Estimates Of Genetic Diversity Research Articles

Comparing the Utility of Microsatellites and Single Nucleotide Polymorphisms in Conservation Genetics: Insights from a Study on Two Freshwater Fish Species in France

Biodiversity is facing an unprecedented crisis and substantial efforts are needed to conserve natural populations, especially in river ecosystems. The use of molecular tools to guide conservation practices in rivers has grown in popularity over the last decades, but the amount of precision and/or biological information that would be gained by switching from the traditional short tandem repeats (STRs) to the increasingly used single nucleotide polymorphisms (SNPs) is still debated. Here, we compared the usefulness of STRs and SNPs to study spatial patterns of genetic variability in two freshwater fish species (Phoxinus dragarum and Gobio occitaniae) in southern France. SNPs were obtained from a pool-seq procedure and mapped to new genome assemblies. They provided much more precise estimates of genetic diversity and genetic differentiation than STRs, but both markers allowed the detection of very similar genetic structures in each species, which could be useful for delineating conservation units. While both markers provided similar outcomes, there were two discrepancies in genetic structures that could, nonetheless, be explained by unrecorded stocking events. Overall, we demonstrated that SNPs are not unconditionally superior to STRs in the context of large-scale riverscape genetic conservation, and that the choice of marker should primarily be based on research questions and resources available.

Distribution of genetic diversity of neotropical Biomphalaria (Preston 1910) (Basommatophora: Planorbidae) intermediate hosts for schistosomiasis in Southeast Brazil

IntroductionBiomphalaria glabrata, B. tenagophila, and B. straminea occurrence are crucial for estimating the risk of infectious human schistosomiasis in the neotropics. How different geographic sample strategies influence snail genetic diversity estimations were here investigated for three Schistosoma mansoni hosts.MethodsMitochondrial gene sequences were employed for Cytochrome C Oxidase I (COI), ribosomal RNA (rRNA) 16S, and a dataset with concatenated gene sequences (COI+16S), resulting in an improved scientific hypothesis regarding the geographical distribution of snail species. This study compared the sequences of snails from the Middle Paranapanema (MP) hydrographic basin in a geographically restricted area (inner group) to snails widely distributed across a broad geographical range in São Paulo (outer group), Brazil from 1999 to 2017. DNA sequence polymorphisms and haplotype diversity were estimated using DNAsp software. Haplotype network trees were constructed using a network program. The geographical distribution of the haplotypes was mapped using QGIS. Haplotype variation and distribution were tested for population structure using analysis of molecular variance (AMOVA).Results and discussionThe genetic diversity of B. glabrata, sampled from disconnected but geographically close freshwater collections, was partitioned into two sequence groups. The haplotype network showed that the diversity of B. straminea was more spatially partitioned than in B. tenagophila, which exhibited two population groups. The haplotype distribution pattern for B. tenagophila showed many unique and exclusive haplotypes for all three loci. AMOVA showed that genetic diversity could be high in species inhabiting small geographical areas, and a large river is not a local geographical barrier for snail migration. This study found that the survey dimensions and snail samplings influenced the genetic diversity results obtained by mitochondrial DNA molecular markers.

Global patterns and drivers of genetic diversity among marine habitat‐forming species

AbstractAimIntraspecific genetic diversity is one of the pillars of biodiversity, supporting the resilience and evolutionary potential of populations. Yet, our knowledge regarding the patterns of genetic diversity at macroecological scales, so‐called macrogenetic patterns, remains scarce, particularly in marine species. Marine habitat‐forming (MHF) species are key species in some of the most diverse but also most impacted marine ecosystems, such as coral reefs and marine forests. We characterize the patterns and drivers of genetic diversity in MHF species and provide a macrogenetic baseline, which can be used for conservation planning and for future genetic monitoring programmes.LocationGlobal.Time periodContemporary.Major taxa studiedBryozoans, hexacorals, hydrozoans, octocorals, seagrasses, seaweeds, sponges.MethodsWe analysed a database including genetic diversity estimates based on microsatellites in more than 9,000 georeferenced populations from 140 species, which belong to seven animal and plant taxa. Focusing on expected heterozygosity, we used generalized additive models to test the effect of latitude, taxon, and conservation status. We tested the correlation between the species richness and the genetic diversity.ResultsWe reveal a significant but complex biogeographic pattern characterized by a bimodal latitudinal trend influenced by taxonomy. We also report a positive species genetic diversity correlation at the scale of the ecoregions. The difference in genetic diversity between protected and unprotected areas was not significant.Main conclusionsThe contrasting results between MHF animals and plants suggest that the latitudinal genetic diversity patterns observed in MHF species are idiosyncratic, as reported in terrestrial species. Our results support the existence of shared drivers between genetic and species diversities, which remain to be formally identified. Concerning, these macrogenetic patterns are not aligned from the existing network of marine protected areas. Providing the first macrogenetic baseline in MHF species, this study echoes the call regarding the need to consider genetic diversity in biodiversity assessments and management.

Genomic evaluation of native Walleye in the Appalachian region and the effects of stocking

AbstractObjectiveCreate a quicker and more accurate genetic assignment tool for Walleye Sander vitreus broodstock in the Eastern Highlands region and to quantify genetic diversity of four Walleye populations using next‐generation sequencing.MethodsTo determine the impacts of stocking nonnative Great Lakes strain Walleye on local populations, three Appalachian populations were sampled: two native populations (Rockcastle River, Kentucky, and New River, Virginia) and one population founded from the Great Lakes strain (Tygart Lake, West Virginia). Walleye from Lake Erie were used as a reference for the Great Lakes strain. Utilization of a genotype‐by‐sequencing approach supported genome‐wide estimates of genetic diversity, population structure, and creation of two single‐nucleotide polymorphism assays that can be used to rapidly identify Great Lakes‐strain, native Eastern Highland‐strain, and F1 hybrid Walleye.ResultResults indicate that the four populations we evaluated were genetically distinct from one another and that each population contains varying degrees of genetic differentiation relative to its source population. The stocked Tygart Lake population displayed lower genetic diversity in metrics such as nucleotide diversity (0.172 vs. 0.184), private alleles (4057 vs. 7623), and observed heterozygosity (0.163 vs. 0.204), likely indicative of genetic drift stemming from a founder effect. The two native populations displayed varying levels of genetic diversity. The New River population was found to have a higher ancestry of the Great Lakes strain in their genome than the Rockcastle River population, reflecting the known admixture of New River Walleye following historic stocking of Great Lakes‐derived Walleye. Our results also identified a pure native Eastern Highlands strain population that can be used for future augmentation and restoration of Eastern Highlands Walleye.ConclusionOur results provide a diagnostic single‐nucleotide polymorphism assay to quickly identify Great Lake strain, Eastern Highland strain, and their F1 hybrid for future management efforts and provide key population genetic insights to managers to enhance best management practices.

Characterization of tomato yellow leaf curl virus resistance genes and genetic variability in commercial tomato F1 hybrids

Tomato (Solanum lycopersicum L.) resistance to Tomato Yellow Leaf Curl Virus (TYLCV) is a major objective of breeding programs. Tomato breeders are now interested in the subsequent introgression of many resistance genes to increase resistance levels, expand resistance spectrum, and prolong the longevity of resistant cultivars. Many F1 hybrids are now multigene resistant. To select the best breeding materials, 15 commercial F1 tomato TYLCV-tolerant hybrids were evaluated for TYLCV resistance and productivity during the 2018 and 2019 fall seasons. Resistance genes were identified using gene-based molecular markers. Most hybrids have multiple heterozygous resistance genes. ‘Brivio’, ‘Dania’, ‘SV8320’, and ‘Tyrmes’ comprised resistance genes Ty-1/Ty-3, Ty-2, Ty-4, and ty-5. Thus, F1 hybrids exhibited moderate to mild symptoms, and viral replication was detected in their symptomless plants by PCR and qt-PCR. Genetic variability among hybrids, hybrid relationships, and inter-trait correlations were estimated based on phenotypes of TYLCV-tolerance, productivity, and fruit quality. Most traits had high estimates of genetic variance, genotypical coefficient of variance, and heritability. Genetic variability sufficed in selecting the best genotype. Based on multivariate analyses of principal components and hierarchical clusters, hybrids were highly diversified and divided into three clusters. Clusters 1 and 3 were better at TYLCV tolerance, yield, and fruit quality. Positive genotypical correlations were found between tolerance, total yield, and fruit quality (firmness, equatorial diameter, and TSS content). The use of ‘Brivio’, ‘Dania’, ‘SV8320’, and ‘Tyrmes’ will be very useful in TYLCV resistance breeding programs to pyramiding resistance genes by marker-assisted selection technique.

Estimates of Genetic Parameters for Milk, the Occurrence of and Susceptibility to Clinical Lameness and Claw Disorders in Dairy Goats.

The New Zealand goat industry accesses niche markets for high-value products, mainly formula for infants and young children. This study aimed to estimate the genetic parameters of occurrence and susceptibility of clinical lameness and selected claw disorders and establish their genetic associations with milk production traits. Information on pedigree, lameness, claw disorders, and milk production was collected on three farms between June 2019 and July 2020. The dataset contained 1637 does from 174 sires and 1231 dams. Estimates of genetic and residual (co)variances, heritabilities, and genetic and phenotypic correlations were obtained with uni- and bi-variate animal models. The models included the fixed effects of farm and parity, deviation from the median kidding date as a covariate, and the random effects of animal and residual error. The heritability (h2) estimates for lameness occurrence and susceptibility were 0.07 and 0.13, respectively. The h2 estimates for claw disorder susceptibilities ranged from 0.02 to 0.23. The genotypic correlations ranged from weak to very strong between lameness and milk production traits (-0.94 to 0.84) and weak to moderate (0.23 to 0.84) between claw disorder and milk production traits.

Genetic Variability and Correlation Estimates for Morpho-Physiological Characteristics in Half Sib Progenies of Toona ciliate

Genetic Variability and Correlation Estimates for Morpho-Physiological Characteristics in Half Sib Progenies of Toona ciliate

Genetic Diversity and Spatiotemporal Distribution of SARS-CoV-2 Alpha Variant in India

After the spill to humans, in the evolutionary timeline of SARS-CoV-2, several positively selected variants have emerged. A phylogeographic study on these variants can reveal their spatial and temporal distribution. In December 2020, the alpha variant of the severe acute respiratory syndrome coronavirus (SARS-CoV-2), which has been designated as a variant of concern (VOC) by the WHO, was discovered in the south-eastern United Kingdom (UK). Slowly, it expanded across India, with a considerable number of cases, particularly in North India. This study focuses on determining the prevalence and expansion of the Alpha variants in various parts of India mainly by using phylospatial analysis. The genetic diversity estimation has helped us to understand various evolutionary forces that have shaped the spatial distribution of this variant during its peak. Overall, our study paves the way to understanding the evolution and expansion of a virus variant, which may help to mitigate in the case of any future wave.

Estimation of genetic variability, correlation and path analysis in elite rice genotypes (Oryza sativa L.)

A trial was carried out to explore the variability and correlation among thirty five rice (Oryza sativa L.) germplasm for fifteen characters, during kharif 2017-18 at Bihar Agricultural University, Sabour, (Bihar). Analysis of variance revealed significant differences among all the genotypes and for all fifteen characters, which reflects that considerable amount of variability, were present in the genotypes. Two genotypes LPD104-B-B-1-8-2-1-1and RP5124-11-6-2 were identified as the superior genotypes for yield. The highest magnitude of genotypic coefficient of variation was recorded for length breadth ratio of rice grain, however highest phenotypic coefficients of variation were recorded for grain yield per plant followed by kernel length. High heritability coupled with high genetic advance as per cent mean was observed for kernel length and length breadth ratio. In this experiment grain yield per plant had positive and significant association with biological yield per plant, days to 50 per cent flowering, days to maturity, while remaining characters had non-significant association with yield. Path coefficient analysis revealed that the biological yield per plant, harvest index and kernel length had high positive direct effects on grain yield per plant indicating true relationship of these characters with grain yield. Therefore, these traits could be considered in rice improvement programme.

Genetic Diversity in Some Sesame (Sesamum indicum L.) Accessions Detected by Agro-morphological Characters and RAPD Markers*

Agro-morphological and Randomly Amplified PolymorphicDNA (RAPD) markers were used to determine the diversity andrelationships among 25 accessions of sesame from Sudan. Data on 16agro-morphological characters were collected from a field experiment,carried out at Shambat for three consecutive seasons (2006-2008) andsubjected to the procedure of cluster analysis. The results showed thatcluster analysis, based on Euclidean distance, of the agro-morphologicalcharacters grouped the 25 sesame accessions into seven clusters.Application of RAPD markers generated 48 bands with a 97.9%polymorphism. A dendrogram constructed from the RAPD data classifiedthe 25 sesame accessions into eight major clusters. It was concluded thatfor efficient estimation of genetic diversity and interrelationships amongsesame accessions, information obtained from both agro-morphologicalcharacters and RAPD should be combined.

Estimation of additive genetic variance when there are gene–environment correlations: Pitfalls, solutions and unexplored questions

Abstract Estimating the genetic variation underpinning a trait is crucial to understanding and predicting its evolution. A key statistical tool to estimate this variation is the animal model. Typically, the environment is modelled as an external variable independent of the organism, affecting the focal phenotypic trait via phenotypic plasticity. We studied what happens if the environment is not independent of the organism because it chooses or adjusts its environment, potentially creating non‐zero genotype–environment correlations. We simulated a set of biological scenarios assuming the presence or absence of a genetic basis for a focal phenotypic trait and/or the focal environment (treated as an extended phenotype), as well as phenotypic plasticity (the effect of the environment on the phenotypic trait) and/or ‘environmental plasticity’ (the effect of the phenotypic trait on the local environment). We then estimated the additive genetic variance of the phenotypic trait and/or the environment by applying five animal models which differed in which variables were fitted as the dependent variable and which covariates were included. We show that animal models can estimate the additive genetic variance of the local environment (i.e. the extended phenotype) and can detect environmental plasticity. We show that when the focal environment has a genetic basis, the additive genetic variance of a phenotypic trait increases if there is phenotypic plasticity. We also show that phenotypic plasticity can be mistakenly inferred to exist when it is actually absent and instead environmental plasticity is present. When the causal relationship between the phenotype and the environment is misunderstood, it can lead to severe misinterpretation of the genetic parameters, including finding ‘phantom’ genetic variation for traits that, in reality, have none. We also demonstrate how using bivariate models can partly alleviate these issues. Finally, we provide the mathematical equations describing the expected estimated values. This study highlights that not taking gene–environment correlations into account can lead to erroneous interpretations of additive genetic variation and phenotypic plasticity estimates. If we aim to understand and predict how organisms adapt to environmental change, we need a better understanding of the mechanisms that may lead to gene–environment correlations.

Increasing genomic prediction accuracy for unphenotyped full-sib families by modeling additive and dominance effects with large datasets in white spruce.

Genomic selection is becoming a standard technique in plant breeding and is now being introduced into forest tree breeding. Despite promising results to predict the genetic merit of superior material based on their additive breeding values, many studies and operational programs still neglect non-additive effects and their potential for enhancing genetic gains. Using two large comprehensive datasets totaling 4,066 trees from 146 full-sib families of white spruce (Picea glauca (Moench) Voss), we evaluated the effect of the inclusion of dominance on the precision of genetic parameter estimates and on the accuracy of conventional pedigree-based (ABLUP-AD) and genomic-based (GBLUP-AD) models. While wood quality traits were mostly additively inherited, considerable non-additive effects and lower heritabilities were detected for growth traits. For growth, GBLUP-AD better partitioned the additive and dominance effects into roughly equal variances, while ABLUP-AD strongly overestimated dominance. The predictive abilities of breeding and total genetic value estimates were similar between ABLUP-AD and GBLUP-AD when predicting individuals from the same families as those included in the training dataset. However, GBLUP-AD outperformed ABLUP-AD when predicting for new unphenotyped families that were not represented in the training dataset, with, on average, 22% and 53% higher predictive ability of breeding and genetic values, respectively. Resampling simulations showed that GBLUP-AD required smaller sample sizes than ABLUP-AD to produce precise estimates of genetic variances and accurate predictions of genetic values. Still, regardless of the method used, large training datasets were needed to estimate additive and non-additive genetic variances precisely. This study highlights the different quantitative genetic architectures between growth and wood traits. Furthermore, the usefulness of genomic additive-dominance models for predicting new families should allow practicing mating allocation to maximize the total genetic values for the propagation of elite material.

Survival analysis of productive life in Florida dairy goats using a Cox proportional hazards model.

Longevity is an economically important trait, since extending the functional life of a doe would allow us to keep the most productive females in the herd as long as possible, and this could result in the increased profitability of dairy farms. Thus, the objectives of this study were to determine the most important factors that influence the length of productive life (LPL) of female Florida goats and to estimate its genetic additive variance using a Cox proportional hazards model. The data consisted of 70,695 productive life records from 25,722 Florida females kidding between 2006 and 2020. A total of 19,495 does had completed their productive life while 6227 (24.2%) does had censored information. The pedigree contained information on 56,901 animals. The average censoring age and average failure age after first kidding for LPL were 36 and 47 months respectively. The model included, as time-independent effects, the age at first kidding and the interaction between herd, year and season of birth of the doe, and as time-dependent effects, the age at kidding, the interaction between herd, year and season of kidding, the within-herd class of milk production deviation, and the interaction between the lactation number and the stage of lactation. All fixed effects had a significant effect on LPL (p < 0.05). Does with older ages at the first kidding and an earlier age at kidding were at higher risk of being culled. A large difference among herds was observed in terms of culling risk, which highlighted the importance of adequate management practices. Also, high-producing does were less likely to be culled. The estimate of the additive genetic variance was 1.844 (in genetic standard deviation), with a heritability estimate of 0.58 ± 0.012. The results of this study are expected to contribute to the development of a genetic model for genetic evaluation of the length of the productive life of Spanish dairy goat breeds.

Heritability and genetic variance estimates for agronomic traits and glycoside yield in four elite stevia breeding populations

AbstractHeritability estimates of traits assist breeders in optimizing cultivar development and can help predict gain from selection in breeding programs. Narrow‐sense heritabilities were measured in agronomic traits and glycoside concentration in four elite stevia (Stevia rebaudiana Bertoni) populations using half‐sib family analysis. Gain from selection at 20% selection intensity was estimated for morphological, yield, and glycoside traits. Experiments were conducted in two field locations in North Carolina. Variation was observed across cultigens for agronomic traits including stem height, branch width, and leaf size, for both subjective and objective measurements. Yield, lodging resistance, disease resistance, and percent survival showed a high genetic variation across cultigens. In addition, glycosides including Reb A, Reb C, and Reb D also showed high variation by cultigen. Heritability estimates for plant morphological traits were highest for stem height, and moderate for yield and branch width. However, other traits such as leaf area and lodging resistance showed low heritability (0.10). Glycosides including Reb A, Reb C, Reb D, stevioside and total steviol glycosides (TSG) showed high heritability. The estimated gain from selection per year for stem height (24 mm/year), leaf area (131 mm2/year) and yield (dry weight) (1.2 Mg/ha per year) suggest significant improvements are possible per breeding cycle. The estimated gain for glycoside concentration and percent of TSG of Reb A (26.44 mg/g, 14.51%), Reb C (20.20 mg/g, 20.17%), Reb D (1.70 mg/g, 1.49%), stevioside (6.73 mg/g, 10.72%), and TSG (20.90 mg/g), similarly, indicate significant gains are possible per breeding cycle.

Genetic Variability, Heritability and Genetic Advance of Yield and Yield Contributing Characters in Putative M2 Dolichos Bean (Lablab purpureus L.) Accessions

Dolichos bean (Lablab purpureus L.) is a multipurpose, orphan leguminous crop in Kenya .It is characterized with narrow genetic diversity and low yield output. Use of nuclear techniques such as gamma ray induction in breeding for improved genetic variability is an effective approach in improvement of this important crop. Studies on genetic variability estimates of two Kenyan dolichos bean accessions were undertaken as the pre-requisites for selection of potential high yielding putative accessions for production. This study was conducted between May 2020 and October 2020 at biotechnology department, University of Eldoret research field, Kenya. 0gy, 300gy and 400gy mutant accessions of Eldo maridadi and Eldo black I respectively were raised in Randomized Complete Block Design (RCBD) with three replications. Data was collected either on plot basis or from randomly taken 3 plants on days to 50% flowering, leaf length, number of flower buds per race , raceme length (cm) , plant height (cm), number of nodes per raceme , pod length (cm), 100 seed weight (g), dry seed yield (g). The data collected for each quantitative trait was subjected to analysis of variance (ANOVA) for simple lattice design. There was high PCV and GCV coupled with high heritability in, raceme length (cm), plant height (cm), number of nodes per raceme, pod length (cm), 100 seed weight (g), dry seed yield per plant (g) in Eldo black I accession traits than in Eldo maridadi .The different accession following mutation did exhibit difference in trend of genetic variability estimates. An indication of genotypic differences, response to mutation, lesser influence of environment in expression of the traits, prevalence of additive gene action in their inheritance and amenability of the traits to simple selection. Eldo maridadi accessions exhibited high to low heritability with low genotypic advance as percent of mean in evaluated traits thus direct selection on this traits may not beneficial. Other traits or further improvements on yield potentiality and yield traits on the accessions of this genotype are suggested by creating variation and selection.

Estimation of genetic diversity using seed storage protein (SSP) profiling in wild and cultivated species of Cicer L

The narrow genetic diversity of chickpea is a serious impediment to modern cultivar creation. Seed storage proteins (SSPs) are stable and have minimal or no degradation when subjected to isolation and SDS-PAGE. We have characterized SSPs of 436 chickpea genotypes, belonging to nine annual Cicer species, originated from 47 countries by SDS-PAGE and determined the extent of genetic diversity in chickpea through clustering. Based on scoring, a total of 44 bands (10 to 170kDa) were identified, which were all polymorphic. The least appeared protein bands were 11, 160 and 170kDa where band of 11 and 160kDa was present exclusively in wild type. Five bands were present in < 10% of genotypes. Bands appeared in 200-300 genotypes were suggested less polymorphic, on contrary bands present in 10-150 genotypes were suggested more polymorphic. Polymorphism of protein bands in context to their potential functions reported in literature were explored and suggested that the glubulins were most and glutelins were least abundant, whereas albumins with their known role in stress tolerance can be used as marker in chickpea breeding. Cluster analysis produced 14 clusters, interestingly three clusters contained only Pakistani genotypes and thus Pakistani genotypes appeared as a separate entity from the rest of the genotypes. Our results indicate that SDS-PAGE of SSPs is a powerful technique in determining the genetic diversity plus it is easily adaptable, due to its cost effectiveness in comparison to other genomics tools.

Full-sib progenies show greater genetic diversity than half-sib progenies in sour passion fruit: an approach by ssr markers.

Genetic variability is the most important parameter in plant breeding based on selection. There is a need for morpho-agronomic and molecular characterization of Passiflora species, to exploit their genetic resources more efficiently. No study has yet been carried out to compare half-sib and full-sib families in relation to the magnitude of the genetic variability obtained in them, and then to elucidate the advantages or disadvantages of each one. In the present study, SSR markers were used to evaluate the genetic structure and diversity of half-sib and full-sib progenies of sour passion fruit. Two full-sib progenies (PSA and PSB), and a half-sib progeny (PHS), together with their parents, were genotyped with a set of eight pairs of SSR markers. Discriminant Analysis of Principal Components (DAPC) and Structure software were used to study the genetic structure of the progenies. The results indicate that the half-sib progeny has lower genetic variability, although it has higher allele richness. By the AMOVA most of the genetic variability was found within the progenies. Three groups were clearly observed in the DAPC analysis, while two hypothetical groups (k = 2) were observed in the Bayesian approach. The PSB progeny showed a high genetic mixture between the PSA and PHS progenies. Lower genetic variability is found in half-sib progenies. The results obtained here allow us to suppose that the selection within full-sib progenies will possibly provide better estimates of genetic variance in sour passion fruit breeding programs, since they provide greater genetic diversity.

Validation by SSRs of Morphometric Markers for Genetic Variability in Araucaria araucana (Molina) K. Koch

Araucaria araucana is an important seed and timber-yielding tree that grows naturally in the tropical and subtropical regions of the Andes in Argentina and Chile, and has also been introduced as an ornamental species in Europe. Genetic diversity has been observed in A. araucana native populations, but there have been no prior studies on the genetic diversity estimates of this species introduced in Europe. On the other hand, assessment of the genetic variation in Araucaria populations occurring in Europe might be an important tool in the selection of appropriate germplasms for ornamental nursery production and breeding strategies. In this study, morphological and genetic diversity was analysed using a previously defined descriptor list and SSR molecular markers in four putative populations of A. araucana, individuated in the Pistoia Nursery District (Tuscany, Italy). In total, 26 morphological descriptors and 28 SSR primer pairs were used for a diversity assessment of specimens. Results provide evidence for genetic and morphological correspondence among the four putative Araucaria populations. PCA and cluster analyses based on morphological traits clearly revealed three distinct clusters of specimens. SSR primers yielded 68% polymorphic loci among the considered populations, and 18 of them displayed informativeness for population genetics, according to a Polymorphic Information Content value larger than 0.25. This marker set revealed significant genetic differentiation, and UPGMA analysis enabled separation of these populations on the basis of their genetic distances into three main groups, which largely overlapped with clusters in the dendrogram obtained from the morphological data. In particular, in both cluster diagrams, all accessions belonging to a specific population were well separated from all the others due to matrix distances and differences in the canopy density that are more similar to conifers such as spruce, pine, or fir. ANOVA analysis and the FST value indicated a large between-population genetic variation. The Mantel test suggested that genetic differentiation between the four studied populations was positively correlated with morphological distance (r = 0.141, p &lt; 0.05). Thus, both morphological and genetic markers showed applicability across populations of different seed origins and proved suitable for the identification and characterization of A. araucana accessions.

Are There Edge Effects on the Genetic Diversity of the Trap-Jaw Ant Odontomachus chelifer (Formicidae: Ponerinae) in a Neotropical Savanna Fragment? A First Assessment.

Habitat fragmentation is considered an important threat to biodiversity, increasing species exposure to edge effects. The Brazilian Cerrado savanna is considered a biodiversity hotspot and has been converted to small, isolated fragments due to human activities. Ant communities and colony survivorship are known to be affected by edge effects in Cerrado, but to date there is no information on the genetic diversity of ant colonies at the edge of fragmented areas. Here, we investigate if colony genetic diversity and structure of Odontomachus chelifer (Latreille) ants (Hymenoptera: Formicidae) are subject to edge effects in a Cerrado reserve in southeast Brazil. Using microsatellites, we evaluated the number of breeders (queens and males) and the genetic diversity in O. chelifer colonies located in the interior versus edge of a Cerrado fragment. All O. chelifer nests had multiple queens, which presented a low mating frequency. The number of breeders and most estimates of genetic diversity did not differ between colonies at the edge versus interior of the fragment. Genetic structure was not influenced by nest location as well. However, we detected a small and positive increase in the observed heterozygosity in colonies located at fragment edges. High heterozygosity is thought to be particularly important in fast-changing environments, such as edges, providing an advantage for genetic diversity. Further investigation is needed to assess in greater detail how habitat loss affects O. chelifer biology. Our study is a first step toward elucidating edge effects on genetic diversity of ant colonies, a topic still poorly explored in tropical environments.

Characterization of 35 new microsatellite markers for the blacktip reef shark (Carcharhinus melanopterus) and cross-species amplification in eight other shark species.

Shark species are overfished at a global scale, as they are poached for the finning industry or are caught as bycatch. Efficient conservation measures require fine-scale spatial and temporal studies to characterize shark habitat use, infer migratory habits, analyze relatedness, and detect population genetic differentiation. Gathering these types of data is costly and time-consuming, especially when it requires collection of shark tissue samples. Genetic tools, such as microsatellite markers, are the most economical sampling method for collecting genetic data, as they enable the estimation of genetic diversity, population structure and parentage relationships and are thus an efficient way to inform conservation strategies. Here, a set of 45 microsatellite loci was tested on three blacktip reef shark (Carcharhinus melanopterus) populations from three Polynesian islands: Moorea, Morane and Tenararo. The set was composed of 10 previously published microsatellite markers and 35 microsatellite markers that were developed specifically for C. melanopterus as part of the present study. The 35 novel and 10 existing loci were cross-amplified on eight additional shark species (Carcharhinus amblyrhynchos, C. longimanus, C. sorrah, Galeocerdo cuvier, Negaprion acutidens, Prionacea glauca, Rhincodon typus and Sphyrna lewini). These species had an average of 69% of successful amplification, considered if at least 50% of the individual samples being successfully amplified per species and per locus. This novel microsatellite marker set will help address numerous knowledge gaps that remain, concerning genetic stock identification, shark behavior and reproduction via parentage analysis.