Current Projects
The evolution of head glands in salamanders: Since the late 1800s and early 1900s, few studies have examined glands associated with the head in salamanders. Are some of these glands sexually dimorphic as indicated by prominent herpetologists such as G.K. Noble? If so, how are the glands involved in reproduction? Do some glands serve as synapomorphies for different lineages of salamanders? Currently, undergraduate students are working to answer these questions. Click HERE for our first manuscript on orbital glands in Eurycea longicauda.
Identification and evolution of secondary sexual characteristics in salamanders: Secondary sexual characteristics are structures that are involved in mating/fertilization but are not necessarily required for mating/fertilization; e.g., a pheromone producing gland (secondary sexual characteristic) versus a sperm duct (primary sexual characteristic). In more general terms, structures involved with reproduction that are not required for the formation, transport, or transfer of gametes. These structures typically manifest themselves as sexually dimorphic traits. Click HERE for a recent manuscript on mental gland evolution in plethodontid salamanders.
The role of the kidney in salamander reproduction: One of the most exciting aspects of the reproductive biology of salamanders is the role that the kidney plays in reproduction as a primary and secondary sexual characteristic. Nephrons (the functional unit of the kidney) act as sperm conduits for transfer of sperm from the testes to the Wolffian ducts and also produce a seminal fluid-like substance during the mating season. My students and I have spent the last few years examining modifications of salamander nephrons for reproductive function. Click HERE for a recent manuscript on comparative renal corpuscle morphology in Notophthalmus viridescens.
The evolution of salamander reproductive cycles: When organisms reproduce is a function of their environment and evolutionary history. Historically, multiple environmental factors were implicated as stimuli for different reproductive events. However, few studies detail variation in reproductive cycles between vertebrates from multiple geographic locations. A long term goal of mine is to examine the evolution of reproductive cycles in salamanders by comparing the reproductive cycles of numerous salamander lineages in a phylogenetic context. Click HERE for a recent paper on spermatogenic cycles in plethodontid salamanders.
