Investigating the genetic diversity and differentiation patterns in the <Emphasis Type="Italic">Penstemon scariosus</Emphasis> species complex under different sample sizes using AFLPs and SSRs

Habitat fragmentation due to anthropogenic activities is the major cause of biodiversity loss. Endemic and narrowly distributed species are the most susceptible to habitat degradation. Penstemon scariosus is one of many species whose natural habitat is vulnerable to industrialization. All varieties of P. scariosus (P. scariosus var. albifluvis, P. scariosus var. cyanomontanus, P. scariosus var. garrettii, P. scariosus var. scariosus) have small distribution ranges, but only P. scariosus var. albifluvis is being considered for listing under the Endangered Species Act. We used eight microsatellites or simple sequence repeats (SSRs) loci and two amplified fragment length polymorphism (AFLP) primer combinations to investigate the population genetic structure and diversity of P. scariosus varieties. Moreover, we compared the utility of the two marker systems in conservation genetics and estimated an appropriate sample size in population genetic studies. Genetic differentiation among populations based on F_st ranged from low to moderate (F_st?=?0.056–0.157) and from moderate to high when estimated with D_es (D_es?=?0.15–0.32). Also, AMOVA analysis shows that most of the genetic variation is within populations. Inbreeding coefficients (F_is) were high in all varieties (0.20–0.56). The Bayesian analysis, STRUCTURE, identified three clusters from SSR data and four clusters from AFLPs. Clusters were not consistent between marker systems and did not represent the current taxonomy. MEMGENE revealed that a high proportion of the genetic variation is due to geographic distance (R²?=?0.38, P?=?0.001). Comparing the genetic measurements from AFLPs and SSRs, we found that AFLP results were more accurate than SSR results across sample size when populations were larger than 25 individuals. As sample size decreases, the estimates become less stable in both AFLP and SSR datasets. Finally, this study provides insight into the population genetic structure of these varieties, which could be used in conservation efforts.     

Phylogenetic Inferences and the Evolution of Plastid DNA in Campynemataceae and the Mycoheterotrophic <Emphasis Type="Italic">Corsia dispar</Emphasis> D.L Jones &amp; B. Gray (Corsiaceae)

The phylogenetic positions of the families Campynemataceae and Corsiaceae within the order Liliales remains unclear. To date, molecular data from the plastid genome of Corsiaceae has been obtained exclusively from Arachnitis, for which alignment and phylogenetic inference has proved difficult. The extent of gene conservation among mycoheterotrophic species within Corsiaceae remains unknown. To clarify the phylogenetic position of Campynemataceae and Corsiaceae within Liliales, functional plastid-coding genes of species representing both families have been analyzed. Examination of two phylogenetic data sets of plastid genes employing parsimony, maximum-likelihood, and Bayesian inference methods strongly supported both families forming a basal clade to the remaining taxa of Liliales. The first data set consists of five functional plastid-encoded genes (matK, rps7, rps2, rps19, and rpl2) sequenced from Corsia dispar (Corsiaceae). The data set included 31 species representing all families within Liliales, as well as selected orders that are related closely to Liliales (10 outgroup species from Asparagales, Dioscoreales, and Pandanales). The second phylogenetic analysis was based on 75 plastid genes. This data set included 18 species from Liliales, representing major clades within the order, and 10 outgroup species from Asparagales, Dioscoreales, and Pandanales. In this latter data set, Campynemataceae was represented by 60 plastid-encoded genes sequenced from herbarium material of Campynema lineare. A large proportion of the plastid genome of C. dispar was also sequenced and compared to the plastid genomes of photosynthetic plants within Liliales and mycoheterotrophic plants within Asparagales to explore plastid genome reduction. The plastid genome of C. dispar is in the advanced stages of reduction, which signifies its high dependency on mycorrhizal fungi and is suggestive of a loss in photosynthetic ability. Functional plastid genes found in C. dispar may be applicable to other species in Corsiaceae, which will provide a basis for in-depth molecular analyses of interspecies relationships within the family, once molecular data from other members become available.     

Impacts of granivorous and frugivorous arthropods on pre-dispersal seed production of western juniper (<Emphasis Type="Italic">Juniperus occidentalis</Emphasis>)

Arthropods impact seed production in various juniper species, but effects of pre-dispersal seed predation are generally unknown for arthropods that feed on western juniper (Juniperus occidentalis). From 2009 to 2013, we quantified impacts of three arthropod granivores and a frugivorous insect on western juniper seed production at two N. California field sites—Madeline and Shinn Peak. Insect larvae were genetically identified using the COI barcode region. Seed damage by all arthropod taxa varied both spatially and temporally. Juniper berry mites (Trisetacus quadricetus) had the greatest effect on reducing seed production at Madeline, and granivorous moths (Periploca spp. and Argyresthia spp.) had the greatest effect at Shinn Peak. Three findings supported the predator satiation hypothesis, which suggests that unpredictable masting events overwhelm responses of seed predators. First, estimated berry production had significant negative effects on the proportion of seeds damaged across sites by a chalcidoid wasp (Eurytoma juniperina) and by granivorous moths at Shinn Peak. Second, seed damage by granivorous moths was significantly reduced in a mast year of juniper berry production. Third, number of seeds per berry positively affected seed damage across sites by granivorous moths in all years except the mast year as well as damage by a frugivorous tortricid moth (Henricus infernalis) at Madeline. Distance to neighboring trees had positive, site-specific effects on damage by granivorous moths and Henricus, perhaps due to limited movement of parasitoids that attack these insects. Our results suggest that arthropod damage can significantly impact seed production of western juniper.     

Molecular phylogeny and genetic diversity of genus <Emphasis Type="Italic">Capparis</Emphasis> (Capparaceae) based on plastid DNA sequences and ISSR markers

Capparis (Capparaceae) has been used as a medicinal plant since ancient time. Capparis species were divided into Old World and New World taxa as described by the sectional division of Capparis. However, plastid DNA sequence data of Indian Capparis species were not analyzed in previous phylogenetic studies. Here, we have added Indian Capparis data in previous phylogeny and analyzed the relationship of Indian Capparis with Old World and New World taxa. The plastid phylogeny presented here includes Capparis taxa from its major distribution areas, New World and African capparoids. The presented phylogeny is used for the determination of biogeographic history of Capparis and recently segregated genera. Phylogenetic analyses of the combined plastid data revealed that the Indian Capparis are more closely related to Old World taxa and have connections with African, Australian and Eastern Asian species. Sectional classification of Old World and Indian Capparis considered in this study is reflected from the presented plastid phylogeny. The ancestral area reconstruction using Bayesian Binary Markov Chain Monte Carlo method strongly supports for the Africa as the ancestral region for both Old World and New World Capparis. Molecular marker-based genetic diversity studies on Indian Capparis are scarce. This work also includes the genetic diversity study of Indian Capparis species. Utility and efficacy of ISSR markers to study inter- and intraspecies variation in Capparis is evident from the AMOVA results.     

African Cycad Ecology,Ethnobotany and Conservation: A Synthesis

Africa hosts a rich assemblage of cycads: 66 Encephalartos species, Stangeria eriopus and Cycas thouarsii. Most Encephalartos and S. eriopus adults appear to be fire-tolerant, and certain Encephalartos species may be fire-dependent. Four Encephalartos species and S. eriopus are primarily insect-pollinated. African cycad populations typically have sex ratios of 1:1, with very small populations often male-biased. Coning is typically infrequent and erratic, with many species exhibiting mast-seeding. Viable seed production in Encephalartos populations tends to decline with decreasing population size, and seed predation by weevils is common. Seed dispersal in Encephalartos is usually localized, but vertebrates may facilitate dispersal over longer distances. Stem material of 25 Encephalartos species and S. eriopus is used for traditional medicine, primarily in South Africa. Two-thirds of Africa’s cycad species are threatened, with four species already Extinct in the Wild. The illegal acquisition of cycads from wild populations is the principle threat to their persistence. Further research is recommended on seed and fire ecology, population dynamics, and the outcomes of conservation interventions.     

Reconstruction of molecular phylogeny of closely related <Emphasis Type="Italic">Amorphophallus</Emphasis> species of India using plastid DNA marker and fingerprinting approaches

Plastid DNA markers sequencing and DNA fingerprinting approaches were used and compared for resolving molecular phylogeny of closely related, previously unexplored Amorphophallus species of India. The utility of individual plastid markers namely rbcL, matK, trnH–psbA, trnLC–trnLD, their combined dataset and two fingerprinting techniques viz. RAPD and ISSR were tested for their efficacy to resolves Amorphophallus species into three sections specific clades namely Rhaphiophallus, Conophallus and Amorphophallus. In the present study, sequences of these four plastid DNA regions as well as RAPD and ISSR profiles of 16 Amorphophallus species together with six varieties of two species were generated and analyzed. Maximum likelihood and Bayesian Inference based construction of phylogenetic trees indicated that among the four plastid DNA regions tested individually and their combined dataset, rbcL was found best suited for resolving closely related Amorphophallus species into section specific clades. When analyzed individually, rbcL exhibited better discrimination ability than matK, trnH–psbA, trnLC–trnLD and combination of all four tested plastid markers. Among two fingerprinting techniques used, the resolution of Amorphophallus species using RAPD was better than ISSR and combination of RAPD +ISSR and in congruence with resolution based on rbcL.     

Molecular variation and population structure in endangered <Emphasis Type="BoldItalic">Limonium</Emphasis><Emphasis Type="BoldItalic">bicolor</Emphasis>: genetic diversity of microsatellite markers and amplified fragment length polymorphism analysis

Knowledge and analysis of the genetic structure of an endangered species is important for its conservation and evolutionary process. Simple sequence repeats (SSRs) and amplified fragment length polymorphisms (AFLPs) were used in evaluation of the genetic diversity and population differentiation in Limonium bicolor (Plumbaginaceae), an endangered herb with high medicinal and horticulture value. A total of 117 alleles were detected with an average 5.85 alleles per locus using SSR and 222 bands from AFLP were amplified in six populations. It was found that L. bicolor was characterized by high levels of genetic polymorphism (100 and 83.78%), low levels of total genetic diversity (\(H_{\mathrm{t}}=\) 0.2824 and 0.2424), and moderate degrees of genetic differentiation among populations (\(\Phi _{\mathrm{ST}} =\) 0.284 and 0.251). Analysis of molecular variance (AMOVA) revealed that the main variation component existed within populations (71.56%; 74.93%) rather than among populations (28.44%; 25.07%). Four main clusters were displayed in the UPGMA using TFPGA, which was consistent with the result of principal coordinate analysis (PCA) using NTSYS. Mutations or infrequent gene flow among populations can increase the plant slowly, thus in situ conservation policies should be implemented first for effective and sustainable development. At the same time, ex situ measures, such as those individuals with rare alleles, to maintain the relationships between individuals and populations are also proposed.     

<Emphasis Type="Italic">Tamarix</Emphasis> (Tamaricaceae) hybrids: the dominant invasive genotype in southern Africa

Hybridization is regarded as a rapid mechanism for increasing genetic variation that can potentially enhance invasiveness. Tamarix hybrids appear to be the dominant genotypes in their invasions. Exotic Tamarix are declared invasive in South Africa and the exotic T. chinensis and T. ramosissima are known to hybridize between themselves, and with the indigenous T. usneoides. However, until now, it was not known which species or hybrid is the most prevalent in the invasion. With a biocontrol programme being considered as a way of suppressing the alien Tamarix populations, it is important to document the population genetic dynamics of all species in the region. This investigation sought to identify Tamarix species in southern Africa and their hybrids, describe their population structure, and reveal the geographic origin of the invasive species. To achieve this, nuclear Internal Transcribed Spacer (ITS) sequence data and the multilocus Amplified Fragment Length Polymorphisms (AFLPs) markers were used. Phylogenetic analysis and population genetic structure confirmed the presence of three species in South Africa (T. chinensis, T. ramosissima and T. usneoides) with their hybrids. The indigenous T. usneoides is clearly genetically distant from the alien species T. chinensis and T. ramosissima. Interestingly, the Tamarix infestation in South Africa is dominated (64.7 %) by hybrids between T. chinensis and T. ramosissima. The exotic species match their counterparts from their places of origin in Eurasia, as well as those forming part of the invasion in the US.     

Spatial genetic structure in seed stands of <Emphasis Type="Italic">Pinus lumholtzii</Emphasis> B.L. Rob. &amp; Fernald in Durango,Mexico

Sad pine is one of the most prominent pine species in Mexico due to its conspicuous pendulous foliage and extreme habitat. However, scientific studies of the species are scarce, and genetic information on sad pine populations is lacking. This endemic tree species occurs naturally on the Sierra Madre Occidental where it covers a total area of about 1,600,000 ha. It typically grows with several species of Quercus and Pinus or in pure stands in uneven-aged forests. Pinus lumholtzii is naturally spatially fragmented, and genetic research on seed and pollen dispersal patterns and spatial genetic structure (SGS)—and the possible implications of these in terms of evolution, conservation and breeding management—is particularly important. Given the fragmented occurrence of the preferred soil type, the goal of this research was to use amplified fragment length polymorphism (AFLP) markers to identify potential differences in spatial genetic structure within and between five P. lumholtzii seed stands at fine and large scales. At the fine scale, we almost always observed non-significant autocorrelation, suggesting that the genetic variants of P. lumholtzii are randomly distributed in space within each sampled seed stand. At the larger scale, our findings provide strong support for the theory of isolation by distance that predicts the expected pattern of SGS at drift–dispersal equilibrium. We recommend a network of P. lumholtzii seed stands of maximum distances of 100 km among stands to prevent greater loss of local genetic variants and use the seeds for reforestations in a radius of maximal 50 km from their proveniences.     

Genome skimming and plastid microsatellite profiling of alder trees (<Emphasis Type="Italic">Alnus</Emphasis> spp., Betulaceae): phylogenetic and phylogeographical prospects

Alders (Alnus spp.) represent keystone species trees of riparian and mountainous habitats of the northern hemisphere. Previous genetic studies have suggested a complex intrageneric diversification with numerous events of interspecific hybridization and polyploidization. Here, we first aim to test the present taxonomical treatment of Alnus by generating phylogenetic hypotheses based on plastid and nuclear data obtained from species belonging to the three main alder subgenera (Alnus, Alnobetula, and Clethropsis). A genome-skimming strategy was used to assemble the complete plastome and the nuclear ribosomal DNA cluster of 22 Eurasian and American alder individuals. Phylogenies based on these data strongly support an early diverging subgenus Alnobetula, while members of the subgenus Clethropsis do not constitute a monophyletic clade and are embedded within the subgenus Alnus. Incongruent topologies also sustain reticulate evolution within this group. Our results thus suggest considering the subgenera Clethropsis and Alnus within the same taxonomical unit. Our second aim is to test for the utility of highly variable plastid markers (microsatellites) to investigate the phylogeographic patterns of Eurasian alder species. Fifty-two polymorphic plastid microsatellite markers were developed and tested on 33 populations of the subgenus Alnus in western Eurasia. On average, 4.3 alleles per locus were revealed in 131 individuals of Alnus glutinosa, allowing the identification of 30 chlorotypes (multiloci profiles). Strong phylogeographic signals and recurrent cytoplasmic captures between co-occurring species are revealed, demonstrating that our plastid microsatellite profiling method is suitable for tracing the post-glacial spread of maternal lineages among alder species. All these results finally support the use of nuclear genomic regions for species identification and of plastid markers for phylogeographic aspects and origin certification in genetic resource management.     

Biochemical evidence bearing on the domestication of<Emphasis Type="Italic">Phaseolus</Emphasis> (Fabaceae) beans

The genusPhaseolus (Fabaceae) consists of some 50 species, all of which are distributed in the Americas. Four of these contain cultigens.P. vulgaris (common bean),P. lunatus (lima bean),P. acutifolius (tepary bean),P. coccineus subsp.coccineus (runner bean); andP. coccineus subsp.polyanthus (no English vernacular name). Biochemical markers—phaseolin seed storage protein and isozymes—have provided new evidence on the organization of the first three species. Domestication has possibly caused a strong reduction in genetic diversity inP. vulgaris andP. acutifolius. BothP. vulgaris andP. lunatus cultivars result from at least two independent domestications, in Mesoamerica and in the Andes. These two species consist of two gene pools, each of which includes wild ancestors and their respective cultivated descendants. Our findings suggest the need for additional emphasis on genetic conservation of wild ancestors and their use in breeding programs and for a comparison of inter-gene pool vs. intra-gene pool crosses in breeding programs.     

The effects of introduced vespid wasps (<Emphasis Type="Italic">Vespula germanica</Emphasis> and <Emphasis Type="Italic">V. vulgaris</Emphasis>) on threatened native butterfly (<Emphasis Type="Italic">Oreixenica ptunarra</Emphasis>) populations in Tasmania

Introduced vespid wasps (Vespula germanica and V. vulgaris) are highly efficient predators of native invertebrates. They have the potential to reduce populations of threatened species and change ecosystem dynamics, yet their impact is largely unknown in Australia. The introduction of vespid wasps has coincided with a decline in numbers of threatened Ptunarra brown butterflies (Oreixenica ptunarra) in Tasmania, Australia. The Ptunarra brown butterfly is endemic to Tasmania, where its habitat has been fragmented by clearance for agriculture and forestry. Local extinctions of the species were previously thought to be principally due to its inability to fly the long distances between habitat patches in this disjointed landscape. We investigate the importance of the new threat of vespid wasp predation in the decline of O. ptunarra in the highland grasslands of northwest Tasmania. Numbers of O. ptunarra analysed over a period of 15 years dramatically declined after the arrival of vespid wasps. Wasp control was trialled to determine whether it affected butterfly numbers. Current control methods decreased wasp numbers considerably, resulting in a small increase in butterfly numbers, indicating that wasp predation is keeping O. ptunarra at low densities. Without ongoing conservation measures, it is likely that butterfly numbers will stay low, potentially leading to genetic bottlenecks and more local extinctions. An increase in the intensity of wasp control, in combination with other conservation management methods, is required for the protection and recovery of O. ptunarra.     

Species delimitation and conservation genetics of the Canarian endemic <Emphasis Type="Italic">Bethencourtia</Emphasis> (Asteraceae)

Bethencourtia Choisy ex Link is an endemic genus of the Canary Islands and comprises three species. Bethencourtia hermosae and Bethencourtia rupicola are restricted to La Gomera, while Bethencourtia palmensis is present in Tenerife and La Palma. Despite the morphological differences previously found between the species, there are still taxonomic incongruities in the group, with evident consequences for its monitoring and conservation. The objectives of this study were to define the species differentiation, perform population genetic analysis and propose conservation strategies for Bethencourtia. To achieve these objectives, we characterized 10 polymorphic SSR markers. Eleven natural populations (276 individuals) were analyzed (three for B. hermosae, five for B. rupicola and three for B. palmensis). The results obtained by AMOVA, PCoA and Bayesian analysis on STRUCTURE confirmed the evidence of well-structured groups corresponding to the three species. At the intra-specific level, B. hermosae and B. rupicola did not show a clear population structure, while B. palmensis was aggregated according to island of origin. This is consistent with self-incompatibility in the group and high gene flow within species. Overall, the genetic diversity of the three species was low, with expected heterozygosity values of 0.302 (B. hermosae), 0.382 (B. rupicola) and 0.454 (B. palmensis). Recent bottleneck events and a low number of individuals per population are probably the causes of the low genetic diversity. We consider that they are naturally rare species associated with specific habitats. The results given in this article will provide useful information to assist in conservation genetics programs for this endemic genus.     

Population size and land use affect the genetic variation and performance of the endangered plant species <Emphasis Type="Italic">Dianthus seguieri</Emphasis> ssp. <Emphasis Type="Italic">glaber</Emphasis>

Human activity and land use changes in the past decades have led to landscape homogenization and small-scale fragmentation of grassland habitats in most regions of central Europe. As a result, populations of many grassland species are small and strongly fragmented, facing extinction due to genetic depauperation and local maladaptation in remnant habitats. In this study, remaining populations of the strongly endangered grassland species Dianthus seguieri ssp. glaber (“Ragged Pink”) in Bavaria were investigated in order to evaluate the environmental factors influencing its genetic variation and performance. We first evaluated habitat, vegetation and population structure. Species performance was then studied by assessing the number of generative shoots, flowers and fertile capsules; and evaluating seed weight and seed viability. Finally, genetic variation was analyzed using molecular markers (AFLPs). Our analyses revealed that population size and land use abandonment have the strongest impact on genetic variation and species’ performance. Large and extended populations were most variable. 72 % of overall genetic variability of Dianthus seguieri ssp. glaber was found to be within populations, whereas 28 % remained between populations. Increased vegetation height and coverage, and a high proportion of gramineous species resulting from the lack of land use, reduced genetic variation, effective fruit and seed set. Our study shows that both population size and land use abandonment need to be considered to ensure the long term protection of endangered plant species. Maintaining an open habitat structure and adequate soil nutrient conditions through targeted annual mowing regime, over-storey vegetation trimming and green waste removal and the establishment of vegetation buffer strips will allow this species’ persistence and continuous recruitment.     

Identification of candidate genes of QTLs for seed weight in <Emphasis Type="Italic">Brassica napus</Emphasis> through comparative mapping among <Emphasis Type="Italic">Arabidopsis</Emphasis> and <Emphasis Type="Italic">Brassica</Emphasis>species

Background

Map-based cloning of quantitative trait loci (QTLs) in polyploidy crop species remains a challenge due to the complexity of their genome structures. QTLs for seed weight in B. napus have been identified, but information on candidate genes for identified QTLs of this important trait is still rare.

Results

In this study, a whole genome genetic linkage map for B. napus was constructed using simple sequence repeat (SSR) markers that covered a genetic distance of 2,126.4 cM with an average distance of 5.36 cM between markers. A procedure was developed to establish colinearity of SSR loci on B. napus with its two progenitor diploid species B. rapa and B. oleracea through extensive bioinformatics analysis. With the aid of B. rapa and B. oleracea genome sequences, the 421 homologous colinear loci deduced from the SSR loci of B. napus were shown to correspond to 398 homologous loci in Arabidopsis thaliana. Through comparative mapping of Arabidopsis and the three Brassica species, 227 homologous genes for seed size/weight were mapped on the B. napus genetic map, establishing the genetic bases for the important agronomic trait in this amphidiploid species. Furthermore, 12 candidate genes underlying 8 QTLs for seed weight were identified, and a gene-specific marker for BnAP2 was developed through molecular cloning using the seed weight/size gene distribution map in B. napus.

Conclusions

Our study showed that it is feasible to identify candidate genes of QTLs using a SSR-based B. napus genetic map through comparative mapping among Arabidopsis and B. napus and its two progenitor species B. rapa and B. oleracea. Identification of candidate genes for seed weight in amphidiploid B. napus will accelerate the process of isolating the mapped QTLs for this important trait, and this approach may be useful for QTL identification of other traits of agronomic significance.

     

Tree squirrel habitat selection and predispersal seed predation in a declining subalpine conifer

Differential responses by species to modern perturbations in forest ecosystems may have undesirable impacts on plant-animal interactions. If such disruptions cause declines in a plant species without corresponding declines in a primary seed predator, the effects on the plant could be exacerbated. We examined one such interaction between Pinus albicaulis (whitebark pine), a bird-dispersed, subalpine forest species experiencing severe population declines in the northern part of its range, and Tamiasciurus hudsonicus (red squirrel), an efficient conifer seed predator, at 20 sites in two distinct ecosystems. Hypotheses about squirrel habitat preferences were tested to determine how changes in forest conditions influence habitat use and subsequent levels of predispersal cone predation. We performed habitat selection modeling and variable ranking based on Akaike’s information criterion; compared the level and variance of habitat use between two forest types (P. albicaulis dominant and mixed conifer); and modeled the relationship between P. albicaulis relative abundance and predispersal cone predation. T. hudsonicus did not demonstrate strong habitat preference for P. albicaulis, and thus, declines in the pine were not met with proportional declines in squirrel habitat use. P. albicaulis habitat variables were the least important in squirrel habitat selection. Squirrel habitat use was lower and varied more in P. albicaulis-dominant forests, and predispersal cone predation decreased linearly with increasing P. albicaulis relative abundance. In Northern Rocky Mountain sites, where P. albicaulis mortality was higher and abundance lower, squirrel predation was greater than in Central Rocky Mountain sites. In ecosystems with reduced P. albicaulis abundance, altered interactions between the squirrel and pine may lead to a lower proportion of P. albicaulis contributing to population recruitment because of reduced seed availability. Reducing the abundance of competing conifers will create suboptimal squirrel habitat, thus lowering cone predation in P. albicaulis and ensuring more seeds are available for avian dispersal.     

Introgression from non-native species unveils a hidden threat to the migratory Neotropical fish <Emphasis Type="Italic">Prochilodus hartii</Emphasis>

Invasive species are one of the greatest threats to biodiversity, due to competition, predation, pathogen spread, and hybridization. The latter may remain undetected and impair the survival of species, due to genetic admixture and hybrid swarming (i.e., interbreeding between hybrid individuals and backcrossing with parental species). The impact of invasive species remains poorly studied in the Neotropical ichthyofauna, particularly when considering the potential for hybridization between native and introduced species. Due to fisheries importance and its commercial value, species of the Prochilodus genus have been introduced to other catchments in Brazil. Here, we evaluate the introduction of non-native Prochilodus species and the potential effect of hybridization with the native migratory fish P. hartii. To evaluate possible introgression of Prochilodus spp. to P. hartii in the Jequitinhonha river basin (JRB), we employed a morphogenetic approach, analysing 219 specimens sampled from a broad extent of the river basin. Morphological analyses using meristic characters were incongruent with molecular identification by DNA barcoding (COI) in 22.83% of the analysed specimens. Haplotypes from three non-native species (P. argenteus, P. costatus, and P. lineatus) were recovered from specimens morphologically identified as P. hartii. Hybridization between P. hartii and introduced species was confirmed using co-dominant nuclear microsatellite markers. We observed a pronounced introgression pattern in this Neotropical basin, and paradoxically, despite being one of the most abundant migratory species native to the JRB, due to ongoing levels of introgression, P. hartii’s genetic integrity and conservation might be affected.     

<Emphasis Type="Italic">Bruguiera hainesii</Emphasis>, a critically endangered mangrove species,is a hybrid between <Emphasis Type="Italic">B. cylindrica</Emphasis> and <Emphasis Type="Italic">B. gymnorhiza</Emphasis> (Rhizophoraceae)

Bruguiera hainesii (Rhizophoraceae) is one of the two Critically Endangered mangrove species listed in the IUCN Red List of Threatened Species. Although the species is vulnerable to extinction, its genetic diversity and the evolutionary relationships with other Bruguiera species are not well understood. Also, intermediate morphological characters imply that the species might be of hybrid origin. To clarify the genetic relationship between B. hainesii and other Bruguiera species, we conducted molecular analyses including all six Bruguiera species using DNA sequences of two nuclear genes (CesA and UNK) and three chloroplast regions (intergenic spacer regions of trnL-trnF, trnS-trnG and atpB-rbcL). For nuclear DNA markers, all nine B. hainesii samples from five populations were heterozygous at both loci, with one allele was shared with B. cylindrica, and the other with B. gymnorhiza. For chloroplast DNA markers, the two haplotypes found in B. hainesii were shared only by B. cylindrica. These results suggested that B. hainesii is a hybrid between B. cylindrica as the maternal parent and B. gymnorhiza as the paternal one. Furthermore, chloroplast DNA haplotypes found in B. hainesii suggest that hybridization has occurred independently in regions where the distribution ranges of the parental species meet. As the IUCN Red List of Threatened Species currently excludes hybrids (except for apomictic plant hybrids), the conservation status of B. hainesii should be reconsidered.