Cranial morphometric and fine scale genetic variability of two adjacentMastomys natalensis (Rodentia: Muridae) populations

Abstract

C. 2009. Cranial morphometric and fine scale genetic variability of two adjacent Mastomys natalensis (Rodentia: Muridae) populations. Acta Theriologica 54: 171-181.The objective of this multidisciplinary project was to study the intra-specific morphometric and genetic variability between two adjacent populations of Mastomys natalensis Smith, 1834 living in different environments. The study of micro-evolutionary processes at work by using geometrical morphometrics allowed us to define two groups, characterized by different features of the skull shape. Using molecular microsatellites analysis, we showed that the two populations exchanged high gene flow and could be considered as a single panmictic unit. These results suggest that this widely-distributed species exhibits a local population-level differentiation in shape variation of skulls, probably due to different ecological situations. We speculate that the variability in the cranial characteristics (connected with the feeding ability) could reveal a local adaptation preferentially based on the food availability. We propose an explanation linking the shape differences to the fitness gain in the exploitation of resources available in the two environments. Since we suggest a potential differentiation process between populations, we believe that the two groups constitute even better models to understand the factors involved in the early stages of local adaptations.

Congruent morphological and genetic differentiation as a signature of range expansion in a fragmented landscape

“…When discrepancies between the two were observed, the phenotypic divergence was usually attributed to variations in the local environment or food availability (Lalis et al. ; DeLeon et al. ; Sistrom et al.…”

“…Such high congruence between phenotypic traits and microsatellites has not often been reported. When discrepancies between the two were observed, the phenotypic divergence was usually attributed to variations in the local environment or food availability (Lalis et al 2009 ; DeLeon et al 2012 ; Sistrom et al 2012 ). Divergent patterns of phenotypic and genotypic differentiation suggest that the phenotypic trait studied is under selection.…”

Localized versus generalist phenotypes in a broadly distributed tropical mammal: how is intraspecific variation distributed across disparate environments?

“…LA LIBERTAD: Otuzco , Hacienda Llagueda, 2250 m, -7.72; -78.72 (FMNH 19317, 19321, 19325) [23]; Otuzco , Summit between Otuzco and Llagueda, 2850 m, -7.90; -78.58 (FMNH 19849, 19851) [24]; Sánchez Carrión , Sanagorán, 2850 m, -7.79; -78.14 (lhl 85, llw 1219, 1220, 1221, 1222, 1225, 1226, 1227, 1232) [25]; Sánchez Carrión , Sanagorán, 2750 m, -7.78; -78.15 (vpt 2251, 2252, 2263) [26]; Santiago de Chuco , Cachicadán, 2870 m, -8.06; -78.17 (vpt 2277) [27]; Santiago de Chuco , Campamento Callacuyán, Quebrada Quishuara Sur, 4040 m, -7.94; -78.23 (avg 143) [28]; Santiago de Chuco , Campamento Callacuyán, arriba de Laguna Negra, 4020 m, -7.95; -78.24 (mvc 313, 323) [29]; Santiago de Chuco , Campamento Callacuyán, hondonada Laguna Viscachas, 4110 m, -7.95; -78.23 (mvc 325, 326) [30]; Santiago de Chuco , Campamento Callacuyán, Bosque de Polylepis, 3990 m, -7.92; -78.25 (mvc 333) [31]; Santiago de Chuco , Campamento Callacuyán, Laguna Pozo Hondo, 4130 m, -7.95; -78.25 (vpt 2380, 2387, 2390) [32]; Trujillo , Menocucho, 540 m, -8.02; -78.8 (FMNH 19329, 19333, 19335, 19343) [33]. …”

“…To investigate this issue, we focus on skull morphological variation because of its fundamental role in food processing and perceiving sensory information that allows vertebrates to interact with its environment [25], as evidenced by environmentally induced morphological changes in mice skulls [25,26]. For example, functional links between skull variation and environmental differences have been demonstrated by studies on the biomechanics of mastication under different diets [27,28] or differing selective regimes [29,30]. In particular, differentiation across disparate environments might be evident in areas of the skull that serve for muscle attachment (e.g., zygomatic arches [31]), influence bite force (e.g., rostrum [32]), or have been shown to covary with environmental gradients (e.g., the auditory bullae with aridity [27], or the palatal region with temperature [33]).…”

Ecological preference between generalist and specialist rodents: spatial and environmental correlates of phenotypic variation

“…More recently, Lalis et al . () found both genetic and morphometric differences between two adjacent populations of the African Mastomys natalensis separated only by 5 km. Similarly, Ledevin & Millien () and Rogic et al .…”