Igor V. Fadeev

Bio: Igor V. Fadeev is an academic researcher. The author has contributed to research in topics: Holarctic & Population. The author has an hindex of 11, co-authored 16 publications receiving 486 citations.

Complex biogeographic history of a Holarctic passerine.

Abstract: Our analysis of the ND2 sequences revealed six clades within winter wrens (Troglodytes troglodytes). These clades corresponded to six geographical regions: western Nearctic, eastern Nearctic, eastern Asia, Nepal, Caucasus and Europe, and differed by 3-8.8% of sequence divergence. Differences among regions explained 96% of the sequence variation in winter wren. Differences among individuals within localities explained 3% of the sequence variation, and differences among localities within regions explained 1%. Grouping sequences into subspecies instead of localities did not change these proportions. Proliferation of the six clades coincided with Early and Middle Pleistocene glaciations. The distribution of winter wren clades can be explained by a series of five consecutive vicariant events. Western Nearctic wrens diverged from the Holarctic ancestor 1.6 Myr before the present time (MYBP). Eastern Nearctic and Palaearctic wrens diverged 1 MYBP. Eastern and western Palaearctic birds diverged 0.83 MYBP. Nepalese and east Asian wrens diverged 0.67 MYBP, and Caucasian birds diverged from European wrens 0.54 MYBP. The winter wren has a much greater degree of inter- and intracontinental differentiation than the three other Holarctic birds studied to date--dunlin (Calidris alpina), common raven (Corvus corax) and three-toed woodpecker (Picoides trydactylus)--and represents an example of cryptic speciation that has been overlooked.

Mitochondrial phylogeny of Locustella and related genera

Abstract: We used maximum likelihood analysis of complete mitochondrial ND2 sequences (1041 bp) to clarify the taxonomy and relationships of various species and genera of grass and bush warblers. The tree revealed two clades of grass and bush warblers. One clade was comprised of all four western Palearctic Locustella and two species of Asian Bradypterus. The other clade included five eastern Palearctic Locustella (including the distinctive Sakhalin warbler Locustella amnicola ) and the marsh grassbird Megalurus pryeri . African Bradypterus and Australian little grassbird Megalurus gramineus were distantly related to their Asian congeners. Therefore, current taxonomy of these genera does not reflect their evolutionary history and needs revision. It is proposed that a phylogenetic analysis of morphology and ecological preferences would show that the current taxonomy of grass and bush warblers reflects species’ habitat preferences and morphology related to locomotion and foraging in their habitats, rather than their shared ancestry. Distinct clades were found in grasshopper warbler Locustella naevia and Pallas’s grasshopper warbler L. certhiola . Detailed phylogeographic studies are needed to elucidate the species status of the clades within these two species.

Recent evolutionary history of the bluethroat (Luscinia svecica) across Eurasia

Abstract: We analysed mitochondrial DNA (mtDNA) sequences from 154 bluethroats ( Luscinia svecica ) sampled at 21 sites throughout much of their Eurasian range. A previously reported, single base-pair mtDNA difference between L. s. svecica and L. s. namnetum was inconsistent upon expanded geographical sampling. A significant F ST value (0.29) and an isolation-by-distance effect show the existence of geographical differentiation. Phylogenetic analysis of haplotypes revealed northern and southern groups, although lineage sorting is incomplete. There was no geographical structure to the haplotype tree within groups, and currently recognized subspecies were not supported. A minimum evolution tree based on pairwise mtDNA genetic distances among average samples showed the same two broadly distributed northern and southern groups. These groups abut in the centre of the latitudinal range, and were possibly isolated by forest that developed and spread westward over the last 15 000 years. Pairwise F ST values averaged 0.16 in the southern group, 0.04 in the northern group, and 0.42 between groups. Mismatch distributions suggested population growth in each group, with that in the south being more recent. In the northern group, the geographical pattern in tau suggested northward and eastward expansion. Analysis of nucleotide diversity suggested westward expansion in the southern group. The northern group had higher nucleotide diversity than the southern group, consistent with a larger current population size in the north. Given the significant F ST , incompletely sorted haplotype tree, and broadly patterned minimum evolution tree, L. svevica appears to represent a species at an intermediate stage of differentiation between panmixia and reciprocal monophyly.

Limited Phylogeographic Signal in Sex-Linked and Autosomal Loci Despite Geographically, Ecologically, and Phenotypically Concordant Structure of mtDNA Variation in the Holarctic Avian Genus Eremophila

Abstract: Phylogeographic studies of Holarctic birds are challenging because they involve vast geographic scale, complex glacial history, extensive phenotypic variation, and heterogeneous taxonomic treatment across countries, all of which require large sample sizes. Knowledge about the quality of phylogeographic information provided by different loci is crucial for study design. We use sequences of one mtDNA gene, one sex-linked intron, and one autosomal intron to elucidate large scale phylogeographic patterns in the Holarctic lark genus Eremophila. The mtDNA ND2 gene identified six geographically, ecologically, and phenotypically concordant clades in the Palearctic that diverged in the Early - Middle Pleistocene and suggested paraphyly of the horned lark (E. alpestris) with respect to the Temminck's lark (E. bilopha). In the Nearctic, ND2 identified five subclades which diverged in the Late Pleistocene. They overlapped geographically and were not concordant phenotypically or ecologically. Nuclear alleles provided little information on geographic structuring of genetic variation in horned larks beyond supporting the monophyly of Eremophila and paraphyly of the horned lark. Multilocus species trees based on two nuclear or all three loci provided poor support for haplogroups identified by mtDNA. The node ages calculated using mtDNA were consistent with the available paleontological data, whereas individual nuclear loci and multilocus species trees appeared to underestimate node ages. We argue that mtDNA is capable of discovering independent evolutionary units within avian taxa and can provide a reasonable phylogeographic hypothesis when geographic scale, geologic history, and phenotypic variation in the study system are too complex for proposing reasonable a priori hypotheses required for multilocus methods. Finally, we suggest splitting the currently recognized horned lark into five Palearctic and one Nearctic species.

Mitochondrial DNA and plumage evolution in the white wagtail Motacilla alba

Abstract: 336.We analyzed sequences of two mitochondrial DNA (mtDNA) gene regions (controlregion and ND2) totaling 1477 base-pairs from 232 specimens of the white wagtailMotacilla alba obtained from 27 localities throughout Eurasia. Although overallhaplotype diversity was relatively low (0.79) and the most common haplotype wasshared by 45% of individuals, belonging to six subspecies, a high level of populationdifferentiation was detected. The mtDNA tree revealed three clades: (1) mostindividuals from Krasnodar (belonging to M. a. alba subspecies), (2) all individualsfrom Almaty and some from Primor’e (belonging to M. a. personata, M. a. lugens andM. a. leucopsis subspecies), and (3) the remaining individuals (representing allsubspecies and all localities except Almaty). We suggest that these three cladesrepresent historically isolated populations that relatively recently came into secondarycontact in Krasnodar and Primor’e. None of the six subspecies were reciprocallymonophyletic in the mtDNA tree. The Krasnodar population appeared to receiveimmigrants from other localities, but distinctive haplotypes from this locality did notappear elsewhere, suggesting asymmetric gene flow. Signatures of recent gene flowbetween northern populations were detected, and there was no evidence of isolation bydistance within the northern group of populations. Mismatch distributions for mostlocalities were consistent with population expansions. We also analyzed 12 maleplumage characters from 93 study skins sampled from 24 populations. Phylogenetictrees resulting from separate genetic and morphological analyses were incongruent.Plumage evolution seems to be under strong sexual or natural selection, which favorsparticular phenotypes in various areas irrespective of the mitochondrial background.Dispersal events at different evolutionary times could have obscured the effectsof earlier isolation events. The mtDNA data does not support species status forM. a. lugens and M. a. personata, which shared haplotypes with other subspecies ofM. alba. We recommend that M. lugens and M. personata are placed as juniorsynonyms of M. alba.A. Pavlova and R. M. Zink (correspondence), Bell Museum of Natural History,University of Minnesota, St. Paul, MN 55108, E-mail: rzink@biosci.umn.edu. S. Rohwer,Burke Museum and Department of Zoology, University of Washington, Seattle,Washington 98195-3010. E. A. Koblik and Y. A. Red’kin, Moscow State University,Zoological Museum, Moscow, Bol’shaya Nikitskaya 6, Russia. I. V. Fadeev and E. V.Nesterov, State Darwin Museum, 57 Vavilova street, Moscow 117292, Russia.

An Update of Wallace’s Zoogeographic Regions of the World

Abstract: Modern attempts to produce biogeographic maps focus on the distribution of species, and the maps are typically drawn without phylogenetic considerations. Here, we generate a global map of zoogeographic regions by combining data on the distributions and phylogenetic relationships of 21,037 species of amphibians, birds, and mammals. We identify 20 distinct zoogeographic regions, which are grouped into 11 larger realms. We document the lack of support for several regions previously defined based on distributional data and show that spatial turnover in the phylogenetic composition of vertebrate assemblages is higher in the Southern than in the Northern Hemisphere. We further show that the integration of phylogenetic information provides valuable insight on historical relationships among regions, permitting the identification of evolutionarily unique regions of the world.

Mitochondrial DNA under siege in avian phylogeography.

Abstract: Mitochondrial DNA (mtDNA) has been the workhorse of research in phylogeography for almost two decades. However, concerns with basing evolutionary interpretations on mtDNA results alone have been voiced since the inception of such studies. Recently, some authors have suggested that the potential problems with mtDNA are so great that inferences about population structure and species limits are unwarranted unless corroborated by other evidence, usually in the form of nuclear gene data. Here we review the relative merits of mitochondrial and nuclear phylogeographical studies, using birds as an exemplar class of organisms. A review of population demographic and genetic theory indicates that mitochondrial and nuclear phylogeographical results ought to concur for both geographically unstructured populations and for populations that have long histories of isolation. However, a relatively common occurrence will be shallow, but geographically structured mtDNA trees--without nuclear gene corroboration--for populations with relatively shorter periods of isolation. This is expected because of the longer coalescence times of nuclear genes (approximately four times that of mtDNA); such cases do not contradict the mtDNA inference of recent isolation and evolutionary divergence. Rather, the nuclear markers are more lagging indicators of changes in population structure. A review of the recent literature on birds reveals the existence of relatively few cases in which nuclear markers contradict mitochondrial markers in a fashion not consistent with coalescent theory. Preliminary information from nuclear genes suggests that mtDNA patterns will prove to be robust indicators of patterns of population history and species limits. At equilibrium, mitochondrial loci are generally a more sensitive indicator of population structure than are nuclear loci, and mitochondrial estimates of F(ST)-like statistics are generally expected to exceed nuclear ones. Hence, invoking behavioural or ecological explanations of such differences is not parsimonious. Nuclear genes will prove important for quantitative estimates of the depths of haplotype trees, rates of population growth and values of gene flow.

Systematics And The Origin Of Species

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The role of subspecies in obscuring avian biological diversity and misleading conservation policy

Abstract: Subspecies are often used in ways that require their evolutionary independence, for example as proxies for units of conservation. Mitochondrial DNA sequence data reveal that 97% of continentally distributed avian subspecies lack the population genetic structure indicative of a distinct evolutionary unit. Subspecies considered threatened or endangered, some of which have been targets of expensive restoration efforts, also generally lack genetic distinctiveness. Although sequence data show that species include 1.9 historically significant units on average, these units are not reflected by current subspecies nomenclature. Yet, it is these unnamed units and not named subspecies that should play a major role in guiding conservation efforts and in identifying biological diversity. Thus, a massive reorganization of classifications is required so that the lowest ranks, be they species or subspecies, reflect evolutionary diversity. Until such reorganization is accomplished, the subspecies rank will continue to hinder progress in taxonomy, evolutionary studies and especially conservation.