This project will contribute to a better understanding of the cryptic diversity within dwarf galagos in Eastern Africa, integrating genetic, morphological and bio-acoustic data. This study will strive to 1) describe the genetic relationship within and among currently recognized dwarf galago species and, 2) test the importance of vocal communication in maintaining reproductive isolation between cryptic species. The project will yield the most comprehensive molecular assessment of galagid evolutionary relationships undertaken to date and will help elucidate likely causes of diversification and speciation among cryptic primates. From a conservation perspective, it will contribute to understand the diversity of nocturnal galagids in Eastern Africa, which is crucial for developing effective conservation and management programs. The study also promotes international collaboration at many levels.

Understanding and describing biological diversity is one of the main goals for biologists. This task, however, is particularly challenging when speciation is not always accompanied by noticeable morphological change. An appreciation of such cryptic species is not only important for better understanding biological diversity, but it may also affect our ability to explore models and patterns of speciation. Nocturnal dwarf galagos (Galagoides) are among the most morphologically cryptic of all primates and their evolutionary history is one of the most longstanding problems in primatology. Given the lack of morphological differentiation, galago species have been mostly described based on their advertisement calls. Within galagids, acoustic communication plays a critical role and vocal signals are used to maintain contact with other members of the same species and to attract mates. Species cohesiveness is therefore likely to be maintained by non-visual recognition systems, and advertisement calls have been suggested to play a critical role in reproductive isolation. The lack of genetic data, however, has not allowed testing of whether specific differences in vocal signals can really contribute to species cohesion, and whether "vocal species" are actually genetically distinct.

Project Report

Understanding biodiversity is one of the main goals in evolutionary biology and primatology. A clear comprehension of global biodiversity relies on estimation of species richness and it is critical for prioritizing habitats for conservation. Cryptic species, such most nocturnal mammals, represent a challenge for conservation biologists because their biodiversity may be easily underestimated with critical implications for natural resource management. For example, species that are considered of ‘least concern’ might be composed of multiple cryptic species that are more rare than previously supposed and might require specific conservation strategies. Bushbabies (Galagidae) are amongst the most cryptic and least studied primates and, until recently, no species were considered endangered because their biodiversity was not well described. However, recent surveys have uncovered several new species, including the Rondo dwarf galagos classified as Critically Endangered and among the 25 most endangered primates. Given the lack of morphological differentiation, galagid species have been mostly described based on their vocal behavior. Advertisement calls have been suggested to play a critical role in reproductive isolation, however the lack of genetic data does not allow researchers to test whether specific differences in vocal signals are representative of species diversity. Genetic studies on this cryptic complex are therefore essential in order to avoid the possibility of some species going extinct before they have even been identified. The specific goals of this project were: to investigate the evolutionary history of Lorisoidea, with particular attention to the phylogenetic relationships and the time of divergence among the galagids; Investigate phylogeographic history of the genus Galagoides (dwarf galagos) in order to provide a better understanding of the main factors that promoted diversification in the forest of Eastern Africa; to investigate species boundaries between two cryptic species of dwarf galagos by comparing genetic and acoustic data. Activities conducted: Field work was conducted in three separate field seasons, one in Kenya (2010) and two in Tanzania (2011 and 2012), for a total number of ~9 months in the field. Overall 12 different localities was visitied and samples were collected for three different species of galagos, Galagoides cocos, G. zanzibaricus, and Otolemur garnettii. In addition to biological samples for genetic analyses, we also collected over 70h of acoustic recordings from multiple populations. Lab work was conducted at NYU Molecular Anthropology lab. We developed 27 independent nuclear loci to analyze phylogenetic relationships and species boundaries within galagids. To test congruence between acoustic and genetic data, I also analyzed over 200 advertising calls across eight different sites. The major outcomes of our projects were the following: 1. Phylogeny: While galagids form a well-supported monophyletic clade, the interrelationships between Asian and African lorisids remain poorly supported. Within Galagidae, the genus Euoticus was identified as the basal sister taxon to the rest of galagids. The genus Galagoides was not recovered as monophyletic and a new generic name for the Zanzibar complex is required. The origins for the most recent common ancestor of all living galagids were quite old, soon after the Eocene-­Oligocene boundary (~34Ma). 2. Species boundaries: Collectively, the results from the combination of genetic and acoustic data confirmed that Galagoides cocos and G. zanzibaricus represent two different cryptic species of dwarf galagos. This study supports the hypothesis that vocalizations may provide information about species identity and may be used as a noninvasive tool for species discrimination within galagids. The goal of this project was to better describe the biodiversity of one of the most neglected groups of primates, providing critical information about its taxonomy, phylogeny and phylogeography in Eastern Africa. Galagos are poorly known and only a few studies have been conducted on this group. This project represent the most comprehensive molecular study of galagids to date. Moreover understanding their true diversity and their relationships may provide critical information for future studies on the behavioral ecology and morphology of these primates. The study we conducted produced the first multilocus phylogeny for this understudied group of primates, and it helped filling an important gap in strepsirhine evolution, and more generally, in evolutionary primatology. The results of our study will set the basis for future research aimed to better investigate the biogeography and the evolutionary history of this group. This research also provided for the first time some preliminary but critical information to understand if vocal signals might act as reproductive isolation systems within nocturnal galagids. The proposed study explored for the first time species boundaries galagids by integrating genetic, morphological, and bioacoustic data. Although the proposed research was not meant to be comprehensive, the outcomes of this study contribute to the theoretical debate regarding species boundaries in morphological cryptic taxa. Investigating cryptic speciation has been shown to be extremely challenging for evolutionary biologists, and it is now recognized that an under-appreciation of cryptic diversity may affect our comprehension of global biodiversity and also affect our priorities for habitat conservation

National Science Foundation (NSF)
Division of Behavioral and Cognitive Sciences (BCS)
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Carolyn Ehardt
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New York University
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