Biomedical subjects

Anjali Goswami

Publications and source records attributed to Anjali Goswami.

3 recordsLinked to original sources

PubMed2006

Amber from western Amazonia reveals Neotropical diversity during the middle Miocene.

Tertiary insects and arachnids have been virtually unknown from the vast western Amazonian basin. We report here the discovery of amber from this region containing a diverse fossil arthropod fauna (13 hexapod families and 3 arachnid species) and abundant microfossil inclusions (pollen, spores, algae, and cyanophyceae). This unique fossil assemblage, recovered from middle Miocene deposits of northeastern Peru, greatly increases the known diversity of Cenozoic tropical-equatorial arthropods and microorganisms and provides insights into the biogeography and evolutionary history of modern Neotropical biota. It also strengthens evidence for the presence of more modern, high-diversity tropical rainforest ecosystems during the middle Miocene in western Amazonia.

Amber↗

PubMed2006

Cranial modularity shifts during mammalian evolution.

The mammalian skull has been studied as several separate functional components for decades, but the study of modularity is a more recent, integrative approach toward quantitative examination of independent subsets of highly correlated traits, or modules. Although most studies of modularity focus on developmental and genetic systems, phenotypic modules have been noted in many diverse morphological structures. However, few studies have provided empirical data for comparing modules across higher taxonomic levels, limiting the ability to assess the broader evolutionary significance of modularity. This study uses 18-32 three-dimensional cranial landmarks to analyze phenotypic modularity in 106 mammalian species and demonstrates that cranial modularity is generally conserved in the evolution of therian mammals (marsupials and placentals) but differs between therians and monotremes, the two extant subclasses of Mammalia. Within therians, cluster analyses identify six distinct modules, but only three modules display significant integration in all species. Monotremes display only two highly integrated modules. Specific hypotheses of functional and developmental influences on cranial bones were tested. Theoretical correlation matrices for bones were constructed on the basis of shared function, tissue origin, or mode of ossification, and all three of these models are significantly correlated with observed correlation matrices for the mammalian cranium.

Animals↗

PubMed2006

Morphological integration in the carnivoran skull.

The correlated evolution of traits may be a principal factor in morphological evolution, but it is typically studied in genetic or developmental systems. Most studies examining phenotypic trait correlations, through analysis of morphological integration, consider only few taxa, with limited ability to test hypotheses of the influence of trait integration on morphological variation and diversity. The few comparative studies in less inclusive groups have yielded varying relationships of integration to the key factors of phylogeny and diet. In this paper, I present analyses of cranial morphological integration in 30 species from the mammalian order Carnivora, spanning eight extant families and a wide range of ecological and morphological diversity. Fifty-five cranial landmarks were captured through three-dimensional digitization of 15-22 specimens for each species. Using a node-based phylogenetic distance matrix, a significant correlation was found between similarity in patterns of integration and phylogenetic relatedness within Felidae (cats) and Canidae (dogs), but not within more inclusive clades, when size-related variation was removed. When size was included, significant correlations were found across all Caniformia, Musteloidea, Mustelidae, and Felidae. There was a significant correlation between phylogeny and morphological integration only within the higher-level clade Feliformia (cats, civets, mongooses, and hyaenas) when a branch-length-based phylogenetic distance matrix was analyzed, with and without size. In contrast, diet was significantly correlated with similarity in morphological integration in arctoid carnivorans (bears, raccoons, and weasels), but had no significant relationship with integration in feliforms or canids. These results support the proposition that evolutionary history is correlated with cranial integration across large clades, although in some smaller clades diet also exerts significant influence on the correlated evolution of traits.

Animals↗