Didelphid marsupials are considered a morphologically unspecialized group with a generalist diet that includes vertebrates,invertebrates,and plant matter.While cranium and scapula variation has alreadybeen examined wi...Didelphid marsupials are considered a morphologically unspecialized group with a generalist diet that includes vertebrates,invertebrates,and plant matter.While cranium and scapula variation has alreadybeen examined within Didelphidae,variation inmandible shape,usually associated with diet or phylogeny in other mammalian groups,has not yet been properly assessed in the family.We evaluated the variation in mandible shape and size of didelphids(2470 specimens belonging to 94 species)using 2D geometric morphometrics.We classified the diet of the didel-phids into four broad categories to assess whether morphospace ordination relates to dietary habits.We also provided the most comprehensive phylogeny for the family(i23 out of the 126 living species)using 10 nuclear and mitochondrial genes.We then mapped mandible size and shape onto that phylogeny for 93 selected taxa and ancestral size and shapes were reconstructed by parsimony.We found phylogenetically structured variation in mandible morphology between didelphid groups,and our results indicate that they have a significant phylogenetic signal.The main axis of shape variation is poorly related to size,but the second is strongly allometric,indicating that allometry is not the main factor in shaping morphological diversity on their mandibles.Our results indicate that the shape and size of the ancestral mandible of didelphids would be similar to that of the current species of the genus Marmosa.展开更多
Usually considered a morphologically conservative group, didelphid marsupials present consider- able variation in ecology and body size, some of which were shown to relate to morphological structures. Thus, changes on...Usually considered a morphologically conservative group, didelphid marsupials present consider- able variation in ecology and body size, some of which were shown to relate to morphological structures. Thus, changes on orbit morphology are likely and could be related to that variation. We calculated orbit orientation in 873 specimens of 16 Didelphidae genera yielding estimates of orbits convergence （their position relative to midsagittal line） and verticality （their position relative to frontal plane）. We then compared similarities in these variables across taxa to ecological, morpho- logical and phylogenetic data to evaluate the influencing factors on orbit orientation in didelphids. We found an inverse relation between convergence and verticality. Didelphids orbits have low ver- ticality but are highly convergent, yet orbit orientation differs significantly between taxa, and that variation is related to morphological aspects of the cranium. Rostral variables are the only morpho- logical features correlated with orbit orientation： increasing snout length yields more convergent orbits, whereas increase on snout breadth imply in more vertical orbits. Size and encephalization quotients are uncorrelated with orbit orientation. Among ecological data, diet showed significant correlation whereas locomotion is the factor that less affects the position of orbits. Phylogeny is uncorrelated to any orbital parameters measured. Ecological factors seemingly play a more import- ant role on orbit orientation than previously expected, and differentiation on orbit orientation seems to be more functional than inherited. Thus, despite the apparent homogeneity on didelphid morphology, there is subtle morphological variability that may be directly related to feeding behavior.展开更多
Among the factors thar may influence parasitism are ecological and phylogenetic aspects(Krasnov et al.2005),where a host species may acquire a parasite by contact with other hosts co-occurring in a given environment o...Among the factors thar may influence parasitism are ecological and phylogenetic aspects(Krasnov et al.2005),where a host species may acquire a parasite by contact with other hosts co-occurring in a given environment or because of its ancestor(Hoberg and Brooks 2008).Thus,the parasite community can be considered a reflection of the ecological characteristics and the phylogeny of the host(Krasnov et al.2005).展开更多
文摘Didelphid marsupials are considered a morphologically unspecialized group with a generalist diet that includes vertebrates,invertebrates,and plant matter.While cranium and scapula variation has alreadybeen examined within Didelphidae,variation inmandible shape,usually associated with diet or phylogeny in other mammalian groups,has not yet been properly assessed in the family.We evaluated the variation in mandible shape and size of didelphids(2470 specimens belonging to 94 species)using 2D geometric morphometrics.We classified the diet of the didel-phids into four broad categories to assess whether morphospace ordination relates to dietary habits.We also provided the most comprehensive phylogeny for the family(i23 out of the 126 living species)using 10 nuclear and mitochondrial genes.We then mapped mandible size and shape onto that phylogeny for 93 selected taxa and ancestral size and shapes were reconstructed by parsimony.We found phylogenetically structured variation in mandible morphology between didelphid groups,and our results indicate that they have a significant phylogenetic signal.The main axis of shape variation is poorly related to size,but the second is strongly allometric,indicating that allometry is not the main factor in shaping morphological diversity on their mandibles.Our results indicate that the shape and size of the ancestral mandible of didelphids would be similar to that of the current species of the genus Marmosa.
文摘Usually considered a morphologically conservative group, didelphid marsupials present consider- able variation in ecology and body size, some of which were shown to relate to morphological structures. Thus, changes on orbit morphology are likely and could be related to that variation. We calculated orbit orientation in 873 specimens of 16 Didelphidae genera yielding estimates of orbits convergence （their position relative to midsagittal line） and verticality （their position relative to frontal plane）. We then compared similarities in these variables across taxa to ecological, morpho- logical and phylogenetic data to evaluate the influencing factors on orbit orientation in didelphids. We found an inverse relation between convergence and verticality. Didelphids orbits have low ver- ticality but are highly convergent, yet orbit orientation differs significantly between taxa, and that variation is related to morphological aspects of the cranium. Rostral variables are the only morpho- logical features correlated with orbit orientation： increasing snout length yields more convergent orbits, whereas increase on snout breadth imply in more vertical orbits. Size and encephalization quotients are uncorrelated with orbit orientation. Among ecological data, diet showed significant correlation whereas locomotion is the factor that less affects the position of orbits. Phylogeny is uncorrelated to any orbital parameters measured. Ecological factors seemingly play a more import- ant role on orbit orientation than previously expected, and differentiation on orbit orientation seems to be more functional than inherited. Thus, despite the apparent homogeneity on didelphid morphology, there is subtle morphological variability that may be directly related to feeding behavior.
基金We are grateful to the Universidade Federal de Sergipe(PROAP/CAPESAJFS)for logistical supportThis study was financed in part by the Coordenaqao de Aperfeiqoamento de Pessoal de Nivel Superior-Brasil(CAPES)-Finance Code 001.
文摘Among the factors thar may influence parasitism are ecological and phylogenetic aspects(Krasnov et al.2005),where a host species may acquire a parasite by contact with other hosts co-occurring in a given environment or because of its ancestor(Hoberg and Brooks 2008).Thus,the parasite community can be considered a reflection of the ecological characteristics and the phylogeny of the host(Krasnov et al.2005).
