Nearly all land plants post-transcriptionally modify specific nucleotides within RNAs, a process known as RNA editing. This adaptation allows the correction of deleterious mutations within the asexually reproducing and presumably non-recombinant chloroplast and mitochondrial genomes. There are no reports of RNA editing in any of the green algae so this phenomenon is presumed to have originated in embryophytes either after the invasion of land or in the now extinct algal ancestor of all land plants. This was challenged when a recent in silico screen for RNA edit sites based on genomic sequence homology predicted edit sites in the green alga Chara vulgaris, a multicellular alga found within the Streptophyta clade and one of the closest extant algal relatives of land plants. In this study, the organelle transcriptomes of C. vulgaris and Chlamydomonas reinhardtii were deep sequenced for a comprehensive assessment of RNA editing. Initial analyses based solely on sequence comparisons suggested potential edit sites in both species, but subsequent high-resolution melt analysis, RNase H-dependent PCR (rhPCR), and Sanger sequencing of DNA and complementary DNAs (cDNAs) from each of the putative edit sites revealed them to be either single-nucleotide polymorphisms (SNPs) or spurious deep sequencing results. The lack of RNA editing in these two lineages is consistent with the current hypothesis that RNA editing evolved after embryophytes split from its ancestral algal lineage.
Little is known about how vertical rock habitats are selected by organisms in forest ecosystems. Multiple lungless salamanders use rock outcrops in the Appalachian Mountains of eastern North America, with Green Salamanders (Aneides aeneus (Cope and Packard, 1881)) showing the strongest associations as an outcrop specialist. Although previous work has identified environmental correlates of rock face and arboreal habitat use in this species, it remains to be known if and how Green Salamanders select crevice refugia as a function of both outcrop morphology and the context of outcrops within the surrounding forest. We performed an intensive survey of an abundant Green Salamander population on Virginia’s Appalachian Plateau to examine which features of vertical habitats are associated with salamander occupancy. Occupancy was highest in deeper rock crevices closer to surrounding trees, a likely consequence of arboreal behavior and the ability for crevice refugia to modulate the surrounding microclimate. Although uncertainty exists with regards to the generality of these results across the species’ range, our results underscore linkages between embedded rock outcrop habitats and their surrounding forest contexts for amphibians. Our results also provide a model of Green Salamander habitat associations that may be valuable to efforts to elucidate its geographic distribution.
The Green Salamander (Aneides aeneus) is a secretive, arboreal cliff specialist distributed discontinuously across the southern and central Appalachian Mountains, USA. While intensively studied in some parts of its range in the Appalachian Plateau and Blue Ridge Provinces, the distribution of A. aeneus is still poorly understood, particularly in the Cumberland Mountains physiographic province of the Appalachian region. This data deficiency is partly the result of a lack of formal historic surveys across this region, coupled with a high amount of privately owned land that is inaccessible to traditional biotic surveys. We used a combination of citizen science efforts and traditional field surveys to investigate the distribution and status of A. aeneus across the Cumberland Mountains of southwestern Virginia, USA. Local landowners and outdoor recreation enthusiasts reported a relatively high rate of encounters with A. aeneus, verifying the species’ persistence at four historic localities and leading to the discovery of 36 previously unknown populations. Although we are cautious about making inferences about the true conservation status of A. aeneus across this region given the scarcity of current data, these findings suggest that the distribution of A. aeneus in Virginia has been vastly underestimated and that expanded monitoring programs are needed to further ascertain this species’ status. More broadly, our results illustrate the utility of coupling public initiatives with more traditional field surveys to expand the biogeographic knowledge of secretive, difficult-to-study amphibian species.
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