A recent article in Ecology and Evolution featured the discovery of hybrid snowcocks (Tetraogallus) and speculated on the hybrid origin of an extant species (T. altaicus). Comprehensive re‐analyses ...of original data from the latter paper reliably refute the phylogenetic hypothesis taken as firm evidence of a past hybridization event in these birds. The new re‐analyses showed that there is no evidence of hybridization in these snowcocks from the data available so far.
Tropical mountains are hotspots of biodiversity, but the factors that generate this high diversity remain poorly understood. To identify possible mechanisms that influence avian species assemblages ...in the tropical Andes, we studied the functional and phylogenetic diversity and the structure of species assemblages of an avian feeding guild. We analysed how functional and phylogenetic diversity, structure and composition of frugivorous bird assemblages changed along a 3300 m elevational transect from the lowlands to the tree line with a novel combination of functional and phylogenetic approaches, and used null models to infer possible drivers of the observed patterns. Species richness, functional richness and phylogenetic diversity decreased almost monotonically with increasing elevation, but assemblage structure and composition changed abruptly in the Andean foothills at around 1200 m. In the lowland assemblages, species were functionally and phylogenetically less similar than expected from null models, whereas species in the highland assemblages were functionally and phylogenetically more similar than expected by chance, suggesting an abrupt reduction in the number of functionally and phylogenetically distinct species in the transition from lowlands to the highlands. Nevertheless, the functional and phylogenetic evenness of the assemblages, i.e. the regularity of the spacing of species in functional trait space and phylogeny, remained constant along the gradient, which suggests that the mechanisms that influence the co-occurrence of species within the assemblages are similar in lowlands and highlands. The observed differences between lowland and highland assemblages imply sharp distributional limits for frugivorous bird species in the Andean foothills, probably caused by environmental factors other than climate, e.g. changes in habitat types or topography, or independent species radiations in lowlands and highlands. These strong distributional limits may hinder uphill range shifts of frugivorous bird species, and the plant species they disperse, in the tropical Andes as a response to climate change.
Bird songs and morphometry are frequently used to distinguish bird species which are plumage-cryptic, or to delineate boundaries of subspecies. Rubigula flaviventris, Pycnonotus finlaysoni and ...Brachypodius melanocephalos have each recognized subspecies along the Thai-Malay Peninsula, however the range-limit of the subspecies distribution is still ambiguous and genetic data from a previous own study suggests a revision of the subspecies distribution and the subspecies barriers is warranted. To analyze the subspecies boundaries based on potential song and morphometric traits, we recorded, measured, and analyzed song characters and morphometry of the three bulbuls along the Thai-Malay Peninsula. The geographic variation of songs and morphometry differs significantly for specific traits; however, we could not find any trait discontinuities that would be in accordance with previously documented phylogeographic divides. Instead trait variation was mostly clinal and followed a North-South gradient in line with Bergmann’s rule. Due to the lack of distinctiveness of any subspecific taxon, we conclude that shallow genetic divides on the Thai-Malay Peninsula are not indicative of potential species-level splits in the three species of our study.
Encompassing some of the major hotspots of biodiversity on Earth, large mountain systems have long held the attention of evolutionary biologists. The region of the Qinghai‐Tibet Plateau (QTP) is ...considered a biogeographic source for multiple colonization events into adjacent areas including the northern Palearctic. The faunal exchange between the QTP and adjacent regions could thus represent a one‐way street (“out of” the QTP). However, immigration into the QTP region has so far received only little attention, despite its potential to shape faunal and floral communities of the QTP. In this study, we investigated centers of origin and dispersal routes between the QTP, its forested margins and adjacent regions for five clades of alpine and montane birds of the passerine superfamily Passeroidea. We performed an ancestral area reconstruction using BioGeoBEARS and inferred a time‐calibrated backbone phylogeny for 279 taxa of Passeroidea. The oldest endemic species of the QTP was dated to the early Miocene (ca. 20 Ma). Several additional QTP endemics evolved in the mid to late Miocene (12–7 Ma). The inferred centers of origin and diversification for some of our target clades matched the “out of Tibet hypothesis’ or the “out of Himalayas hypothesis” for others they matched the “into Tibet hypothesis.” Three radiations included multiple independent Pleistocene colonization events to regions as distant as the Western Palearctic and the Nearctic. We conclude that faunal exchange between the QTP and adjacent regions was bidirectional through time, and the QTP region has thus harbored both centers of diversification and centers of immigration.
The Qinghai‐Tibet Plateau (QTP) is considered a source region for colonization of adjacent areas such as the northern Palearctic. Using an ancestral area reconstruction approach on a phylogeny of 279 bird species, we suggest that faunal exchange between the QTP and adjacent regions was bidirectional through time and the QTP region has harbored both centers of diversification (for example of snowfinches) and centers of immigration.
The Mediterranean Basin represents a Global Biodiversity Hotspot where many organisms show high inter- and intraspecific differentiation. Extant phylogeographic patterns of terrestrial ...circum-Mediterranean faunas were mainly shaped through Pleistocene range shifts and range fragmentations due to retreat into different glacial refugia. Thus, several extant Mediterranean bird species have diversified by surviving glaciations in different hospitable refugia and subsequently expanded their distribution ranges during the Holocene. Such a scenario was also suggested for the Eurasian Wren (Nannus troglodytes) despite the lack of genetic data for most Mediterranean subspecies. Our phylogenetic multi-locus analysis comprised 18 out of 28 currently accepted subspecies of N. troglodytes, including all but one subspecies which are present in the Mediterranean Basin. The resulting phylogenetic reconstruction dated the onset of the entire Holarctic radiation of three Nannus species to the early Pleistocene. In the Eurasian Wren, two North African subspecies represented separate basal lineages from the Maghreb (N. t. kabylorum) and from the Libyan Cyrenaica (N. t. juniperi), being only distantly related to other Mediterranean populations. Although N. troglodytes appeared to be paraphyletic with respect to the Nearctic Winter Wren (N. hiemalis), respective nodes did not receive strong statistical support. In contrast, paraphyly of the Ibero-Maghrebian taxon N. t. kabylorum was strongly supported. Southern Iberian populations of N. t. kabylorum did not clade with Maghrebian populations of the same subspecies but formed a sister clade to a highly diverse European clade (including nominate N. t. troglodytes and eight further taxa). In accordance with a pattern also found in other birds, Eurasian populations were split into a western clade (Europe, Caucasus) and an eastern clade (Central Asia, Sino-Himalayas, East Asia). This complex phylogeographic pattern revealed cryptic diversification in N. troglodytes, especially in the Iberio-Maghrebian region.
AIM: For terrestrial organisms, a faunal transition zone between the Indochinese and Sundaic regions is delimited north of the Isthmus of Kra on the Thai‐Malay Peninsula. We used a mitochondrial ...marker to test the predicted location of intraspecific north–south divides for four species of bulbuls (Pycnonotus). Phylogenetic relationships among Thai‐Malay populations and their closest relatives from the Greater Sundas were reconstructed from a multilocus data set including 35 Pycnonotus species. LOCATION: Indochina, Thai‐Malay Peninsula, Greater Sundas. METHODS: We sampled target species along a north–south transect spanning the Isthmus of Kra and reconstructed phylogeographical patterns based on ND2 haplotype networks. Phylogenies were reconstructed using Maximum likelihood and Bayesian inference. Divergence time estimates were inferred from single‐locus and multilocus data using *beast. RESULTS: We found mitochondrial north–south divides in all target species. Haplotypes of southern genetic clusters were distributed all across the Thai‐Malay Peninsula and north into Central Thailand. Local overlap of genetic lineages was confirmed at one location in one species only. In three of the focal species, the southern limits of southern haplotype clusters were restricted to the Thai‐Malay Peninsula and did not extend into the Greater Sundas. Peninsular north–south divides were dated to the late Pleistocene, whereas Indochinese‐Sundaic lineage divergence was dated to the late Pliocene. MAIN CONCLUSIONS: Population boundaries did not coincide with the Isthmus of Kra, but instead were located north of the Thai‐Malay Peninsula in Central Thailand. Only one of four divides represented an Indochinese‐Sundaic transition. Different phylogeographical patterns among target species were presumably shaped by different ecological preferences in Pleistocene palaeohabitats. Pliocene Indochinese‐Sundaic lineage divergence in bulbuls coincides with strong vegetational changes on the Peninsula that shaped two phytogeographical transitions. Distribution limits of bird species roughly coincide with these transition zones and therefore the avifaunal Thai‐Malay transition represents a broad zone rather than a sharp boundary.
In this paper we provide a molecular phylogeny based on three mitochondrial and three nuclear markers for all long-tailed tit species of the genus
Aegithalos including several doubtful subspecies (17 ...taxa) plus three close allies of SE Asian
Leptopoecile and North American
Psaltriparus. Genus
Aegithalos is divided into three major clades, two of them showing only minor differentiation. Separation of two mitchondrial haploytpe clusters in the N Palearctic Long-tailed Tit,
Ae. caudatus, was dated back to the Late Pleistocene, however, descendants from both lineages underwent a rapid post-Pleistocene range expansion and largely mixed over the entire distribution area. The Chinese populations of the
glaucogularis subspecies group represent a slightly earlier Pleistocene split from the
Ae. caudatus clade.
Genetic differentiation among several doubtful SE Asian species taxa on the sister clade of the latter N Palearctic/Chinese clade matches the intraspecific differentiation within
Ae. caudatus. Unexpectedly, cytochrome-
b distances among Himalayan
Ae. iouschistos (including the subspecies
bonvaloti from China and
sharpei from Myanmar) and the Chinese endemic
Ae. fuliginosus range at approximately 0.5% and apparently all these extant populations separated only very recently during late Pleistocene times, too. W Himalayan
Ae. niveogularis clearly appeared as the sister species of the latter taxon assemblage.
Unlike the two latter major clades,
Ae. concinnus shows strong intraspecific differentiation with cyt-b distances as high as 6% among two Himalayan populations of ssp.
iredalei, ssp.
manipurensis from Myanmar and a fourth lineage from SW and SC China including ssp.
talifuensis and nominate
concinnus. A sister-group relationship between all
Ae. concinnus and
Ae. leucogenys was strongly supported.
N American bushtits of genus
Psaltriparus represent the sister clade to Palearctic genus
Aegithalos, including a clear split between the
minimus and the
plumbeus subspecies group which was again dated back to Pleistocene times. The two tit-warbler species of genus
Leptopoecile are strongly differentiated from one another and represent an early split from the Aegithalidae tree.
In the Himalayas, a number of secondary contact zones have been described for vicariant vertebrate taxa. However, analyses of genetic divergence and admixture are missing for most of these examples. ...In this study, we provide a population genetic analysis for the coal tit (Periparus ater) hybrid zone in Nepal. Intermediate phenotypes between the distinctive western “spot‐winged tit” (P. a. melanolophus) and Eastern Himalayan coal tits (P. a. aemodius) occur across a narrow range of <100 km in western Nepal. As a peculiarity, another distinctive cinnamon‐bellied form is known from a single population so far. Genetic admixture of western and eastern mitochondrial lineages was restricted to the narrow zone of phenotypically intermediate populations. The cline width was estimated 46 km only with a center close to the population of the cinnamon‐bellied phenotype. In contrast, allelic introgression of microsatellite loci was asymmetrical from eastern P. a. aemodius into far western populations of phenotypic P. a. melanolophus but not vice versa. Accordingly, the microsatellite cline was about 3.7 times wider than the mitochondrial one.
In our study, we analysed patterns of divergence and admixture in the Himalayan hybrid zone of coal tits across a transect of about 1400 km from Afghanistan to East Nepal. Due to the scarcity of study material from that region only a few phylogeographic or population genetic studies exist from this area. In these cases, museum collections are a valuable source of genetic material, such as the large collections from Afghanistan and Nepal from the 1960ies to 1970ies at ZFMK Bonn used in this study.
Under different environmental conditions, hybridization between the same species might result in different patterns of genetic admixture. Particularly, species pairs with large distribution ranges ...and long evolutionary history may have experienced several independent hybridization events over time in different zones of overlap. In birds, the diverse hybrid populations of the house sparrow (Passer domesticus) and the Spanish sparrow (Passer hispaniolensis) provide a striking example. Throughout their range of sympatry, these two species do not regularly interbreed; however, a stabilized hybrid form (Passer italiae) exists on the Italian Peninsula and on several Mediterranean islands. The spatial distribution pattern on the Eurasian continent strongly contrasts the situation in North Africa, where house sparrows and Spanish sparrows occur in close vicinity of phenotypically intermediate populations across a broad mosaic hybrid zone. In this study, we investigate patterns of divergence and admixture among the two parental species, stabilized and nonstabilized hybrid populations in Italy and Algeria based on a mitochondrial marker, a sex chromosomal marker, and 12 microsatellite loci. In Algeria, despite strong spatial and temporal separation of urban early‐breeding house sparrows and hybrids and rural late‐breeding Spanish sparrows, we found strong genetic admixture of mitochondrial and nuclear markers across all study populations and phenotypes. That pattern of admixture in the North African hybrid zone is strikingly different from i) the Iberian area of sympatry where we observed only weak asymmetrical introgression of Spanish sparrow nuclear alleles into local house sparrow populations and ii) the very homogenous Italian sparrow population where the mitogenome of one parent (P. domesticus) and the Z‐chromosomal marker of the other parent (P. hispaniolensis) are fixed. The North African sparrow hybrids provide a further example of enhanced hybridization along with recent urbanization and anthropogenic land‐use changes in a mosaic landscape.
In this study, we investigate patterns of gene flow between the house sparrow, the Spanish sparrow, and their phenotypical hybrids on two study sites in Algeria. Unlike in European areas of sympatry, nuclear markers suggest strong genetic admixture across Algerian populations and across phenotypes.
...the link between climatic changes and niche evolution, i.e. niche changes (or conservatism) over time and especially across phylogenies remains complex and fascinating. ...they use a high ...diversity of movement strategies (e.g. elevational migration, nomadic or erratic movements), which are related to the very unpredictable seasonality of alpine environments (e.g. climate conditions and resource availability; Borras et al. 2010, Henry 2011, Boyle 2018, Novoa et al. 2020, Resano-Mayor et al. 2020, Barras et al. 2021). According to the authors, such a wider niche should be related to a ‘dramatic niche evolution event', leading to a niche expansion dated perhaps 2.6 mya ago, which allowed this species to occupy warmer areas in the western Palearctic, such as southern Europe. ...unlike other typical alpine species like wheatears, water pipits and alpine choughs, observations in warmer areas at low elevation are extremely rare despite the potential suitability of habitat (Knaus et al. 2018) and are more likely to occur in the case of prolonged, exceptionally cold or snowy periods and mostly linked to food shortage at higher elevation (Cramp and Perrins 1994, Glutz von Blotzheim and Bauer 1997).
PDF
