21 research outputs found
Ancient DNA of the pygmy marmoset type specimen Cebuella pygmaea (Spix, 1823) resolves a taxonomic conundrum
The pygmy marmoset, the smallest of the anthropoid primates, has a broad distribution in Western Amazonia. Recent studies using molecular and morphological data have identified two distinct species separated by the Napo and SolimĂ”es-Amazonas rivers. However, reconciling this new biological evidence with current taxonomy, i.e., two subspecies, Cebuella pygmaea pygmaea (Spix, 1823) and Cebuella pygmaea niveiventris (Lönnberg, 1940), was problematic given the uncertainty as to whether Spixâs pygmy marmoset (Cebuella pygmaea pygmaea) was collected north or south of the Napo and SolimĂ”es-Amazonas rivers, making it unclear to which of the two newly revealed species the name pygmaea would apply. Here, we present the first molecular data from Spixâs type specimen of Cebuella pygmaea, as well as novel mitochondrial genomes from modern pygmy marmosets sampled near the type locality (Tabatinga) on both sides of the river. With these data, we can confirm the correct names of the two species identified, i.e., C. pygmaea for animals north of the Napo and SolimĂ”es-Amazonas rivers and C. niveiventris for animals south of these two rivers. Phylogenetic analyses of the novel genetic data placed into the context of cytochrome b gene sequences from across the range of pygmy marmosets further led us to re-evaluate the geographical distribution for the two Cebuella species. We dated the split of these two species to 2.54 million years ago. We discuss additional, more recent, subdivisions within each lineage, as well as potential contact zones between the two species in the headwaters of these rivers
Action to protect the independence and integrity of global health research
Storeng KT, Abimbola S, Balabanova D, et al. Action to protect the independence and integrity of global health research. BMJ GLOBAL HEALTH. 2019;4(3): e001746
Geometric morphometrics and finite element analyses reveal the Haast's eagle (Harpagornis moorei) to be a mixed predator-scavenger
The extinct Haastâs eagle (Harpagornis moorei) was 30-40% heavier than the largest extant eagle. There have been speculations about
its evolutionary history and ecology, though there is still no consensus on its feeding behaviour. This study aims at understanding the
evolution and ecology of Harpagornis by combining 3D geometric morphometrics and finite element analysis (FEA) on three-dimensional
models constructed from CT-data of skulls and talons of Accipitridae.
Statistical analyses revealed the presence of two independent modules (beak and neurocranium) and of a strong allometric effect in
the skull. Size-free shape analysis of the two modules revealed that Harpagornisâ beak was similar to the eagles, while itâs neurocranial
morphology was more like a vulture. In most cranial FEA loading cases, there seems to be a dichotomy between Cathartidae on the one
side and Accipitridae on the other. FEA on the skull, nevertheless, indicates that Harpagornis and the scavenging species of our dataset
are well adapted to perform a pull-back motion.
The talon results suggest Harpagornis was an active hunter. Harpagornisâ talon occupies a position in morphospace close to its closest
living relative Hieraaetus (smallest extant eagle), suggesting a phylogenetic constraint on talon shape. However, FEA showed that the
talon of Harpagornis undergoes similar stresses to that of other hunting raptors which rely on large-sized prey (e.g. Aquila audax).
Neurocranial morphology and FEA, however, clearly indicate a feeding behaviour more similar to vultures, possibly because of the large
size of its prey (e.g., giant Moa). Harpagornisâ neurocranial adaptation probably allowed a stronger and faster pull back motion to quickly
remove large chunks of meat from the prey, similarly to vultures. Moreover, our results document a rapid evolutionary change, which might
have allowed Harpagornis to exploit large sized prey. Harpagornis moorei therefore represents an extreme example of how freedom from
competition in island ecosystems can rapidly influence morphological adaptation