Cyrtodactylus jambangan, western Mindanao.
As part of a collaborative effort with colleagues at the University of Kansas and the National Museum of the Philippines, phylogenetic and species delimitation analyses for Philippine Bent-toed geckos have yielded a more than two fold increase in the described species diversity in the archipelago.
This is an ongoing project, but to date, this work has taken the known diversity in the group from 4 species to 9, with a number of additional lineages awaiting description. This work has utilized standard, taxonomically informative morphological characters, as well as robust phylogenetic inferences. Please visit the Publications page to view the relevant literature related to this project.
As part of a collaborative effort with colleagues at the University of Kansas and the National Museum of the Philippines, phylogenetic and species delimitation analyses for Philippine Bent-toed geckos have yielded a more than two fold increase in the described species diversity in the archipelago.
This is an ongoing project, but to date, this work has taken the known diversity in the group from 4 species to 9, with a number of additional lineages awaiting description. This work has utilized standard, taxonomically informative morphological characters, as well as robust phylogenetic inferences. Please visit the Publications page to view the relevant literature related to this project.
Varanus bitatawa, northern Luzon. Photo by J.C. Gonzalez.
In 2010, I was fortunate to take the lead on the description of Varanus bitatawa, just the third known species of frugivorous monitor lizard. As with other frugivorous species, V. bitatawa is a forest obligate, requiring large tracts of intact habitat for survival. Therefore, it is our hope that this species will serve as a flagship species for conservation in the Philippines.
Distinguished by unique reproductive morphology, and charismatic dorsal patterning, this species is highly prized by indigenous peoples as a "bush meat" delicacy. Interestingly, while the species was virtually unknown to science until the first part of this century, it has been known to indigenous peoples for generations, with distinctions between frugivorous monitors and the common water monitors ("biawak") present in tribal dialects throughout it's range along the central and northern Sierra Madre mountains of eastern Luzon Island. The specific epithet, bitatawa, is derived from the name used by the Agta peoples.
Continued field work throughout Luzon have identified additional populations of both Varanus bitatawa and it's sister species V. olivaceus, extending the known ranges of both taxa. Please visit the Publications page to view the relevant literature related to this project.
In 2010, I was fortunate to take the lead on the description of Varanus bitatawa, just the third known species of frugivorous monitor lizard. As with other frugivorous species, V. bitatawa is a forest obligate, requiring large tracts of intact habitat for survival. Therefore, it is our hope that this species will serve as a flagship species for conservation in the Philippines.
Distinguished by unique reproductive morphology, and charismatic dorsal patterning, this species is highly prized by indigenous peoples as a "bush meat" delicacy. Interestingly, while the species was virtually unknown to science until the first part of this century, it has been known to indigenous peoples for generations, with distinctions between frugivorous monitors and the common water monitors ("biawak") present in tribal dialects throughout it's range along the central and northern Sierra Madre mountains of eastern Luzon Island. The specific epithet, bitatawa, is derived from the name used by the Agta peoples.
Continued field work throughout Luzon have identified additional populations of both Varanus bitatawa and it's sister species V. olivaceus, extending the known ranges of both taxa. Please visit the Publications page to view the relevant literature related to this project.
Varanus marmoratus, central Luzon.
My Master's research at the University of Kansas focused phylogenetic affinities, species boundaries, historical biogeography, and conservation of the Asian water monitor (Varanus salvator Complex), with particular emphasis on the Philippine members of the group.
This project has resulted in three major publications. The first was a phylo-forensic analysis of samples encountered in the Manila pet trade, revealing not only an overwhelming harvest pressure on Varanus marmoratus, but also an apparent deliberate misrepresentation of the provenance of animals in order to presumably inflate their value. Additionally, we found potential evidence for the presence of V. rudicollis on the island of Palawan. While these individuals may have actually been smuggled into the Philippines to supply trade demands, the possibility of natural populations of V. rudicollis on Palawan does exist. In this species' original description, the Philippines was listed as the type locality, a claim that has since been viewed as erroneous.
The second, and primary publication from this project is the first genetic analysis of the V. salvator Complex, based on a multi-locus dataset, and incorporating phylogenetic, network, structure, and species delimitation analyses. This work has highlighted the polyphyletic nature of the Philippine assemblage of the V. salvator Complex, with samples from Sulawesi (V. togianus), Java (V. salvator bivittatus), and Sumatra, Singapore, W. Malaysia, and Myanmar (V. s. macromaculatus), representing a nested subset of lineages within a predominately Philippine clade. Additionally, the northern Philippine species V. marmoratus is found to be paraphyletic . As it is currently recognized, this taxon is actually comprised of three distinct lineages, none of which are each other's closest relative. These "cf. marmoratus" lineages are unique, in that both are geographically proximal to true V. marmoratus, with one actually occurring sympatrically on Luzon Island (Bicol Peninsula, and Polillo and Catanduanes islands) but being more closely related to V. nuchalis from the central Visayan islands, and the other present on Mindoro and Semirara islands (off the southwest coast of Luzon) but being closely related to V. palawanensis from Palawan Island. This is a fascinating group, both within the Philippines and otherwise, and there remains much to learn about their population level dynamics. Water monitors, as their name suggests, are quite proficient dispersers, and have been documented swimming in the open ocean, on rocky crags off the coasts of peninsular Malaysia, and were even some of the first vertebrates to colonize Krakatoa after volcanic eruption. It can only be assumed that gene flow in this group is rampant, potentially confounding species boundaries. Future work on this group, utilizing dense sampling from outside of the Philippines and Next Generation sequence data, will likely identify additional, unrecognized lineages.
The final chapter of this work is in preparation, incorporating fossil calibrations, and ancestral area and geological reconstructions in an effort to infer the historical biogeography of the Varanus salvator Complex. The dynamic geological nature of Southeast Asia during the past 30 million years, coupled with the climatic changes during the Pliocene and Pleistocene, have created a fascinating system for the production and shaping of biodiversity. It is in this scenario that the Asian water monitor has evolved and diversified. With the highest taxonomic diversity present in the Philippines, the view of this country as a fringing archipelago, and a depauperate subset of mainland taxa, appears to be a falsehood as it relates to monitor lizards. But rather, the Philippines appears to be a generator of diversity in this group, a emerging pattern seen throughout a growing number of squamate and amphibian taxa.
Please visit the Publications page to view the relevant literature related to this project.
My Master's research at the University of Kansas focused phylogenetic affinities, species boundaries, historical biogeography, and conservation of the Asian water monitor (Varanus salvator Complex), with particular emphasis on the Philippine members of the group.
This project has resulted in three major publications. The first was a phylo-forensic analysis of samples encountered in the Manila pet trade, revealing not only an overwhelming harvest pressure on Varanus marmoratus, but also an apparent deliberate misrepresentation of the provenance of animals in order to presumably inflate their value. Additionally, we found potential evidence for the presence of V. rudicollis on the island of Palawan. While these individuals may have actually been smuggled into the Philippines to supply trade demands, the possibility of natural populations of V. rudicollis on Palawan does exist. In this species' original description, the Philippines was listed as the type locality, a claim that has since been viewed as erroneous.
The second, and primary publication from this project is the first genetic analysis of the V. salvator Complex, based on a multi-locus dataset, and incorporating phylogenetic, network, structure, and species delimitation analyses. This work has highlighted the polyphyletic nature of the Philippine assemblage of the V. salvator Complex, with samples from Sulawesi (V. togianus), Java (V. salvator bivittatus), and Sumatra, Singapore, W. Malaysia, and Myanmar (V. s. macromaculatus), representing a nested subset of lineages within a predominately Philippine clade. Additionally, the northern Philippine species V. marmoratus is found to be paraphyletic . As it is currently recognized, this taxon is actually comprised of three distinct lineages, none of which are each other's closest relative. These "cf. marmoratus" lineages are unique, in that both are geographically proximal to true V. marmoratus, with one actually occurring sympatrically on Luzon Island (Bicol Peninsula, and Polillo and Catanduanes islands) but being more closely related to V. nuchalis from the central Visayan islands, and the other present on Mindoro and Semirara islands (off the southwest coast of Luzon) but being closely related to V. palawanensis from Palawan Island. This is a fascinating group, both within the Philippines and otherwise, and there remains much to learn about their population level dynamics. Water monitors, as their name suggests, are quite proficient dispersers, and have been documented swimming in the open ocean, on rocky crags off the coasts of peninsular Malaysia, and were even some of the first vertebrates to colonize Krakatoa after volcanic eruption. It can only be assumed that gene flow in this group is rampant, potentially confounding species boundaries. Future work on this group, utilizing dense sampling from outside of the Philippines and Next Generation sequence data, will likely identify additional, unrecognized lineages.
The final chapter of this work is in preparation, incorporating fossil calibrations, and ancestral area and geological reconstructions in an effort to infer the historical biogeography of the Varanus salvator Complex. The dynamic geological nature of Southeast Asia during the past 30 million years, coupled with the climatic changes during the Pliocene and Pleistocene, have created a fascinating system for the production and shaping of biodiversity. It is in this scenario that the Asian water monitor has evolved and diversified. With the highest taxonomic diversity present in the Philippines, the view of this country as a fringing archipelago, and a depauperate subset of mainland taxa, appears to be a falsehood as it relates to monitor lizards. But rather, the Philippines appears to be a generator of diversity in this group, a emerging pattern seen throughout a growing number of squamate and amphibian taxa.
Please visit the Publications page to view the relevant literature related to this project.