共查询到20条相似文献,搜索用时 15 毫秒
1.
Jessica A. Oswald Michael G. Harvey Rosalind C. Remsen DePaul U. Foxworth Donna L. Dittmann Steven W. Cardiff Robb T. Brumfield 《Molecular ecology》2019,28(7):1675-1691
Geographic range shifts can cause secondary contact and hybridization between closely related species, revealing mechanisms of species formation and integrity. These dynamics typically play out in restricted geographic regions, but highly vagile species may experience major distributional changes resulting in broad areas of contact. The Glossy Ibis (Plegadis falcinellus) is a dispersive waterbird of the Old World and Australia that colonized eastern North America in the early 19th century and came into contact with the native White‐faced Ibis (P. chihi). Putative hybrids between the two species have been observed across North America. To examine the population genomic consequences of this natural invasion, we sequenced 4,616 ultraconserved elements from 66 individuals sampled across the distributions of falcinellus, chihi, and the Puna Ibis (P. ridgwayi) of South America. We found genomic differentiation among the three species. Loci with high sequence divergence were often shared across all pairwise species comparisons, were associated with regions of high nucleotide diversity, and were concentrated on the Z chromosome. We detected signals of genetic admixture between chihi and falcinellus in individuals both near and far from their core area of sympatry. Genomic cline analyses revealed evidence of greater introgression into falcinellus from chihi, but we found little evidence for selection against hybrids. We also found signals of admixture between ridgwayi and South American populations of chihi. Our results indicate vagile species can experience pervasive introgression upon secondary contact, although we suggest these dynamics may be more ephemeral than the stable hybrid zones often observed in less dispersive organisms. 相似文献
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Dispersal strategies are important mechanisms underlying the spatial distribution and colonizing ability of all mobile species. In the current study, we use highly polymorphic microsatellite markers to evaluate local dispersal and colonization dynamics of the round goby (Neogobius melanostomus), an aquatic invader expanding its range from lake to river environments in its introduced North American range. Genetic structure, genotype assignment and genetic diversity were compared among 1262 round gobies from 20 river and four lake sites in three Great Lakes tributaries. Our results indicate that a combination of short-distance diffusion and long-distance dispersal, collectively referred to as 'stratified dispersal', is facilitating river colonization. Colonization proceeded upstream yearly (approximately 500 m/year; 2005-2009) in one of two temporal replicates while genetic structure was temporally stable. Contiguous dispersal from the lake was observed in all three rivers with a substantial portion of river fish (7.3%) identified as migrants. Genotype assignment indicated a separate introduction occurred upstream of the invasion front in one river. Genetic diversity was similar and relatively high among lake and recently colonized river populations, indicating that founder effects are mitigated through a dual-dispersal strategy. The remarkable success of round goby as an aquatic invader stresses the need for better diffusion models of secondary range expansion for presumably sessile invasive species. 相似文献
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Human‐aided dispersal can result in phylogeographic patterns that do not reflect natural historical processes, particularly in species prone to intentional translocations by humans. Here, we use a multiple‐gene sequencing approach to assess the effects of human‐aided dispersal on phylogeography of the tench Tinca tinca, a widespread Eurasian freshwater fish with a long history in aquaculture. Spatial genetic analysis applied to sequence data from four unlinked loci and 67 geographic localities (38–382 gene copies per locus) defined two groups of populations that were little structured geographically but were significantly differentiated from each other, and it identified locations of major genetic breaks, which were concordant across genes and were driven by distributions of two phylogroups. This pattern most reasonably reflects isolation in two major glacial refugia and subsequent range expansions, with the Eastern and Western phylogroups remaining largely allopatric throughout the tench range. However, this phylogeographic variation was also present in all 17 cultured breeds studied, and some populations at the western edge of the native range contained the Eastern phylogroup. Thus, natural processes have played an important role in structuring tench populations, but human‐aided dispersal has also contributed significantly, with the admixed genetic composition of cultured breeds most likely contributing to the introgression. 相似文献
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Microbial symbionts can influence their hosts in stunningly diverse ways. Emerging research suggests that an underappreciated facet of these relationships is the influence microbes can have on their host''s responses to novel, or stressful, environmental conditions. We sought to address these and related questions in populations resulting from the recent introduction and subsequent rapid range expansion of Onthophagus taurus dung beetles. Specifically, we manipulated both microbial communities and rearing temperature to detect signatures of developmental and life history differentiation in response to the local thermal conditions in two populations derived from the southern most (Florida) and northern most (Michigan) extremes of the exotic Eastern U.S. range of O. taurus. We then sought to determine the contributions, if any, of host‐associated microbiota to this differentiation. We found that when reared under common garden conditions individuals from Florida and Michigan populations differed significantly in developmental performance measures and life history traits, consistent with population divergence. At the same time, and contrary to our predictions, we failed to find support for the hypothesis that animals perform better if reared at temperatures that match their location of origin and that performance differences may be mediated by host‐associated microbiota. Instead, we found that microbiome swapping across host populations improved developmental performance in both populations, consistent with enemy release dynamics. We discuss the implications of our results for our understanding of the rapid spread of exotic O. taurus through the Eastern United States and the significance of symbiosis in host responses to novel environmental conditions more broadly. 相似文献
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Alexander Suárez-Mariño Gerardo Arceo-Gómez Paula Sosenski Víctor Parra-Tabla 《American journal of botany》2019,106(10):1308-1315
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Pristionchus pacificus has been developed as a model system in evolutionary developmental biology, evolutionary ecology, and population genetics. This species has a well-known ecological association with scarab beetles. Generally, Pristionchus nematodes have a necromenic association with their beetle hosts. Arrested dauer larvae invade the insect and wait for the host's death to resume development. Only one Pristionchus species is known to frequently associate with a non-scarab beetle. Pristionchus uniformis has been isolated from the chrysomelid Leptinotarsa decemlineata, also known as the Colorado potato beetle, in Europe and North America, but is also found on scarab beetles. This unusual pattern of association with two unrelated groups of beetles on two continents requires the involvement of geographical and host range expansion events. Here, we characterized a collection of 81 P. uniformis isolates from North America and Europe and from both scarab beetles and L. decemlineata. We used population genetic and phylogenetic analyses of the mitochondrial gene nd2 to reconstruct the genetic history of P. uniformis and its beetle association. Olfactory tests on beetles chemical extracts showed that P. uniformis has a unique chemoattractive profile toward its beetle hosts. Our results provide evidence for host range expansion through host-switching events in Europe where P. uniformis was originally associated with scarab beetles and the nematode's subsequent invasion of North America. 相似文献
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Abstract Woody plants have been increasing in many woodland and savanna ecosystems owing to land use changes in recent decades. We examined the effects of encroachment by the indigenous shrub Leptospermum scoparium (Myrtaceae) on herb‐rich Eucalyptus camaldulensis woodlands in southern Australia. Species richness and compositional patterns were examined under the canopy of L. scoparium and in surrounding open areas to determine the species most susceptible to structural changes. Richness was significantly lower in areas of moderate to high L. scoparium cover (>15%), suggesting that a threshold shrub cover caused major change in this ecosystem. Shrubs were associated with a significant reduction in above‐ground biomass of the ground‐layer flora and a significant shift in community composition. The few species that were positively associated with high L. scoparium cover were also common in the woodland flora; no new species were recorded under the shrub canopy. Important environmental changes associated with L. scoparium cover were decreased light availability and increased litter cover, which were likely a consequence of encroachment. Leptospermum scoparium cover was also associated with greater surface soil moisture, which may be a consequence of increased shading under the shrub canopy or indicate favourable soil conditions for L. scoparium establishment. Reductions in species richness and abundance of the germinable seed bank were found in soil samples taken from under L. scoparium. With ongoing recruitment of L. scoparium and consequent increases in shrub cover, ground‐layer diversity in these species‐rich woodlands should continue to decline over time. 相似文献
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Schrey AW Grispo M Awad M Cook MB McCoy ED Mushinsky HR Albayrak T Bensch S Burke T Butler LK Dor R Fokidis HB Jensen H Imboma T Kessler-Rios MM Marzal A Stewart IR Westerdahl H Westneat DF Zehtindjiev P Martin LB 《Molecular ecology》2011,20(6):1133-1143
Introduced species offer unique opportunities to study evolution in new environments, and some provide opportunities for understanding the mechanisms underlying macroecological patterns. We sought to determine how introduction history impacted genetic diversity and differentiation of the house sparrow (Passer domesticus), one of the most broadly distributed bird species. We screened eight microsatellite loci in 316 individuals from 16 locations in the native and introduced ranges. Significant population structure occurred between native than introduced house sparrows. Introduced house sparrows were distinguished into one North American group and a highly differentiated Kenyan group. Genetic differentiation estimates identified a high magnitude of differentiation between Kenya and all other populations, but demonstrated that European and North American samples were differentiated too. Our results support previous claims that introduced North American populations likely had few source populations, and indicate house sparrows established populations after introduction. Genetic diversity also differed among native, introduced North American, and Kenyan populations with Kenyan birds being least diverse. In some cases, house sparrow populations appeared to maintain or recover genetic diversity relatively rapidly after range expansion (<50 years; Mexico and Panama), but in others (Kenya) the effect of introduction persisted over the same period. In both native and introduced populations, genetic diversity exhibited large-scale geographic patterns, increasing towards the equator. Such patterns of genetic diversity are concordant with two previously described models of genetic diversity, the latitudinal model and the species diversity model. 相似文献
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Yangzhou Wang Kyung Seok Kim Wenchao Guo Qiyun Li Yunyue Zhang Zhenying Wang Brad S. Coates 《Molecular ecology》2017,26(24):6892-6907
The Asian corn borer, Ostrinia furnacalis, and European corn borer, O. nubilalis (Lepidoptera: Crambidae), cause damage to cultivated maize in spatially distinct geographies and have evolved divergent hydrocarbons as the basis of sexual communication. The Yili area of Xinjiang Uyghur Autonomous Region in China represents the only known region where O. furnacalis has invaded a native O. nubilalis range, and these two corn borer species have made secondary contact. Genetic differentiation was estimated between Ostrinia larvae collected from maize plants at 11 locations in Xinjiang and genotyped using high‐throughput SNP and microsatellite markers. Maternal lineages were assessed by direct sequencing of mitochondrial cytochrome c oxidase subunit I and II haplotypes, and a high degree of genotypic diversity was demonstrated between lineages based on SNP genotypes. Furthermore, historical introgression was predicted among SNP genotypes only at sympatric locations in the Yili area, whereas in Xinjiang populations only O. furnacalis haplotypes were detected and no analogous introgressed genotypes were predicted. Our detection of putative hybrids and historical evidence of introgression defines Yili area as a hybrid zone between the species in normal ecological interactions and furthermore, might indicate that adaptive traits could spread even between seemingly divergent species through horizontal transmission. Results of this study indicate there may be a continuum in the degree of reproductive isolation between Ostrinia species and that the elegance of distinct and complete speciation based on modifications to the pheromone communication might need to be reconsidered. 相似文献
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This study examined the chromatin morphology, in vitro development, and expression of selected genes in cloned embryos produced by transfer of mouse embryonic fibroblasts (MEF) into the bovine ooplasm. After 6 hr of activation, inter-species nuclear transfer (NT) embryos (MEF-NT) had one (70%) or two pronuclei (20%), respectively. After 72 hr of culture in vitro, 62.6% of the MEF-NTs were arrested at the 8-cell stage, 31.2% reached the 2- to 4-cell stage, and only 6.2% had more than eight blastomeres, but none of these developed to the blastocyst stage. Whereas, 20% of NT embryos derived from bovine embryonic fibroblast fused with bovine ooplasm (BEF-NT) reached the blastocyst stage. Donor MEF nuclei expressing an Enhanced Green Fluorescent Protein (EGFP) transgene resulted in 1- to 8-cell stage MEF-NT that expressed EGFP. The expression of selected genes was examined in 8-cell MEF-NTs, 8-cell mouse embryos, enucleated bovine oocytes, and MEFs using RT-PCR. The mRNA for heat shock protein 70.1 (Hsp 70.1) gene was detected in MEF-NTs and MEF, but not in mouse embryos. The hydroxy-phosphoribosyl transferase (HPRT) mRNA was found in normal mouse embryos and MEF but not in MEF-NTs. Expression of Oct-4 and embryonic alkaline phospatase (eAP) genes was only detected in normal mouse embryos and not in the inter-species NT embryos. Abnormal gene expression profiles were associated with an arrest in the development at the 8-cell stage, but MEF-NT embryos appeared to have progressed through gross chromatin remodeling, typical of intra-species NT embryos. Therefore, molecular reprogramming rather than chromatin remodeling may be a better indicator of nuclear reprogramming in inter-species NT embryos. 相似文献
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HELGE NORF LEIF G. KNIGGENDORF ALBRECHT FISCHER HARTMUT ARNDT ARMIN KURECK 《Freshwater Biology》2010,55(12):2510-2520
1. The Ponto‐Caspian polychaete Hypania invalida (Archiv für Naturgeschichte, 1860, 26, 109) is undergoing rapid range expansion in the Rhine and other central European waterways. We examined its reproductive traits in an attempt to account for its remarkable invasive success. 2. For the first time in this species, we found males, dioecy (gonochorism) and an exclusively sexual mode of reproduction; no indication for hermaphroditism or (unisexual) parthenogenesis, that could explain the rapid range expansion of H. invalida, was found. 3. Our experimental evidence shows that H. invalida reproduces by males discharging their sperm into the water column while eggs are retained and fertilised in the female dwelling tubes. This mode of ‘spermcast’ reproduction is common in sessile benthic animals on wave‐washed shores. 4. Fecundity of H. invalida ranged between 60 and 260 eggs per clutch and is increased by iteroparity (i.e. multiple cycles of oogenesis and egg‐laying per specimen). Offspring are brooded for about 2 weeks before they leave the maternal dwelling tubes and disperse in the water column. 5. After connection to a supply of Rhine water, sediments in flumes were rapidly colonised up to a density of 12 000 ind. m?2 via the settlement of small larvae (<300 μm) from the water column; these reached sexual maturity approximately 12 weeks after settlement. 6. The reproductive traits of H. invalida give the species a high rate of dispersal. The capacity of its larvae to survive passage through pumps before settlement enables them to travel in the ballast water of ships. This might explain the upstream expansion of H. invalida in rivers. We conclude that further range expansion, and especially intercontinental transport of this polychaete, can only be prevented by improved ballast water treatment. 相似文献
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From August to September 2013, c. 21 specimens of the blue runner Caranx crysos were caught by commercial fishermen in two locations off the south coast of Newfoundland, Canada. These samples represent the first records of C. crysos in Newfoundland waters, and a potential northward range expansion of this species in the north‐western Atlantic Ocean. They also illustrate the importance of fisher‐derived sampling that spans times and locations outside of the limited range targeted by scientific surveys in this region. 相似文献
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Leonardo Campagna Cecilia Kopuchian Pablo L. Tubaro Stephen C. Lougheed 《Biological journal of the Linnean Society. Linnean Society of London》2014,111(4):863-868
Understanding how genetic and phenotypic differences that arise in geographically isolated populations influence the outcome of secondary contact advances our knowledge of speciation. In the present study, we investigate the secondary contact between divergent lineages of a widespread Neotropical songbird, the Rufous‐collared sparrow (Zonotrichia capensis). Zonotrichia capensis is morphologically and behaviourally diverse, and shows a pattern of lineage diversification produced by a Pleistocene expansion and colonization of South America from a probable Central American origin. Consistent with previous results, we find three lineages throughout the species range, showing between 1.5% and 2.5% divergence in mitochondrial control region sequences. These lineages come into secondary contact in the Dominican Republic, La Paz (Bolivia), and North‐eastern Argentina. We use DNA microsatellite data to study a broad secondary contact zone in North‐eastern Argentina, finding that Bayesian clustering analyses do not assign individuals to their respective mitochondrial lineages. Overall, we did not observe nuclear genetic discontinuities in the study area. We conclude that, if genetic, morphological, and/or cultural differences accumulated among lineages during isolation, they were insufficient to prevent gene flow after secondary contact. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 863–868. 相似文献
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A total of 134 bird species were recorded at Jianfengling, Hainan Island, in China from May 2000 to September 2004, of which 44 participated in one or more of 134 mixed‐species flocks. These flocks averaged 3.8 ± 0.2 species and 20.3 ± 1.2 individuals. Flocking propensity in a given species ranged from 1.5 to 100%. For flocking species, frequency of flocking and number of individuals in flocks was positively correlated with frequency and number in point counts. Among all species pairs with flocking frequency above 5%, cluster and correlation analysis indicated there were two principal groups of flocking birds – canopy species and understorey species: associations were positive within a group, but negative between groups. Canopy birds had a higher flocking propensity than understorey birds. They also made significantly less use of inner branches and trunks and greater use of middle branches, and foraged at a significantly greater height when in mixed‐species flocks than when solitary. For understorey bird species, there were no significant differences in foraging locations between solitary and mixed‐species flocks. Higher flocking frequency occurred in the wet season for canopy birds, but in the dry season for understorey birds. Overall patterns were consistent with the explanation that flocking enables an expansion of foraging niche by reducing the risk of predation. 相似文献
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Fungal diseases are posing tremendous threats to global economy and food safety. Among them, Valsa canker, caused by fungi of Valsa and their Cytospora anamorphs, has been a serious threat to fruit and forest trees and is one of the most destructive diseases of apple in East Asia, particularly. Accurate and robust delimitation of pathogen species is not only essential for the development of effective disease control programs, but also will advance our understanding of the emergence of plant diseases. However, species delimitation is especially difficult in Valsa because of the high variability of morphological traits and in many cases the lack of the teleomorph. In this study, we delimitated species boundary for pathogens causing apple Valsa canker with a multifaceted approach. Based on three independent loci, the internal transcribed spacer (ITS), β‐tubulin (Btu), and translation elongation factor‐1 alpha (EF1α), we inferred gene trees with both maximum likelihood and Bayesian methods, estimated species tree with Bayesian multispecies coalescent approaches, and validated species tree with Bayesian species delimitation. Through divergence time estimation and ancestral host reconstruction, we tested the possible underlying mechanisms for fungal speciation and host‐range change. Our results proved that two varieties of the former morphological species V. mali represented two distinct species, V. mali and V. pyri, which diverged about 5 million years ago, much later than the divergence of their preferred hosts, excluding a scenario of fungi–host co‐speciation. The marked different thermal preferences and contrasting pathogenicity in cross‐inoculation suggest ecological divergences between the two species. Apple was the most likely ancestral host for both V. mali and V. pyri. Host‐range expansion led to the occurrence of V. pyri on both pear and apple. Our results also represent an example in which ITS data might underestimate species diversity. 相似文献
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One of the central questions in invasion biology involves whysome introductions succeed and others fail. Although severalcorrelates of invasion success have been identified, patternsalone cannot identify the mechanisms underlying the invasionprocess. Here, we test the hypothesis that one predictor ofinvasion success, behavioral flexibility, is different betweeninvading and established populations of the same species ofbird. We predicted that neophobia (fear of novelty), a surrogateof behavioral flexibility, would be weaker in an actively invadingpopulation (28 years resident; Colon, Republic of Panama) ofhouse sparrows (Passer domesticus) compared to a populationthat had been resident for more than 150 years (Princeton, NewJersey, USA). To test this hypothesis, we compared latency toconsume novel foods and phobia of novel objects between populationswhen both were kept under similar environmental conditions incaptivity. As predicted, birds from the 150-year-old populationtook significantly longer to approach and consume novel foodsthan birds from the 28-year-old population. Responses to novelobjects were not different between populations however; bothpopulations fed more readily near some novel objects, whichto our knowledge is the first such occurrence in a wild vertebratespecies. Overall, a predilection for trying new foods and beingattracted to novel objects may in part explain how this specieshas so successfully invaded new areas. 相似文献