Showing papers by "Martha M. Robbins published in 2012"
TL;DR: The human–chimpanzee split is dated to at least 7–8 million years and the population split between Neanderthals and modern humans to 400,000–800,000 y ago, which suggests that molecular divergence dates may not be in conflict with the attribution of 6- to 7-million-y-old fossils to the human lineage and 400,,000-Y-old bones to the Neanderthal lineage.
Abstract: Fossils and molecular data are two independent sources of information that should in principle provide consistent inferences of when evolutionary lineages diverged. Here we use an alternative approach to genetic inference of species split times in recent human and ape evolution that is independent of the fossil record. We first use genetic parentage information on a large number of wild chimpanzees and mountain gorillas to directly infer their average generation times. We then compare these generation time estimates with those of humans and apply recent estimates of the human mutation rate per generation to derive estimates of split times of great apes and humans that are independent of fossil calibration. We date the human–chimpanzee split to at least 7–8 million years and the population split between Neanderthals and modern humans to 400,000–800,000 y ago. This suggests that molecular divergence dates may not be in conflict with the attribution of 6- to 7-million-y-old fossils to the human lineage and 400,000-y-old fossils to the Neanderthal lineage.
477 citations
TL;DR: The results emphasize the value of applying a multi-species, longer-term approach to studying variation in habitat use among sympatric species and highlight the impact competitors can exert on one another's distribution.
Abstract: Speciescommonlyexistinsympatry,yetecologicalstudiesareoftenbasedonasinglespeciesapproachwhile ignoring the impact of sympatric competitors. Over 13 mo we used 24 remote video-camera traps to monitor habitat use of sympatric chimpanzee, gorilla and elephant in four different habitat types in Loango National Park, Gabon. Habitat use by each species was predicted to vary according to seasonal changes in food availability and precipitation. Increased interspecific competition between the three species was expected at times of reduced resource availability, leading to exclusion of the inferior competitor. Supporting the predictions, species abundance per habitat showed seasonal variation: all three species responded positively to increased fruit availability in all habitats, but the response was only significant for gorilla in mature forest and elephant in coastal forest. Responses to rainfall varied, with the chimpanzee responding negatively to rainfall in swamp forest, the gorilla responding positively to rainfall in coastal andsecondaryforest,andtheelephantrespondingpositivelytorainfallinmatureforest.Elephantpresenceresultedin competitive exclusion of the apes under certain conditions: the chimpanzee was excluded by the elephant where fruit availability was low, whereas the gorilla was excluded by the elephant in areas of low herb density despite high fruit availability. Our results emphasize the value of applying a multi-species, longer-term approach to studying variation in habitat use among sympatric species and highlight the impact competitors can exert on one another's distribution.
94 citations
TL;DR: Among 19 adult male gorillas monitored for up to 12.5 years, it was found that all three phenotypic traits were positively correlated with the average number of mates per male, but only crest size and gluteal muscle size were significantly correlated with offspring survival and the annual rate of siring offspring that survive to weaning age.
50 citations
Academy of Sciences of the Czech Republic1, University of Veterinary and Pharmaceutical Sciences Brno2, Robert Koch Institute3, Primate Research Institute4, Makerere University5, Harvard University6, University of California, San Diego7, Max Planck Society8, Wildlife Conservation Society9, Washington University in St. Louis10, University College London11, Lincoln Park Zoo12, Yamaguchi University13, Virginia–Maryland Regional College of Veterinary Medicine14
TL;DR: A very low diversification of T. abrassarti is found in chimpanzees across Africa, which may point to the presence of an ancestral Type II found throughout the Lower Guinean rainforest dating back to the common Pan ancestor, or imply a historical overlap of the species' distribution ranges.
Abstract: The entodiniomorphid ciliate Troglody- tella abrassarti is a colonic mutualist of great apes. Its host specificity makes it a suitable model for studies of primate evolution. We explored molecular diversity of T. abrassarti with regard to large geographical distribu- tion and taxonomic diversity of its most common host, the chimpanzee. We found a very low diversification of T. abrassarti in chimpanzees across Africa. Distribution of two types of T. abrassarti supports evolutionary sepa- ration of the Western chimpanzee, P. t. verus, from popu- lations in Central and East Africa. Type I T. abrassarti is probably a derived form, which corresponds with the Central African origin of chimpanzees and a founder event leading to P. t. verus. Exclusivity of the respective types of T. abrassarti to Western and Central/Eastern chimpanzees corroborates the difference found between an introduced population of presumed Western chimpan- zees on Rubondo Island and an autochthonous popula- tion in mainland Tanzania. The identity of T. abrassarti from Nigerian P. t. ellioti and Central African chimpan- zees suggests their close evolutionary relationship. Although this contrasts with published mtDNA data, it corroborates current opinion on the exclusive position of P. t. verus within the chimpanzee phylogeny. The type of
14 citations
01 Jun 2012
9 citations