Parallel plumage colour evolution and introgressive hybridization in wheatears

Genetic and phenotypic mosaics, in which various phenotypes and different genomic regions show discordant patterns of species or population divergence, offer unique opportunities to study the role of ancestral and introgressed genetic variation in phenotypic evolution. Here, we investigated the evolution of discordant phenotypic and genetic divergence in a monophyletic clade of four songbird taxa—pied wheatear (O. pleschanka), Cyprus wheatear (Oenanthe cypriaca), and western and eastern subspecies of black‐eared wheatear (O. h. hispanica and O. h. melanoleuca). Phenotypically, black back and neck sides distinguish pied and Cyprus wheatears from the white‐backed/necked black‐eared wheatears. Meanwhile, mitochondrial variation only distinguishes western black‐eared wheatear. In the absence of nuclear genetic data, and given frequent hybridization among eastern black‐eared and pied wheatear, it remains unclear whether introgression is responsible for discordance between mitochondrial divergence patterns and phenotypic similarities, or whether plumage coloration evolved in parallel. Multispecies coalescent analyses of about 20,000 SNPs obtained from RAD data mapped to a draft genome assembly resolve the species tree, provide evidence for the parallel evolution of colour phenotypes and establish western and eastern black‐eared wheatears as independent taxa that should be recognized as full species. The presence of the entire admixture spectrum in the Iranian hybrid zone and the detection of footprints of introgression from pied into eastern black‐eared wheatear beyond the hybrid zone despite strong geographic structure of ancestry proportions furthermore suggest a potential role for introgression in parallel plumage colour evolution. Our results support the importance of standing heterospecific and/or ancestral variation in phenotypic evolution.     

Ecological modeling and distribution analysis of digger scorpions: Odontobuthus doriae,Odonthubutus bidentatus (Scorpiones: Buthidae) and Scorpio maurus (Scorpiones: Scorpionidae) in Iran using the maximum entropy method

Prediction models are essential for the potential geographic distribution of scorpions, prevention of scorpion stings and diverse applications in conservation biology. There is limited information about habitat suitability and the factors affecting the distribution of Iranian digger scorpions. This study was undertaken to model the distribution of three types of digger scorpion in Iran, Odontobuthus doriae Thorell, Odonthubutus bidentatus Lourenco (Scorpiones: Buthidae) and Scorpio maurus Pocockin (Scorpiones: Scorpionidae), and investigate the factors affecting its distribution using the maximum entropy method. A total of 20 environmental and climate variables were used for modeling and evaluation of the ecological niche. The similarities and differences between the ecological overlap of the digger scorpions were evaluated using comparative environmental niche model (ENM Tools software). The results showed that the main factors for habitat suitability of O. doriae were soil type, mean temperature of the wettest quarter and slope. The variables for S. maurus were soil type, precipitation of the coldest quarter and slope. Annual temperature range, mean temperature of the driest quarter and land use had the greatest influence on the distribution of O. bidentatus. The ecological niches for O. doriae and O. bidentatus overlapped. The niche of these species differed from the niche of S. maurus. This approach could be helpful for the prediction of the potential distribution of three digger scorpion species and this model can be an effective for the promotion of health.

     

Phylogeny of Palaearctic wheatears (genus Oenanthe)--congruence between morphometric and molecular data

Wheatears of the genus Oenanthe are birds specialized to desert ecosystems in the Palaearctic region from Morocco to China. Although they have been the subject of many morphological and ecological studies, no molecular data have been used to elucidate their phylogenetic relationships, and, their relationships are still debated. Here we use DNA sequences of 1180 bp of two mitochondrial genes, 16S rRNA and cytochrome oxidase subunit I, from 32 individuals from Middle East and North Africa, and Bayesian methods to derive a phylogeny for 11 species of Oenanthe. The resulting tree supported three major clades: (A) O. alboniger, O. chrysopygia, O. lugens, O. finschii, O. leucopyga, O. picata, O. moesta, (B) O. deserti and O. pleschanka; and (C) O. isabellina and O. oenanthe. These results largely differ from previous hypotheses based on analysis of morphological and chromatic characters. However, the two clades (B) and (C) were also supported by a phenetic analysis of new morphometric data presented here, indicating that characters related to colouration and ecology in Oenanthe are more strongly influenced by homoplasy than those of body shape.     

Phylogeography of the Oenanthe hispanica–pleschanka–cypriaca complex (Aves,Muscicapidae: Saxicolinae): Diversification history of open‐habitat specialists based on climate niche models,genetic data,and morphometric data

The succession of glacials and interglacials during the Pleistocene strongly influenced the diversification and distribution patterns in birds. In contrast to species of temperate regions, open‐habitat specialists should have experienced range expansion during the longer glacial periods, while range contractions occurred during the shorter interglacials. However, only few studies have tested this prediction so far. We studied the Oenanthe hispanica–pleschanka–cypriaca (Aves, Muscicapidae: Saxicolinae) complex characteristic of open habitats in the Palearctic. Based on three mitochondrial and one Z‐linked nuclear marker, we inferred its phylogeny, historical diversification, and demography. Ecological niche modeling was used to reconstruct potential distributions during the last glacial maximum and the last interglacial. Using 19 morphological traits, we tested for morphometric differences among the different taxa. Mitochondrial markers revealed strong genetic differences between O. h. hispanica and the other taxa with a divergence event at around 1.7 million years ago. No consistent genetic differences were revealed between O. cypriaca, O. h. melanoleuca, and O. pleschanka. The latter two hybridize in contact zones, which might explain partly the lack of genetic differentiation; yet, further analyses using genomic data are needed to infer the true divergence history of the complex. Signs of population expansions in the clade comprising O. h. melanoleuca, O. pleschanka, and O. cypriaca at 90,000 years ago coincided with the last glacial as predicted. Population expansion then was also supported by ecological climate niche models. O. h. hispanica was not consistently separated from the other taxa in morphometrics. It might nonetheless warrant species status, pending further analyses.     

Evolutionary history of the Persian Jird,Meriones persicus,based on genetics,species distribution modelling and morphometric data

The Persian Jird, Meriones persicus, is distributed from Eastern Anatolia to Afghanistan and western Pakistan. Six subspecies were described based on skull features and coat colours, but the validity of these subspecies is uncertain, and no molecular work has ever been conducted on this species. Iran appears to be a key geographical region in which to revise the systematic and evolutionary history of this species, because five of the six subspecies are present in this country. To evaluate the phylogeographical history and taxonomy of this species in Iran, we used a combination of genetic (cytochrome b gene sequences of 70 specimens) and geometric morphometric (2D landmarks on the ventral side of skull of 258 specimens) analyses. We also used ecological niche modelling to make inferences about the evolutionary history of these lineages. Our molecular data highlight the existence of four genetic lineages, but they only partly correspond to the previously described subspecies. Our molecular and morphometric data confirm the validity of M. p. rossicus and show that it has a wider geographical range than previously thought. M. p. gurganensis and M. p. baptistae are genetically very close. The skull of M. p. gurganensis is morphologically distinguishable from other subspecies. The subspecies M. p. persicus and M. p. baptistae are genetically distinct, but morphologically close. Meriones p. ambrosius is genetically close to M. p. persicus, and additional analyses with more specimens are needed to validate its subspecific status. The genetic structure observed in Iran seems to fit the topography and biogeography of the country and emphasize the role of the Abarkooh, Central and Lut deserts as barriers to gene flow. All intraspecific divergent events within the Persian Jird occurred during the last 1.4 My, suggesting that climatic changes probably trigger diversification within this species. Our genetic and species niche modelling results suggest that potential refugial areas persisted during glacial periods for this species in north‐western Zagros Mountains, north‐eastern Alborz Mountains and Kohrud Mountains.     

Out of Africa: biogeographic history of the open‐habitat chats (Aves,Muscicapidae: Saxicolinae) across arid areas of the old world

Arid and semi‐arid areas constitute a prominent feature of the earth today, especially in Asia and Africa. Their formation started in the middle Miocene with increased stepwise aridification since the Pliocene. This aridification had strong ecological and evolutionary consequences and not only led to fragmentation of moist‐adapted biota, but also fostered the evolution of arid‐adapted taxa from mesic ancestors and triggered speciation within arid areas. The open‐habitat chats, a clade within Saxicolinae (Aves, Muscicapidae), constitute one of the most significant arid‐adapted passerine groups of Africa and Eurasia. Here, we present a temporal and spatial framework for the diversification of open‐habitat chats, using probabilistic approaches for the reconstruction of their biogeographic history based on a time‐calibrated multilocus molecular phylogenetic hypothesis. The diversification of open‐habitat chats was initiated in the late Miocene at around 7.4 Ma, most likely in sub‐Saharan Africa. Southern Africa and the Horn of Africa acted as centres of diversification and biogeographic expansion. From the latter area, the Arabo‐Sindic region and subsequently further parts of Eurasia and North Africa were colonized. The colonization history out of sub‐Saharan Africa contrasts with that of several other songbird clades, where a biogeographic expansion from Eurasia or northern Africa to southern Africa was prevalent. Habitat fragmentation through forest expansions during intermittent wetter periods in Africa influenced diversification in several clades. However, phases of increased aridity, with hyperarid regions acting as drivers of vicariance, seem to have also been important in radiations of the Arabo‐Sindic region and the Horn of Africa during the Pleistocene. Different processes such as colonization of new areas followed by vicariance or speciation across ecotones might have played a role throughout the radiation of open‐habitat chats.