Publications by authors named "Simon P Loader"

The Eastern Arc Mountains (EAM) and Coastal forests of Tanzania are renowned for harboring large number of threatened and endemic vertebrate species, yet most of these areas have been partially studied. The Kimboza Nature Forest Reserve (KNFR) is a small forest which is in transition between the EAM and Coastal forests, and among the poorly surveyed areas for amphibians and reptiles. We conducted systematic surveys across the KNFR in 2012 and between 2020 and 2023 using a range of approaches with the aim of establishing a comprehensive and updated list of reptile and amphibian species and assess the contribution of EAM and Coastal forests to the KNFR's herpetofauna.

View Article and Find Full Text PDF
Article Synopsis
  • - Systematic assessments of species extinction risk are crucial for effective conservation, and the second Global Amphibian Assessment evaluated over 8,000 species for their threat levels.
  • - Amphibians are the most at-risk vertebrates, with 40.7% of species globally threatened, and their status has worsened since previous assessments, especially in salamanders and the Neotropics.
  • - The major threats contributing to declining amphibian populations include disease, habitat loss, and increasing impacts from climate change, highlighting the urgent need for more conservation funding and initiatives to reverse negative trends.
View Article and Find Full Text PDF

Evolutionary shifts in chromosome compositions (karyotypes) are major drivers of lineage and genomic diversification. Fusion of ancestral chromosomes is one hypothesized mechanism for the evolutionary reduction of the total chromosome number, a frequently implied karyotypic shift. Empirical tests of this hypothesis require model systems with variable karyotypes, known chromosome features, and a robust phylogeny.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF

African amphibian diversity remains underestimated with many cryptic lineages awaiting formal description. An important hotspot of amphibian diversification is the Guineo-Congolian rainforest in Central Africa, its richness attributable to present day and ancestral range fragmentation through geological barriers, habitat expansion and contraction, and the presence of steep ecological gradients. The charismatic Nectophryne tree toads present an interesting case study for diversification in this region.

View Article and Find Full Text PDF

Narrow-mouthed frogs (Anura: Microhylidae) are globally distributed and molecular data suggest the rapid evolution of multiple subfamilies shortly after their origin. Despite recent progress, several subfamilial relationships remain unexplored using phylogenomic data. We analysed 1,796 nuclear ultraconserved elements, a total matrix of 400,664 nucleotides, from representatives of most microhylid subfamilies.

View Article and Find Full Text PDF

A new species of tree snake Dipsadoboa montisilva Branch, Conradie Tolley sp. nov. (Serpentes: Colubridae) is described from the 'sky islands' of Mount Mabu and Mount Ribáuè in northern Mozambique.

View Article and Find Full Text PDF
Article Synopsis
  • Sexual dimorphism, particularly in color (sexual dichromatism), may accelerate speciation and diversification in animals, but studies yield mixed results on its impact.
  • African reed frogs exhibit unique female-biased sexual dichromatism, where females often have more vibrant colors than males, diverging from typical patterns seen in vertebrates.
  • Research shows that sexual dichromatism in these frogs evolved once and is linked to higher diversification rates compared to monochromatic species, although the specific function of this color change in reed frogs remains uncertain.
View Article and Find Full Text PDF

High-throughput sequencing data have greatly improved our ability to understand the processes that contribute to current biodiversity patterns. The "vanishing refuge" diversification model is speculated for the coastal forests of eastern Africa, whereby some taxa have persisted and diversified between forest refugia, while others have switched to becoming generalists also present in non-forest habitats. Complex arrangements of geographical barriers (hydrology and topography) and ecological gradients between forest and non-forest habitats may have further influenced the region's biodiversity, but elucidation of general diversification processes has been limited by lack of suitable data.

View Article and Find Full Text PDF

Ecological niche models (ENMs) have been used in a wide range of ecological and evolutionary studies. In biogeographic studies these models have, among other things, helped in the discovery of new allopatric populations, and even new species. However, small sample sizes and questionable taxonomic delimitation can challenge models, often decreasing their accuracy.

View Article and Find Full Text PDF

How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters.

View Article and Find Full Text PDF

Multiple sources of data in combination are essential for species delimitation and classification of difficult taxonomic groups. Here we investigate a cicada taxon with unusual cryptic diversity and we attempt to resolve seemingly contradictory data sets. Cicada songs act as species-specific premating barriers and have been used extensively to reveal hidden taxonomic diversity in morphologically similar species.

View Article and Find Full Text PDF

Molecular analysis indicates that African material previously referred to Amietophrynus maculatus (Hallowell, 1854; now Sclerophrys maculata), is divisible into two distinct clades: a Western Clade from Cameroon westwards and an Eastern Clade from Central African Republic eastwards, and Uganda southwards to South Africa, extending to Angola-Namibia. Preliminary morphological and bioacoustic data support this division. The two clades are recognised here as two separate species.

View Article and Find Full Text PDF

The niche-filling process predicted by the "ecological opportunity" (EO) model is an often-invoked mechanism for generating exceptional diversity in island colonizers. Whether the same process governs lineage accumulation and trait disparity during continental colonization events is less clear. Here, we test this prediction by investigating the rate dynamics and trait evolution of one of Africa's most widespread amphibian colonizers, the true toads (Bufonidae).

View Article and Find Full Text PDF

The phylogenetic relationships of the African mongrel frog genus Nothophryne are poorly understood. We provide the first molecular assessment of the phylogenetic position of, and diversity within, this monotypic genus from across its range-the Afromontane regions of Malawi and Mozambique. Our analysis using a two-tiered phylogenetic approach allowed us to place the genus in Pyxicephalidae.

View Article and Find Full Text PDF

Background: Peripatric speciation and peripheral isolation have uncertain importance in species accumulation, and are largely overshadowed by assumed dominance of allopatric modes of speciation. Understanding the role of different speciation mechanisms within biodiversity hotspots is central to understanding the generation of biological diversity. Here, we use a phylogeographic analysis of the spiny-throated reed frogs and examine sister pairings with unbalanced current distributional ranges for characteristics of peripatric speciation.

View Article and Find Full Text PDF
Article Synopsis
  • The East African spiny-throated reed frog complex consists of morphologically similar species with fragmented populations, and genetic studies hint at the existence of several cryptic species.
  • Recent analysis of morphological and molecular data has led to the identification of three new distinct species, with key traits such as the structure of male gular flaps and female snout-urostyle length used for differentiation.
  • These findings refine the classification of existing species and highlight conservation concerns due to the restricted habitats of these frogs in the Eastern Afromontane region.
View Article and Find Full Text PDF
Article Synopsis
  • The Eastern Afromontane Region (EAR) is home to many unique species, including chameleons from the genus Trioceros, whose diversity is not well documented.
  • Research utilized various molecular data and species-delimiting methods to identify boundaries and estimate species diversity, revealing that current assessments likely undervalue the number of species present.
  • Notably, T. werneri may actually encompass at least four different species, suggesting that further taxonomic descriptions are needed, and the evolution of these lineages aligns with ancient climatic changes.
View Article and Find Full Text PDF

In 1931, Ernst Ahl described two species of reed frogs inhabiting montane forests of the Albertine Rift in East Africa, Hyperolius alticola and H. discodactylus, which were synonymized two decades later by Raymond Laurent. Since then, this revision has been questioned repeatedly, but taxonomists have been reluctant to make a conclusive decision on the matter, especially since the type material of H.

View Article and Find Full Text PDF

We describe and compare the tadpoles of nine Leptodactylodon species from Cameroon. The tadpoles of Leptodactylodon bicolor, L. mertensi, L.

View Article and Find Full Text PDF

An investigation of name-bearing types and other relevant type specimens of twelve nominal Leptopelis taxa described from or distributed in the Eastern Arc Mountains in East Africa was carried out. Our aim was to clarify their status and where necessary revise respective nomina. We suggest several nomenclatural and taxonomic actions: 1) Leptopelis barbouri Ahl, 1929 is transferred to the synonymy of Leptopelis flavomaculatus (Günther, 1864) as a junior subjective synonym; 2) Leptopelis grandiceps Ahl, 1929 is resurrected from the synonymy of Leptopelis uluguruensis Barbour & Loveridge, 1928 as a valid species conforming to the tree frogs which have been known as 'L.

View Article and Find Full Text PDF

Background: The phylogenetic relationships of many taxa remain poorly known because of a lack of appropriate data and/or analyses. Despite substantial recent advances, amphibian phylogeny remains poorly resolved in many instances. The phylogenetic relationships of the Ethiopian endemic monotypic genus Ericabatrachus has been addressed thus far only with phenotypic data and remains contentious.

View Article and Find Full Text PDF
Article Synopsis
  • Recent studies have shown that West African torrent-frogs (Odontobatrachus) are genetically distinct from Central and East African frog lineages, warranting the creation of a new genus.
  • The phylogenetic analysis reveals that Odontobatrachus is not closely related to any other known frog families and has been separated from other lineages since the Cretaceous period, around 90 million years ago.
  • The findings justify the establishment of a new endemic frog family for West African torrent-frogs, highlighting their unique evolutionary significance in the Upper Guinea biodiversity hotspot.
View Article and Find Full Text PDF

We analyze mitochondrial genomes to reconstruct a robust phylogenetic framework for caecilian amphibians and use this to investigate life-history evolution within the group. Our study comprises 45 caecilian mitochondrial genomes (19 of them newly reported), representing all families and 27 of 32 currently recognized genera, including some for which molecular data had never been reported. Support for all relationships in the inferred phylogenetic tree is high to maximal, and topology tests reject all investigated alternatives, indicating an exceptionally robust molecular phylogenetic framework of caecilian evolution consistent with current morphology-based supraspecific classification.

View Article and Find Full Text PDF