RESUMO
Understanding the impact that climate had in shaping cranial variation is critical for inferring the evolutionary mechanisms that played a role in human diversification. Here, we provide a comprehensive study aiming to analyze the association between climate and cranial variation of high latitude populations living in temperate to cold environments of Asia, North America, and South America. For this, we compiled a large morphometric dataset (N = 2633), which was combined with climatic and genomic data. We tested the influence of climate on the facial skeleton, nasal protrusion, and cranial vault and through multiple statistical tests at two geographical scales: intracontinental and intercontinental. We show that populations living in cold areas share a morphological pattern characterized by an increase in nasal height, facial and orbital heights and widths, a decrease in facial protrusion, and larger, longer, and lower cranial vaults. There are also distinctive features; populations from north Asia present the tallest noses, largest faces, and cranial vaults of the whole sample. Nasal breadth dimensions show small values in Asians, large values in South Americans, and non-significant changes in arctic North America. The morphological pattern in populations living at high latitude may be the result of parallel adaptation, as supported by physiological, morphometric, ecological, and genetic explanations, while the differences in magnitude and phenotypic expression could be due to the diverse population histories, severity of climate, and cultural strategies. Overall, our study shows that climate is a relevant factor shaping modern human morphology and it should be considered when studying modern human evolution and diversification.
Assuntos
Clima , Crânio , Humanos , Adaptação Fisiológica/fisiologia , Ásia , Evolução Biológica , Cefalometria , América do Norte , Crânio/anatomia & histologia , América do SulRESUMO
The echimyid rodents of the genus Thrichomys vary considerably in their behavior and feeding ecology, reflecting their occurrence in environments as different as the Caatinga, Cerrado, Pantanal, and Chaco biomes. While the genus was originally classified as monospecific, a number of Thrichomys species have been recognized in recent decades, based on morphometric, cytogenetic, and molecular analyses. While Thrichomys is well studied, the variation found in its cranial morphology is poorly understood, given the taxonomic and ecological complexities of the genus. Using a geometric morphometric approach, we characterized the differences found in the cranial morphology of four Thrichomys taxonomic units, including three established species, Thrichomys apereoides, Thrichomys fosteri, and Thrichomys laurentius, and one operational taxonomic unit (OTU), Thrichomys aff. laurentius. No significant differences were found among these units in cranium size, but significant variation was found in skull shape. The Procrustes distances provided a quantification of the differences in the shape of the skull, with the largest distances being found between T. aff. laurentius and T. fosteri in the dorsal view, and between T. aff. laurentius and T. apereoides in the ventral view. A Discriminant Function Analysis (DFA) with cross-validation determined that the pairings with the highest correct classification were T. aff. laurentius vs. T. apereoides and T. aff. laurentius vs. T. fosteri, in both views. The principal variation in skull shape was found in the posterior region and the zygomatic arch, which may be related to differences in diet.
Assuntos
Roedores/anatomia & histologia , Crânio/anatomia & histologia , Animais , EcossistemaRESUMO
Pablo Teta, Ricardo A. Ojeda, Sergio O. Lucero, and Guillermo D'Elía (2017) We analyzed the geographic variation in cranial morphology of the Southern Mountain Cavy, Microcavia australis, throughout of its distributional range. Our analysis allows us to recognize three geographically allopatric morphotypes. These morphotypes differ in the general size and shape of the skull and discrete morphological traits of the zygomatic arch, palate and mesopterygoid fossa. Based on these results, we restrict the name australis to populations distributed in southern Argentina and west-central Andes and the name maenas to the morphotype of northwestern and central Argentina. The third morphotype occurs in the Dry Chaco ecoregion and is described here as a new species.
RESUMO
The Cuban fossil vampire bats of the Neotropical genus Desmodus have been recently raised to specific rank. However, the dichotomous taxonomic history of the Cuban Desmodus fossils, plus the discovery of additional and more complete specimens prompted a reanalysis of the previous taxonomic arrangements. Here I document the range of skull variation in Desmodus rotundus geographical populations through a study of qualitative and quantitative osteological analysis to find the taxonomic affinity of the Cuban fossil Desmodus. It was found that the shape and size of D. rotundus skulls are widely variant, especially in the shape of the rostrum, palatal construction, zygomatic morphology, and occipital orientation; characters that have been often employed to separate the Cuban fossils from the extant form. This study demonstrates that the discrete morphology and measurements used to separate the Cuban fossils from the extant D. rotundus do not support the new taxonomic arrangement. The Cuban sample falls instead within the variation range observed in D. rotundus, implying that the fossil Desmodus sample from Cuba belong to the extant D. rotundus. Additionally, sexual dimorphism and minor geographical variation in the size of D. rotundus skulls was statistically supported. These results imply a probable revision of at least one of the fossil species (i.e., D. archaeodaptes), and support
RESUMO
The Cuban fossil vampire bats of the Neotropical genus Desmodus have been recently raised to specific rank. However, the dichotomous taxonomic history of the Cuban Desmodus fossils, plus the discovery of additional and more complete specimens prompted a reanalysis of the previous taxonomic arrangements. Here I document the range of skull variation in Desmodus rotundus geographical populations through a study of qualitative and quantitative osteological analysis to find the taxonomic affinity of the Cuban fossil Desmodus. It was found that the shape and size of D. rotundus skulls are widely variant, especially in the shape of the rostrum, palatal construction, zygomatic morphology, and occipital orientation; characters that have been often employed to separate the Cuban fossils from the extant form. This study demonstrates that the discrete morphology and measurements used to separate the Cuban fossils from the extant D. rotundus do not support the new taxonomic arrangement. The Cuban sample falls instead within the variation range observed in D. rotundus, implying that the fossil Desmodus sample from Cuba belong to the extant D. rotundus. Additionally, sexual dimorphism and minor geographical variation in the size of D. rotundus skulls was statistically supported. These results imply a probable revision of at least one of the fossil species (i.e., D. archaeodaptes), and support