Sometimes taxonomic issues can be intractable without genetic data, yet since old herp holotypes have been formalin-fixed or preserved in ethanol for long periods if time, they generally have highly degraded DNA, thus getting those genetic data can be extremely difficult. Case in point, earlier this year I was part of a publication lead by Jim McGuire that attempted to sequence DNA from the 145 year old holotype of Draco cristatellus. This involved a ton of effort to get DNA from this specimen and then to get sequence from this extract. Read the article to see the extent of work that went into recovering those data from this very old specimen, but in a nutshell we tried a bunch of extraction techniques, and the only thing that worked for extraction was an aDNA protocol. We followed that up with a bunch of NGS sequencing, and recovered a small amount of sequence data -but SUCCESS!!
Why does it matter? Often the reason that these genetic data are needed is to resolve a taxonomic issue. If a species name and type exists but you have two or more unique lineages to which the name could apply, and morphological characters are difficult or impossible to discern based on the type specimen, then without genetic data, assignment of a name to the correct lineage is not straight forward. Genetic data may represent the only way to resolve some of these issues, as was certainly the case for these lizards.
Here is the citation and link to the open access article, so enjoy!
McGuire JA, Cotoras DD, O’Connell B, Lawalata SZS, Wang-Claypool CY, Stubbs A, Huang X, Wogan GOU, Hykin SM, Reilly SB, Bi K, Riyanto A, Arida E, Smith LL, Milne H, Streicher JW, Iskandar DT. (2018) Squeezing water from a stone: high-throughput sequencing from a 145-year old holotype resolves (barely) a cryptic species problem in flying lizards. PeerJ6:e4470https://doi.org/10.7717/peerj.4470
We just published a paper in Global Change Biology calling attention to the invasion of the Wallacea bioregion by the Asian spiny toad (Duttaphrynus melanostictus). While the invasion has been going on for several decades, it has been largely overlooked. The Wallacean islands are naturally toad-free, which means that the native species (predators) are naive about the toxicity of the toads, and therefore, are at risk if they attempt to consume the poisonous toads. Of particular concern is the iconic apex predator, the Komodo Dragon, which is known to be susceptible to the toad toxins. While the toads have not reached the islands on which Komodo Dragons are found, they have reached all of the adjacent islands, suggesting that invasion is possible unless actions are taken to reduce introduce risk. Environmental niche models suggest that if the toads do reach those islands that the climate is suitable for them to establish themselves. We also found that all of the invading toads we tested from throughout Wallacea have the same haplotype and have been introduced from populations from the Sunda Shelf Islands of Java and Sumatra. This suggests that local ferries and boats are transporting the toads.
Here is the citation, and a link to the paper!
S. Reilly*, G. O. U. Wogan*, A. Stubbs, E. Arida, D. Iskandar, and J. McGuire. Toxic Toad Invasion of Wallacea: a Biodiversity Hotspot Characterized by Extraordinary Endemism. Global Change Biology (in press) early view linkDOI: 10.1111/gcb.13877
Also we have had some nice coverage of this paper by Mongabay
We just published a new paper on the invasion of the Spiny Asian toad (Duttaphrynus melanostictus) to Madagascar. This new paper expanded sampling of toads within their native Asian range as well as those introduced in Madagascar. The expanded sampling suggests that the introduction came from Southern Vietnam or Cambodia. We also did some niche modelling to assess the potential distribution of the toad within Madagascar. Anyway, check it out!
Figure 1. from Vences et al. 2017. Tracing a toad invasion: Lack of mitochondrial DNA variation, haplotype origins, and potential distribution of introduced Duttaphrynus melanostictus in Madagascar. Amphibia-Reptilia v. 38: 197-207 DOI:10.1163/15685381-00003104
Recent publications -now with graphical abstracts!
It has been a busy couple of months, here are some quick summaries of recent publications on which I am an author.
Our new publication on the pet trade of Asian newts just came out in Biological Conservation! The over-harvesting of these species for the pet trade has almost driven some Asian newt species to extinction. The trade remains poorly documented and largely unregulated, our paper calls for CITES listing all of these species so at least the trade can be documented.
Our paper on African Batis birds provides new msats and a first pass at assessing population structure for the Batis capensis complex is published in Biochemical Systematics and Ecology. There are five undergraduate co-authors on this one, all of whom did a great job testing and optimizing those new msats!
and another…. this paper uses niche modelling to look at the impact of life history traits on temporal transferability of models for North American birds. This paper is reliant upon data from citizen scientists from the Christmas Bird Count. It is open access and available at PLoS One.
The First is about the Asian Common Toad, Duttaphynus melanostictus. Published in Biology Letters. Below is a nice summary of this work by co-author Bryan Stuart from the North Carolina Museum of Natural Sciences.
Most species are negatively affected when humans transform natural habitats into urban areas and agricultural lands, but a few species actually benefit from these activities. These species- called human commensals- thrive in human-modified environments. One example, the Asian Common Toad (Duttaphrynus melanostictus), is extremely abundant in villages, towns, cities and agricultural areas across much of Southeast Asia, where it feeds on insects that are attracted to artificial lights. Because of this long and close association with people, Asian Common Toads are assumed to easily disperse over large distances, including saltwater barriers between islands, when they are accidentally transported with land and sea cargo. Such long-distance dispersal abilities infers that the toad’s genes also easily move among populations, and that toads in different parts of Southeast Asia are genetically similar.
We tested the hypothesis that Asian Common Toad populations across Southeast Asia are genetically similar owing to their commensal nature and high dispersive ability. To the researcher’s surprise, three genetically divergent groups of toads were found, each in a different geographic area (mainland Southeast Asia, coastal Myanmar and the islands of Java and Sumatra). The ranges of these three groups of toads were also found have statistically different climates. This suggests that the toads may be adapting to local climatic conditions and evolving into separate species. Thus, toads of one group may not be able to disperse and persist within the range of another group because of climatic differences.
This research changes the view on the conservation value of these toads. One common toad may not be the same as another. What is thought to be a single, common species having a large range may actually be three distinct species, each having smaller ranges with specific climatic needs. Asian Common Toads have recently invaded the Southeast Asian islands of Borneo, Sulawesi and Seram and the African island of Madagascar, presumably via shipping containers. The discovery that there are three genetically and ecologically divergent groups of Asian Common Toads may explain why some islands have been successfully colonized and others not- and what the future range of Asian Common Toads will be as humans continue to modify habitats and transport cargo around the world.
Here is the citation
G. O. U. Wogan, B. L. Stuart, D. T. Iskandar, and J. A. McGuire. 2016. Highly structured phylogeographic patterns in a wide-spread human commensal anuran species Duttaphrynus melanostictus in Asia. Biology Letters v. 12 DOI: 10.1098/rsbl.2015.0807 (available online January 13 2016)
Welcome to my new and improved website! I will be posting news and discussing new tools for generating and analyzing genetic data if they fall under the big umbrella of “Evolutionary Biology in a Global Change Context”-exciting! I might also post links to articles that I am particularly amped up about.