Phylogenetic Position and Origin of the Capped-Golden langur lineage
Centre For Ecological Sciences, Indian Institute Of Science.Authors
Kunal Arekar, Dr. Praveen Karanth
Introduction: What conservation problem or question does your study address?
Golden and Capped langur, currently in the genus Trachypithecus, are old world primates belonging to the family Cercopithecidae and subfamily Colobinae. Previous studies have hypothesized hybridization between Semnopithecus and Trachypithecus or incomplete lineage sorting or climatic model theory for their phylogenetic position. This study aims to resolve the debate about its phylogenetic position and assign a more relevant conservation status to them.
Methods: What were the main research methods you used?
We will use molecular tools to address the study. Seven nuclear markers and one mitochondrial (mtDNA) marker will be used to resolve the question. We have collected fecal samples (non-invasive technique), in absolute alcohol, from most parts of their distribution zone and from zoos. DNA extraction, amplification and sequencing were done using standard protocols. Phylogenies will be built by concatenating all the 7 nuclear markers and the mtDNA marker and apart from this individual gene trees will be constructed using Muscle (Edgar, 2004) in MEGA v5.2 and RAxML v1.3. Sequences for other species will be downloaded from Genbank. For the hybridization hypothesis, few gene trees will group the CG lineage with Trachypithecus and few others will group it with Semnopithecus and under the incomplete lineage sorting hypothesis, nuclear tree will group CG with Trachypithecus while the mtDNA tree will group CG with Semnopithecus or vice versa.
Results: What are your most important results?
Preliminary analysis includes 2692 bp of nuclear gene sequence from 7 markers for 16 individuals. All the trees support the sister relation for Golden and Capped langur. Two distinct clades were seen; the Trachypithecus clade including Golden-Capped langur (CG) lineage and the Semnopithecus clade. With the nuclear data the CG lineage is placed within the genus Trachypithecus. It will be interesting to see the results when the mtDNA data is included in the analysis.
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
Nuclear data suggests that the CG lineage is sister to Trachypithecus. However, recent accumulation of two unique nucleotide changes in CG lineage from Semnopithecus, indicates hybridization and introgression of those particular loci. Inclusion of data from uniparental markers (mtDNA) would aid the resolution of taxonomic position of C-G langurs. This would support its elevation to genus level and increase its conservation value.