基于线粒体COⅡ基因序列的双斑长跗萤叶甲中国北方地理种群的遗传多样性研究

双斑长跗萤叶甲Monolepta hieroglyphica (Motschulsky)是自2001年以来在我国北方为害玉米呈加重趋势的一种害虫。为初步探讨中国北方不同地理种群间和种群内该害虫的遗传分化程度、 遗传多样性以及基因流水平, 对来自中国北方的26个不同地理种群的线粒体COⅡ (细胞色素C氧化酶亚基Ⅱ) 基因片段序列的核苷酸多态性进行了研究。结果表明： 在515头个体的长度为484 bp COⅡ片段中共发现了28个变异位点和15种单倍型。单倍型间的系统进化分析发现, 15种单倍型主要分为两大分支。总种群单倍型多样性指数Hd为0.257, 种群内单倍型多样度在0.100～0.515范围内。总种群的Fst为0.585, Gst为0.417, 基因流Nm为0.35。AMOVA分子变异分析结果发现, 双斑长跗萤叶甲的遗传分化主要来自种群之间, 占方差比率的58.58%。实验总种群及大部分种群的中性检验符合中性突变, 说明我国北方双斑长跗萤叶甲在近期没有出现种群扩张现象。研究结果揭示中国北方双斑长跗萤叶甲不同地理种群间基因流水平低, 种群间已发生明显的遗传分化, 分化主要来自种群之间。     

云南西花蓟马rDNA-ITS2遗传多态性及其种群扩张

应用rDNA-ITS2基因序列对云南各地理种群西花蓟马Frankliniella occidentalis(Pergande)的遗传结构和遗传分化程度进行初步研究。经过比对112条序列,共发现了59个变异位点,定义了30种单倍型。云南省西花蓟马的单倍型多态性较高(Hd=0.90219),而核酸多态性较低(Pi=0.00891)。各地理种群西花蓟马的遗传分化指数Fst为0.00810,基因流Nm为30.61,表明各地理种群间遗传分化程度非常低,种群间存在充分的基因交流。对群体进行中性检验、错配分析表明西花蓟马群体曾经历过近期的种群扩张。分子方差分析(AMOVA)表明,云南西花蓟马的遗传变异主要来自于种群内部,种群间的遗传变异水平还非常低。从分子生物学的角度上也证实了西花蓟马近期入侵云南的事实。     

Genetic structure in Brazilian breeding colonies of the Roseate Spoonbill (Platalea ajaja, Aves: Threskiornithidae)

Roseate Spoonbills (Platalea ajaja, Linnaeus) are wading birds present in two of the most important Brazilian wetlands: the Pantanal wetlands and Rio Grande do Sul marshes. Natural populations of these species have not been previously studied with variable nuclear molecular markers. In order to support decision making regarding the management and conservation of these populations, we estimated and characterized the distribution of genetic variability among five Brazilian breeding colonies. The average observed heterozygosity in Brazilian Roseate Spoonbill populations (Ho = 0.575) did not differ significantly from the value determined in a U.S. wild-caught sample of 15 individuals, using data generated by the same set of microsatellite loci. Considering that the U.S. population underwent a recent reduction in size, we discuss this result supposing that the U.S. population was not genetically affected or that both populations had suffered a bottleneck. Global F(ST) indicated the lack of genetic differentiation among colonies, indicating the occurrence of past and/or present gene flow among them. Analysis of molecular variance revealed that most of the genetic variation is distributed within the colonies. Results are explained by a recent origin of colonies or by high levels of gene flow. Management decisions should take into consideration the fact that, even in the presence of high genetic exchange, ecological adaptations to different environments are important for species survival.     

Genetic status of the wood stork (Mycteria americana) from the southeastern United States and the Brazilian Pantanal as revealed by mitochondrial DNA analysis

The wood stork (Mycteria americana) is a colonial wading bird that inhabits the Neotropical region from the southeastern United States (US) to northern Argentina. The species is considered to be endangered in the US due to degradation of its foraging and breeding habitat. In other parts of its range, such as in the Brazilian Pantanal region, breeding populations of this species appear to be stable. We compared the levels of genetic variability and population structuring of the US and the Pantanal breeding populations using mitochondrial DNA (mtDNA) control region sequences. Twenty-seven haplotypes were identified among 88 wood stork samples collected from eight breeding colonies in the US and eight in the Pantanal. Patterns indicative of heteroplasmy were observed in 35.3% of the mtDNA sequences that were examined. Significantly higher levels of haplotype diversity were observed in the Pantanal samples compared to those from the US, suggesting that during the last century, demographic declines or a recent evolutionary bottleneck reduced the levels of mtDNA variability of the US population. Analyses of genetic structuring revealed non-significant genetic differentiation between these regions, indicating that either the populations were only recently separated or that gene flow continues to occur at low levels. Haplotype network analysis indicated low current levels of gene flow between populations that were closely related in the past.     

Population Genetic Study of Mitochondrial DNA in Roseate Spoonbill (Aves; Platalea ajaja) Breeding Colonies from the Pantanal Wetlands, Brazil

Five breeding colonies of the Roseate spoonbill (Aves: Platalea ajaja) from two Brazilian wetland areas (Pantanal and Taim marshes) were sampled, and domain I of the mitochondrial DNA control region (483 bp) was sequenced in 50 birds. The average haplotype diversity (h = 0.75, s = 0.071) and average nucleotide diversity (pi = 0.004, s = 0.003) were evaluated, and nonsignificant differences were found among the colonies studied. The lack of differentiation among breeding colonies revealed by AMOVA analysis was explained either as a consequence of high gene flow or recent expansion. The significantly negative results of the neutrality tests (Fu's F ( s ) = -23.271, P < 0.01; Tajima's D = -1.941, P < 0.01) associated with the star shape of the haplotype tree and mismatch distribution data are evidence supporting the idea that these populations underwent a recent demographic expansion in the Pantanal region. The average time since the expansion is estimated to be 25,773 years, and this agrees with a period of increased moisture that occurred during the last glacial period.     

Among-locus variation in Fst: fish, allozymes and the Lewontin-Krakauer test revisited.

Variation among loci in the distribution of allele frequencies among subpopulations is well known; how to tell when the variation exceeds that expected when all loci are subject to uniform evolutionary processes is not well known. If locus-specific effects are important, the ability to detect those effects should vary with the level of gene flow. Populations with low gene flow should exhibit greater variation among loci in Fst than populations with high gene flow, because gene flow acts to homogenize allele frequencies among subpopulations. Here I use Lewontin and Krakauer's k statistic to describe the variance among allozyme loci in 102 published data sets from fishes. As originally proposed, k > 2 was considered evidence that the variation in Fst among loci is greater than expected from neutral evolution. Although that interpretation is invalid, large differences in k in different populations suggest that locus-specific forces may be important in shaping genetic diversity. In these data, k is not greater for populations with expected low levels of gene flow than for populations with expected high levels of gene flow. There is thus no evidence that locus-specific forces are of general importance in shaping the distribution of allele frequencies at enzyme loci among populations of fishes.     

Genetic diversity in populations of Dalbulus maidis (DeLong and Wolcott) (Hemiptera: Cicadellidae) from distant localities in Brazil assessed by RAPD-PCR markers

Populations of Dalbulus maidis (DeLong and Wolcott) from the northeastern and central-southern regions of Brazil differ morphologically, suggesting that they could be genetically isolated. Here we used the random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) technique to estimate genetic structuring of this leafhopper species among five geographically distant localities across those regions and to estimate gene flow between populations. Ten specimens were sampled per population and genotyped with RAPD markers generated from amplification with nine oligonucleotides. The percentage of polymorphic loci was 78% in relation to the total number of amplified loci, and genetic similarity either between or within populations was higher than 0.72. Cluster analysis grouped specimens from the northeastern population (Mossoró/RN) into a single group, whereas central-southern specimens were not grouped in relation to their places of origin. Overall, the genetic subdivision index (Fst) was low (or= 0.192 and Nm 相似文献   

Morphological divergence and origin of sympatric populations of European whitefish (Coregonus lavaretus L.) in Lake Femund, Norway

Combining morphological and genetic analysis, we compared patterns of diversification within and between morphs among sympatric European whitefish (Coregonus lavaretus L.) populations in Lake Femund, Norway. Seven external populations, from potential colonization routes into Lake Femund were included. We found that deep-, shallow-, river- and bay spawning populations are distinct morphs in Lake Femund. Within morphs, populations range from being similar genetically (Fst=0-0.005) among deep-spawning populations to being highly differentiated (Fst=0.153) between bay-spawning populations. Between morphs, genetic differences ranged from a low (Fst=0.008-0.022) between deep- and shallow-spawning populations to high difference (Fst=0.125-0.143) between shallow- and bay-spawning populations. A higher proportion of molecular variance was seen among (3.9%) than within morphs (2.8%). The adaptive gene combinations behind the four morphs seem to have originated within the lake, although the lake could have been colonized from more than one source population.     

Population structure in the South American tern Sterna hirundinacea in the South Atlantic: two populations with distinct breeding phenologies

The South American tern Sterna hirundinacea is a migratory species for which dispersal, site fidelity and migratory routes are largely unknown. Here, we used five microsatellite loci and 799 bp partial mitochondrial DNA sequences (Cytochrome b and ND2) to investigate the genetic structure of South American terns from the South Atlantic Ocean (Brazilian and Patagonian colonies). Brazilian and Patagonian colonies have two distinct breeding phenologies (austral winter and austral summer, respectively) and are under the influence of different oceanographic features (e.g. Brazil and Falklands/Malvinas ocean currents, respectively), that may promote genetic isolation between populations. Results show that the Atlantic populations are not completely panmictic, nevertheless, contrary to our expectations, low levels of genetic structure were detected between Brazilian and Patagonian colonies. Such low differentiation (despite temporal isolation of the colonies) could be explained by demographic history of these populations coupled with ongoing levels of gene flow. Interestingly, estimations of gene flow through Maximum likelihood and Bayesian approaches has indicated asymmetrical long term and contemporary gene flow from Brazilian to Patagonian colonies, approaching a source–sink metapopulation dynamic. Genetic analysis of other South American tern populations (especially those from the Pacific coast and Falklands–Malvinas Islands) and other seabird species showing similar geographical distribution (e.g. royal tern Thalasseus maximus), are fundamental in gaining a better understanding of the main processes involved in the diversification of seabirds in the southern hemisphere.     

Population genetics of the socially polymorphic ant <Emphasis Type="Italic">Formica podzolica</Emphasis>

Summary. We used microsatellite markers to analyze the hierarchical genetic structure of the North American mound building ant, Formica podzolica. About one-third of all colonies were headed by a single queen (monogynous) whose effective mating frequency was close to one (nestmate worker relatedness r = 0.70), while the remaining colonies were polygynous, with low average nestmate relatedness (r = 0.16). The low worker relatedness found in most polygynous colonies furthermore suggested that the numbers of queens in polygynous colonies of this ant are usually high. Contrary to what has been described from other ants with a queen number dichotomy, we did not find an effect of social form variation on the partitioning of genetic variation above the level of the colony. We found no significant differentiation between the sympatric social forms of F. podzolica, nor did differentiation among populations appear to be affected by colony social organization. These unexpected patterns of genetic structure may have resulted from differences either in the spatial distribution of the social forms or in their social flexibility.Received 12 January 2004; revised 23 February 2004; accepted 10 March 2004.     

GENETIC POPULATION STRUCTURE AND LEVELS OF GENE FLOW IN THE STREAM DWELLING WATERSTRIDER,AQUARIUS (=GERRIS) REMIGIS (HEMIPTERA: GERRIDAE)

Gene flow, in combination with selection and drift, determines levels of differentiation among local populations. In this study we estimate gene flow in a stream dwelling, flightless waterstrider, Aquarius remigis. Twenty-eight Aquarius remigis populations from Quebec, Ontario, New Brunswick, Iowa, North Carolina, and California were genetically characterized at 15 loci using starch gel electrophoresis. Sampling over two years was designed for a hierarchical analysis of population structure incorporating variation among sites within streams, streams within watersheds, watersheds within regions, and regions within North America. Hierarchical F statistics indicated that only sites within streams maintained enough gene flow to prevent differentiation through drift (Nm = 27.5). Above the level of sites within streams gene flow is highly restricted (Nm ≤ 0.5) and no correlation is found between genetic and geographic distances. This agrees well with direct estimates of gene flow based on mark and recapture data, yielding an N_e of approximately 170 individuals. Previous assignment of subspecific status to Californian A. remigis is not supported by genetic distances between those populations and other populations in North America. Previous suggestion of specific status for south-eastern A. remigis is supported by genetic distances between North Carolina populations and other populations in North America, and a high proportion of region specific alleles in the North Carolina populations. However, because of the high degree of morphological and genetic variability throughout the range of this species, the assignment of specific or subspecific status to parts of the range may be premature.     

Genetic structure of continental and island populations of the Mediterranean endemic Cyclamen balearicum (Primulaceae)

Cyclamen balearicum is a self-compatible perennial herb endemic to the western Mediterranean Basin. This species occurs in five geographically isolated terrestrial islands in southern France and on four Balearic islands. In this study, we compare genetic variability and differentiation within and among 11 terrestrial island populations and 17 true island populations. Of nine readable enzyme loci, five were polymorphic in both terrestrial and true islands. F statistics showed a significant heterozygote deficiency in all populations, probably due to high levels of autonomous selfing, restricted gene flow, and subsequent genetic drift. Genetic diversity was higher in terrestrial islands than on the Balearic islands, suggesting that the Balearic islands were colonized when they were in contact with the continent. Population differentiation was greater among terrestrial islands (Fst = 0.417 and Gst = 0.344) than among true islands (Fst = 0.112 and Gst = 0.093). Furthermore, differentiation among populations on the Basses Cévennes terrestrial island was greater (Fst = 0.254) than among populations on the true island of Mallorca (Fst = 0.163). The greater genetic differentiation among terrestrial islands could have been caused by genetic bottlenecks associated with changes in climate and human land use that may have reduced population sizes more severely in terrestrial islands in southern France than on the Balearic islands.     

Cryptic divergence and strong population structure in the colonial invertebrate Pycnoclavella communis (Ascidiacea) inferred from molecular data

We studied sequence variation in the mitochondrial gene cytochrome c oxidase subunit I (COI) for 135 individuals from eight Mediterranean populations of the colonial ascidian Pycnoclavella communis across most of its presently known range of distribution in the Mediterranean. Three haplotypes from Atlantic locations were also included in the study. Phylogenetic, phylogeographic and population genetic analyses were used to unravel the genetic variability within and between populations. The study revealed 32 haplotypes for COI, 29 of them grouped within two Mediterranean lineages of P. communis (mean nucleotide divergence between lineages was 8.55%). Phylogenetic and network analyses suggest the possible existence of cryptic species corresponding to these two lineages. Population genetic analyses were restricted to the five populations belonging to the main genetic lineage, and for these localities we compared the information gleaned from COI sequence data and from eight microsatellite loci. A high genetic divergence between populations was substantiated using both kinds of markers (COI, global Fst=0.343; microsatellite loci, global Fst=0.362). There were high numbers of private haplotypes (COI) and alleles (microsatellites) in the populations studied. Restricted gene flow and inbreeding occur in the present range of distribution of the species. Microsatellite loci showed a strong incidence of failed amplifications, which we attribute to the marked intraspecies variability that hampered the application of these highly specific markers. Our results show important genetic variability at all levels studied, from within populations to between basins, possibly coupled to speciation processes. This variability is attributable to restricted gene flow among populations due to short-distance dispersal of the larvae.     

Population genetic evidence for sex‐specific dispersal in an inbred social spider

Dispersal in most group‐living species ensures gene flow among groups, but in cooperative social spiders, juvenile dispersal is suppressed and colonies are highly inbred. It has been suggested that such inbred sociality is advantageous in the short term, but likely to lead to extinction or reduced speciation rates in the long run. In this situation, very low levels of dispersal and gene flow among colonies may have unusually important impacts on fitness and persistence of social spiders. We investigated sex‐specific differences in dispersal and gene flow among colonies, as reflected in the genetic structure within colonies and populations of the African social spider Stegodyphus dumicola Pocock, 1898 (Eresidae). We used DNA fingerprinting and mtDNA sequence data along with spatial mapping of colonies to compare male and female patterns of relatedness within and among colonies at three study sites. Samples were collected during and shortly after the mating season to detect sex‐specific dispersal. Distribution of mtDNA haplotypes was consistent with proliferation of social nests by budding and medium‐ to long‐distance dispersal by ballooning females. Analysis of molecular variance and spatial autocorrelation analyses of AFLPs showed high levels of genetic similarity within colonies, and STRUCTURE analyses revealed that the number of source populations contributing to colonies ranged from one to three. We also showed significant evidence of male dispersal among colonies at one site. These results support the hypothesis that in social spiders, genetic cohesion among populations is maintained by long‐distance dispersal of female colony founders. Genetic diversity within colonies is maintained by colony initiation by multiple dispersing females, and adult male dispersal over short distances. Male dispersal may be particularly important in maintaining gene flow among colonies in local populations.     

Genetic variability and phylogeographical patterns of a nonindigenous species invasion: a comparison of exotic vs. native zebra and quagga mussel populations

There have been few investigations of the number of founding sources and amount of genetic variability that lead to a successful nonindigenous species invasion, although genetic diversity is believed to play a central role. In the present study, population genetic structure, diversity and divergence patterns were analysed for the zebra mussel Dreissena polymorpha [n=280 samples and 63 putative randomly amplified polymorphic DNA (RAPDs) gene loci] and the quagga mussel D. bugensis (n=136 and 52 loci) from 10 nonindigenous North American and six Eurasian sampling sites, representing their present‐day ranges. Results showed that exotic populations of zebra and quagga mussels had surprisingly high genetic variability, similar to those in the Eurasian populations, suggesting large numbers of founding individuals and consistent with the hypothesis of multiple colonizations. Patterns of genetic relationships indicate that the North American populations of D. polymorpha likely were founded by multiple source populations from north‐western and northcentral Europe, but not from southcentral or eastern Europe. Sampling areas within North America also were significantly divergent, having levels of gene flow and migration about twice those separating long‐established Eurasian populations. Samples of D. bugensis in Lakes Erie and Ontario were significantly different, with the former being more closely related to a native population from the Dnieper River, Ukraine. No evidence for a founder effect was discerned for either species.     

Population subdivision in westslope cutthroat trout (Oncorhynchus clarki lewisi) at the northern periphery of its range: evolutionary inferences and conservation implications

Westslope cutthroat trout (Oncorhynchus clarki lewisi, Salmonidae) are native to the upper Columbia, Missouri, and South Saskatchewan river drainages of western North America and are at the northern periphery of their range in southeastern British Columbia, Canada. We examined geographical variation in allele frequencies at eight microsatellite loci in 36 samples of westslope cutthroat trout from British Columbia to assess levels of population subdivision and to test the hypothesis that different habitat types (principally mainstem vs. above migration barrier habitats) would influence levels of genetic diversity, genetic divergence among populations, and attainment of equilibrium between gene flow and genetic drift. Across all samples, the mean number of alleles per locus was 3.9 and mean expected heterozygosity was 0.56. Population subdivision was extensive with an overall Fst (theta) of 0.32. Populations sampled above migration barriers had significantly fewer alleles, lower expected heterozygosity, but greater average pairwise Fst than populations sampled from mainstem localities. We found evidence for isolation-by-distance from a significant correlation between genetic distance and geographical distance (r = 0.31), but the pattern was much stronger (r = 0.51) when above barrier populations and a population that may have been involved in headwater exchanges were removed. By contrast, isolation-by-distance was not observed when only above barrier populations were tested among themselves. Our data support the maintenance of separate demographic management strategies for westslope cutthroat trout inhabiting different river systems and illustrate how differing habitat structure (e.g. presence of migration barriers) may influence patterns of biodiversity and gene flow-drift equilibrium.     

Similarity of contemporary and historical gene flow among highly fragmented populations of an endangered rattlesnake

Populations of endangered taxa in recently fragmented habitats often show high levels of genetic structure, but the role that contemporary versus historical processes play in generating this pattern is unclear. The eastern massasauga rattlesnake (Sistrurus c. catenatus) is an endangered snake that presently occurs throughout central and eastern North America in a series of populations that are isolated because of habitat fragmentation and destruction. Here, we use data from 19 species-specific microsatellite DNA loci to assess the levels of genetic differentiation, genetic effective population size, and contemporary and historical levels of gene flow for 19 populations sampled across the range of this snake. Eastern massasaugas display high levels of genetic differentiation (overall θ(Fst) = 0.21) and a Bayesian clustering method indicates that each population represents a unique genetic cluster even at regional spatial scales. There is a twofold variation in genetically effective population sizes but little genetic evidence that populations have undergone recent or historical declines in size. Finally, both contemporary and historical migration rates among populations were low and similar in magnitude even for populations located <7 km apart. A test of alternate models of population history strongly favours a model of long-term drift-migration equilibrium over a recent isolation drift-only model. These results suggest that recent habitat fragmentation has had little effect on the genetic characteristics of these snakes, but rather that this species has historically existed in small isolated populations that may be resistant to the long-term negative effects of inbreeding.     

Panmixia on a continental scale in a widely distributed colonial waterbird

Many highly mobile species, such as migratory birds, can move and disperse over long distances, yet exhibit high levels of population genetic structuring. Although movement capabilities may enable dispersal, gene flow may be restricted by behavioural constraints such as philopatry. In the present study, we examined patterns of genetic differentiation across the range of a highly mobile, colonial waterbird. American white pelicans (Pelecanus erythrorhynchos) breed across continental North America and are currently experiencing a range expansion, especially on the eastern range limit. To assess patterns of genetic structuring, we sampled 333 individuals from 19 colonies across their North American range. The use of ten variable microsatellite markers revealed high levels of allelic richness with no population differentiation. Both Bayesian and frequentist approaches to examining genetic structuring revealed a single panmictic population. We found no evidence of genetic structuring across the Continental Divide or between migratory and non‐migratory colonies. The lack of any genetic structure across the range indicates that, unlike other waterbirds with similar life‐history characteristics, extensive gene flow and presumably low philopatry appear to preclude genetic differentiation. The lack of population genetic structure in American white pelicans provides an example of range‐wide panmixia, a rare phenomenon in any terrestrial species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 583–592.     

Structure and genetic variability of golden mussel (Limnoperna fortunei) populations from Brazilian reservoirs

The golden mussel, Limnoperna fortunei a highly invasive species in Brazil, has generated productive, economical, and biological impacts. To evaluate genetic structure and variability of L. fortunei populations present in fish farms in the reservoirs of Canoas I (CANFF), Rosana (ROSFF), and Capivara (CAPFF) (Paranapanema River, Paraná, Brazil), eight microsatellite loci were amplified. Five of those eight loci resulted in 38 alleles. The observed heterozygosity (Ho) was lower than the expected heterozygosity (He) in all populations, with a deviation from the Hardy–Weinberg equilibrium (HWE). The average value for the inbreeding coefficient (Fis) was positive and significative for all populations. There was higher genetic variability within populations than among them. The fixation index (Fst) showed a small genetic variability among these populations. The occurrence of gene flow was identified in all populations, along with the lack of a recent bottleneck effect. The clustering analysis yielded K = 2, with genetic similarity between the three populations. The results demonstrate low genetic structure and suggest a founding population with greater genetic variability (ROSFF). Our data point to the possible dispersal of L. fortunei aided by anthropic factors in the upstream direction. It was concluded that the three populations presented a unique genetic pool for Paranapanema River, with occurrence of gene flow.     

Historical human activities reshape evolutionary trajectories across both native and introduced ranges

The same vectors that introduce species to new ranges could move them among native populations, but how human‐mediated dispersal impacts native ranges has been difficult to address because human‐mediated dispersal and natural dispersal can simultaneously shape patterns of gene flow. Here, we disentangle human‐mediated dispersal from natural dispersal by exploiting a system where the primary vector was once extensive but has since ceased. From 10th to 19th Centuries, ships in the North Atlantic exchanged sediments dredged from the intertidal for ballast, which ended when seawater ballast tanks were adopted. We investigate genetic patterns from RADseq‐derived SNPs in the amphipod Corophium volutator (n = 121; 4,870 SNPs) and the annelid Hediste diversicolor (n = 78; 3,820 SNPs), which were introduced from Europe to North America, have limited natural dispersal capabilities, are abundant in intertidal sediments, but not commonly found in modern water ballast tanks. We detect similar levels of genetic subdivision among introduced North American populations and among native European populations. Phylogenetic networks and clustering analyses reveal population structure between sites, a high degree of phylogenetic reticulation within ranges, and phylogenetic splits between European and North American populations. These patterns are inconsistent with phylogeographic structure expected to arise from natural dispersal alone, suggesting human activity eroded ancestral phylogeographic structure between native populations, but was insufficient to overcome divergent processes between naturalized populations and their sources. Our results suggest human activity may alter species' evolutionary trajectories on a broad geographic scale via regional homogenization and global diversification, in some cases precluding historical inference from genetic data.