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Secondary sympatry amongst sister lineages is strongly associated with genetic and ecological divergence. This pattern suggests that for closely related species to coexist in secondary sympatry, they must accumulate differences in traits that mediate ecological and/or reproductive isolation. Here, we characterized inter‐ and intraspecific divergence in three giant tree frog species whose distributions stretch across West and Central Africa. Using genome‐wide single‐nucleotide polymorphism data, we demonstrated that species‐level divergence coincides temporally and geographically with a period of large‐scale forest fragmentation during the late Pliocene. Our environmental niche models further supported a dynamic history of climatic suitability and stability, and indicated that all three species occupy distinct environmental niches. We found modest morphological differentiation amongst the species with significant divergence in tympanum diameter and male advertisement call. In addition, we confirmed that two species occur in secondary sympatry in Central Africa but found no evidence of hybridization. These patterns support the hypothesis that cycles of genetic exchange and isolation across West and Central Africa have contributed to globally significant biodiversity. Furthermore, divergence in both ecology and reproductive traits appear to have played important roles in maintaining distinct lineages. At the intraspecific level, we found that climatic refugia, precipitation gradients, marine incursions, and potentially riverine barriers generated phylogeographic structure throughout the Pleistocene and into the Holocene. Further studies examining phenotypic divergence and secondary contact amongst these geographically structured populations may demonstrate how smaller scale and more recent biogeographic barriers contribute to regional diversification. see also the Perspective by Bryan C. Carstens and Shelby P. Moshier [ABSTRACT FROM AUTHOR]

Gene flow and reticulation are increasingly recognized as important processes in the diversification of many taxonomic groups. With the increasing ease of collecting genomic data and the development of multispecies coalescent network approaches, such reticulations can be accounted for when inferring phylogeny and diversification. Caribbean Anolis lizards are a classic example of an adaptive radiation in which species have independently radiated on the islands of the Greater Antilles into the same ecomorph classes. Within the Jamaican radiation at least one species, Anolis opalinus , has been documented to be polyphyletic in its mitochondrial DNA, which could be the result of an ancient reticulation event or incomplete lineage sorting (ILS). Here, we generate mtDNA and genotyping-by-sequencing (GBS) data and implement gene tree, species tree, and multispecies coalescent network methods to infer the diversification of this group. Our mtDNA gene tree recovers the same relationships previously inferred for this group, which is strikingly different from the species tree inferred from our GBS data. Posterior predictive simulations suggest that our genomic data violate commonly adopted assumptions of the multispecies coalescent model (MSCM), so we use network approaches to infer phylogenetic relationships. The inferred network topology contains a reticulation event but does not explain the mtDNA polyphyly observed in this group; however, coalescent simulations suggest that the observed mtDNA topology is likely the result of past introgression. How common a signature of gene flow and reticulation is across the radiation of Anolis is unknown; however, the reticulation events that we demonstrate here may have allowed for adaptive evolution, as has been suggested in other, more recent, adaptive radiations. [Adaptive radiation; hybridization; introgression; multispecies network coalescent; posterior predictive simulation.] [ABSTRACT FROM AUTHOR]

Research shows that the two-dimensional silicidation reaction that occurs in titanium is not inhibited by small geometry. Silicon posts measuring 1000 angstroms in radius and silicon lines measuring 1200 angstroms wide can grow thick self-aligned silicide in complementary metal oxide semiconductor devices. The two-dimensional silicidation process is discussed. Evidence indicates that the silicidation process may involve high atomic number and molecular level mobility.

The article discusses the corrected taxonomic history of the North American ratsnakes (Pantherophis obsoletus Complex). It mentions that differential isolation across the genomes of geographic lineages is possible, with some chromosomal regions showing low levels of introgression and others showing considerable admixture. It states that differential level of migration among loci is expected under a process of speciation with ecological adaptation via natural selection.

The Príncipe giant tree frog Leptopelis palmatus is endemic to the small oceanic island of Príncipe in the Gulf of Guinea. For several decades, this charismatic but poorly known species was confused with another large tree frog species from continental Africa, L. rufus. Phylogenetic relationships within the African genus Leptopelis are poorly understood and consequently the evolutionary history of L. palmatus and its affinity to L. rufus remain unclear. In this study, we combined mitochondrial DNA (mtDNA), morphological, and acoustic data for L. palmatus and L. rufus to assess different axes of divergence between the species. Our mtDNA gene tree for the genus Leptopelis indicated that L. palmatus is not closely related to L. rufus or other large species of Leptopelis. Additionally, we found low mtDNA diversity in L. palmatus across its range on Príncipe. We found significant morphological differences between females of L. rufus and L. palmatus, but not between males. We characterised the advertisement call of L. palmatus for the first time, which is markedly distinct from L. rufus. Finally, we summarised our observations of L. palmatus habitats and additional notes on phenotypic variation and behaviour. Our study reinforces the distinctiveness of L. palmatus and provides information important for the conservation of this endangered species. [ABSTRACT FROM AUTHOR]

We study the compound flooding processes as occurred in Hurricane Florence (2018) that was accompanied by heavy precipitation, using a 3D creek-to-ocean hydrodynamic model. We examine the important role played by barrier islands in the observed compound surges in the coastal watershed. Locally very high resolution is used in some watershed areas in order to resolve small features that turn out to be critical for capturing the observed High Water Marks locally. The wave effects are found to be significant near barrier islands and have contributed to some observed over-toppings and breaches. Sensitivity results from applying each of the three major forcing factors (oceanic, fluvial and pluvial) separately are succinctly summarized in a dominance map that highlights significant compound effects in most of the affected coastal watersheds, estuaries and back bays behind the barrier islands. Operational forecasts based on the current model are being set up at NOAA to help coastal resource and emergency managers with disaster planning and mitigation effort. [ABSTRACT FROM AUTHOR]