Section

Herpetology

Our research activities focus on the study of the herpetofauna of the Neotropics (Central and South America, Mexico and the West Indies) and Southeast Asia. Currently, faunistic, taxonomic and zoogeographic studies are undertaken in the following countries: Thailand, Myanmar, Mexico, Costa Rica, Panama, and Bolivia.

Our studies are taxonomic, zoogeographic, and phylogenetic in nature. We address our research questions with an integrative approach including morphological, bioacoustic, molecular genetic, zoogeographic and ecological data and methods. The large and historically grown herpetological collection at the institute in Frankfurt is an important basis and reference for our scientific work. Due to own collecting of amphibians and reptiles during expeditions into the habitats of our study objects, the collection is still growing steadily.

Our studies belong to the Senckenberg Research Field Biodiversity and Systematics.

Since 1995 we have conducted herpetological research in all Central American countries, as well as in selected South American countries. Projects on the Antilles are in preparation. We plan to do fieldwork on Hispaniola in October and November of this year. Thus, we have established excellent contacts and some long-term colaborations with scientists, universities, museums, and ministries in Latin America. The Senckenberg herpetological laboratory in Frankfurt, Germany, is the only lab in the world that is undertaking projects on the diversity, taxonomy, and phylogeny of the herpetofauna throughout Central America (Mexico, Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama). This makes possible large-scale comparisons and, in some cases, this can highlight problems that would otherwise not be visible or obvious, e.g., the study of the geographic variation of a “species” that is subsequently understood to represent actually a complex of species. Also for the evaluation of supra-regional phenomena such as population dynamics in anurans, this holistic perspective is helpful because it makes it easier to detect patterns.

For the past several years, the focus of our herpetological research in South America has been in Bolivia, Paraguay, Peru, and Ecuador. In Bolivia, Senckenberg has established a Research Station (Ecological Research Station Chiquitos, San Sebastian) providing an infrastructure that has allowed the completion of two doctoral dissertations and several undergraduate research projects. In Costa Rica, we are the leading partners in a long-term herpetology monitoring project.

Aside from numerous publications in international journals, the results of our work in Latin America has resulted in the publication of several books on the diversity, taxonomy, and identification of the Central American herpetofauna, as well as several regional identification guides. Two of the more prominent works are the following comprehensive monographs on the herpetofauna of Central America:

Köhler, G. (2008): Reptiles of Central America. 2nd edition. Offenbach (Herpeton), 400 pp.
Köhler, G. (2011): Amphibians of Central America. Offenbach (Herpeton), 379 pp.

The anoles (Anolis sensu lato), with close to 400 recognized species, represents the most diverse lizard genus, with more species being described almost every year. The phylogenetic relationships and taxonomy of this group of lizards remain subject to serious controversy in the recent literature. Indeed, our understanding of the systematics of these lizards is still at a low level. For most “species groups” of anoles, as proposed by various researchers in the literature, the evidence that these actually represent monophyletic groups is meager. Some of them probably are natural groups of species, while others represent artificial groupings of species that are simply similar and are placed together because of particular character resemblances.

Based on morphological characteristics, such as pholidosis, body proportions, osteology, and hemipenial morphology, the Central American anoles are being revised. In addition to fieldwork in the natural habitat, the extensive collections in European, North American, and Central American museums are being integrated into this study.

Hemipenial morphology as a source of information for systematics and taxonomy in anoles had received relatively little attention in the past. A comparative study of shape and surface ornamentation of the male copulatory organs indicates an enormous diversity in these lizards. Intraspecific and geographic variation is negligible, whereas there is substantial variation among species. We have documented 12 species pairs of Central American anoles that are extremely similar in their external morphology (scalation and morphometrics), but differ drastically in their hemipenial morphology. Typically, one of the species in each pair has a large bilobed hemipenis whereas the other has a small unilobed organ. Thus, these are cryptic species that were differentiated based on their divergent hemipenial morphology. In all cases studied, we found a close correlation between female cloacal morphology and male hemipenial morphology.

We can assume that differentiation took place in isolation (allopatry) with males and females coevolving. The available molecular data indicate a close relationship of the differing hemipenial morphs. This situation suggests that changes in genital morphology evolve very quickly in Anolis, probably by a self enhancing process like “runaway evolution by cryptic female choice” or “chase away evolution by sexual conflict.”

Along contact zones between closely related species, individuals with intermediate hemipenal morphologies are found, indicating that hybridization occurs. This is confirmed by looking at hemipenial morphology of hybrids produced in the laboratory. This phenomenon raises the question of functional neutrality for anole genital morphology. Female cloacal morphology closely matches the hemipenial morphology of sympatric males. Thus, hemipenial morphology is probably not functionally neutral. However, there is no evidence of reinforcement along contact zones of closely related anole species. Differences in hemipenal morphology does not prevent hybridization, indicating that a “key-lock” mechanism is not operating in anoles.

Genital morphology in anoles is an understudied yet promising area of research. There are many potential projects for investigating the role that genital morphology plays in speciation in the genus Anolis, including the mating systems in anoles, processes during copulation, sperm storage, and the effects of genital morphology on sperm storage.

Publications