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In May 2023, herpetologists from six countries converged at the 8th Conference on the Biology of Plethodontid Salamanders in Hammond, Louisiana to share their latest cutting-edge research. The conference was hosted by the Department of Biological Sciences at Southeastern Louisiana University. Dr. Richard Bruce was the honoree. The presentations covered a diverse array of topics from gene expression to behavior to speciation, illustrating the value of plethodontid salamander biology to a range of disciplines. This special issue of Herpetologica includes 16 papers highlighting a range of research on plethodontids and encouraging new approaches to tackle old and new questions. [ABSTRACT FROM AUTHOR]

In some populations of the Two-Lined Salamander (Eurycea bislineata) species complex, males exhibit two alternative reproductive tactics: "searching" and "guarding." Searching males have secondary sexual characters—including a large, pheromone-producing mental gland—used in terrestrial courtship, whereas guarding males have hypertrophied jaw musculature used in mate-guarding behavior near aquatic nesting sites. Although this polymorphism occurs in at least four evolutionarily distinct lineages, previous histological studies have only focused on soft-tissue differences in one of these species and no studies have evaluated osteological differences between alternative reproductive tactics. Herein, we present new histological and osteological data from three evolutionarily distinct lineages within the E. bislineata species complex. We confirmed that traditional mental glands are restricted to searching males and that caudal courtship glands are present in both male phenotypes, but not in females. We also found variation in other skin glands that warrants further investigation. Cleared and stained specimens and microcomputed tomography data both revealed substantial osteological differences in skull morphology. Compared with searching males, guarding males have increased skull ossification, fewer and larger teeth, and more pronounced otic and squamosal crests. Together, these data expand our knowledge of morphological differences between alternative reproductive tactics, and we discuss the implications of our results for hypotheses regarding phenotypic plasticity throughout the lifetime of an individual male. [ABSTRACT FROM AUTHOR]

Male Ensatina eschscholtzii do not have a mental gland, a macrogland used by males during courtship that is considered an ancestral character of plethodontids. We tested whether males and females have nonmental courtship glands associated with the integument of the rostrum and mentum (chin). We found that both male and female E. eschscholtzii possess courtship-like integumentary glands (modified granular glands) in the upper labia extending dorsally along the rostrum and lower labia extending ventrally across the mental region. These glands are sexually dimorphic in size (larger in females) and react positively with periodic acid–Schiff. We hypothesize that these glands are involved in courtship through production of pheromones that may or may not be similar to pheromones produced in courtship glands of other plethodontid salamanders. These rostral glands are structurally and chemically unique in comparison with glands of the rostrum that empty along the length of nasolabial grooves (nasolabial glands) of Ensatina, which do not appear to be involved in pheromone production. Both females and males have relatively few traditional mucous glands throughout the skin in comparison with other species of plethodontids, although some clusters are identified at the anterior edges of the labia. [ABSTRACT FROM AUTHOR]

Authentic research experiences are valuable components of effective undergraduate education. Research experiences during the first years of college are especially critical to increase persistence in science, technology, engineering, and mathematics fields. The Science Education Alliance Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) model provides a high-impact research experience to first-year students but is usually available to a limited number of students, and its implementation is costly in faculty time and laboratory space. To offer a research experience to all students taking introductory biology at Gonzaga University (n = 350/yr), we modified the traditional two-semester SEA-PHAGES course by streamlining the first-semester Phage Discovery lab and integrating the second SEA-PHAGES semester into other courses in the biology curriculum. Because most students in the introductory course are not biology majors, the Phage Discovery semester may be their only encounter with research. To discover whether students benefit from the first semester alone, we assessed the effects of the one-semester Phage Discovery course on students' understanding of course content. Specifically, students showed improvement in knowledge of bacteriophages, lab math skills, and understanding experimental design and interpretation. They also reported learning gains and benefits comparable with other course-based research experiences. Responses to open-ended questions suggest that students experienced this course as a true undergraduate research experience.

Introductory biology students can be overwhelmed by the diversity of life. By focusing on learning characteristics of individual taxa, they often lose and miss the larger perspective--that all taxa are connected through evolution, resulting in the Tree of Life. In this article, the authors present an exercise that helps students develop an evolutionary framework of thought--to think of taxa as branches of phylogenetic trees. This exercise helps students: (1) appreciate the evolutionary relationships among organisms and understand how such relationships are determined; (2) understand that there is one Tree of Life--that all of life is connected through evolution; (3) learn that trees are hypotheses, subject to modification with new data; and (4) create a framework to view biodiversity and to review and compare different clades. To master this, students build their own tree of life using digital images of organisms. Visualizing the evolutionary connections between organisms in this way helps students become more evolutionarily literate. The Tree of Life exercise is adaptable to a variety of classes and to all levels of students. (Contains 1 footnote.)

Course-based research experiences (CREs) are powerful strategies for promoting learning and persistence for all students, both science majors and nonscience majors. Here we address the crucial components of CREs (context, discovery, ownership, iteration, communication, presentation) found across a broad range of such courses at a variety of academic institutions. We also address how the design of a CRE should vary according to the background of student participants; no single CRE format is perfect. We provide a framework for implementing CREs across multiple institutional types and several disciplines throughout the typical four years of undergraduate work, designed to a variety of student backgrounds. Our experiences implementing CREs also provide guidance on overcoming barriers to their implementation. [ABSTRACT FROM AUTHOR]