The gut microbiome is affected by host intrinsic factors, diet, environment, and strongly linked to host's health. Although fluctuations of microbiome composition are normal, some are due to changes in host environmental conditions. When species are moved into captive environments for conservation, education, or rehabilitation, these new conditions can influence a change in gut microbiome composition. Here, we compared the microbiomes of wild and captive Comal Springs riffle beetles (Heterelmis comalensis) by using amplicon sequencing of the 16S rRNA gene. We found that the microbiome of captive beetles was more diverse than wild beetle microbiomes. We identified 24 Amplicon Sequence Variants (ASVs) with relative abundances significantly different between the wild and captive beetles. Many of the ASVs overrepresented in captive beetle microbiomes belong to taxa linked to nitrogen-rich environments. This is one of the first studies comparing the effects of captivity on the microbiome of an endangered insect species. Our findings provide valuable information for future applications in the management of captive populations of H. comalensis.

Background: Regeneration of complex patterned structures is well described among, although limited to a small sampling of, amphibians. This limitation impedes our understanding of the full range of regenerative competencies within this class of vertebrates, according to phylogeny, developmental life stage, and age. To broaden the phylogenetic breath of this research, we characterized the regenerative capacity of the Texas blind salamander (Eurycea rathbuni), a protected salamander native to the Edwards Aquifer of San Marcos, Texas and colonized by the San Marcos Aquatic Resource Center. As field observations suggested regenerative abilities in this population, the forelimb stump of a live captured female was amputated in the hopes of restoring the structure, and thus locomotion in the animal. Tails were clipped from two males to additionally document tail regeneration.Results: We show that the Texas blind salamander exhibits robust limb and tail regeneration, like all other studied Plethodontidae. Regeneration in this species is associated with wound epithelium formation, blastema formation, and subsequent patterning and differentiation of the regenerate. Conclusions:The study has shown that the Texas blind salamander is a valuable model to study regenerative processes, and that therapeutic surgeries offer a valuable means to help maintain and conserve this vulnerable species.

We present a landmark success of a pilot study in the noninvasive, topical hormonal stimulation of reproduction of salamanders using Texas blind salamanders (Eurycea rathbuni) as a model species. Improved reproduction is a critical milestone in the conservation of imperiled species. Captive reproduction of amphibians is often challenging due to specific and ambiguous environmental cues for each species. The Texas blind salamander is a federally listed troglobitic amphibian found only in the Edwards Aquifer beneath San Marcos, Texas. This species is long-lived, paedomorphic, and obligately aquatic. As with other cave-dwelling organisms, Texas blind salamanders exhibits delayed reproductive maturity and low reproductive output. The US Fish & Wildlife San Marcos Aquatic Resources Center maintains a captive assurance population of wild individuals to supplement natural populations in the case of a catastrophic impacts on the wild population. Despite housing this species since the 1980s, unassisted reproductive events remain infrequent and unpredictable. In 2020, we developed the noninvasive use of the topical application of GnRH-A to stimulate reproduction in 12 females combined with 12 males during a pilot study, that resulted in 11 clutches over a five-month period.

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Eurycea pterophila is a fully aquatic paedomorphic salamander species classified as under review for federal listing and distributed in restricted sections of the Comal River (Comal CO., TX). Unlike Eurycea sosorum, which constitutes the only documented wild sightings of Eurycea eggs in the region, no eggs of Eurycea pterophila have been documented in the wild. During a routine collection of Eurycea pterophila for a captive assurance population, two eggs were found in the Comal River, TX near Spring Island, and successfully raised in captivity. Captive Eurycea pterophila eggs were laid at the same time the wild eggs were found; thus, data are presented here for a comparison.