Niche dynamics of two cryptic <Emphasis Type="Italic">Prosopis</Emphasis> invading South American drylands

Whether or not species track native climatic conditions during invasions (i.e., climate match hypothesis) is fundamental to understand and prevent potential impacts of invasive species. Recent empirical work suggests that climatic mismatches between native and invasive ranges are pervasive. Whether these differences are due to adaptation to new climatic spaces in the invasive range or due to partial filling of the potential climatic space are still subject to debate. Here, we analyze climatic niche dynamics associated with the invasion of the two most common invasive plants in Brazilian semi-arid areas, Prosopis juliflora and Prosopis pallida. These species have been simultaneously introduced in the region, which creates a unique opportunity to compare their niche dynamics during invasion. Given that P. juliflora have a much wider native range size, we expect these species would present different dispersal potentials, which might translate into different unfilling levels. Using an ordination method with kernel smoother and null models, we contrasted climate spaces occupied by each species in both native and invasive ranges. We further used ecological niche models (ENMs) to compare reciprocal predictions of potentially suitable areas. Against our expectation based on differences in native range sizes, climatic niches of P. juliflora and P. pallida overlapped greatly, both in their native and invasive ranges. Our results support niche conservatism during the invasion process. Climatic mismatches among native and invaded ranges were exclusively attributed to unfilling of native climates in the invasive range. Both species showed similar unfilling levels. Likewise, ENMs predicted regions not yet occupied in the invasive range, revealing a potential for further expansion. We discuss colonization time lag and founder effect as potential mechanisms that may have prevented these species to fully occupy their native niches in the invasive range.     

Present and future distribution of three aquatic plants taxa across the world: decrease in native and increase in invasive ranges

Inland aquatic ecosystems are vulnerable to both climate change and biological invasion at broad spatial scales. The aim of this study was to establish the current and future potential distribution of three invasive plant taxa, Egeria densa, Myriophyllum aquaticum and Ludwigia spp., in their native and exotic ranges. We used species distribution models (SDMs), with nine different algorithms and three global circulation models, and we restricted the suitability maps to cells containing aquatic ecosystems. The current bioclimatic range of the taxa was predicted to represent 6.6–12.3% of their suitable habitats at global scale, with a lot of variations between continents. In Europe and North America, their invasive ranges are predicted to increase up to two fold by 2070 with the highest gas emission scenario. Suitable new areas will mainly be located to the north of their current range. In other continents where they are exotic and in their native range (South America), the surface areas of suitable locations are predicted to decrease with climate change, especially for Ludwigia spp. in South America (down to ?55% by 2070 with RCP 8.5 scenario). This study allows to identify areas vulnerable to ongoing invasions by aquatic plant species and thus could help the prioritisation of monitoring and management, as well as contribute to the public awareness regarding biological invasions.     

High invasion potential of Hydrilla verticillata in the Americas predicted using ecological niche modeling combined with genetic data

Ecological niche modeling is an effective tool to characterize the spatial distribution of suitable areas for species, and it is especially useful for predicting the potential distribution of invasive species. The widespread submerged plant Hydrilla verticillata (hydrilla) has an obvious phylogeographical pattern: Four genetic lineages occupy distinct regions in native range, and only one lineage invades the Americas. Here, we aimed to evaluate climatic niche conservatism of hydrilla in North America at the intraspecific level and explore its invasion potential in the Americas by comparing climatic niches in a phylogenetic context. Niche shift was found in the invasion process of hydrilla in North America, which is probably mainly attributed to high levels of somatic mutation. Dramatic changes in range expansion in the Americas were predicted in the situation of all four genetic lineages invading the Americas or future climatic changes, especially in South America; this suggests that there is a high invasion potential of hydrilla in the Americas. Our findings provide useful information for the management of hydrilla in the Americas and give an example of exploring intraspecific climatic niche to better understand species invasion.     

Effects of admixture in native and invasive populations of <Emphasis Type="Italic">Lythrum salicaria</Emphasis>

Intraspecific hybridization between diverged populations can enhance fitness via various genetic mechanisms. The benefits of such admixture have been proposed to be particularly relevant in biological invasions, when invasive populations originating from different source populations are found sympatrically. However, it remains poorly understood if admixture is an important contributor to plant invasive success and how admixture effects compare between invasive and native ranges. Here, we used experimental crosses in Lythrum salicaria, a species with well-established history of multiple introductions to Eastern North America, to quantify and compare admixture effects in native European and invasive North American populations. We observed heterosis in between-population crosses both in native and invasive ranges. However, invasive-range heterosis was restricted to crosses between two different Eastern and Western invasion fronts, whereas heterosis was absent in geographically distant crosses within a single large invasion front. Our results suggest that multiple introductions have led to already-admixed invasion fronts, such that experimental crosses do not further increase performance, but that contact between different invasion fronts further enhances fitness after admixture. Thus, intra-continental movement of invasive plants in their introduced range has the potential to boost invasiveness even in well-established and successfully spreading invasive species.     

Geographic independence and phylogenetic diversity of red shiner introductions

Identifying areas at risk of invasion can be difficult when the distribution of a non-native species encompasses geographically disjunct regions. Understanding genealogical relationships among native and non-native populations can clarify the origins of fragmented distributions, which in turn can clarify how fast and far a non-native species may spread. We evaluated genetic variation across the native and invasive ranges of red shiner (Cyprinella lutrensis), a minnow known to displace and hybridize with native species, to reconstruct invasion pathways across the United States (USA). Examination of mitochondrial cytochrome-b variation found that native range populations of red shiner fall into four highly divergent lineages that likely warrant species recognition. Introduced red shiner populations in the eastern and western USA are derived from only two of these lineages. Western USA populations originate from the mid-western and western genetic lineages, whereas eastern introductions derive only from the mid-western lineage. Western USA invasive populations exhibit fewer, but more diverse haplotypes compared to eastern USA invasive populations. We also recovered an undescribed, divergent lineage of Cyprinella that has been cryptically introduced into the western USA, which raises the possibility that hybridization has proceeded following secondary contact between previously allopatric lineages. Approximate Bayesian Computation modeling suggests that the disjunct distribution of red shiner across North America is an agglomeration of independent regional invasions with distinct origins, rather than stepwise advance of an invasion front or secondary introductions across regions. Thus localized control may be effective in managing non-native red shiner, including further spread to areas of conservation concern.     

Habitat fragmentation provides a competitive advantage to an invasive tree squirrel, <Emphasis Type="Italic">Sciurus carolinensis</Emphasis>

Changes in the composition of biological communities can be elicited by competitive exclusion, wherein a species is excluded from viable habitat by a superior competitor. Yet less is known about the role of environmental change in facilitating or mitigating exclusion in the context of invasive species. In these situations, decline in a native species can be due to the effects of habitat change, or due to direct effects from invasive species themselves. This is summarized by the “driver-passenger” concept of native species loss. We present a multi-year study of tree squirrels that tested the hypothesis that tree canopy fragmentation, often a result of human development, influenced the replacement of native western gray tree squirrels (Sciurus griseus) by non-native eastern gray tree squirrels (Sciurus carolinensis). We tested this hypothesis along a continuum of invasion across three study sites in central California. We found that within the developed areas of the University of California at Santa Cruz campus and city of Santa Cruz, S. carolinensis excluded S. griseus from viable habitat. The competitive advantage of S. carolinensis may be due to morphological and/or behavioral adaptation to terrestrial life in fragmented hardwood forests. We classify S. carolinensis as a “driver” of the decline of native S. griseus in areas with high tree canopy fragmentation. Future habitat fragmentation in western North America may result in similar invasion dynamics between these species. Our study warrants consideration of existing and predicted interactions between potentially invasive species that co-occur with native species where land use change is proposed.     

Unresolved native range taxonomy complicates inferences in invasion ecology: <Emphasis Type="Italic">Acacia dealbata</Emphasis> Link as an example

Elaborate and expensive endeavours are underway worldwide to understand and manage biological invasions. However, the success of such efforts can be jeopardised due to taxonomic uncertainty. We highlight how unresolved native range taxonomy can complicate inferences in invasion ecology using the invasive tree Acacia dealbata in South Africa as an example. Acacia dealbata is thought to comprise two subspecies based on morphological characteristics and environmental requirements within its native range in Australia: ssp. dealbata and spp. subalpina. Biological control is the most promising option for managing invasive A. dealbata populations in South Africa, but it remains unknown which genetic/taxonomic entities are present in the country. Resolving this question is crucial for selecting appropriate biological control agents and for identifying areas with the highest invasion risk. We used species distribution models (SDMs) and phylogeographic approaches to address this issue. The ability of subspecies-specific and overall species SDMs to predict occurrences in South Africa was also explored. Furthermore, as non-overlapping bioclimatic niches between the two taxonomic entities may translate into evolutionary distinctiveness, we also tested genetic distances between the entities using DNA sequencing data and network analysis. Both approaches were unable to differentiate the two putative subspecies of A. dealbata. However, the SDM approach revealed a potential niche shift in the non-native range, and DNA sequencing results suggested repeated introductions of different native provenances into South Africa. Our findings provide important information for ongoing biological control attempts and highlight the importance of resolving taxonomic uncertainties in invasion ecology.     

Phylogeography and population genetics of introduced Silver Carp (<Emphasis Type="Italic">Hypophthalmichthys molitrix</Emphasis>) and Bighead Carp (<Emphasis Type="Italic">H. nobilis</Emphasis>) in North America

The success of a biological invasion and the ability to control an invader may partially depend on the genetic diversity of the invasive species and the amount of dispersal and gene flow occurring throughout its introduced range. Here, we used nuclear microsatellites to analyze genetic diversity and structure and whole mitogenomic sequences to analyze the phylogeography of Silver Carp (SC; Hypophthalmichthys molitrix) and Bighead Carp (BHC; H. nobilis) across their North American ranges. Our objectives were to assess: (1) the number of mitochondrial haplotypes that were introduced and how they are distributed in North America, which may provide insight into the history of the invasion, (2) how genetic diversity compares between the native Asian and introduced North American populations, (3) how genetic variation is structured across the North American ranges of SC and BHC as well as between the two species, and (4) whether patterns of genetic diversity and structure are likely to affect success of environmental DNA programs for monitoring these species. In both species, we found relatively few mitochondrial haplotypes, and most were present throughout the range. For both SC and BHC, unique haplotypes were found only in a portion of the species’ range, possibly indicating the location of additional, more recent introductions. In both species, genetic diversity was moderately lower in North American populations (i.e., 75–90% of that found in Asian populations), but genetic diversity still remained high. We found very little population genetic structure, consistent with a rapidly spreading invasive species, and did not find evidence of cryptic interspecific hybrids. The markers developed for eDNA monitoring will be effective for detecting the majority of individuals of these species in North America. The relatively high level of genetic variation and lack of population structure of SC and BHC in North America indicate that genetic diversity likely will not limit their persistence and that high connectivity will likely complicate efforts to control these invasive species.     

Identification and genetic diversity of two invasive <Emphasis Type="Italic">Pissodes</Emphasis> spp. Germar (Coleoptera: Curculionidae) in their introduced range in the southern hemisphere

During the first half of the twentieth century, two accidental cases of introduction of Pissodes weevils were recorded from the southern hemisphere. The weevils in South Africa were identified as the deodar weevil (Pissodes nemorensis) and those in South America as the small banded pine weevil (Pissodes castaneus). Wide distribution of the two species in their invasive range, general difficulty in identifying some Pissodes spp., and the varying feeding and breeding behaviours of the species in South Africa has necessitated better evidence of species identity and genetic diversity of both species and population structure of the species in South Africa. Barcoding and the Jerry-to-Pat region of the COI gene were investigated. Morphometric data of the South African species was analysed. Our results confirmed the introduction of only one Pissodes species of North American origin to South Africa. However, this species is not P. nemorensis, but an unrecognized species of the P. strobi complex or a hybrid between P. strobi and P. nemorensis. Only P. castaneus, of European origin, was identified from South America. We identified ten mitochondrial DNA haplotypes from South Africa with evidence of moderate genetic structure among geographic populations. Terminal leader and bole-feeding weevils did not differ at the COI locus. A single haplotype was identified from populations of P. castaneus in South America. Results of the present study will have implications on quarantine, research and management of these insect species.     

Reaping benefits from an invasive species: role of <Emphasis Type="Italic">Harmonia axyridis</Emphasis> in natural biological control of <Emphasis Type="Italic">Aphis glycines</Emphasis> in North America

Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is an invasive species present in numerous agroecosystems in North America. Despite adverse impacts as a threat to native biodiversity, a nuisance household invader and a pest in fruit production, H. axyridis also plays a beneficial role as a major component of assemblages of generalist predators in several agricultural crops. Here, we review the role of H. axyridis as a natural enemy of Aphis glycines Matsumura (Hemiptera: Aphididae), an invasive pest of soybean, Glycine max (L.) Merrill (Fabales: Fabaceae), in North America. Harmonia axyridis is often the most abundant predator species attacking A. glycines in soybean agroecosystems. This predator has the potential to both prevent and suppress A. glycines outbreaks. Further studies are needed to fully understand and utilize the potential of H. axyridis as a natural enemy in the management of A. glycines and other agricultural pests in agroecosystems worldwide.     

<Emphasis Type="Italic">Pattersoniomyces tillandsiae</Emphasis> gen. et comb. nov.: linking sexual and asexual morphs of the only known smut fungus associated with Bromeliaceae

The enigmatic species Ustilago tillandsiae is the only known smut fungus associated with Bromeliaceae. Its generic position is evaluated by morphological, physiological, and molecular phylogenetic analyses using large subunit rDNA sequences. Phylogenetic analyses resolved U. tillandsiae as a member of the Ustilaginales in a sister relationship to the lineage containing Tranzscheliella species. However, U. tillandsiae differs from Tranzscheliella species by the development of sori in flowers, a different structure of sori and a different type of spore ornamentation. Consequently, a new genus Pattersoniomyces is described to accommodate U. tillandsiae. The new combination Pattersoniomyces tillandsiae is substantiated. In the sexual stage (teleomorph), this species infects bromeliads: Tillandsia flabellata, Tillandsia leiboldiana, and Tillandsia sp. in Central America between southern Mexico and Costa Rica. The yeast stage (anamorph) of P. tillandsiae was found associated with the phylloplane of Canistrum improcerum and in water tanks (phytotelmata) of Vriesea minarum, two bromeliads occurring in northeast and southeast Brazil, respectively. The link between the teleomorph and anamorphic strains is supported by identical sequences of the D1/D2 domains of the large subunit rDNA. Pattersoniomyces represents the tenth endemic smut genus to the Americas, but the only one that occurs in both North and South America, being a truly neotropical genus. The host plant families of Ustilaginales are extended to the Bromeliaceae. As far as we know, Pattersoniomyces represents the single event of a host jump from Cyperaceae or Poaceae to Bromeliaceae, apparently without further species radiation on multiple bromeliad species and genera growing in South America.     

Understanding the influence of urbanization on invasibility: <Emphasis Type="Italic">Carpobrotus edulis</Emphasis> as an exemplar

Coastal dune areas are valuable ecosystems, generally impacted by habitat destruction and invasive alien species. In this study, we assessed how human disturbance and invasion by Carpobrotus edulis impact the soils and the establishment of native flora in the north-western coastal regions of Spain. We compared soil characteristics (pH, conductivity, water content, nutrients and enzymatic activities) and native plant as well as C. edulis fitness correlates (germination and early growth) between uninvaded and invaded soils from urban and natural coastal dune areas. We found that human disturbance impacts coastal soils by increasing organic matter and water content, modifying soil nutrients and cycles, and reducing the pH in urban soils. The presence of invasive C. edulis further increases these impacts. These changes in soil characteristics allow for the establishment of the native, but ruderal, Scolymus hispanicus and non-native C. edulis, both of which are not adapted to the typically limiting conditions of coastal dunes. In some instances, the coastal dune endemic, Malcolmia littorea, showed no fitness effects in response to urbanization or the presence of C. edulis. These results suggest that human disturbed coastal areas might be more easily invaded than natural areas. More broadly, our findings of differential responses of different native species to disturbance and invasion, illustrate the need for multi-taxon approaches when assessing the impacts of invasive species.     

The Evolutionary History and Genetic Diversity of Kinkajous, <Emphasis Type="Italic">Potos flavus</Emphasis> (Carnivora,Procyonidae)

The genus Potos (Procyonidae) is currently recognized as a monotypic genus comprising the single species Potos flavus, the kinkajou. Kinkajous are widely distributed throughout forested habitats of tropical Central and South America, extending from eastern Brazil across central Bolivia, eastern Peru, northern Ecuador, Guianas, Suriname, Venezuela, Colombia, and then through Central America and into western Mexico. The taxonomic history of the species is complex, with seven or eight subspecies historically recognized to acknowledge the phenotypic variation among populations. In this study, the systematics and the evolutionary history of Potos flavus were investigated based on the mitochondrial gene cytochrome b, including specimens from a large range of localities, covering most of the distribution of the species, from central Middle America (Costa Rica and Panama) through South America (Ecuador, Peru, Bolivia, Brazil, Guyana, and French Guiana). Analyses of 30 Potos flavus sequences showed 27 haplotypes that were grouped in five main clades in all phylogenetic analyses. These clades suggested a high geographic structure with specimens from (1) Costa Rica, (2) Guianas and North Brazil, (3) North Peru, (4) Ecuador and Panama, (5a) interfluves Branco-Negro rivers in the Brazilian Amazon, (5b) Eastern Atlantic Forest, (5c) Amazonian lowlands east Negro river including Bolivia, Peru, and West Brazil. Each of these clades differs from 4.5 % to 9.3 % in their genetic distance estimates, which suggests that the specific status of some of these lineages should be reconsidered. Divergence dating and biogeographic analysis suggested that crown Potos diversified in the Miocene-Pliocene in South America, and geographic barriers, such as savannas and rivers, may have played a significant role in the kinkajou diversification.     

<Emphasis Type="Italic">Drosophila</Emphasis> as models to understand the adaptive process during invasion

The last few decades have seen a growing number of species invasions globally, including many insect species. In drosophilids, there are several examples of successful invasions, i.e. Zaprionus indianus and Drosophila subobscura some decades ago, but the most recent and prominent example is the invasion of Europe and North America by the pest species, Drosophila suzukii. During the invasive process, species often encounter diverse environmental conditions that they must respond to, either through rapid genetic adaptive shifts or phenotypic plasticity, or by some combination of both. Consequently, invasive species constitute powerful models for investigating various questions related to the adaptive processes that underpin successful invasions. In this paper, we highlight how Drosophila have been and remain a valuable model group for understanding these underlying adaptive processes, and how they enable insight into key questions in invasion biology, including how quickly adaptive responses can occur when species are faced with new environmental conditions.     

Evidence for ongoing introduction of non-native earthworms in the Washington,DC metropolitan area

Earthworm introductions and invasions are ongoing, with significant consequences for ecological characteristics and function where populations of invasive species reach high densities. In North America the influx of people, goods and materials to coastal cities has long been recognized to be related to introduction and establishment of many different invasive organisms. We conducted surveys for soil invertebrates in the Washington, DC area along the Potomac River corridor to examine the influence of historic soil profile disrupting disturbances on the composition of soil invertebrate communities. Here we report three earthworm taxa that either (1) had never been previously reported in North America (Lumbricidae: Helodrilus oculatus), (2) had never been reported from “wild” caught samples in forested soils (Lumbricidae: Eisenia fetida), or (3) represented a notable range expansion for an introduced species (Lumbricidae: Murchieona muldali). All three species reported here have attributes that give reason for concern over their expansion into North American soils, not least of which is their potential for competitive interactions with the remaining native earthworm species.     

Genetic diversity and population structure identify the potential source of the invasive red clover casebearer moth, <Emphasis Type="Italic">Coleophora deauratella</Emphasis>, in North America

The red clover casebearer, Coleophora deauratella, is an invasive pest of red clover grown for seed in North America. In 2006, an outbreak in Alberta, Canada was discovered that resulted in significant seed losses, while further invasion threatens the world’s largest red clover forage seed production region in Oregon, USA. Prior to the recent outbreak, C. deauratella was thought to be restricted to eastern North America in its invasive range. We sequenced a 615-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene, and developed three microsatellite markers to assess the genetic diversity and population structure of C. deauratella in North America and its native range in Europe. We observed signatures of a founder effect in North American populations and a further loss of genetic diversity within Alberta populations. Most genetic differentiation was found between continents, with no evidence of isolation-by-distance within each continent. From the limited number of European populations sampled, a single introduction from Switzerland is the most probable source of North American populations based on similar mitochondrial diversity and lack of population differentiation. Within North America, based on increased genetic diversity compared to the rest of the continent, the first North American record from Ithaca, NY, and the first documented outbreak in southern Ontario in 1989, the initial C. deauratella invasion most likely occurred in southern Ontario, Canada or adjacent states in the USA, followed by transport throughout the continent. This study provides insight into the phylogeographic history of C. deauratella in North America and Europe and may help to identify a regional source of future classical biological control agents.     

Current status of American bullfrog, <Emphasis Type="Italic">Lithobates catesbeianus</Emphasis>, invasion in Uruguay and exploration of chytrid infection

The American bullfrog Lithobates catesbeianus is an invasive species that can strongly affect native amphibian communities through competition, predation, or introduction of diseases. This frog has invaded multiple areas in South America, for which niche models predict suitable environments across much of the continent. This paper reveals the state of the invasion of this species in Uruguay and its possible relationship with the chytrid pathogenic fungus, Batrachochytrium dendrobatidis. Surveys at invaded sites were conducted from 2007 to 2015, identified two populations undergoing recent range expansion (one of them exponential), two populations that failed to establish, and a new record in an urban area of the capital city, Montevideo. In all the analysed feral populations, chytridiomycosis was found. Our data suggest that the invasion of L. catesbeianus in Uruguay is at an early stage, with very localized populations, which might allow for the implementation of cost-effective management plans, with eradication constituting a plausible option.     

Feasibility assessment for the classical biological control of <Emphasis Type="Italic">Tamarix</Emphasis> in Argentina

Saltcedars are woody plants in the genus Tamarix L. (Caryophyllales: Tamaricaceae) and are native to Eurasia and Africa. Several species have become invasive in the Americas, Australia and South Africa. In Argentina there are four species of Tamarix distributed in arid, semi-arid and coastal areas of most provinces. The taxonomic isolation of Tamarix spp. in Argentina, their widespread distribution, negative impact to natural areas and lack of impact from existing natural enemies all indicate that Tamarix is an ideal candidate for classical biological control in Argentina. Biological control of Tamarix spp. has been rapid and highly successful in the USA after the introduction of four Diorhabda spp. (Coleoptera: Chrysomelidae). Biological control of Tamarix spp. in Argentina could be implemented easily, rapidly, and at a low cost by utilizing the information developed in the USA.     

Multiple introductions of <Emphasis Type="Italic">Sirex noctilio</Emphasis> (Hymenoptera: Siricidae) in northeastern North America based on microsatellite genotypes,and implications for biological control

The invasive woodwasp Sirex noctilio (Hymenoptera: Siricidae) has been moved from Eurasia into regions in the Southern Hemisphere, where extensive tree mortality has occurred in pines (Pinus spp.) introduced for forestry. More recently this woodwasp was found in northeastern North America, where pines are native, and it is a species of concern due to the economic importance of pines. Understanding the genetic diversity of North American S. noctilio points to new areas of inquiry, particularly regarding the ability of parasitic nematodes to sterilize woodwasps, which could provide control methods in the US and/or Canada. We investigated the genetic diversity of 924 S. noctilio from nine populations from New York and Pennsylvania (US), Ontario (CA), and Queensland (AU) using nine microsatellite loci. To avoid inflating the number of populations estimated by Bayesian inference, we measured the full-sibling relationships of woodwasps within 13 trees and removed all but one member of each full-sib family from the genetic analysis, resulting in a final sample size of 741 S. noctilio. Within a tree, on average 39% of woodwasps did not have a full sibling, and there were 5.6 families with at least two full-sibling members per tree. The mean family size across trees was 1.9 when single offspring (i.e., no full siblings) were included. Given the short time span since invasion, variation within North American S. noctilio is likely due to differences among founding genotypes. Genetic analyses support the hypothesis that at least two separate introductions occurred. Within North America, genetic distance measures were greatest between a site in southwestern Ontario and all other sites, suggesting that this population could represent a separate introduction event. Two methods of Bayesian clustering also support this idea; they detected 4 or 5 distinct genetic clusters with little admixture between the southwestern Ontario site and other North American populations. The wasps from Australia, where biological control with nematodes has been successful, showed low genetic diversity and clustered with the southwestern Ontario population in one out of two Bayesian analyses. Within the Ontario subset of samples, high woodwasp activity level (i.e., attack and mortality of trees) was associated with one genetic cluster more strongly than another. Population variation should be taken into account in studies of S. noctilio spread and management within North America.     

The invasion of the azooxanthellate coral <Emphasis Type="Italic">Tubastraea</Emphasis> (Scleractinia: Dendrophylliidae) throughout the world: history,pathways and vectors

In this review, we describe the history, pathways and vectors of the biological invasion of the azooxanthellate coral Tubastraea (Scleractinia: Dendrophylliidae) throughout the world. In order to do so we consulted previous reports in the literature and also compiled new unpublished information on the distribution of the three species of Tubastraea which have been reported as non indigenous species, both within their native and non-native ranges and also on vectors, and where cryptogenic. We combine these data with historical aspects of marine vectors in order to get insights into how Tubastraea species have successfully spread around the world, established and invaded and where future studies would be best focused. T. coccinea and T. tagusensis are recognized as being highly invasive and are causing significant environmental, economic, and social impacts requiring management actions. The third species, T. micranthus so far only reported outside its native range on oil platforms, may have similar potential for negative impact. The vectors of introduction of Tubastraea may have changed throughout history and the biological invasion of these invasive corals may reflect changing practices, demands and legislation in shipping activities over the years. Today it is clear that these corals are fouling organisms strongly associated with oil and gas platforms worldwide which are thus primary vectors for new introductions.