Search for: All records

The spiny-throated reed frog species group is a small radiation of Hyperolius frogs from East Africa. Unlike many members of the genus which have relatively wide distributions, these species tend to be small-range endemics found in montane and submontane forests. Recent discovery of a golden-hued frog with the clade-specific traits of spines on their gular discs prompted a morphological and genetic exploration of the distinctness of this new lineage and relationships to other members of the clade. Genetic (mitochondrial and nuclear loci) results resolved many sister-relationships, but deeper nodes in the phylogeny were poorly resolved. A reduced-representation genome-wide Single Nucleotide Polymorphism (SNP) dataset was able to fully resolve the phylogenetic relationships within this clade, placing this new lineage, here named after the mountain range in which is it found– H . ukaguruensis sp. nov., as an early diverging lineage within the group. This new species is distinct from all other spiny-throated reed frogs, necessitating further understanding as a single-mountain endemics vulnerable to habitat loss and potential decline. Morphometric analyses identify clear morphological characteristics that are distinct for the herein described species, most noticeably in that the eyes are significantly smaller than other members of the genus for which we have samples. 

Human modification of the environment has drastically changed ecosystems around the globe. While forest‐loss (deforestation) has been well studied for its effects on ecosystems, afforestation also has major impacts. The Udzungwa Plateau in Tanzania is naturally a mix of forests and grasslands. However, non‐native pine plantations have recently increased in the area displacing the native grasslands of the montane plateau. In this study, we explored the effects of land use change on amphibian communities by comparing amphibian surveys before non‐native plantations were introduced (~2000) and after (2017–2019). To put these amphibian surveys into wider context across the plateau and to distinguish local population loss compared to plateau‐wide extinctions, we sample diversity at new sampling locations and locations with multiple surveys through time. We then assessed landscape change through remotely sensed data and ground surveys. Amphibian encounter surveys found approximately the same species diversity across all sampling locations, but local extinctions appear likely. Remaining amphibians appear to be limited to small refugia in non‐pine wetlands. Approximately half (45%) of the species found have limited distributional ranges (<72,000 km²) and are described as habitat specialists by the IUCN Red List. Monitoring pine plantation growth using remote sensing techniques suggested only limited extensions of plantations between 2000 through to 2013–2016, but ground surveys found small pines (<3 years old) throughout almost all areas identified as grasslands on satellite imagery. Our study highlights the plight of this narrowing biome on the African continent and calls for more research on the impact of non‐native plantations on natural communities.

Abstract in Swahili is available with online material.

 

Theory predicts that sexually dimorphic traits under strong sexual selection, particularly those involved with intersexual signaling, can accelerate speciation and produce bursts of diversification. Sexual dichromatism (sexual dimorphism in color) is widely used as a proxy for sexual selection and is associated with rapid diversification in several animal groups, yet studies using phylogenetic comparative methods to explicitly test for an association between sexual dichromatism and diversification have produced conflicting results. Sexual dichromatism is rare in frogs, but it is both striking and prevalent in African reed frogs, a major component of the diverse frog radiation termed Afrobatrachia. In contrast to most other vertebrates, reed frogs display female-biased dichromatism in which females undergo color transformation, often resulting in more ornate coloration in females than in males. We produce a robust phylogeny of Afrobatrachia to investigate the evolutionary origins of sexual dichromatism in this radiation and examine whether the presence of dichromatism is associated with increased rates of net diversification. We find that sexual dichromatism evolved once within hyperoliids and was followed by numerous independent reversals to monochromatism. We detect significant diversification rate heterogeneity in Afrobatrachia and find that sexually dichromatic lineages have double the average net diversification rate of monochromatic lineages. By conducting trait simulations on our empirical phylogeny, we demonstrate that our inference of trait-dependent diversification is robust. Although sexual dichromatism in hyperoliid frogs is linked to their rapid diversification and supports macroevolutionary predictions of speciation by sexual selection, the function of dichromatism in reed frogs remains unclear. We propose that reed frogs are a compelling system for studying the roles of natural and sexual selection on the evolution of sexual dichromatism across micro- and macroevolutionary timescales.