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1.
Reduced vocal diversity in founder populations of songbirds is particularly well described in congeners and conspecifics introduced to remote islands but has rarely been examined in species that have been introduced to both island and mainland systems across an expansive geographical range. We examined male between‐ and within‐song complexity variations between founder and native populations of the widely distributed Common Myna Acridotheres tristis and predicted reduced complexity within individuals from founder populations. The percentage of unique songs within a repertoire and within‐song complexity were significantly lower in Mynas from founder populations. This reduced song complexity suggests that vocal founder effects may be exhibited in both island and mainland founder populations.  相似文献   

2.
Common Mynas Acridotheres tristis were introduced to the small, isolated barren island of Ascension in the tropical Atlantic Ocean in the 1880s. The founder population of 52 pairs increased at a rate of 2 % per annum. Mynas cause egg losses in other species by puncturing and consuming eggs, puncturing eggs with no consumption or displacing incubating birds that then desert viable eggs. The principal target seabirds of Mynas on Ascension Island are Sooty Terns Onychoprion fuscatus which number 388,000 birds and constitute 97 % of all seabirds on the island. Five censuses of Mynas and 20 of the Sooty Tern population were carried out between 1994 and 2015, and Myna depredation was monitored on 10 occasions between 2000 and 2008. Of all seabird eggs laid annually, we estimated that 19 % of them were depredated by c. 1000 Mynas. In declining severity of impacts of Mynas on all eggs lost, we estimated that 40 % was attributable to desertion, 39 % to puncturing eggs with no consumption and 21 % to puncturing and consumption. As far as we know, our study is the first to estimate the scale of seabird egg depredation by Mynas. Care is needed when applying our findings to other seabird populations. The scarcity of alternative food sources and the ease of locating high densities of Sooty Tern eggs on Ascension Island may have magnified the frequency of egg depredation by Mynas. That said, it is clear that Mynas are major egg predators and the severity of their impacts on native avian populations can be high.  相似文献   

3.
European pond turtles represent a phylogeographically deeply structured complex of distinct taxa. Here, we use mitochondrial DNA sequences (cytochrome b gene) and eight polymorphic microsatellite loci to investigate genetic differentiation and gene flow of Sicilian, Corsican and Sardinian pond turtles and of subspecies involved in two secondary contact zones in the Pyrenean region and Southern Italy. Mitochondrial and microsatellite differentiation is largely concordant in populations from the core regions of the distribution ranges of the studied taxa. Both marker systems provide no evidence for gene flow between Sicilian pond turtles (Emys trinacris) and Southern Italian subspecies of E. orbicularis. By contrast, in the contact zones limited gene flow occurs between distinct subspecies of E. orbicularis. Although the Southern Italian contact zone is significantly older than the Pyrenean contact zone of Holocene age, patterns of asymmetric introgression are similar. Introgressive hybridization leads to the exchange of mitochondria, but microsatellite data indicate only a few individuals with mixed ancestry. This suggests that incipient isolating mechanisms maintain largely discrete nuclear genomic gene pools. Furthermore, this implies that Southern Italy acted as a hotspot rather than as a melting pot of genetic diversity during the last glacial. Pond turtles from Corsica and Sardinia are not differentiated from continental populations of the subspecies E. o. galloitalica, neither in the mitochondrial nor in the quickly evolving microsatellite markers. As the fossil record argues for a continuous presence of pond turtles on both islands since the Middle Pleistocene, this suggests that the native island populations became extinct and the extant turtles were later introduced by prehistoric settlers. The lack of genetic differentiation of pond turtles from Corsica and Sardinia supports the view that the subspecies described from these islands are not valid.  相似文献   

4.
Allophylus conraui Gilg ex Radlk. as treated in the Flora of West Tropical Africa is reassessed and shown to comprise two distinct taxa, one of which, a spiny shrub or small tree of upper submontane forest in Cameroon and Nigeria, is described as Allophylus ujori Cheek. The second taxon, a lowland to lower submontane spineless small shrub, of Cameroon is redescribed as Allophylus conraui and neotypified. The affinities and conservation status of both these threatened species are discussed. Both taxa are illustrated.  相似文献   

5.
The eastern‐Mediterranean Abies taxa, which include both widely distributed species and taxa with minuscule ranges, represent a good model to study the impacts of range size and fragmentation on the levels of genetic diversity and differentiation. To assess the patterns of genetic diversity and phylogenetic relationships among eastern‐Mediterranean Abies taxa, genetic variation was assessed by eight nuclear microsatellite loci in 52 populations of Abies taxa with a focus on those distributed in Turkey and the Caucasus. Both at the population and the taxon level, the subspecies or regional populations of Abies nordmanniana s.l. exhibited generally higher allelic richness, private allelic richness, and expected heterozygosity compared with Abies cilicica s.l. Results of both the Structure analysis and distance‐based approaches showed a strong differentiation of the two A. cilicica subspecies from the rest as well as from each other, whereas the subspecies of A. nordmanniana were distinct but less differentiated. ABC simulations were run for a set of scenarios of phylogeny and past demographic changes. For A. ×olcayana, the simulation gave a poor support for the hypothesis of being a taxon resulting from a past hybridization, the same is true for Abies equi‐trojani: both they represent evolutionary branches of Abies bornmuelleriana.  相似文献   

6.
Asian elephants (Elephas maximus) in western zoos are likely to become extinct unless elephants are regrouped into breeding units or additional elephants are imported from range States. There have been proposals for the export of elephants from elephant camps in Sumatra, Indonesia. In exchange, zoos would be expected to provide funds or support ‘in kind’ for the camps or for the conservation of wild elephants. Most of the elephants in the Sumatran camps were captured because of crop‐raiding problems around protected areas or because elephant habitat has been and continues to be lost to development schemes and illegal conversion of protected areas to agriculture. Capture‐related mortality rates are high and conditions in the camps are poor, with low standards of veterinary care and husbandry. This is partly due to over‐crowding and inadequate budgets. It might seem, therefore, that the loan of elephants to western zoos would improve the lot of these elephants and reduce the pressures on the camps. However, we show that both total and annual demand for Asian elephants, and particularly Sumatran elephants (E. m. sumatranus), by western zoos are low, and consequently the resources generated by any loan scheme would be limited. Elephant loan schemes are unlikely to have significant beneficial impact on either the conservation or welfare of elephants in Sumatra. More importantly, a credible loan scheme would require a permanent moratorium on the capture of wild elephants in Sumatra. Such a moratorium is needed to prevent illicit captures for sale or loan. At present, wild elephants are caught to replace those that die at the camps or are moved to other facilities. Without a moratorium, the loan of elephants to overseas zoos would contribute directly to reductions in wild elephant populations in Sumatra. However, a moratorium is likely to prove impossible to enforce, and this alone should call into question the desirability of any loan scheme. Zoo Biol 25:235–246, 2006. © 2006 Wiley‐Liss, Inc.  相似文献   

7.
Among the European fauna, the Sardinian hare (Lepus sp.) is peculiar in that it differs from all other hares inhabiting the continent. Here, we report on the variation of a 461 bp sequence of hypervariable domain 1 of the mitochondrial control region, examined in 42 hares collected throughout Sardinia and compared to the corresponding sequences of different Lepus taxa. Seventeen novel haplotypes were found in the Sardinian population, resulting in a haplotype diversity of 0.840 and a nucleotide diversity of 0.012. As a result of Bayesian and principal coordinates analyses, Sardinian hares were grouped with North African hares, constituting a monophyletic clade that diverges from all other Old World hares, including Cape hares from South Africa and East Asia. Hence, our data agree that populations inhabiting North Africa and Sardinia form a distinct taxon, which could possibly be included in the L. capensis superspecies. Moreover, two corresponding lineages can be found in Sardinia and Tunisia, providing evidence of a common origin of the two populations and thus supporting the hypothesis that North African hares were introduced into the island in historical times. Our data show that the two lineages differ in their geographic distribution throughout the island and that the wild Sardinian population also shows the signature of a postintroduction demographic expansion.  相似文献   

8.
Novel transmission routes can directly impact the evolutionary ecology of infectious diseases, with potentially dramatic effect on host populations and knock‐on effects on the wider host community. The invasion of Varroa destructor, an ectoparasitic viral vector in Western honeybees, provides a unique opportunity to examine how a novel vector affects disease epidemiology in a host community. This specialist honeybee mite vectors deformed wing virus (DWV), an important re‐emerging honeybee pathogen that also infects wild bumblebees. Comparing island honeybee and wild bumblebee populations with and without V. destructor, we show that V. destructor drives DWV prevalence and titre in honeybees and sympatric bumblebees. Viral genotypes are shared across hosts, with the potentially more virulent DWV‐B overtaking DWV‐A in prevalence in a current epidemic. This demonstrates disease emergence across a host community driven by the acquisition of a specialist novel transmission route in one host, with dramatic community level knock‐on effects.  相似文献   

9.
Vocal characteristics have been used extensively to distinguish different taxonomic units of gibbons (family Hylobatidae). The agile gibbon (Hylobates agilis) has a disjunct distribution range in the Southeast Asian archipelago (remnants of the former Sunda landmass), and populations on different islands are currently recognized as distinct subspecies or even species. We recorded great calls from female agile gibbons from two populations on Sumatra and two populations on Borneo and examined the vocal variability on four levels: within‐individuals, between‐individuals, between‐populations and between‐islands. The primary objective was to evaluate the effect of geographical isolation on variability in song pattern and to test whether proposed island‐specific song characteristics exist, reflecting evolutionary divergence between Sumatran and Bornean agile gibbons. One hundred great calls were recorded from 20 females and analyzed for 18 spectral and temporal acoustic parameters. Principal component analysis followed by a nested ANOVA on components revealed a complex pattern of song variability not likely to reflect taxonomic or evolutionary relationship. We found no evidence that Sumatran and Bornean agile gibbons have evolved different vocal characteristics, refuting a distinction between them based on vocal characteristics. A high level of plasticity was found in great calls from the same individual, and generally the inferred pattern of variability suggested that ecological or social factors may confound any genetically based island dialects. Am. J. Primatol. 72:142–151, 2010. © 2009 Wiley‐Liss, Inc.  相似文献   

10.
Many animal populations that are endangered in mainland areas exist in stable island populations, which have the potential to act as an “ark” in case of mainland population declines. Previous studies have found neutral genetic variation in such species to be up to an order of magnitude lower in island compared to mainland populations. If low genetic variation is prevalent across fitness-related loci, this would reduce the effectiveness of island populations as a source of individuals to supplement declining mainland populations or re-establish extinct mainland populations. One such species, the black-footed rock-wallaby (Petrogale lateralis lateralis), exists within fragmented mainland populations and small island populations off Western Australia. We examined sequence variation in this species within a fitness-related locus under positive selection, the MHC class II DAB β1 locus. The mainland populations displayed greater levels of allelic diversity (4–7 alleles) than the island population, despite being small and isolated, and contained at least two DAB gene copies. The island population displayed low allelic diversity (2 alleles) and fewer alleles per individual in comparison to mainland populations, and probably possesses only one DAB gene copy. The patterns of DAB diversity suggested that the island population has a markedly lower level of genetic variation than the mainland populations, in concordance with results from microsatellites (genotyped in a previous study), but preserved unique alleles which were not found in mainland populations. Where possible, conservation actions should pool individuals from multiple populations, not only island populations, for translocation programs, and focus on preventing further declines in mainland populations.  相似文献   

11.
Barrier island taxa provide an opportunity to investigate recent evolutionary processes, such as colonization and isolation of recently diverged taxa, and provide important insights into understanding contemporary diversity and the assessment of conservation units. Using rapidly evolving genetic markers (mitochondrial DNA and microsatellites), we studied the Atlantic coast beach mouse subspecies (Peromyscus polionotus decoloratus, P. p. niveiventris, and P. p. phasma). Our data indicate that each of the extant coastal subspecies (P. p. niveiventris and P. p. phasma) is comprised of unique haplotypes indicative of their isolation, while the extinct subspecies, P. p. decoloratus, contain a single haplotype, which was shared with P. p. phasma. Moreover, all the coastal haplotypes originate from a single mainland haplotype found in central Florida, USA. The microsatellite data indicated high levels of genetic structure among our sampled populations. Additionally, these data group the populations into three distinct genetic clusters, with each of the extant coastal subspecies belonging to their own cluster and the mainland individuals forming a separate cluster. The extant Atlantic coast beach mice are on separate evolutionary trajectories, thus representative of separate taxonomic units. Therefore, the data support that two extant subspecies on the Florida Atlantic coast fit the Distinct Population Segment designation and should be managed and conserved as two separate independent units.  相似文献   

12.
Phylogenetic conflicts between genetic markers can help to disentangle complex histories of phylogeography and introgression among taxa. We previously proposed that the Chinese mainland subspecies of the intermediate horseshoe bat Rhinolophus affinis himalayanus colonized Hainan Island to form the subspecies R. a. hainanus. Subsequent recolonization of the mainland formed a third taxon, R. a macrurus, and a secondary contact zone with the ancestral himalayanus. To test for historical and recurrent genetic exchange between these mainland subspecies, we sampled populations of each from two parapatric zones and undertook analyses using one mtDNA marker, three nuclear genes and 14 microsatellites. Nuclear DNA, echolocation call frequencies and morphological data all recovered two taxa; however, a mtDNA phylogeny revealed two himalayanus clades, of which one clustered with macrurus, as well as some shared or related mtDNA haplotypes in eastern populations. Isolation‐with‐migration (IM) models suggested some mtDNA gene flow from macrurus to himalayanus. However, strong population structure in himalayanus raises the possibility that macrurus captured mtDNA from a coastal population of himalayanus that has since become rare or extinct. To reconcile these two sets of results, we suggest that the IM estimates might reflect historical mtDNA gene flow among populations of himalayanus, before mtDNA was subsequently captured by macrurus. Finally, microsatellite‐based ABC analyses supported the island origin of macrurus; however, mtDNA‐based ABC analyses suggest this taxon might have evolved on the mainland. Our findings highlight the importance of understanding population history and structure for interpreting hybridization and introgression events.  相似文献   

13.
Various bacterial taxa have been identified both in association with animals and in the external environment, but the extent to which related bacteria from the two habitat types are ecologically and evolutionarily distinct is largely unknown. This study investigated the scale and pattern of genetic differentiation between bacteria of the family Acetobacteraceae isolated from the guts of Drosophila fruit flies, plant material and industrial fermentations. Genome‐scale analysis of the phylogenetic relationships and predicted functions was conducted on 44 Acetobacteraceae isolates, including newly sequenced genomes from 18 isolates from wild and laboratory Drosophila. Isolates from the external environment and Drosophila could not be assigned to distinct phylogenetic groups, nor are their genomes enriched for any different sets of genes or category of predicted gene functions. In contrast, analysis of bacteria from laboratory Drosophila showed they were genetically distinct in their universal capacity to degrade uric acid (a major nitrogenous waste product of Drosophila) and absence of flagellar motility, while these traits vary among wild Drosophila isolates. Analysis of the competitive fitness of Acetobacter discordant for these traits revealed a significant fitness deficit for bacteria that cannot degrade uric acid in culture with Drosophila. We propose that, for wild populations, frequent cycling of Acetobacter between Drosophila and the external environment prevents genetic differentiation by maintaining selection for traits adaptive in both the gut and external habitats. However, laboratory isolates bear the signs of adaptation to persistent association with the Drosophila host under tightly defined environmental conditions.  相似文献   

14.
Using up to 2117 bp of mitochondrial DNA and up to 2012 bp of nuclear DNA, we analysed phylogeographic differentiation of six widely distributed species of African hinged terrapins (Pelusios spp.) representing different habitat types. Two taxa each live in savannahs or in forests and mesic savannahs, respectively, and the remaining two species occur in intermediate habitats. The species living in forests and mesic savannahs do not enter dry savannahs, whereas the savannah species may occur in dry and wet savannahs and even in semi‐arid steppe regions. We found no obvious correlation between habitat type and phylogeographic pattern: one savannah species (P. rhodesianus) shows phylogeographic structure, i.e. pronounced genetic differences among geographically distinct populations, and the other (P. nanus) not. One species inhabiting forests and mesic savannahs (P. carinatus) has phylogeographic structure, the other (P. gabonensis) not. The same pattern is true for the two ecologically intermediate species, with phylogeographic structure present in P. castaneus and absent in P. chapini. Nuclear evidence suggests that the latter two taxa with abutting and partially overlapping ranges are distinct, while mtDNA is only weakly differentiated. Pelusios castaneus shows pronounced phylogeographic structure, which could reflect Pleistocene range interruptions correlated with the fluctuating forest cover in West and Central Africa. Our results do not support the recognition of an extinct subspecies of P. castaneus for the Seychelles. Pelusios carinatus contains two well supported clades, which are separated by the Congo River. This species is closely related to P. rhodesianus, a taxon consisting of two deeply divergent mitochondrial clades. One of these clades is paraphyletic with respect to P. carinatus, but the two clades of P. rhodesianus are not differentiated in the studied nuclear markers and, again, paraphyletic with respect to P. carinatus. Using mtDNA sequences from the type material of P. rhodesianus, we were able to allocate this name to one of the two clades. However, owing to the confusing relationships of P. rhodesianus and P. carinatus, we refrain from taxonomic decisions.  相似文献   

15.
Aim We investigated how Pleistocene refugia and recent (c. 12,000 years ago) sea level incursions shaped genetic differentiation in mainland and island populations of the Scinax perpusillus treefrog group. Location Brazilian Atlantic Forest, São Paulo state, south‐eastern Brazil. Methods Using mitochondrial and microsatellite loci, we examined population structure and genetic diversity in three species from the S. perpusillus group, sampled from three land‐bridge islands and five mainland populations, in order to understand the roles of Pleistocene forest fragmentation and sea level incursions on genetic differentiation. We calculated metrics of relatedness and genetic diversity to assess whether island populations exhibit signatures of genetic drift and isolation. Two of the three island populations in this study have previously been described as new species based on a combination of distinct morphological and behavioural characters, thus we used the molecular datasets to determine whether phenotypic change is consistent with genetic differentiation. Results Our analyses recovered three distinct lineages or demes composed of northern mainland São Paulo populations, southern mainland São Paulo populations, and one divergent island population. The two remaining island populations clustered with samples from adjacent mainland populations. Estimates of allelic richness were significantly lower, and estimates of relatedness were significantly higher, in island populations relative to their mainland counterparts. Main conclusions Fine‐scale genetic structure across mainland populations indicates the possible existence of local refugia within São Paulo state, underscoring the small geographic scale at which populations diverge in this species‐rich region of the Atlantic Coastal Forest. Variation in genetic signatures across the three islands indicates that the populations experienced different demographic processes after marine incursions fragmented the distribution of the S. perpusillus group. Genetic signatures of inbreeding and drift in some island populations indicate that small population sizes, coupled with strong ecological selection, may be important evolutionary forces driving speciation on land‐bridge islands.  相似文献   

16.
The oceanic island of Simeulue, west of Sumatra, is inhabited by a distinct subspecies of the long-tailed macaque (Macaca fascicularis fusca) [Miller, 1903]. In January 1982 and March 1984, a survey was conducted to establish its population status. The monkey is morphologically different from other Sunda shelf M. fascicularis populations. In productive habitats, it lives in small groups (10–15 individuals) and reaches a density of more than one monkey/hectare (ha). The island's total population is estimated to be at least 50,000. The authors suggest that the location of a proposed reserve be shifted to include more of the most favorable habitat, i.e., alluvial forest.  相似文献   

17.
Isolated islands and their often unique biota continue to play key roles for understanding the importance of drift, genetic variation and adaptation in the process of population differentiation and speciation. One island system that has inspired and intrigued evolutionary biologists is the blue tit complex (Cyanistes spp.) in Europe and Africa, in particular the complex evolutionary history of the multiple genetically distinct taxa of the Canary Islands. Understanding Afrocanarian colonization events is of particular importance because of recent unconventional suggestions that these island populations acted as source of the widespread population in mainland Africa. We investigated the relationship between mainland and island blue tits using a combination of Sanger sequencing at a population level (20 loci; 12 500 nucleotides) and next‐generation sequencing of single population representatives (>3 200 000 nucleotides), analysed in coalescence and phylogenetic frameworks. We found (i) that Afrocanarian blue tits are monophyletic and represent four major clades, (ii) that the blue tit complex has a continental origin and that the Canary Islands were colonized three times, (iii) that all island populations have low genetic variation, indicating low long‐term effective population sizes and (iv) that populations on La Palma and in Libya represent relicts of an ancestral North African population. Further, demographic reconstructions revealed (v) that the Canary Islands, conforming to traditional views, hold sink populations, which have not served as source for back colonization of the African mainland. Our study demonstrates the importance of complete taxon sampling and an extensive multimarker study design to obtain robust phylogeographical inferences.  相似文献   

18.
The Sumatran rhinoceros (Dicerorhinus sumatrensis) is the smallest and one of the most endangered rhinoceros species, with less than 100 individuals estimated to live in the wild. It was originally divided into three subspecies but only two have survived, D. sumatrensis sumatrensis (Sumatran subspecies), and D. s. harrissoni (Bornean). Questions regarding whether populations of the Sumatran rhinoceros should be treated as different management units to preserve genetic diversity have been raised, particularly in light of its severe decline in the wild and low breeding success in captivity. This work aims to characterize genetic differentiation between Sumatran rhinoceros subspecies using complete mitochondrial genomes, in order to unravel their maternal evolutionary history and evaluate their status as separate management units. We identified three major phylogenetic groups with moderate genetic differentiation: two distinct haplogroups comprising individuals from both the Malay Peninsula and Sumatra, and a third group from Borneo. Estimates of divergence time indicate that the most recent common ancestor of the Sumatran rhinoceros occurred approximately 360,000 years ago. The three mitochondrial haplogroups showed a common divergence time about 80,000 years ago corresponding with a major biogeographic event in the Sundaland region. Patterns of mitochondrial genetic differentiation may suggest considering Sumatran rhinoceros subspecies as different conservation units. However, the management of subspecies as part of a metapopulation may appear as the last resource to save this species from extinction, imposing a conservation dilemma.  相似文献   

19.
Abstract: ‘Totanuslartetianus, Elorius paludicola and ‘Tringagracilis are the three scolopacid birds from the early Miocene of Saint‐Gérand‐le‐Puy described by the French palaeontologist Milne‐Edwards in the 19th century. Since then, no revision of these taxa has been performed. Our re‐examination revealed that not much of the material originally assigned to ‘Totanuslartetianus can be retained within the species. Presumably plesiomorphic features of the humerus – and potentially the coracoid we attributed to this taxon – indicate that it is misplaced in the extant scolopacid genus and may not even belong to the Scolopacidae (sandpipers and allies), and we therefore place it in the new genus Scolopacimilis. Comparisons of the material assigned to Elorius paludicola and ‘Tringagracilis show that they are morphologically similar, both exhibiting distinct scolopacid anatomical features. The latter, however, cannot be referred to the extant taxon Tringa and is classified into the new genus Parvelorius. We further introduce three new species, ?Elorius limosoides sp. nov., and ?Parvelorius calidris sp. nov., which we have tentatively assigned to the extinct scolopacid genera Elorius and Parvelorius, respectively, and Becassius charadriioides gen. et. sp. nov., which, together with Scolopacimilis, display a morphology uncharacteristic for extant Scolopaci. For the first time we have assigned skulls to some of the postcranial elements described in this study. The presence of at least six species of Scolopaci from the early Miocene considerably increases the number of members of the group known from this time.  相似文献   

20.
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