The global extinction crisis demands immediate action to conserve species at risk. However, if entire clades such as superfamilies are at risk due to shared evolutionary history, a shift towards conserving clades rather than individual species may be needed. Using phylogenetic autocorrelation analysis, we demonstrate that multiple kinds of extinction threat clump within the amphibian tree of life. Our study provides insight into how these threats may collectively influence the extinction risk of whole clades, consistent with the supposition that related species, with similar traits, share an intrinsic vulnerability to common kinds of threat. Most strikingly, we find a significant concentration of ‘enigmatic’ decline and critically endangered status within families of the hyloid frogs. This phylogenetic clumping of risk is also geographically concentrated, with most threats found in Central and South America, and Australia, coinciding with reported outbreaks of chytridiomycosis. We speculate that the phylogenetic clumping of threat represents, in part, shared extinction proneness due to shared evolutionary history. However, even if the phylogenetic clumping of threat were simply a by‐product of shared geography, this concordance between phylogenetic and geographical patterns represents a prime opportunity. Where practical, we should implement conservation plans that focus on biogeographical regions where threatened clades occur, thereby improving our ability to conserve species. This approach could outperform the usual triage approach of saving individual species after they have become critically endangered.

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Phylogeographic analyses using mitochondrial DNA (mtDNA) have revealed many examples of apparently deep historical subdivisions ('phylogroups') within many vertebrates. It remains unclear whether these phylogroups represent independently evolving, adaptively differentiated lineages or groups that show little functional differentiation and, hence, will merge on contact. Here, we use mtDNA sequence data to evaluate the phylogeographic relationships between two of the northernmost populations of black ratsnakes (Pantherophis obsoletus complex) in Ontario, Canada and previously analysed populations in the United States. We then use population-level analyses to evaluate the level of adaptive divergence between previously established mtDNA phylogroups. Phylogenetic analyses show that southern Ontario snakes have mtDNA haplotypes that fall within the Central mtDNA phylogroup, as designated by Burbrink et al. (2000). In contrast, snakes in eastern Ontario carry either Central or Eastern-specific haplotypes. Within the hybrid region, we found highly variable frequencies of mtDNA haplotypes among isolated sub-populations, no association between variation in cytonuclear (mtDNA) and nuclear (microsatellite DNA) markers, no difference in survival or reproductive success among snakes with different mtDNA haplotypes, and no effect of mate similarity in mtDNA on female clutch size. These results argue that the Eastern and Central phylogroups have merged in this region, likely due to a lack of adaptive differentiation between individuals in each lineage. Hence, in these snakes, phylogeographic structure in mtDNA is more a reflection of historical isolation rather than adaptive divergence. The observed reticulation between lineages and lack of evidence for hybrid disgenesis also bears on the classification of these lineages as distinct species.

Rapid, global declines among amphibians are partly alarming because many occur for apparently unknown or enigmatic reasons. Moreover, the relationship between phylogeny and enigmatic declines in higher clades of the amphibian phylogeny appears at first to be an intractable problem. I present a working solution by assessing threatening processes potentially underlying enigmatic declines in the family, Hylidae. Applying comparative methods that account for various evolutionary scenarios, I find extreme concentrations of threatening processes, including pollution and habitat loss, in the clade Hylini, potentially influenced by traits under selection. The analysis highlights hotspots of declines under phylogenetic influence in the genera Isthmohyla, Plectrohyla and Ptychohyla, and geographically in Mexico and Guatemala. The conservation implications of concentrated phylogenetic influence across multiple threatening processes are twofold: Data Deficient species of threatened clades should be prioritized in future surveys and, perhaps, a greater vulnerability should be assigned to such clades for further consideration of clade-level conservation priorities

Aim  We evaluate whether remotely sensed land‐cover change within a newly protected area signalled human‐driven ecological degradation. Vegetation density changed in a quarter of pixels during the first 13 years (1986–1999) following the sanctuary's formal enclosure, with many patches showing a decrease in density. We use on‐the‐ground data collected in 2006 in 132 random plots to explore whether these changes in vegetation density reliably signalled latent shifts in local diversity of woody plants and whether they could be attributed to illicit activities including fuel wood collection and livestock grazing.Location  Kumbhalgarh Wildlife Sanctuary, Rajasthan, India.Results  Species richness, species sharing, species assemblages, and incidence of invasive and useful species were statistically similar among plots in which vegetation density had decreased, increased or remained similar. Likewise, intensity of disturbance associated with human activities was similar across these plot types.Main conclusions  Our data provide no clear evidence that local changes in vegetation density signalled latent shifts in local diversity of woody plants. They also fail to reveal any clear association between local changes in vegetation density and human‐related activities. Finding no evidence that land‐cover change led to biotic erosion, we reflect on the utility of resource‐use bans in protected areas, particularly those embedded within historically coupled human‐nature systems.