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Teslin Chaney, Olivier S. G. Pauwels, Zoltán T. Nagy, Václav Gvoždík, Chifundera Kusamba, Gabriel Badjedjea, Franck M. Masudi, Jeannot B. Akuboy, Raffael Ernst, Jean-François Trape, Laurent Chirio, Werner Conradie, Chad Keates, Van Wallach, Ange-Ghislain Zassi-Boulou, Eugene R. Vaughan, Eli Greenbaum
GrayiaGünther 1858 is a genus of relatively large (1.2–2.5 m) aquatic Afrotropical snakes. Recent molecular phylogenies recovered Grayia in its own distinct subfamily (Grayiinae), which was supported as the sister group to Colubrinae. Tropical African snakes are generally understudied, so the relationships within Grayia are poorly known. High degrees of intra- and interspecies variation can make identification difficult, and previous studies involving Grayia included misidentified specimens in other genera. The goal of this study is to create a phylogenetic tree that can be used to understand the relationships and taxonomy of Grayia via an integrative taxonomic approach that combines molecular data for 60 specimens and morphological data for 719 specimens. Two nuclear (BDNF, NT3) and four mitochondrial genes (COI, cyt b, 16S, and ND4) were used to construct phylogenetic trees with Maximum Likelihood and Bayesian Inference algorithms. The phylogenetic trees recovered two clades, Grayia caesar + G. tholloni and G. ornata + G. smythii, which the time-calibrated Bayesian Evolutionary Analysis Sampling Tree (BEAST) analysis estimated to have diverged from each other in the mid-Oligocene. This deep divergence, combined with distinct morphological differences, led us to resurrect the name Xenurophis Günther 1863 as a subgenus [G. (Xenurophis) caesar, G. (Xenurophis) tholloni]. Molecular and morphological evidence further supports a new cryptic species of Grayia from the Upper and Middle Congo River and its tributaries. This new species is estimated to have diverged from its nearest sister species, G. ornata, in the Late Miocene—which coincides with the divergence dates of sister taxa within other Central African snake genera. Grayia ornata sensu stricto was found to consist of several evolutionary lineages, which mirror the patterns recovered in other Central African vertebrates.
Anthropogenic activities in disturbance-mediated ecosystems might affect certain ecological processes that, in turn, can affect the stability and resilience of those ecosystems. In upland pine forests, land-use practices such as intensive silviculture and fire suppression have contributed to the loss of diversity-rich pine savannahs throughout the southeast. Whereas the application of management strategies has been shown to alter forest structure in pine ecosystems, less is known about how these efforts influence pathways of energy flow and the consumer–resource relationships therein. Here, we investigated the effects of frequency of forest management on the trophic structure and resource use of snake communities in two pine forests under high and low frequencies of management (i.e., shorter fire return intervals and thinning versus longer fire return intervals and limited thinning). We sampled snakes, prey, and dominant basal resources across each site for three summers from 2018 to 2020. Using stable isotope analysis, we compared community-wide metrics of trophic structure and generated isotopic mixing models to determine the relative contribution of resources to snake consumers. We found that the high-frequency site supported an increased diversity of snake species, and that species exhibited increased trophic redundancy. The low-frequency site supported fewer snake species that relied on a wider range of resources, and occupied a wider range of relative tropic positions. Mixing models of consumer–resource relationships, and prey relative abundance, indicated that snakes were more generalized in their resource use in the high-frequency site, and utilized a broader diversity of prey more evenly. In contrast, snakes in the low-frequency site were more specialized in their prey use. We suggest that anthropogenic activities mimicking natural disturbances can drive food-web structure in these forest ecosystems. Increased frequency of forest management practices such as prescribed fires and thinning operations might support snake species diversity while also increasing trophic redundancy. Consequently, such management applications can lead to greater stability and resilience in pine-forest ecosystems. Our research further highlights the importance of ecological restoration that incorporates food-web perspectives to ensure the health of pine ecosystems.
M. Caitlin Fisher-Reid, Kristine L. Grayson, Sara R. Grouleff, Madelyn A. Hair, Tanya J. Hawley Matlaga, Angelina K. Ireland, Louise S. Mead, Alyssa St John, Meigan Starr, Sean C. Sterrett, Kody N. Streeter
What makes a model organism? Identifying the qualities of a model organism has been given a great deal of attention in the biomolecular sciences, but less so in the fields of evolution, ecology, and behavior (EEB). In contrast to the biomolecular sciences, within EEB, biotic and abiotic variation are features to understand, not bugs to get rid of, and EEB scientists often select organisms to study which best suit the scientific question at hand. Successful EEB model organisms can be studied at multiple biological scales and often have a wealth of accumulated knowledge on which current research programs build. A recent call within EEB communities to invest in the development of diverse model systems led us to evaluate the standing of a widespread, abundant, terrestrial salamander in this review: the Eastern Red-backed Salamander (Plethodon cinereus). We first look at salamanders as EEB models more generally and determine where P. cinereus fits in this broader context. The core of our monograph reviews over 400 recent studies on P. cinereus and highlights inconsistencies, gaps in our knowledge, and future directions in the context of our findings and those of three prior comprehensive reviews: two comprehensive reviews published in 1998 and 2013, and a book published in 2016 focused on the behavioral ecology of P. cinereus. After completing our review, we conclude by evaluating the current status of P. cinereus as a model organism in EEB and describe how a collaborative research network, SPARCnet, can serve as a starting point for improving the range-wide understanding of P. cinereus ecology, evolution, and behavior. More generally, we argue that collaborative research networks can and should be applied to other EEB model systems, so that future EEB research may benefit from model systems that accurately represent, in Darwin's words, “endless forms most beautiful and most wonderful.”
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