepatus chinga (Molina, 1782) (Carnivora: Mephitidae)

Abstract

a b s t r a c tBergmann's rule is one of the most known biological rules and relates the body size variation to changes in latitude or temperature. Most recently, a "resource rule" had been presented, which explains several trends in body size, as a consequence of availability of resources. South American Conepatus chinga is one of the most widespread small carnivores in the Neotropics, being geographically distributed from Perú and Brazil to southern Argentina and Chile. This widely distributed species encounters a high environmental variability, which could affect body size and morphological variations. Here, I analyze geographical patterns of variation in body size and morphology estimated using a geometric morphometric approach from museum specimens. The associations between geographical patterns of variation in body size and morphometry and climatic and/or environmental variables were evaluated, using several databases and multiple regressions and redundancy analysis. Throughout the study, the presence of spatial autocorrelation was analyzed, and Spatial Eigenvector Mapping (SEVM) was used. The arid diagonal was identified as containing the smaller specimens of C. chinga, primarily related to net primary productivity (NPP). Bergmann's rule seems not to be valid for this species. Instead, evidence seems to support the "resource rule" as the primarily explanation for body size variation. A lower amount of morphological variation was explained by NPP, mainly related to relative size variation of premolar and molars.

Geographical variation of body size in sigmodontine rodents depends on both environment and phylogenetic composition of communities

“…The rule is probably most applicable at the intraspecific level, less so between closely related species, and even less so for this assemblage (Meiri, ). Indeed, there is evidence that the rule fits well at the intraspecific level for some South American mammal species (Gay & Best, ; Martinez et al ., ), although not for others (Schiaffini, ). Our study sheds light on the long‐standing discussion (Mayr, ; James, ; Blackburn et al ., ; Meiri, ) of on what level Bergmann's rule should be treated, and helps to show that some early suspicions may be valid, i.e.…”

“…This rule predicts that the body mass of homeothermic animals tends to increase with latitude and related ecological processes, as a mechanism to optimize heat retention (Bergmann, ; Meiri, ). This empirical generalization seems to fit well for land mammals of the Northern Hemisphere (Blackburn & Hawkins, ; Rodríguez et al ., ; O'Keefe et al ., ), although it poorly predicts mammal body size variation in the Southern Hemisphere (Medina et al ., ; Rodríguez et al ., ; Schiaffini, ). Rodríguez et al .…”

“…Geographical patterns of body size have been documented for a large number of taxa at the intraspecific level (Martinez et al ., ; Schiaffini, ), across species (Medina et al ., ; Adams & Church, ), and in assemblages (Blackburn & Hawkins, ; Rodríguez et al ., , ; Olalla‐Tárraga et al ., , ). One of the most frequently recognized patterns of body size variation across broad scales is predicted by Bergmann's rule.…”

Not playing by the rules: mixed support of ecogeographic rules in an arid‐adapted African ground squirrel

“…This rule predicts that decreasing resource availability causes a decrease in body size intraspecifically, both spatially and temporally (McNab, 2010). In Molina's hog‐nosed skunks ( Conepatus chinga ), body size variation is related to net primary productivity and not to temperature, supporting the resource rule but not Bergmann's rule (Schiaffini, 2016). The Australian sandy inland mouse ( Pseudomys hermannsburgensis ) and the house mouse ( Mus domesticus ), while very similar in body mass, general ecology and distribution, differ in their response to temperature, aridity and rainfall (Tomlinson & Withers, 2008).…”

Environmentally‐ and human‐induced body‐size responses in Macropus robustus and Macropus rufus, two widespread kangaroo species with largely overlapping distributions

“…These centre on: thermoregulatory response (Bergmann 1847;James 1970;Speakman & Kr ol 2010); primary productivity (food availability) (Rosenzweig 1968;Wigginton & Dobson 1999;McNab 2010); evolutionarily relevant Net Primary Productivity (eNPP) (food availability that is regulated by the NPP of plants during the growing season) , 2011; and seasonality (Lindsey 1966). Of these hypotheses, primary productivity has received most support as the primary predictor of spatial body-size variation in numerous species of mammals (Rosenzweig 1968;Kolb 1978;Yom-Tov & Nix 1986;Yom-Tov & Geffen 2006;Blois et al 2007;G€ ur 2010;G€ ur & G€ ur 2012;Alhajeri & Steppan 2016;Correll et al 2016;Schiaffini 2016;Yom-Tov et al 2016).…”