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How environmental factors shape patterns of biotic diversity in tropical ecosystems is an active field of research, but studies examining the possibility of ecological speciation in terrestrial tropical ecosystems are scarce. We use the isolated rainforest herpetofauna on the Montagne d'Ambre (Amber Mountain) massif in northern Madagascar as a model to explore elevational divergence at the level of populations and communities. Based on intensive sampling and DNA barcoding of amphibians and reptiles along a transect ranging from ca. 470–1470 m above sea level (a.s.l.), we assessed a main peak in species richness at an elevation of ca. 1000 m a.s.l. with 41 species. The proportion of local endemics was highest (about 1/3) at elevations >1100 m a.s.l. Two species of chameleons (Brookesia tuberculata, Calumma linotum) and two species of frogs (Mantidactylus bellyi, M. ambony) studied in depth by newly developed microsatellite markers showed genetic divergence up the slope of the mountain, some quite strong, others very weak, but in each case with genetic breaks between 1100 and 1270 m a.s.l. Genetic clusters were found in transect sections significantly differing in bioclimate and herpetological community composition. A decrease in body size was detected in several species with increasing elevation. The studied rainforest amphibians and reptiles show concordant population genetic differentiation across elevation along with morphological and niche differentiation. Whether this parapatric or microallopatric differentiation will suffice for the completion of speciation is, however, unclear, and available phylogeographic evidence rather suggests that a complex interplay between ecological and allopatric divergence processes is involved in generating the extraordinary species diversity of Madagascar's biota. Our study reveals concordant patterns of diversification among main elevational bands, but suggests that these adaptational processes are only part of the complex of processes leading to species formation, among which geographical isolation is probably also important. [ABSTRACT FROM AUTHOR]

Earth's biodiversity is still so poorly known that only about two million (Bánki et al., 2021) of the estimated nine million or more eukaryotic species (Larsen et al., 2017; Mora et al., 2011) have been described. Meierotto et al. (2019), when first proposing the minimalist approach, failed to merge their new DNA barcode-based species with existing species for which barcodes are not available. COI BARCODES ARE NOT SUITABLE ON THEIR OWN The default assumption of Sharkey, Janzen, et al. (2021) is that COI barcode clusters (Barcode Index Numbers [or BINs] computed by BOLD systems) equate to species. [Extracted from the article]

The omission of critical data in the pursuit of "revolutionary" methods to accelerate the description of species However, the latter authors failed to diagnose their 15 new I Zelomorpha i Ashmead, 1900 species from 51 out of 52 previously known species (only the type species was used in the analysis) and their three new I Hemichoma i Enderlein, 1920 species from any of the five previously known species. (2004) proposed to recognize ten species of skipper butterflies (genus I Astraptes i ) based on DNA characters and ecology and some morphological characters, but the species were not formally named until Brower (2010) described them based exclusively on unique mutations in the DNA barcode region. DNA barcoding is a rapid means to sort specimens into clusters, identify species and discover new ones (when a library of the relevant named species is already available), but does not overcome the bottleneck of the description process itself. [Extracted from the article]

The emerging picture of non‐monophyly of scolecophidian snakes is increasingly indicative that fossorial lifestyle, myrmecophagous diet, and miniaturisation are powerful drivers of morphological evolution in squamate skulls. We provide a detailed description of the skull of Xenotyphlops grandidieri, with reference to the skulls of other scolecophidian snakes. The skull, which shows dramatic ventral inflection of the snout complex, is remarkably bizarre, and the mouth opening is more ventrally oriented than in other typhlopoids. The eyes are strongly reduced, and the enlarged and rather flat anterior head shield is covered in numerous sensillae. We put forward several potential explanations for the evolution of these unusual modifications. On the other hand, Xenotyphlops shares numerous synapomorphies with other typhlopoid snakes, including the highly specialized jaw mechanism. We argue that the key differences between the jaw mechanisms of Leptotyphlopidae, Anomalepididae, and Typhlopoidea provide compelling evidence for a strong role of convergence in the evolution of the scolecophidian bauplan, and these clades therefore cannot be interpreted as representative of ancestral anatomy or ecology among snakes. [ABSTRACT FROM AUTHOR]

Premise of the study: Over the past 75 Myr, successive groups of plants have entered the "oil bee pollination niche," meaning that they depend on oil-collecting bees for their pollination. The highly dissimilar numbers of plant species and bee species involved in these mutualisms imply evolutionary host switching, asymmetric mutual dependencies, and uncoupled diversification. Among the clades with the best field data on oil bee behavior is the Angelonieae, which we here investigate to better understand the evolutionary time frame of this pollination syndrome. • Methods: We generated nuclear and plastid data matrices for 56% of the Angelonieae species (plus outgroups) and used Bayesian methods of molecular clock dating, ancestral state reconstruction, and biogeographic inference. • Key results: We found that Angelonieae have two major clades, Angelonia (including Monopera) and Basistemon, and Monttea, Melosperma, and Ourisia. • Conclusions: Angelonieae date back to the Uppermost Eocene, ca. 35 (26-47) Myr ago (Ma) and diversified in dry areas of southern South America; they switched from nectar to oil as a reward four or five times over the past 25 Ma. As predicted in a previous non-clock-dated study, dispersal to Australasia dates to the Miocene/Pliocene. [ABSTRACT FROM AUTHOR]