Colonization patterns of the invasive Brazilian peppertree, Schinus terebinthifolius, in Florida

Invasive species are believed to spread through a process of stratified dispersal consisting of short-distance diffusive spread around established foci and human mediated long-distance jumps. Brazilian peppertree (Schinus terebinthifolius), native to South America, was introduced twice as an ornamental plant into Florida, USA, just over 100 years ago. A previous study indicated that these two introductions were from genetically differentiated source populations in the native range. In this study, we took advantage of these contrasting genetic signatures to study the spatial spread of Brazilian peppertree across its entire range in Florida. A combination of spatial genetic and geostatistical analyses using chloroplast and nuclear microsatellite markers revealed evidence for both diffusive dispersal and long-distance jumps. Chloroplast DNA haplotype distributions and extensive bands of intra-specific hybridization revealed extensive dispersal by both introduced populations across the state. The strong genetic signature around the original introduction points, the presence of a general southeast to northwest genetic cline, and evidence for short-distance genetic spatial autocorrelation provided evidence of diffusive dispersal from an advancing front, probably by birds and small mammals. In the northernmost part of the range, there were patches having a high degree of ancestry from each introduction, suggesting long-distance jump dispersal, probably by the movement of humans. The evidence for extensive movement throughout the state suggests that Brazilian peppertree will be capable of rapidly recolonizing areas from which it has been eradicated. Concerted eradication efforts over large areas or the successful establishment of effective biocontrol agents over a wide area will be needed to suppress this species.     

The Brazilian peppertree seed-borne pathogen,Neofusicoccum batangarum,a potential biocontrol agent

The invasive exotic Brazilian peppertree, Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae) has become a serious threat to the delicate ecosystem of Everglades National Park in Florida, USA. More than 4000 ha in the Hole-in-the-Donut (HID) area within the park have been infested with Brazilian peppertree. Brazilian peppertree is a prolific seed producer, which enhances its invasive potential. Native phytopathogens can be a viable tool in the management of exotic species; no prior studies have reported on the occurrence of native seed-borne pathogens of Brazilian peppertree in Florida. This study showed that drupes of Brazilian peppertree are affected by seed-borne fungal pathogens. These fungal pathogens either cause germination failure or attack seedlings after germination, which results in reduced vigor or seedling death. The seed-borne fungal isolate BPSPF-1 was found to be virulent, and when inoculated it was able to kill Brazilian peppertree seedlings in seedling assays, and 1 year old saplings in greenhouse trials. Field inoculation of Brazilian peppertree branches with BPSPF-1 resulted in dieback symptoms. Host range studies on one related native species (winged sumac, Rhus copallinum) and one non-native species (mango, Mangifera indica) showed that neither was affected by girdle inoculation of stems. The BPSPF-1 isolate produced dark melanized mycelium on agar media and did not produce conidia or other fruiting structures. Based on ITS DNA sequence analyses, the isolate was identified as Neofusicoccum batangarum.     

Development of microsatellite markers for Qualea grandiflora (Vochysiaceae), a typical species of the Brazilian cerrado

? Premise of the study: Microsatellite primers were developed to investigate genetic diversity and population structure of Qualea grandiflora, a typical species of the Brazilian cerrado. ? Methods and Results: Eight microsatellite loci were isolated using an enrichment cloning protocol. These loci were tested on a population of 110 individuals of Q. grandiflora collected from a cerrado fragment in S?o Paulo State, Brazil. The loci polymorphism ranges from seven to 19 alleles and the average heterozygosity value is 0.568, while the average polymorphic information content is 0.799. ? Conclusions: The developed markers were found to be highly polymorphic, indicating their applicability to studies of population genetic diversity in Q. grandiflora.     

Microsatellite markers for the Amazon peacock bass (Cichla piquiti)

A set of primers to amplify 10 microsatellite DNA loci was developed for the Neotropical fish Cichla piquiti, one of the largest sized cichlids in the Amazon Basin. These loci were used to genotype individuals from two populations, one native population from the Tocantins River, the other an introduced population in southeast Brazil, Upper Paraná River. Cross-amplification was also successful for another species of peacock bass, C. kelberi. An average of 4.4 alleles per locus (2-9 alleles) was detected. These markers will be useful for the characterization of genetic structure of native populations, and also for invasive biology studies since Cichla species have been introduced in many river basins outside their native ranges.     

Testing the role of genetic factors across multiple independent invasions of the shrub Scotch broom (Cytisus scoparius)

Knowledge of the introduction history of invasive plants informs on theories of invasiveness and assists in the invasives management. For the highly successful invasive shrub Scotch broom, Cytisus scoparius, we analysed a combination of nuclear and chloroplast microsatellites for eight native source regions and eight independent invasion events in four countries across three continents. We found that two exotic Australian populations came from different sources, one of which was derived from multiple native populations, as was an invasive sample from California. An invasive population from New Zealand appeared to be predominantly sourced from a single population, either from the native or exotic ranges. Four invasive populations from Chile were genetically differentiated from the native range samples analysed here and so their source of introduction could not be confirmed, but high levels of differentiation between the Chilean populations suggested a combination of different sources. This extensive global data set of replicated introductions also enabled tests of key theories of invasiveness in relation to genetic diversity. We conclude that invasive populations have similar levels of high genetic diversity to native ranges; levels of admixture may vary across invasive populations so admixture does not appear to have been an essential requirement for invasion; invasive and native populations exhibit similar level of genetic structure indicating similar gene flow dynamics for both types of populations. High levels of diversity and multiple source populations for invasive populations observed here discount founder effects or drift as likely explanations for previously observed seed size differences between ranges. The high levels of genetic diversity, differential and source admixture identified for most exotic populations are likely to limit the ability to source biocontrol agents from the native region of origin of invasive populations.     

Characterization of polymorphic microsatellite loci in the invasive Brazilian pepper,Schinus terebinthifolius

Brazilian pepper trees (Schinus terebinthifolius) pose a significant threat to south Florida ecosystems. To identify the source population of this exotic species we developed eight trinucleotide (AAT) microsatellite loci. Polymorphism ranged from two to six alleles and heterozygosity from 30 to 100% in a sample of 10 individuals from across south Florida. Cross‐species amplification indicated that these loci may be useful in some members of the Anacardiaceae.     

Life history and host range of Oxydia vesulia transpeneus,an unsuitable biological control agent of Brazilian peppertree

The suitability of Oxydia vesulia transpeneus (Cramer) (Lepidoptera: Geometridae) was assessed as a potential biological control agent of the invasive weed Brazilian Peppertree Schinus terebinthifolia Raddi. Larvae were collected in Brazil feeding on the plant in its native range and colonised in quarantine where life history and host range studies were conducted (27?±?2°C; 50RH). Development time from neonate to adults when fed Brazilian peppertree leaves was 48.0 (±2.2) days for females and 51.0 (±1.3) days for males. Larvae generally required five (occasionally six) instars to reach the adult stage. Females had greater pupal weights 1004.1 (±45.9) mg compared with males 668.5 (±19.7) mg. Larvae were tested on seven non-target plant species from Florida natives, ornamentals, to economic species. Larvae completed development on all but one of these valued plant species. These results suggest that the host range of O. vesulia is not sufficiently specific for release as a biological control against Brazilian peppertree in the USA.     

The genetic consequences of a demographic bottleneck in an introduced biological control insect

Population bottlenecks may result in the loss of genetic diversity, with potentially negative consequences for species of interest in conservation biology, including rare species, invasive species and biological control agents. We examined mtDNA sequence data and four variable microsatellite loci (SSRs) in the melaleuca psyllid Boreioglycaspis melaleucae, which was introduced from Australia to Florida as a biological control agent of the invasive plant Melaleuca quinquenervia. We sampled psyllids in the native and introduced ranges as well as individuals stored from the original founding population. There was a clear loss of mtDNA haplotype diversity, as well as a loss of rare microsatellite alleles, in the introduced range. However, there was little genetic differentiation between the home and introduced ranges, and no evidence for a genetic bottleneck based on an analysis of heterozygosity with the microsatellite markers. Overall, the data showed that the demographic bottleneck had a limited effect on the genetics of populations in the new range.     

Land barriers and open oceans: effects on gene diversity and population structure in Avicennia germinans L. (Avicenniaceae)

Avicennia germinans L. is a widespread mangrove species occupying the west coast of Africa and the Atlantic and Pacific coasts of the Americas from the Bahamas to Brazil and Baja California to Peru. An amplified fragment length polymorphism (AFLP) molecular analysis was carried out to assess genetic architecture within this species and to evaluate the effects of the Atlantic Ocean and the Central American Isthmus (CAI) on population and regional genetic diversity and differentiation. In total, 349 polymorphic AFLP fragments were identified among 144 individuals from 14 populations from the east Atlantic, west Atlantic and east Pacific. Levels of genetic diversity varied considerably among populations, but were generally higher in populations from the east Atlantic. Regional differentiation between the Pacific coast and Atlantic populations was greater than between east and west Atlantic populations, suggesting that the CAI has had an important influence on population genetic structure in this species. The lower level of divergence of east Atlantic from west Atlantic populations suggests some dispersal across the Atlantic Ocean, although migration rates are probably low; Nm from GST equal to 0.41 and accumulation of private and rare alleles in the east Atlantic. Population differentiation did not appear to follow an isolation by distance model and has probably resulted from complex patterns of population bottlenecks, and founder events due to landscape changes during the Pleistocene, particularly in the west Atlantic. The molecular data provide no support for the treatment of east Atlantic populations as a separate species A. africana.     

Effect of herbivory on growth and biomass allocation of Brazilian peppertree (Sapindales: Anacardiaceae) seedlings in the laboratory

Brazilian peppertree (Schinus terebinthifolius Raddi), native to South America, is invading many ecosystems in south and central Florida. The defoliating tortricid moth Episimus unguiculus Clarke was selected as a potential biocontrol agent of Brazilian peppertree in Florida. The objective of this study was to examine the effect of different levels of herbivore damage on growth and biomass allocation of Brazilian peppertree seedlings in the laboratory. Three treatments were established: (1) no herbivory (control), (2) low herbivory (~4 larvae/plant), and (3) high herbivory (~12 larvae/plant). High levels of herbivory significantly reduced the number of leaflets, plant height, foliar biomass, foliar relative growth rate (RGR) and shoot: root ratio of Brazilian peppertree seedlings. Moreover, plants were not able to recover from herbivory after 2 months. The performance of Brazilian peppertree subjected to low herbivory levels did not differ from the control plants (no herbivory). The potential effectiveness of the biocontrol agent E. unguiculus to suppress this noxious weed is examined.     

Host range of the leaf-tier Tentamen atrivirgulatum Metz (Lepidoptera: Gelechiidae); an unsuitable candidate for biological control of Brazilian peppertree

ABSTRACT

The life history and host range of the South American leaf-tier Tentamen atrivirgulatum Metz, 2019 (Lepidoptera: Gelechiidae) was evaluated to determine its suitability for classical biological control of invasive Brazilian peppertree, Schinus terebinthifolia, in the USA. Larvae were collected during a survey in the native range of Brazil feeding on Brazilian peppertree. A quarantine colony was established and no-choice tests were conducted to determine the host range of this species. The results of these tests indicated that the larvae fed and completed development on seven of the eleven non-target species tested. Percent survival on these non-targets ranged from 20% to 100%. Larval survival was 50% when fed the target weed Brazilian peppertree. When larvae were fed leaves of these non-targets, pupal weights were significantly lower only for those fed Pistacia chinensis. Development time to the pupal and adult stages did not differ with larval diet. These no-choice results indicate T. atrivirgulatum larvae have a broad host range and thus this species will not be developed as a biological control agent for Brazilian peppertree in the USA.     

Signature of mid‐Pleistocene lineages in the European silver fir (Abies alba Mill.) at its geographic distribution margin

In a conservation and sustainable management perspective, we identify the ecological, climatic, and demographic factors responsible for the genetic diversity patterns of the European silver fir (Abies alba Mill.) at its southwestern range margin (Pyrenees Mountains, France, Europe). We sampled 45 populations throughout the French Pyrenees and eight neighboring reference populations in the Massif Central, Alps, and Corsica. We genotyped 1,620 individuals at three chloroplast and ten nuclear microsatellite loci. We analyzed within‐ and among‐population genetic diversity using phylogeographic reconstructions, tests of isolation‐by‐distance, Bayesian population structure inference, modeling of demographic scenarios, and regression analyses of genetic variables with current and past environmental variables. Genetic diversity decreased from east to west suggesting isolation‐by‐distance from the Alps to the Pyrenees and from the Eastern to the Western Pyrenees. We identified two Pyrenean lineages that diverged from a third Alpine–Corsica–Massif Central lineage 0.8 to 1.1 M years ago and subsequently formed a secondary contact zone in the Central Pyrenees. Population sizes underwent contrasted changes, with a contraction in the west and an expansion in the east. Glacial climate affected the genetic composition of the populations, with the western genetic cluster only observed in locations corresponding to the coldest past climate and highest elevations. The eastern cluster was observed over a larger range of temperatures and elevations. All demographic events shaping the current spatial structure of genetic diversity took place during the Mid‐Pleistocene Transition, long before the onset of the Holocene. The Western Pyrenees lineage may require additional conservation efforts, whereas the eastern lineage is well protected in in situ gene conservation units. Due to past climate oscillations and the likely emergence of independent refugia, east–west oriented mountain ranges may be important reservoir of genetic diversity in a context of past and ongoing climate change in Europe.     

Galls induced by Calophya latiforceps (Hemiptera: Calophyidae) reduce leaf performance and growth of Brazilian peppertree

Schinus terebinthifolia Raddi (Anacardiaceae) (Brazilian peppertree) is one of the most serious terrestrial invasive plants in Florida. The leaf galling psyllid, Calophya latiforceps Burckhardt (Hemiptera: Calophyidae), was discovered feeding on the Brazilian peppertree in Bahia, Brazil, in 2010, and is being evaluated for release as a biological control agent. In order to understand how this candidate biological control agent affects the growth of S. terebinthifolia, we measured the effect of the psyllid on photosynthesis, leaf chlorophyll content and plant growth. Infested plants had lower photosynthesis compared to uninfested plants 30 and 45 days after gall initiation, and chlorophyll content was lower over a 70-d period. Plant height was reduced 31% and biomass 11% after three months of infestation. Results of these studies suggest that C. latiforceps will negatively affect the growth of the Brazilian peppertree if released in Florida.     

Genetic relationships between feral cattle from Chirikof Island, Alaska and other breeds

The origin of cattle on Chirikof Island, off the coast of Alaska, is not well documented. We assessed genetic differentiation of cattle isolated on Chirikof Island from several breeds commonly used for commercial production in North America including breeds popularly believed to have contributed to the Chirikof Island population. A set of 34 microsatellite loci was used to genotype Angus, Charolais, Hereford, Highland, Limousin, Red Angus, Salers, Shorthorn, Simmental, Tarentaise and Texas Longhorn cattle sampled from North America and the Chirikof Island population. Resulting F(ST) statistics for these loci ranged from 0.06 to 0.22 and on average, 14% of total genetic variation was between breeds. Whether population structure was modelled as a bifurcating tree or genetic network, Chirikof Island cattle appeared to be unique and strongly differentiated relative to the other breeds that were sampled. Bayesian clustering for multiple-locus assignment to genetic groups indicated low levels of admixture in the Chirikof Island population. Thus, the Chirikof Island population may be a novel genetic resource of some importance for conservation and industry.     

Population genetic structure in Atlantic and Pacific Ocean common murres (Uria aalge): natural replicate tests of post‐Pleistocene evolution

Understanding the factors that influence population differentiation in temperate taxa can be difficult because the signatures of both historic and contemporary demographics are often reflected in population genetic patterns. Fortunately, analyses based on coalescent theory can help untangle the relative influence of these historic and contemporary factors. Common murres (Uria aalge) are vagile seabirds that breed in the boreal and low arctic waters of the Northern Hemisphere. Previous analyses revealed that Atlantic and Pacific populations are genetically distinct; however, less is known about population genetic structure within ocean basins. We employed the mitochondrial control region, four microsatellite loci and four intron loci to investigate population genetic structure throughout the range of common murres. As in previous studies, we found that Atlantic and Pacific populations diverged during the Pleistocene and do not currently exchange migrants. Therefore, Atlantic and Pacific murre populations can be used as natural replicates to test mechanisms of population differentiation. While we found little population genetic structure within the Pacific, we detected significant east–west structuring among Atlantic colonies. The degree that population genetic structure reflected contemporary population demographics also differed between ocean basins. Specifically, while the low levels of population differentiation in the Pacific are at least partially due to high levels of contemporary gene flow, the east–west structuring of populations within the Atlantic appears to be the result of historic fragmentation of populations rather than restricted contemporary gene flow. The contrasting results in the Atlantic and Pacific Oceans highlight the necessity of carefully considering multilocus nonequilibrium population genetic approaches when reconstructing the demographic history of temperate Northern Hemisphere taxa.     

Laboratory biology and impact of a stem-boring weevil Apocnemidophorus pipitzi (Coleoptera: Curculionidae) on Schinus terebinthifolia

Brazilian peppertree, Schinus terebinthifolia Raddi (Anacardiaceae), was introduced into Florida, USA, from South America as an ornamental plant in the late 19th and early 20th centuries. It eventually escaped cultivation and is a serious threat to the state’s biodiversity. In the 1980s, this invasive weed was targeted for classical biocontrol. Surveys for natural enemies of Brazilian peppertree conducted in the native range resulted in the discovery of several candidate biocontrol agents. A stem-boring weevil identified as Apocnemidophorus pipitzi (Faust) was collected in Paraguay and transported under permit to Florida, USA. A laboratory colony of A. pipitzi was established in April 2007 by caging adults on cut branches of Brazilian peppertree supplemented with leaf bouquets. Adults are defoliators that feed mainly on the upper surface of subterminal leaflets. Females deposit eggs singly inside the stems and larvae feed under the bark where they damage the vascular cambium. There are five instars, pupation occurs inside the stem and a new generation is produced in 3–4 months. Growth of potted plants with and without exposure to weevil herbivory was compared over an 11-month period. Feeding damage by adults and larvae significantly increased leaf abscission and reduced leaf and root biomass accumulation.     

Origins and distribution of invasive Rubus fruticosus L. agg. (Rosaceae) clones in the Western United States

In facultatively asexual invasive species, an understanding of the origins and diversity of clones can reveal introduction and invasion pathways and inform management efforts. In this study, we use microsatellite and chloroplast DNA markers to infer clonal diversity of the Rubus fruticosus agg. invasion in the Western United States, determine the relationship of these clones to clones found in other exotic ranges, and determine the geographic and genetic origins of the invasive clones. We found two invasive clones in the Western United States, where the invasion had previously been thought to consist of a single asexual lineage. The most common clone was genetically identical to the microspecies R. armeniacus from the native range of Germany, while the second clone was identical to the microspecies R. anglocandicans in the invaded range of Australia and closely related to samples from the native ranges of England and Serbia. A third distinct clone was identified in a collection from the exotic range of Chile. Our results demonstrate that cryptic genetic diversity may be present in asexual invasions that are thought to be homogeneous. However, the asexual relationships between R. fruticosus agg. clones in the native and multiple exotic ranges indicate that preadaptation has played an important role in invasion success in this species aggregate.     

Multiplex PCR panel of microsatellite markers for the tambaqui, Colossoma macropomum, developed as a tool for use in conservation and broodstock management

The tambaqui, Colossoma macropomum, native to Brazil, is widely used in aquaculture systems. We developed a multiplex PCR panel for this species, comprising 12 microsatellite loci. This panel was used to genotype 73 specimens collected from Juruti, a city in the Brazilian Amazon. The mean number of alleles per locus was 8.8, the mean observed heterozygosity was 0.76, and the combined power of discrimination and the combined power of exclusion were 0.99999999999999993 and 0.999991762, respectively. We observed no significant deviation from Hardy-Weinberg equilibrium in this population. All amplified alleles were clearly typed, and easily interpretable results were obtained. This method will be useful for paternity analysis, population genetics and conservation studies, as well as for selective breeding programs for C. macropomum.     

Microsatellite Markers to Determine Population Genetic Structure in the Golden Anchovy,Coilia dussumieri

Coilia dussumieri (Valenciennes, 1848) commonly called as golden anchovy, constitutes a considerable fishery in the northern part of both the west and east coasts of India. Despite its clear-cut geographic isolation, the species is treated as a unit stock for fishery management purposes. We evaluated 32 microsatellite primer pairs from three closely related species (resource species) belonging to the family Engraulidae through cross-species amplification in C. dussumieri. Successful cross-priming was obtained with 10 loci, which were sequenced for confirmation of repeats. Loci were tested for delineating the genetic stock structure of four populations of C. dussumieri from both the coasts of India. The number of alleles per locus ranged from 8 to 18, with a mean of 12.3. Results of pairwise F _ST indicated genetic stock structuring between the east and west coast populations of India and also validated the utilization of identified microsatellite markers in population genetic structure analysis.