Repeated jumps from Northwest Africa to the European continent: The case of peripheral populations of an annual plant

Peripheral populations (i.e., those occurring on the edge of a species’ distribution range) can have different origins and genetic characteristics, and they may be critical for the conservation of genetic diversity. We investigated European peripheral populations of Scrophularia arguta, a widespread, annual plant distributed from Arabia to Northwest Africa and Macaronesia. Only two small disjunct population groups of this species occur in Europe, specifically in West‐Central and Southeast Iberia. To disclose the origin of these populations and determine their importance for the conservation of S. arguta genetic diversity, we analyzed DNA sequences from two nuclear and two plastid regions and amplified fragment length polymorphism markers in populations sampled mainly across the western distribution range of the species, and modeled the species distribution under present and late Quaternary conditions. The analyses revealed the presence of three distinct lineages of S. arguta in Europe, as a result of multiple colonization waves at different times in the Quaternary. Two of these lineages, occurring in Southeast Iberia, are the result of more or less recent dispersal from Northwest Africa. In contrast, West‐Central Iberian populations are strongly differentiated from the remaining range of S. arguta and can be considered as peripheral relict populations. Our study is the first to demonstrate the occurrence of at least three colonizations of the European continent from Africa by a native plant species. The diverse histories and genetic makeup of the resulting populations confirm the importance of peripheral populations, and particularly of ancient relict populations, for the conservation of global genetic diversity in widespread species.     

Are we conserving peripheral populations? An analysis of range structure of longhorn beetles (Coleoptera: Cerambycidae) in Finland

This paper characterises range structures of longhorn beetles (Coleoptera: Cerambycidae) occurring in Finland and classifies species as resource (host plant), substrate (specific host plant qualities) or climate limited. This information is then used to evaluate whether the IUCN red-list classification applied in Finland is directed towards peripheral European populations. Thirty (37%) longhorn beetle species are red-listed in Finland. Limited host plant distribution is adequate in explaining the red-list status for 43% of the red-listed species. All of these species are dependent on hardwood trees. Of the red-listed species that are dependent on widespread host plants, 30% have a limited extent of occurrence as well as a small area of occupancy in Finland. As these species are widespread outside Fennoscandia, their range in Finland is most likely limited by climate. Twenty per cent of the red-listed species have a wide extent of occurrence, albeit a small area of occupancy in Finland. As these species are dependent on widespread host plant species, but require specific substrate qualities (e.g. decaying, large diameter trunks), it is likely that their range is restricted by anthropogenic activities, mainly forestry and agriculture. The present study shows that the red-list classification in Finland is directed towards peripheral European populations. This study, however, did not address the conservation value of these populations.     

Report of Xiphophorus hellerii in the arid Metztitlán Canyon Biosphere Reserve in Mexico

Biosphere reserves have been established around the world as a means to protect sensitive or threatened ecoregions and the biodiversity within them. As such, the organisms occurring within these reserves are important from a conservation perspective as they often represent endemic species or remnant populations. Here we provide genetic evidence of widespread occurrence of Xiphophorus helleri within the Metztitlán Canyon Biosphere Reserve in Hidalgo, Mexico. One nuclear and two mitochondrial genes were sequenced from four populations within the canyon and confirmed that the specimens collected were X. hellerii. When compared to published sequences of X. hellerii from multiple localities within the documented natural range of the species, the specimens from Metztitlán were found to exhibit between 0 and 1.6 % sequence divergence. Possible scenarios for colonization of the canyon and conservation implications are discussed.     

Conservation biogeography of large Mediterranean islands. Butterfly impoverishment, conservation priorities and inferences for an ecologica "island paradigm"

Conservation biogeography is considered the Cinderella of biological conservation. Nevertheless biogeography provides the basis for establishing species distributions over space and time, therefore conservation priorities among areas and individual species. We demonstrate that there is no need to simplify analyses by using subsets of species (rare species, endemics) as surrogates. In doing so, we apply strict biogeographical techniques to determine butterfly impoverishment on three of the west Mediterranean's largest islands (Sardinia, Corsica and Sicily). The analyses performed on species, both collectively and individually, reveal that regional species richness in the Mediterranean zone can be largely predicted by latitude, altitude and latitudinal range (maximum minus minimum latitude), but that Sardinia and Corsica have clearly impoverished faunas. Logistic regression at individual species level demonstrates that several species, predicted to be present in these islands on the basis of their continental distributions, are actually absent. When compared with species that are present in these islands, such missing species are disclosed as having ecological traits which reduce their colonization capability. Probabilities of occurrence are calculated for each species on each island; they reflect the potential for each butterfly species to migrate to and colonise each island, and can be considered as a measure of conservation value. As such, species present on islands but having low immigration probabilities are predicted to represent isolated populations from the mainland that are unlikely to re-colonize the islands in the case of extinction. Island endemic species and races are shown to have lower occurrence probabilities compared to widespread species occurring on islands and illustrate the usefulness of occurrence probabilities for identifying isolated populations in need of conservation attention.     

Past tree range dynamics in the Iberian Peninsula inferred through phylogeography and palaeodistribution modelling: A review

The forests in the Iberian Peninsula have been strongly influenced by past climatic changes, but reconstructing their historical distributions and dynamics is very difficult due to the complex climatic characteristics and relief of the region. Research disciplines such as phylogeography and species distribution modelling can describe the past range dynamics of individual tree species in relatively great detail and help elucidate how these species have reacted to climatic changes. Here we review phylogeographical and modelling studies from species representative of the major Iberian forest types and attempt to extract general trends from the diversity of individual species histories in the Peninsula. To date most studies focus on geographical range dynamics during the Pleistocene, but an increasing body of evidence shows that some species have also retained the genetic imprints of much more ancient processes. Many widespread Iberian species show a deep and often remarkably clear-cut divide between populations from the Mediterranean and from the Atlantic regions of the Iberian Peninsula, suggesting that both areas have independently sustained viable populations over extended periods. In fact, phylogeographical studies commonly find that species had several glacial refugia across the Iberian Peninsula. On the other hand, distribution models help identifying further suitable areas that could have sustained so far undetected refugia. Such studies are of interest for species conservation, because refugium populations are high-priority targets due to their long-term persistence and unique evolutionary trajectory. Overall, we conclude that palaeoecology, phylogeography and species distribution modelling have a great potential to inform each other because of their complementary perspectives and results. A true integration of these approaches is therefore fundamental for further progress in our understanding of past Iberian environments and the organisms they harboured.     

Partnering conservation actions. <Emphasis Type="Italic">Inter situ</Emphasis> solutions to recover threatened species in South West Western Australia

South West Western Australia has a rich endemic flora of global significance. The threats facing this floral diversity are increasing in type, severity and scale, demonstrated by the rising numbers of species threatened with extinction. In particular, the root-rot pathogen Phytophthora cinnamomi is causing widespread destruction, threatening the survival of many of the region’s unique plants. In situ conservation of wild plants is considered the most essential component of a flora conservation program, but the ability to conserve some species adequately is often unachievable in the short term and urgent management intervention is required to prevent extinction. We present data on the status and management of wild populations of four threatened species from the region, including an ex situ program, and describe our efforts to bridge the gap between these two components. Such inter situ conservation recovery work enables monitoring of biological attributes, research into reproductive biology and collection of genetic material for further ex situ conservation, and provides the source of material for future restoration of wild populations.     

Conservation of genetic diversity in old‐growth forest communities of the southeastern United States

Question: How do studies of the distribution of genetic diversity of species with different life forms contribute to the development of conservation strategies? Location: Old‐growth forests of the southeastern United States. Methods: Reviews of the plant allozyme literature are used to identify differences in genetic diversity and structure among species with different life forms, distributions and breeding systems. The general results are illustrated by case studies of four plant species characteristic of two widespread old‐growth forest communities of the southeastern United States: the Pinus palustris – Aristida stricta (Longleaf pine – wiregrass) savanna of the Coastal Plain and the Quercus – Carya – Pinus (Oak‐hickory‐pine) forest of the Piedmont. Genetic variation patterns of single‐gene and quantitative traits are also reviewed. Results: Dominant forest trees, represented by Pinus palustris(longleaf pine) and Quercus rubra (Northern red oak), maintain most of their genetic diversity within their populations whereas a higher proportion of the genetic diversity of herbaceous understorey species such as Sarracenia leucophylla and Trillium reliquum is distributed among their populations. The herbaceous species also tend to have more population‐to‐population variation in genetic diversity. Higher genetic differentiation among populations is seen for quantitative traits than for allozyme traits, indicating that interpopulation variation in quantitative traits is influenced by natural selection. Conclusion: Developing effective conservation strategies for one or a few species may not prove adequate for species with other combinations of traits. Given suitable empirical studies, it should be possible to design efficient conservation programs that maintain natural levels of genetic diversity within species of conservation interest.     

Does Species Range and Rarity Affect Population Genetics? A Case Study of Four Graptophyllum Species from Queensland,Australia

There are four species of Graptophyllum (Acanthaceae) in Australia which span a gradient in rarity and conservation status from the most endangered, Graptophyllum reticulatum (endangered), to G. ilicifolium (vulnerable), to G. excelsum (rare), to the least endangered G. spinigerum (widespread). Graptophyllum reticulatum and G. ilicifolium are each only known from three locations. All species were found to have quite high levels of genetic diversity (H_e, A, A_p, P) and there was no significant difference among species in genetic diversity ( P > 0.05), thus, genetic diversity was unrelated to conservation status or species geographic range. All species had high allelic fixation values ( F  ), indicating that populations were effectively inbred regardless of conservation status and geographic range. The genetic diversity among populations (F_ST) was not related to rarity and contrasted among the most restricted species, where diversity among populations was twice as high among G. reticulatum populations (F_ST, 0.22) compared with among G. ilicifolium populations (F_ST, 0.11).     

Range-wide comparisons of northern leatherside chub populations reveal historical and contemporary patterns of genetic variation

Patchily distributed species are those taxa whose populations occupy geographically insular habitats and their conservation often depends on an understanding of the relationship among disjunct populations. The objective of our study was to use molecular data and analytical techniques to separate the effects of historical and contemporary processes influencing the distribution of a high-desert minnow, the northern leatherside chub (Lepidomeda copei). Individuals from 23 populations were sequenced for 1,140 base pairs of the cytochrome B gene of the mitochondrial genome and genotyped at seven nuclear microsatellite loci. We estimated gene flow and examined population structure using both microsatellite and mtDNA data. Low sequence divergence and the distribution of shared haplotypes in multiple watersheds suggest historical connectivity between populations over a large geographic area. In contrast, patterns of microsatellite diversity indicate that populations of leatherside chub are isolated from one another with low levels of contemporary gene flow between populations. Our results suggest that populations of leatherside chub were historically more widely inter-connected and have recently been isolated, likely through a combination of natural and anthropogenic habitat fragmentation. As populations become increasingly isolated, they are more vulnerable to extirpation as a result of stochastic events. For northern leatherside chub, recent isolation and lack of gene flow among populations may affect their long-term survival in the arid landscapes of the Great Basin and surrounding watersheds because of widespread and increasing habitat alteration and fragmentation.     

Identifying mechanisms of genetic differentiation among populations in vagile species: historical factors dominate genetic differentiation in seabirds

Elucidating the factors underlying the origin and maintenance of genetic variation among populations is crucial for our understanding of their ecology and evolution, and also to help identify conservation priorities. While intrinsic movement has been hypothesized as the major determinant of population genetic structuring in abundant vagile species, growing evidence indicates that vagility does not always predict genetic differentiation. However, identifying the determinants of genetic structuring can be challenging, and these are largely unknown for most vagile species. Although, in principle, levels of gene flow can be inferred from neutral allele frequency divergence among populations, underlying assumptions may be unrealistic. Moreover, molecular studies have suggested that contemporary gene flow has often not overridden historical influences on population genetic structure, which indicates potential inadequacies of any interpretations that fail to consider the influence of history in shaping that structure. This exhaustive review of the theoretical and empirical literature investigates the determinants of population genetic differentiation using seabirds as a model system for vagile taxa. Seabirds provide a tractable group within which to identify the determinants of genetic differentiation, given their widespread distribution in marine habitats and an abundance of ecological and genetic studies conducted on this group. Herein we evaluate mitochondrial DNA (mtDNA) variation in 73 seabird species. Lack of mutation–drift equilibrium observed in 19% of species coincided with lower estimates of genetic differentiation, suggesting that dynamic demographic histories can often lead to erroneous interpretations of contemporary gene flow, even in vagile species. Presence of land across the species sampling range, or sampling of breeding colonies representing ice‐free Pleistocene refuge zones, appear to be associated with genetic differentiation in Tropical and Southern Temperate species, respectively, indicating that long‐term barriers and persistence of populations are important for their genetic structuring. Conversely, biotic factors commonly considered to influence population genetic structure, such as spatial segregation during foraging, were inconsistently associated with population genetic differentiation. In light of these results, we recommend that genetic studies should consider potential historical events when identifying determinants of genetic differentiation among populations to avoid overestimating the role of contemporary factors, even for highly vagile taxa.     

Population genetics of Mioscirtus wagneri,a grasshopper showing a highly fragmented distribution

The genetic consequences of population fragmentation and isolation are major issues in conservation biology. In this study we analyse the genetic variability and structure of the Iberian populations of Mioscirtus wagneri, a specialized grasshopper exclusively inhabiting highly fragmented hypersaline low grounds. For this purpose we have used seven species‐specific microsatellite markers to type 478 individuals from 24 localities and obtain accurate estimates of their genetic variability. Genetic diversity was relatively low and we detected genetic signatures suggesting that certain populations of M. wagneri have probably passed through severe demographic bottlenecks. We have found that the populations of this grasshopper show a strong genetic structure even at small geographical scales, indicating that they mostly behave as isolated populations with low levels of gene flow among them. Thus, several populations can be regarded as independent and genetically differentiated units which require adequate conservation strategies to avoid eventual extinctions that in highly isolated localities are not likely to be compensated for with the arrival of immigrants from neighbouring populations. Overall, our results show that these populations probably represent the ‘fragments’ of a formerly more widespread population and highlight the importance of protecting Iberian hypersaline environments due to the high number of rare and endangered species they sustain.     

Dispersal and gene flow in the rare, parasitic Large Blue butterfly Maculinea arion

Dispersal is crucial for gene flow and often determines the long‐term stability of meta‐populations, particularly in rare species with specialized life cycles. Such species are often foci of conservation efforts because they suffer disproportionally from degradation and fragmentation of their habitat. However, detailed knowledge of effective gene flow through dispersal is often missing, so that conservation strategies have to be based on mark–recapture observations that are suspected to be poor predictors of long‐distance dispersal. These constraints have been especially severe in the study of butterfly populations, where microsatellite markers have been difficult to develop. We used eight microsatellite markers to analyse genetic population structure of the Large Blue butterfly Maculinea arion in Sweden. During recent decades, this species has become an icon of insect conservation after massive decline throughout Europe and extinction in Britain followed by reintroduction of a seed population from the Swedish island of Öland. We find that populations are highly structured genetically, but that gene flow occurs over distances 15 times longer than the maximum distance recorded from mark–recapture studies, which can only be explained by maximum dispersal distances at least twice as large as previously accepted. However, we also find evidence that gaps between sites with suitable habitat exceeding ～20 km induce genetic erosion that can be detected from bottleneck analyses. Although further work is needed, our results suggest that M. arion can maintain fully functional metapopulations when they consist of optimal habitat patches that are no further apart than ～10 km.     

DNA barcoding and microsatellites help species delimitation and hybrid identification in endangered galaxiid fishes

The conservation of data deficient species is often hampered by inaccurate species delimitation. The galaxiid fishes Aplochiton zebra and Aplochiton taeniatus are endemic to Patagonia (and for A. zebra the Falkland Islands), where they are threatened by invasive salmonids. Conservation of Aplochiton is complicated because species identification is hampered by the presence of resident as well as migratory ecotypes that may confound morphological discrimination. We used DNA barcoding (COI, cytochrome b) and a new developed set of microsatellite markers to investigate the relationships between A. zebra and A. taeniatus and to assess their distributions and relative abundances in Chilean Patagonia and the Falkland Islands. Results from both DNA markers were 100% congruent and revealed that phenotypic misidentification was widespread, size-dependent, and highly asymmetric. While all the genetically classified A. zebra were correctly identified as such, 74% of A. taeniatus were incorrectly identified as A. zebra, the former species being more widespread than previously thought. Our results reveal, for the first time, the presence in sympatry of both species, not only in Chilean Patagonia, but also in the Falkland Islands, where A. taeniatus had not been previously described. We also found evidence of asymmetric hybridisation between female A. taeniatus and male A. zebra in areas where invasive salmonids have become widespread. Given the potential consequences that species misidentification and hybridisation can have for the conservation of these endangered species, we advocate the use of molecular markers in order to reduce epistemic uncertainty.     

Comparison of population genetic diversity between a rare, narrowly distributed species and a common, widespread species of Alnus (Betulaceae)

Comparisons of population genetic diversity between related rare and widespread species provide valuable insights to the consequences of rarity and are critical for conservation planning. Population genetic diversity of A. maritima, a rare species, was compared with its common, widespread congener A. serrulata to evaluate the impacts of small population size and high isolation on genetic diversity in A. maritima and to provide population genetic data to be used in conservation planning for A. maritima. Genetic data were also used to evaluate whether the disjunct distribution of A. maritima was due to range reduction or anthropogenic dispersal. Genetic diversity was lower in A. maritima (H(e) = 0.217) than in A. serrulata (H(e) = 0.268), and there is also higher inbreeding within A. maritima populations (f = 0.483) than A. serrulata populations (f = 0.269). The partitioning of genetic variation was also higher among A. maritima populations (Θ = 0.278), but not significantly different from that of A. serrulata (Θ = 0.197). Significant genetic differences among A. maritima populations support using local populations as seed sources for regional conservation efforts. The results also indicate that the highly disjunct distribution of A. maritima is due to natural range reduction in the past and not anthropogenic establishment of Oklahoma and Georgia populations.     

甘肃省麦积山景区——生态过渡带自然和文化遗产杰出范例

直到现在,生物多样性管护的主要注意力放在热点地区,但T．B．Smith等生态学家提出,管护战略必须把注意力不仅放在热点地区。而且也耍放在相联系的过渡带。他们争论说后者区域可能保有许多种群之间的适应变异,并因而对于生物多样性的产生和保持很重要。虽然生态过渡带常常拥有高的物种丰富度,但它们大多数是广泛分布的物种,它们的分布范围在生态过渡带相遇。甘肃省的麦积山景区是我国生态过渡带的自然和文化遗产地的杰出代表。麦积山景区不仅具有温凉、半湿润、四季分明的气候和复杂的地质地貌与土壤条件,使它的生物多样性独特丰富,具有过渡的特点,为我国同纬度其它地区无法相比,它的古文化遗存也丰富多彩,在一定程度上展现了印度佛教文化向中国化的过渡。     

TELOSCHISTES FLAVICANSIN GREAT BRITAIN: DISTRIBUTION AND ECOLOGY

Over the last century, the distribution ofTeloschistes flavicanshas contracted from being widespread in the southern half of England and Wales to being limited to South-West England with outlying populations in Pembrokeshire and North Wales. Twelve core sites have been identified where the species is well established: ten of these are saxicolous/terricolous habitats on windy coastal cliff tops; the other two are lines of sycamore trees near the coast. At 39 further localities, some inland, the species is in very small amounts (often on one tree) and vulnerable to extinction. It is normally a member of theParmelietum revolutaeor theRamalinetum scopularisassociations. The conservation of the species is discussed.     

Global conservation priorities for marine turtles

Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widely distributed and exhibit intra-specific variations in population sizes and trends, as well as reproduction and morphology. However, current global extinction risk assessment frameworks do not assess conservation status of spatially and biologically distinct marine turtle Regional Management Units (RMUs), and thus do not capture variations in population trends, impacts of threats, or necessary conservation actions across individual populations. To address this issue, we developed a new assessment framework that allowed us to evaluate, compare and organize marine turtle RMUs according to status and threats criteria. Because conservation priorities can vary widely (i.e. from avoiding imminent extinction to maintaining long-term monitoring efforts) we developed a “conservation priorities portfolio” system using categories of paired risk and threats scores for all RMUs (n = 58). We performed these assessments and rankings globally, by species, by ocean basin, and by recognized geopolitical bodies to identify patterns in risk, threats, and data gaps at different scales. This process resulted in characterization of risk and threats to all marine turtle RMUs, including identification of the world''s 11 most endangered marine turtle RMUs based on highest risk and threats scores. This system also highlighted important gaps in available information that is crucial for accurate conservation assessments. Overall, this priority-setting framework can provide guidance for research and conservation priorities at multiple relevant scales, and should serve as a model for conservation status assessments and priority-setting for widespread, long-lived taxa.     

Defining population boundaries: use of three Bayesian approaches with microsatellite data from British natterjack toads (Bufo calamita)

Defining boundaries between populations is often difficult in the absence of information about current levels of gene flow. Such definitions can be important, however, both for the understanding of population dynamics and for conservation planning. Recently developed Bayesian methods for analysing genetic data now provide a powerful approach to this problem. Natterjack toads Bufo calamita are endangered in Britain, where their distribution is restricted to four geographically discrete regions. In three of these regions the boundaries between populations are often uncertain. We therefore used Bayesian approaches with microsatellite data to try and define British natterjack population structure, and thus inform conservation management. A large sample of natterjack toads from all 38 locations in Britain where the species is native was genotyped at eight microsatellite loci. The genetic diversity of natterjack populations declined as a function of increasing latitude, echoing postglacial colonization dynamics. Comparisons of three assignment methods (structure, baps and geneland) generated some broad similarities but also some inconsistencies in the definitions of population structure, especially in the most complex region (south Cumbria). Implications of the analyses for the future conservation of Bufo calamita in Britain are discussed.     

The rehabilitation value of a small culturally significant island based on the arthropod natural capital

Small islands are particularly vulnerable to degradation by invasive species and often lack source populations to replace those lost during localized extinctions. Robben Island, a significant South African cultural heritage site, has a long history of anthropogenic impact. Introduced alien mammals and trees have resulted in numerous localized plant extinctions with their impact on arthropod biodiversity remaining unclear. We used Robben Island’s arthropod fauna as focal group to investigate the rehabilitation potential of this transformed island. Ground surface-living, foliage-inhabiting and flower-visiting arthropods were collected using five sampling techniques. Arthropod diversity was highest in the two ‘natural’ habitats compared to alien Eucalyptus plantations. Arthropod compositional diversity differed significantly between alien plantations and natural habitats. Nevertheless, a remarkable 17 % of all species were confined to plantations. However, when we corrected for the effect of rarity, only 15 species (4 %) were unique to alien plantations and all those identified to species level were either alien in origin or were widespread generalists only normally associated with transformed areas. This emphasizes the need to identify species that drive similarity indices to fully comprehend the conservation value of alien vegetation. Arthropods found in the remaining natural vegetation showed remarkable tolerance of long-term grazing pressures from introduced alien mammals. Only eight Orthoptera species were sampled, yet one was a rediscovery of a rare species and another a range extension. All indigenous species showed strong preferences for natural habitats. Thus, Robben Island could still hold conservation value if the natural habitats are rehabilitated and the Eucalyptus plantations removed.     

Population genetics of Cordia alliodora (Boraginaceae), a neotropical tree. 1. Genetic variation in natural populations

We provide an estimate of genetic differentiation within and among 11 populations of Cordia alliodora, an economically important timber tree Cordia alliodora is a widespread species that is distributed throughout Central and South America. Our survey of isozyme variation was conducted on material gathered for international provenance trials over approximately 1,000 km in Central America. Results from provenance trials indicate that there are significant differences between Atlantic and Pacific coast provenances for quantitative characters. Genetic data support some of these findings. Populations of C. alliodora show significant differences in allele frequency at various loci. Significant differences in multilocus allele frequencies occur at 13 of the 55 possible combinations. Eight of these 13 populations are situated on opposite coasts. This physical separation corresponds well with the results of provenance trials that indicate differentiation among the Atlantic and Pacific populations in quantitative morphological traits. We also found a significant negative correlation between levels of heterozygosity and the amount of rainfall, indicating that populations from the drier zone are genetically more heterogenous than populations from the wet zone. Our study indicates that in situ and ex situ conservation should accord high priority to the dry zone populations; furthermore, conservation of this widespread species would require preservation of multiple populations.