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 Solimoes-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 Spix’s pygmy marmoset(Cebuella pygmaea pygmaea)was collected north or south of the Napo and Solimoes-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 Spix’s 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 Solimoes-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 reevaluate 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.

Female reproductive success in a species with an age-inversed hierarchy

In most group-living mammals,reproductive success declines with increasing age and increases with increasing rank.Such effects have mainly been studied in matrilineal and in“age positive”hierarchies,which are stable and in which high ranking females often outperform low ranking ones.These relationships are less well-under­stood in age-inversed dominance hierarchies,in which a female’s rank changes over time.We analyzed demo­graphic data of 2 wild,unprovisioned groups of gray langurs(Semnopithecus schistaceus)near Ramnagar,Ne­pal covering periods of 5 years each.Female rank was unstable and age-inversed.We measured reproductive success via birth rates(57 births),infant survival(proportion of infants surviving to 2 years)and number of off­spring surviving to 2 years of age(successful births)for 3 age and 3 rank classes.We found that old females performed significantly worse than expected(birth rate P=0.04;successful births P=0.03).The same was true for low ranking females(P=0.04,and P<0.01,respectively).Infant survival was highest for young and mid­dle-aged as well as for high and middle ranking females.Overall,the results for these unstable hierarchies were rather similar to those for stable hierarchies of other mammals,particularly several nonhuman primates.Com­pared to a provisioned population of a closely related species,the wild and unprovisioned population exam­ined(i)showed stronger age effects,while(ii)female reproductive success was equally affected by rank.Future comparative studies are needed to examine whether captive or provisioned populations deviate predictably from wild populations.