I am interested in patterns of diversity and the processes that generate, maintain, or limit these patterns. Research topics include biogeography, species formation and the “species problem,” predator-mediated natural selection in the wild, the evolution and function of anti-predator adaptations, and conservation biology. In general, my approach is grounded in organismal biology and natural history while pursuing a modern research agenda in evolutionary and conservation biology. Salamanders are my main study group, but I have also worked on lizards, frogs, and damselflies. In my lab, we pursue a diversity of approaches, including phylogeography and phylogenetics, genomics and population genetics, morphometrics, and field ecology.
Species formation & adaptive divergence in the
salamander ring species Ensatina eschscholtzii
The Ensatina complex is a classic example of the process of speciation because it is a "ring species," or a species in which two reproductively isolated lineages are connected by a chain of intergrading populations. Ring species are valuable because they illustrate how the factors producing intraspecific variation can create new species.
In conjunction with David Wake and colleagues, I worked on a detailed biogeographic analysis of the celebrated ring species Ensatina eschscholtzii (Kuchta et al. 2009a, b). I have also investigated the ecological function of divergent phenotypes in the Ensatina complex. For example, I showed that the subspecies E. e. xanthoptica is a warningly colored Batesian mimic of newts (Kuchta, 2005; Kuchta et al. 2008), whereas the subspecies platensis is camouflaged by way of disruptive coloration (Kuchta et al., in prep.).
For a historical analysis of ring species and divergent views on species formation going back to Darwin, check out my paper “Wherefore and whither the ring species?” (Kuchta & Wake, 2016).
Biogeography and systematics of Appalachian salamanders
The complex relationship between biogeography and species formation is a primary research interest of mine, and much of my research touches on this topic in some manner. I am engaged in a number of systematic studies of Appalachian salamanders with my collaborators Richard Highton (University of Maryland), Addison Wynn & Jeremy Jacobs (Smithsonian), Emily Lemmon & Alan Lemmon (Florida State University), Carl Anthony & Cari-Ann Hickson (John Carrol University), and my graduate students Tom Radomski, Maggie Hantak, Michael Haughey, and Brian Waldron.
Most recently, I have investigated the P. wehrlei and P. punctatus, and found the latter to be phylogenetically nested within the former (P. wehrlei is thus "paraphyletic"). In this same study, we recognized a new species as well: P. dixi, from the Dixie Caverns area in Virginia. Work on this species complex is ongoing.
We also recently published an analysis of genetic variation and the problems associated with species delimitation in the Cumberland Plateau Salamander, Plethodon kentucki (Kuchta et al., 2016a). In the Spring Salamander (Gyrinophilus porphyriticus), which is widespread throughout Appalachia, we show that historical drainage systems account for more genetic variation then do contemporary drainage systems (Kuchta et al., 2016b).
Several studies of patterns of genetic variation in the Eastern Red-backed Salamander, P. cinereus, are in review or will be completed shortly. Stay tuned!
Amphibian & reptile conservation
I have recently expanded my research to include a number of conservation projects, many in collaboration with my colleague Dr. Willem Roosenburg. Our shared graduate student Paul Converse studied population structure, gene flow, and phylogeography in the Diamondback Terrapin, Malaclemys terrapin (Converse et al., 2015; Converse & Kuchta, 2017, 2018).
I am also involved in studies of the impact of roads on amphibian and reptile populations. Studies began in the spring of 2015, and three my graduate students Garrett Sisson (graduated in 2017), Charlene Hopkins, and Krissy Harman.
Finally, my graduate student Merri Collins studied the distribution and abundance of the Mudpuppy, Necturus maculosus, in southeastern Ohio. Not much is known about the conservation status of this species, except this it has become considerably less common in recent decades. This work combines field studies with environmental DNA, and her thesis in now in review.
The evolution and ecology of color polymorphisms
All of the salamanders to the left are Eastern Red-backed Salamanders, Plethodon cinereus, and all were found in the same population. In other words, this species is polymorphic. How do morphs evolve? What evolutionary processes maintain a polymorphism? What are the implications of polymorphism for adaptation, speciation, and biogeography? I am working to address these questions with my graduate student Maggie Hantak (Hantak & Kuchta, 2018), as well as with Carl Anthony & Cari Hickerson at John Carroll University, and Robert Page at Texas A&M University-San Antonio (Hantak et al. 2015). Work is ongoing, and there is much to come on this research front.
I am particularly interested in relationship between polymorphism and species formation. My initial work in this area was conducted in collaboration with Ammon Corl and Barry Sinervo on the Side-blotched Lizard, Uta stansburiana (Corl et al., 2010a, 2010b).
Predator-mediated natural selection
Individuals must avoid being eaten if they are to pass their genes on to future generations. In collaboration with my graduate student Kaili Boarman and my colleague Erik Svensson (Lund University, Sweden), I am studying natural selection in the Banded demoiselle, Calopteryx splendens. This damselfly is depredated by an avian predator, the Wagtail (genus Motacilla), which captures damselflies and takes them to regular feeding stations (aka “slaughter stations”), where the wings are removed and the body eaten. By collecting wings from feeding stations and comparing them to the variation present in natural populations, we calculated the strength of natural selection on wing traits. In Kuchta & Svensson (2014), we found found that selection was stronger on secondary sexual traits than on size and shape, suggesting a tradeoff between predation and sex. My graduate student Kaili Boarman recently tested this by simultaneously estimating predator-mediated natural selection and sexual selection to probe for fitness tradeoffs.
Biogeography & systematics of Pacific newts, genus Taricha
A biogeographic and molecular systematic analysis of newts in the genus Taricha was the focus of my thesis research. Three species of Pacific newts have long been recognized: Taricha torosa, T. granulosa, and T. rivularis. In addition, I elevated a fourth species, T. sierrae, following molecular systematic investigations and an analysis of hybrid zone dynamics (Kuchta & Tan, 2006a, Kuchta, 2007). Phylogeographic studies of all four species tell different stories, including range expansion, divergence in allopatry, isolation by distance, and species formation (Kuchta & Tan 2005; 2006a, 2006b).
In addition to biogeography and systematics, I have also investigated the possibility of mimicry between Taricha and the salamander Ensatina eschscholtzii xanthoptica (the Yellow-eyed Ensatina). See the Ensatina research section above for details.