Variable signatures of selection despite conserved recombination landscapes early in speciation

Recently diverged taxa often exhibit heterogeneous landscapes of genomic differentiation, characterized by regions of elevated differentiation on an otherwise homogeneous background. While divergence peaks are generally interpreted as regions responsible for reproductive isolation, they can also arise due to background selection, selective sweeps unrelated to speciation, and variation in recombination and mutation rates. To investigate the association between patterns of recombination and landscapes of genomic differentiation during the early stages of speciation, we generated fine-scale recombination maps for six southern capuchino seedeaters (Sporophila) and two subspecies of White Wagtail (Motacilla alba), two recent avian radiations in which divergent selection on pigmentation genes has likely generated peaks of differentiation. We compared these recombination maps to those of Collared (Ficedula albicollis) and Pied Flycatchers (Ficedula hypoleuca), non-sister taxa characterized by moderate genomic divergence and a heterogenous landscape of genomic differentiation shaped in part by background selection. Although recombination landscapes were conserved within all three systems, we documented a weaker negative correlation between recombination rate and genomic differentiation in the recent radiations. All divergence peaks between capuchinos, wagtails, and flycatchers were located in regions with lower-than-average recombination rates, and most divergence peaks in capuchinos and flycatchers fell in regions of exceptionally reduced recombination. Thus, co-adapted allelic combinations in these regions may have been protected early in divergence, facilitating rapid diversification. Despite largely conserved recombination landscapes, divergence peaks are specific to each focal comparison in capuchinos, suggesting that regions of elevated differentiation have not been generated by variation in recombination rate alone.

Highly Conservative Pattern of Sex Chromosome Synapsis and Recombination in Neognathae Birds

We analyzed the synapsis and recombination between Z and W chromosomes in the oocytes of nine neognath species: domestic chicken Gallus gallus domesticus, grey goose Anser anser, black tern Chlidonias niger, common tern Sterna hirundo, pale martin Riparia diluta, barn swallow Hirundo rustica, European pied flycatcher Ficedula hypoleuca, great tit Parus major and white wagtail Motacilla alba using immunolocalization of SYCP3, the main protein of the lateral elements of the synaptonemal complex, and MLH1, the mismatch repair protein marking mature recombination nodules. In all species examined, homologous synapsis occurs in a short region of variable size at the ends of Z and W chromosomes, where a single recombination nodule is located. The remaining parts of the sex chromosomes undergo synaptic adjustment and synapse non-homologously. In 25% of ZW bivalents of white wagtail, synapsis and recombination also occur at the secondary pairing region, which probably resulted from autosome−sex chromosome translocation. Using FISH with a paint probe specific to the germline-restricted chromosome (GRC) of the pale martin on the oocytes of the pale martin, barn swallow and great tit, we showed that both maternally inherited songbird chromosomes (GRC and W) share common sequences.

The nesting ecology and postembryonic development of the Baikal white wagtail Motacilla alba baicalensis

The goal of the paper is to identify the features of the breeding ecology of the Motacilla alba baicalensis in the Baikal region and Transbaikalia. The nesting ecology study deliverable of the Motacilla alba baicalensis in the Baikal region and Transbaikalia showed that this subspecies, unlike other forms, is more synanthropic, more than 95% of populations live in localities and other anthropogenic habitats, and only 23% of populations inhabit natural biotopes. At the same time, the Motacilla alba baicalensis in the region prefers small rural settlements and livestock camps in open landscapes near reservoirs. When the Motacilla alba baicalensis builds nests, like other subspecies, it is quite plastic and easily finds shelter in various anthropogenic and natural biotopes. The higher nesting efficiency of this subspecies indicates its wide opportunities to develop anthropogenic landscapes. Due to the short favorable nesting period, most pairs manage to hatch chicks once, but only a small number of pairs manage to raise chicks twice a season. A comparison of the nesting ecology of the Motacilla alba baicalensis with other forms of the Northern Eurasian species did not reveal any fundamental differences. The differences relate to the phenology of different stages of the breeding season, as well as the timing of arrival and departure of birds.

Особенности размножения птиц зеленых насаждений города Сыктывкара

Изучены особенности гнездовой биологии двух видов дуплогнездников (полевого воробья – Passer montanus L. и мухоловки-пеструшки – Ficedula hypoleuca Pall.) и шести видов открытогнездящихся птиц (белой трясогузки – Motacilla alba L., дрозда-белобровика – Turdus iliacus L., дрозда-рябинника – Turdus pilaris L., серой вороны – Corvus cornix L., грача – C. frugilegus L. и сороки – Picapica L.) в условиях зеленых насаждений г. Сыктывкара и его окрестностей. Показано, что в условиях культурного ландшафта, как и в природных экосистемах, наблюдается межвидовая, сезонная и годовая изменчивость успешности размножения. Изменчивость показателей успешности размножения у разных видов зависела от совокупного действия хищничества (66–75 % общей гибели яиц и птенцов) и эмбриональной смертности (25–60 % гибели яиц и птенцов). В городе на успешность размножения птицбольшое влияние оказывает деятельность человека (25 % общей гибели яиц и птенцов), к которой, главным образом, относятся технические мероприятия, прямое разорение гнезд.

The importance of Motacilla Alba behavior on hitting its own mirror reflection

Self-awareness is considered as a capability of recognize oneself and increasingly received attention. However, self-awareness in the bird Motacilla Alba is unclear. To study the self-recognition in Motacilla Alba, the subject is observed by mirror while eating. The bird performed the look around, confirm again the surroundings, become alert, hit the mirror. These behaviors suggests that presently Motacilla Alba does not have the capacity of self-awareness by the test.

The evolutionary history of the white wagtail species complex, (Passeriformes: Motacillidae: Motacilla alba)

The white wagtail (Motacilla alba) species complex with its distinctive plumage in separate geographical areas can serve as a model to test evolutionary hypotheses. Its extensive variety in plumage, despite the genetic similarity between taxa, and the evolutionary events connected to this variety are poorly understood. Therefore we sampled in the breeding range of the white wagtail: 338 individuals were analyzed from 74 areas in the Palearctic and Mediterranean. We studied the white wagtail complex based on two mitochondrial DNA markers to make inferences about the evolutionary history. Our phylogenetic trees highlight mtDNA sequences (ND2, CR), and one nuclear marker (CHD1Z), which partly correspond to earlier described clades: the northern Palearctic (clade N); eastern and central Asia (clade SE); south-western Asia west to the British Isles (clade SW); and Morocco (clade M). The divergence of all clades occurred during the Pleistocene. We also used ecological niche modelling for three genetic lineages (excluding clade M); results showed congruence between niche and phylogenetic divergence in these clades. The results of the white wagtail ancestral area reconstruction showed the influence of dispersal on the distribution and divergence of this complex species. The most important vicariance event for the white wagtail complex may have been caused by the Gobi and Taklamakan deserts. We conclude that the ancestral area of the white wagtail complex was probably in the Mediterranean, with its geography having a considerable effect on speciation processes.