Phylogeographic carrion, hooded and jungle crows (Aves, Corvidae) from data on partial sequencing of the mitochondrial DNA cytochrome B gene

Distribution of mitochondrial DNA cytochrome b gene haplotypes in two crow species was examined by means of sequencing of the 336-bp gene fragment. The topology of the NJ and UPGMA trees showed that the carrion crow range was split into two parts due to the presence of significantly diverged ancestral lineage localized in the southeastern part of the range. The carrion crow populations, inhabiting a territory ranging from France to northern Sakhalin, along with interspersed hooded crow populations and hybrid Siberian populations, shared a common haplotype. The border between two carrion crow lineages revealed is located in central Sakhalin. The subdivision of two weakly differentiated lineages within the jungle crown range, also observed within this territory, coincided with the subspecies division of this species. The estimated genetic distances indicate the isolation of the subgenus Coloeus. These data also suggest the convergent similarity between the chough Pyrrhocorax pyrrhocorax and the Corvus genus, as well as the conspecificity of Corvus corone corone and C. c. cornix.     

Genetic diversity of carrion and jungle crows from RAPD-PCR analysis data

RAPD-PCR analysis of the genetic diversity of the carrion crow (Corvus corone) and jungle crow (C. macrorhynchos) living in the continental parts of their species ranges and on some Russian and Japanese Far Eastern islands has been performed. Taxon-specific molecular markers have been found for each species. The genetic diversity of the carrion crow is considerably less than that of the jungle crow at the same genetic distance (P95 = 68.2%, DN = 0.27 and P95 = 88.4%, DN = 0.24, respectively). In both species, the genetic polymorphism of island samples is almost two times greater than that of continental samples (62 and 31.8%, respectively, for C. corone and 81.5 and 47.2%, respectively, for C. macrorhynchos). In addition, differences in genetic diversity between males and females (P95 = 55.1 and P95 = 72.1, respectively) has been found in the carrion crow but not in the jungle crow. The gene diversity of C. macrorhynchos is greater than that of C. corone: the mean numbers of alleles per locus are 2 and 1.81, effective numbers of alleles are 1.62 and 1.43, and the mean expected heterozygosities are 0.39 and 0.30, respectively. The phenograms and phylograms significantly segregate the clusters of the carrion and jungle crows. The clustering patterns of carrion crows corresponds to the intraspecies taxonomic and geographic differentiation: subspecies C. c. corone and C.c. orientalis living in the western and eastern parts of the species range, respectively, form different subclusters. The cluster of the jungle crow does not exhibit differentiation into subspecies C. m. mandshuricus and C. m. japonensis; molecular genetic differences between them are small.     

Phylogenetic relationships of three species of crows (Corvidae, Aves) based on the restriction site variation of nuclear ribosomal RNA gene

Southern blot analysis of nuclear ribosomal DNA (rDNA) was carried out to examine phylogenetic relationships between three species of crows: Corvus cornix, C. corone and C. macrorhynchos. In this purpose DNA samples of birds were digested by 12 restriction enzymes (EcoRI, HindIII, PstI, BamHI, DraI, PvuII, KpnI, XbaI, BglII, BclI, SacI and AatI) and hybridized with the clones of mouse rDNA probes (18S, 28S and INT). Based on the data obtained and Gallus gallus restriction map as a standard the restriction site maps of the main rDNA repeating unit types (repetypes) were constructed. The length of crow rDNA genes was estimated to be 22.5 kb for Jungle and 22.0 kb for Hooded and Carrion crows. C. corone and C. cornix shared a common repetype which differed, by presence of two restriction sites (XbaI and PvuII) in the spacer region, from that of C. macrorhynchos with the estimated sequence divergence of 0.26%. Restriction-size variation was revealed between individuals of C. corone and C. cornix, although the substantial meanings of this variation remain unclear yet. These data suggest that the crow species evolve with slower rate of molecular evolution, as generally observed in other avian species, compared with the higher extent in external morphology, ecological features and behavior.     

Aprocta matronensis in crows (Corvus corone corone) from northern Italy.

Aprocta matronensis (Nematoda, Spirurida) has been found in the orbital cavities of carrion crows. Hooded crows and crows from the hybrid crow zone in the studied areas were not infected. The parasite population showed the typical morphology described for this species. This is the first record of A. matronensis in crows in Italy and in Corvus corone corone. Some hypotheses about the distribution of the parasites in crow populations are discussed.     

Identification of 20 polymorphic microsatellite loci in European crow (Corvus corone) from existing passerine loci

The European crow (Corvus corone) occurs in two subspecies (or species) with distinct plumage coloration: the black carrion crow (C. c. corone) and the grey and black hooded crow (C. c. cornix). We tested 42 passerine microsatellite loci for amplification in the European crow and identified 20 loci that were both polymorphic and easy to score. In 50 individuals sampled in the Danish part of the species’ pan‐European hybrid zone, the number of alleles ranged between two and 21. One locus deviated from Hardy–Weinberg equilibrium and had a high estimated null allele frequency. These 20 loci were highly successful in amplifying polymorphic products also in other crow populations and in another Corvidae species, the rook (Corvus frugilegus).     

Phylogeographic patterns in widespread corvid birds

Intraspecific genetic diversity and phylogeography of Corvus corone was investigated using the mitochondrial (mt) control region as a molecular marker. A split into two distinct mt lineages was observed. One represents individuals from a wide geographic range spanning from England to the Russian Far East (Kamchatka), while the other one was found in the Primorye and Khabarovsk regions (southern parts of Russian Far East) as well as Japan. For comparison, we investigated several widespread Palearctic corvid taxa with respect to their phylogeographic patterns. A deep split into two lineages was revealed in five cases: Besides C. corone, within Corvus frugilegus, Pica pica, and between the species pairs Corvus monedula-Corvus dauuricus and Cyanopica cyanus-Cyanopica cooki. Although these taxa display a variety of distribution patterns, from disjunct, para/allopatric to continuous, the genetic pattern and level of divergence between clades is very similar. This implies that the differentiation started in about the same time range. In contrast, no differentiation into highly divergent lineages was detected in Corvus corax, Perisoreus infaustus, and Nucifraga caryocatactes. We try to explain the two phylogeographic patterns in corvid birds with ecological factors accompanying the changing climatic conditions during the Pleistocene. The deep genetic splits within several widely distributed Palearctic corvids are discussed with respect to taxonomic questions.     

History,environment and social behaviour: experimentally induced cooperative breeding in the carrion crow

Kin-based cooperative breeding, where grown offspring delay natal dispersal and help their parents to rear new young, has a long history in some avian lineages. Family formation and helping behaviour in extant populations may therefore simply represent the retention of ancestral features, tolerated under current conditions, rather than a current adaptive process driven by environmental factors. Separating these two possibilities challenges evolutionary biologists because of the tight coupling that normally exists between phylogeny and the environmental distribution of species and populations. The carrion crow Corvus corone corone, which exhibits extreme interpopulational variation in the extent of cooperative breeding, with populations showing no delayed dispersal and helping at all, provides a unique opportunity for an experimental approach. Here we show that offspring of non-cooperative carrion crows from Switzerland will remain on the natal territory and express helping behaviour when raised in a cooperative population in Spain. When we transferred carrion crow eggs from Switzerland to Spain, five out of six transplanted juveniles delayed dispersal, and two of those became helpers in the following breeding season. Our results provide compelling experimental evidence of the causal relationship between current environmental conditions and expression of cooperative behaviour.     

Population boundaries and genetic diversity in the endangered Mariana crow (Corvus kubaryi)

The Mariana crow (Corvus kubaryi) is an endangered species that is restricted to the islands of Guam and Rota in the Mariana archipelago. Predation by the introduced brown tree snake (Boiga irregularis) has decimated bird populations on Guam, and the crow population there is the last wild remnant of the endemic forest avifauna. The population on Guam is critically endangered and, despite intensive management, the population has continued to decline. Additional management options include intermixing the Guam and Rota populations, but such options are best evaluated within a population genetics framework. We used three types of molecular markers to assay genetic variation in the Mariana crow: mitochondrial DNA (mtDNA) sequences, minisatellites and microsatellites. The two populations could be differentiated by mtDNA sequencing and they differed in allele frequencies at nuclear markers. Thus, the populations could be designated as evolutionarily significant units. However, the Guam population is genetically more diverse than the Rota population, and its survival probability if managed separately is very low. All markers did indicate that the two populations are closely related and separated by a shallow genealogical division. Intermixing the populations is justified by two rationales. First, the apparent population differences may result from recent human activities. Second, a greater amount of genetic information may be preserved by joint management. The translocation of birds from Rota to Guam has begun, but strategies that will ensure maintenance of the variation in the Guam population warrant further exploration.     

An analysis of population genetic differentiation and genotype–phenotype association across the hybrid zone of carrion and hooded crows using microsatellites and MC1R

The all black carrion crow ( Corvus corone corone ) and the grey and black hooded crow ( Corvus   corone cornix ) meet in a narrow hybrid zone across Europe. To evaluate the degree of genetic differentiation over the hybrid zone, we genotyped crows from the centre and edges of the zone, and from allopatric populations in northern (Scotland–Denmark–Sweden) and southern Europe (western–central northern Italy), at 18 microsatellites and at a plumage candidate gene, the MC1R gene. Allopatric and edge populations were significantly differentiated on microsatellites, and populations were isolated by distance over the hybrid zone in Italy. Single-locus analyses showed that one locus, CmeH9, differentiated populations on different sides of the zone at the same time as showing only weak separation of populations on the same side of the zone. Within the hybrid zone there was no differentiation of phenotypes at CmeH9 or at the set of microsatellites, no excess of heterozygotes among hybrids and low levels of linkage disequilibrium between markers. We did not detect any association between phenotypes and nucleotide variation at MC1R , and the two most common haplotypes occurred in very similar frequencies in carrion and hooded crows. That we found a similar degree of genetic differentiation between allopatric and edge populations irrespectively of their location in relation to the hybrid zone, no differentiation between phenotypes within the hybrid zone, and neither heterozygote excess nor consistent linkage disequilibrium in the hybrid zone, is striking considering that carrion and hooded crows are phenotypically distinct and sometimes recognised as separate species.     

Early Ontogeny of the Behavior of Young in Large-Billed Crows (Corvus macrorhynchos) in Their Natural Habitat

Biology Bulletin - The early ontogeny of behavior of corvid juveniles in their natural habitat was studied, and the large-billed crow (Corvus macrorhynchos) taken as an example. Research was...     

Foot-use laterality in the Japanese jungle crow (Corvus macrorhynchos)

Laterality of foot-use behaviour was examined in jungle crows (Corvus macrorhynchos). Consistency of laterality was also verified in comparison with two different behaviours. One was beak-scratching, and another was food-holding. Significant bias of foot-use laterality was found in 11 of 13 tested subjects for beak-scratching and in 10 of 12 tested subjects for food-holding. Bias of foot-use laterality was not common among footed subjects, suggesting no population-level bias. However, a significant number of footed subjects (10 of 12) who were tested in both behaviours showed consistent laterality irrespective of behavioural differences. These results suggest that jungle crows have strong individual-level laterality in foot-use behaviour.     

Global invasive potential of the house crow Corvus splendens based on ecological niche modelling

Summaries of recent rapid range expansions shown by the house crow Corvus splendens have provided insights into the global nature of this invasion process, but its long-term potential has not yet been evaluated. To explore the potential dimensions of this geographic expansion, we used ecological niche modeling based on known occurrences of the species on its native distributional area, in the context of GIS data sets describing climatic variables, topographic information, and human presence. Our models provided predictions of areas already invaded that were statistically significantly more coincident than expected under random (null) models. The predicted potential range of the species includes areas already affected, as well as potentially suitable areas in Central America, the Caribbean, equatorial and West Africa, and mainland and insular Southeast Asia, not yet colonized.     

Seed dispersal and seedling establishment of Rhus trichocarpa promoted by a crow (Corvus macrorhynchos) on a volcano in Japan

The interaction between frugivorous birds and trees producing bird-dispersed seeds in devastated areas has been considered to be weak, owing to the paucity of avifauna and/or food resources for birds. Here, we present evidence that strong interactions between birds and plants may promote the enlargement of tree distribution on harsh environments. The summit of Mount Koma, northern Japan, was denuded by the 1929 volcanic eruption. Vegetation cover gradually decreases from the bottom (secondary forest) to the top (bareground) of the mountain. We recorded 48 bird species in the four seasons of 2001, along a 5-km line transect on the southwestern slope of the mountain. Birds faeces collected along the transect contained seeds of more than 14 plant taxa. Five of the 14 taxa were bird-dispersal tree species ( Rhus trichocarpa , Sorbus commixta , Prunus ssiori , Prunus maximowiczii and Prunus sargentii ) and were established in the summit area. Most faeces were derived from Corvus spp. (mostly C . macrorhynchos ) and Turdus naumanni . In particular, the seeds of R . trichocarpa were found mostly from the faeces of Corvus spp. and the seeds of Gaultheria miqueriana , a shrub species, were only from T . naumanni . Rhus trichocarpa retained fruits on the canopy at all times of the year, and crows could feed on them even when food resources were poor in winter. Rhus trichocarpa seedlings established well near rock at higher elevation, while they occurred mostly under the larch canopy of larches at lower elevation. Crows mostly utilized tree canopies and rocks as perches in respective habitats. Therefore, seedlings should be abundant in specific habitats at different elevations. Size-class distribution of seedlings suggested that seedling mortality was lower at higher elevation where open sites were more abundant. These findings indicate that strong mutual advantages for C . macrorhynchos and R . trichocarpa on denuded areas play an important role on revegetation.     

Genetic diversity of native and introduced populations of the invasive house crow (<Emphasis Type="Italic">Corvus splendens</Emphasis>) in Asia and Africa

The common house crow (Corvus splendens) is one of the best known and most wide spread species of the family Corvidae. It is a successful invasive species able to exploit urban environments, well removed from its natural distribution. It is considered a pest as it attains high population densities, can cause serious economic losses and has many adverse effects on native fauna and flora, including predation, competitive displacement and disease transmission. Little genetic research on the house crow has been undertaken so we have only a limited understanding of its natural genetic population structure and invasion history. In this study, we employ microsatellite and mitochondrial DNA markers to assess genetic diversity, phylogeography and population structure of C. splendens within its native range represented by Sri Lanka and Bangladesh and introduced range represented by Malaysia, Singapore, Kenya and South Africa. We found high levels of genetic diversity in some of the invasive populations for which multiple invasions are proposed. The lowest genetic diversity was found for the intentionally introduced population in Selangor, Malaysia. Sri Lanka is a possible source population for Malaysia Selangor consistent with a documented introduction over 100 years ago, with port cities within the introduced range revealing possible presence of migrants from other unsampled locations. We demonstrate the power of the approach of using multiple molecular markers to untangle patterns of invasion, provide insights into population structure and phylogeographic relationships and illustrate how historical processes may have contributed to making this species such a successful invader.     

Population structure of chum salmon Oncorhynchus keta in the Russian Far East, as revealed by microsatellite markers

Chum salmon populations in the Russian Far East have a complex multi-level genetic structure. A total of 53 samples (2446 fish) were grouped into five major regional clusters: the southern Kurils, eastern Sakhalin, southwestern Sakhalin, the Amur River, and a northern cluster. The northern cluster consists of chum salmon populations from a vast geographical region, including Chukotka, Kamchatka, and the continental coast of the Sea of Okhotsk. However, the degree of its genetic differentiation is low, 1.9%. In contrast, the southern population cluster exhibits much higher variation; for example, differentiation between chum salmon groups within Sakhalin Island reaches 4.6%, and the differentiation between Iturup Island and Sakhalin Island chum salmon is 7.7%. This suggests that southern populations of Asian chum salmon have a more ancient evolutionary history than northern populations. In contrast to the available data, our study indicates a great deviation of southwestern Sakhalin populations from other Sakhalin chum salmon. The Russian Far East chum salmon are genetically diverse and show statistically significant differentiation even within small geographic localities. This can be used to assign samples of unknown origins to definite local populations.     

Sexual aggression by intruders in hooded crow <Emphasis Type="Italic">Corvus cornix</Emphasis>

The hooded crow Corvus cornix is a west Palaearctic, solitary nesting, monogamous corvid. In the breeding season, populations are characterized by a social organization wherein breeding pairs are territorial and non-breeding individuals, called floaters, live in flocks. During a study of the breeding ecology of the hooded crow, conducted in a protected flooded area, we monitored nests with video cameras. We recorded two separate incidents when intruders attacked a female at the nest. We believe that she remained in the nest in order to prevent the strangers cannibalizing the nestlings by mantling over the brood. The spatio-temporal occurrence of these attacks suggests that the observed behaviour is intraspecific sexual aggression wherein non-breeding males mounted an immobilized female.     

Vocal culture in New Caledonian crows Corvus moneduloides

While recent research suggests that some animal species may possess ‘cultural’ traditions, much of the current evidence for wild populations remains contentious. This is largely due to the difficulty of demonstrating a fundamental prerequisite for the existence of culture: social learning. As the only case where social learning has been demonstrated conclusively, and subsequently linked to spatial or temporal trait variation, avian vocal dialects are the best studied, and most widely accepted, form of animal culture. Here, we investigate the potential for vocal culture in one of the few animals for which material culture has been suggested: the New Caledonian crow Corvus moneduloides. We show that this species: (1) possesses the capacity for social learning of vocalizations (experimental evidence in the form of a captive subject that reproduces human speech and other anthropogenic noises); and (2) exhibits significant large‐scale, population‐level variation in its vocalizations (cross‐island playback experiments, with analyses controlling for a substantial set of potentially confounding variables). In combination, this provides strong evidence for the existence of ‘culture’ in these birds. More specifically, our findings reveal that the species exhibits sufficient social learning mechanisms, and within‐population structuring, to generate and perpetuate cultural variation in at least one behavioural domain. This is a critical first step towards demonstrating cultural transmission in other behaviours, including tool manufacture and tool use, opening the door for the simultaneous investigation of vocal and material culture in a nonhuman species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 767–776.     

The genetic drivers for the successful invasive potential of a generalist bird,the House crow

Biological Invasions - What kind of genetic structure helps the rapid range expansion of the invasive species is fundamental to understand spread of invasion. The House crow (Corvus splendens), an...     

Reproduction in a population of the hooded crow Corvus cornix

Nest density was stable during the 8-year study period. The mean clutch size was 4.3, and the production of fledglings was 2.0 per pair. Incubation started, on average, when there were still two eggs to be laid and lasted for 18 days. Few eggs were lost but 23% of all broods of nestlings were lost to predators. Single nestlings in a brood were not lost to predators but often starved to death, this applied to 25% of all nestlings. A large proportion of the nestlings were probably infected by Syngamus tracheae , and some of these succumbed during the first weeks after fledging. A comparison with other studies of crow populations shows that the major causes of breeding failure are different in different populations. The causes of variation in breeding success between populations are discussed, especially considering the role of nonbreeding crows.     

Isolation and characterization of microsatellite loci in a cooperatively breeding corvid,the American crow (Corvus brachyrhynchos)

We describe 11 microsatellite loci isolated from the American crow (Corvus brachyrhynchos), the most wide‐spread cooperatively breeding bird in North America. Polymorphism at these loci ranged from four to 43 alleles, and observed heterozygosities from 0.53 to 0.92. Genetic parentage analyses using these markers will allow us to describe the mating system of this common but socially complex species, and to interpret their behavioural interactions in light of relatedness.