Population Genetics of New Zealand Pagrus auratus and Genetic Variation of an Aquaculture Broodstock

<p>Fisheries and aquaculture are major contributors of nutrition and animal protein worldwide. Understanding the genetic variation and differentiation within and between wild populations is important for both sustainable fisheries management and selection of aquaculture broodstock. This study determined the genetic variation and differentiation of New Zealand Pagrus auratus based on mitochondrial DNA control region sequencing and microsatellite DNA genotyping. Low but significant differentiation was measured between several sample sites, but otherwise the population was genetically panmictic. The M-ratio test and Fu’s Fs statistics indicate that there may have been historical bottlenecks at all sample sites and a more recent bottleneck in the Tasman Bay. Two South Island sites were identified that had not been through recent bottlenecks and were not significantly differentiated from the Tasman Bay, which may provide a source of gene flow to aid its genetic recovery. Comparison of the broodstock and wild genetic variation indicate that the broodstock represented most of the genetic variation found in high frequency in wild populations, but further wild-caught individuals may be needed, based on the criteria used in several previous studies. Simulations indicate that adding approximately 20 and 48 wild-caught individuals from multiple populations to the current broodstock was needed to represent all genetic variation above a target frequency of 0.05 in the Tasman Bay and all sample sites, respectively.</p>

Population Genetics of New Zealand Pagrus auratus and Genetic Variation of an Aquaculture Broodstock

<p>Fisheries and aquaculture are major contributors of nutrition and animal protein worldwide. Understanding the genetic variation and differentiation within and between wild populations is important for both sustainable fisheries management and selection of aquaculture broodstock. This study determined the genetic variation and differentiation of New Zealand Pagrus auratus based on mitochondrial DNA control region sequencing and microsatellite DNA genotyping. Low but significant differentiation was measured between several sample sites, but otherwise the population was genetically panmictic. The M-ratio test and Fu’s Fs statistics indicate that there may have been historical bottlenecks at all sample sites and a more recent bottleneck in the Tasman Bay. Two South Island sites were identified that had not been through recent bottlenecks and were not significantly differentiated from the Tasman Bay, which may provide a source of gene flow to aid its genetic recovery. Comparison of the broodstock and wild genetic variation indicate that the broodstock represented most of the genetic variation found in high frequency in wild populations, but further wild-caught individuals may be needed, based on the criteria used in several previous studies. Simulations indicate that adding approximately 20 and 48 wild-caught individuals from multiple populations to the current broodstock was needed to represent all genetic variation above a target frequency of 0.05 in the Tasman Bay and all sample sites, respectively.</p>

Evidence of a Recent Bottleneck in Plasmodium falciparum Populations on the Honduran–Nicaraguan Border

The countries of Central America and the island of Hispaniola have set the goal of eliminating malaria in less than a decade. Although efforts to reduce the malaria burden in the region have been successful, there has been an alarming increase in cases in the Nicaraguan Moskitia since 2014. The continuous decrease in cases between 2000 and 2014, followed by a rapid expansion from 2015 to the present, has generated a potential bottleneck effect in the populations of Plasmodium spp. Consequently, this study aimed to evaluate the genetic diversity of P. falciparum and the decrease in allelic richness in this population. The polymorphic regions of the pfmsp-1 and pfmsp-2 genes of patients with falciparum malaria from Honduras and Nicaragua were analyzed using nested PCR and sequencing. Most of the samples were classified into the K1 allelic subfamily of the pfmsp-1 gene and into the 3D7 subfamily of the pfmsp-2 gene. Despite the low genetic diversity found, more than half of the samples presented a polyclonal K1/RO33 haplotype. No sequence polymorphisms were found within each allelic subfamily. This study describes a notable decrease in the genetic diversity of P. falciparum in the Moskitia region after a bottleneck phenomenon. These results will be useful for future epidemiological investigations and the monitoring of malaria transmission in Central America.

Molecular analysis revealed genetic decline in hatchery-produced Cyprinus carpio

Population genetic structure of cultured fish species is vital for improving the fisheries management and stock enhancement programs. The genetic variability and population genetic structure at fourteen microsatellite loci of a total 210 individuals of Cyprinus carpio from six selected hatcheries were analyzed. The data obtained through microsatellite markers showed a low- to-moderate level of genetic diversity in terms of allele numbers (Na), allelic richness (Ar), effective allele numbers (Nae) and observed heterozygosity (Ho) in all the populations. At the examined loci, 32 out of 84 possible tests were observed to be significantly (P<0.05) deviated from the Hardy-Weinberg equilibrium. Maximal gene flow (Nm) and lower population differentiation (FST) was experienced among populations. However, significant (P<0.05) differentiation was observed among some populations. An analysis of the distribution of genetic variation indicated within individual was very high (69.07%), while, among individuals within populations and among populations was low (29.56% and 1.37%, respectively). Recent bottleneck was detected with the shifted mode. Phylogenetic neighbor joining tree analysis showed the two distinct clusters. The inferences of this study would be helpful for setting up effective management strategies for the better conservation of genetic integrity in the hatchery stocks of C. carpio.

Moderate Genetic Diversity and Demographic Reduction in the Threatened Giant Anteater, Myrmecophaga tridactyla

In general, large mammal species with highly specialized feeding behavior and solitary habits are expected to suffer genetic consequences from habitat loss and fragmentation. To test this hypothesis, we analyzed the genetic diversity distribution of the threatened giant anteater inhabiting a human-modified landscape. We used 10 microsatellite loci to assess the genetic diversity and population structure of 107 giant anteaters sampled in the Brazilian Central-Western region. No genetic population structuring was observed in this region suggesting no gene flow restriction within the studied area. On the other hand, the moderate level of genetic diversity (Ho = 0.54), recent bottleneck detected and inbreeding (Fis, 0.13; p ≤ 0.001) signatures suggest potential impacts on the genetic variation of this Xenarthra. Additionally, a previous demographic reduction was suggested. Thus, considering the increased human-promoted impacts across the entire area of distribution of the giant anteater, our results can illustrate the potential effects of these disturbances on the genetic variation, allowing us to request the long-term conservation of this emblematic species.

PipeMaster: inferring population divergence and demographic history with approximate Bayesian computation and supervised machine-learning in R

Understanding population divergence involves testing diversification scenarios and estimating historical parameters, such as divergence time, population size and migration rate. There is, however, an immense space of possible highly parameterized scenarios that are difsficult or impossible to solve analytically. To overcome this problem researchers have used alternative simulation-based approaches, such as approximate Bayesian computation (ABC) and supervised machine learning (SML), to approximate posterior probabilities of hypotheses. In this study we demonstrate the utility of our newly developed R-package to simulate summary statistics to perform ABC and SML inferences. We compare the power of both ABC and SML methods and the influence of the number of loci in the accuracy of inferences; and we show three empirical examples: (i) the Muller’s termite frog genomic data from Southamerica; (ii) the cottonmouth and (iii) and the copperhead snakes sanger data from Northamerica. We found that SML is more efficient than ABC. It is generally more accurate and needs fewer simulations to perform an inference. We found support for a divergence model without migration, with a recent bottleneck for one of the populations of the southamerican frog. For the cottonmouth we found support for divergence with migration and recent expansion and for the copperhead we found support for a model of divergence with migration and recent bottleneck. Interestingly, by using an SML method it was possible to achieve high accuracy in model selection even when several models were compared in a single inference. We also found a higher accuracy when inferring parameters with SML.

Genetic diversity of the Griffon vulture population in Serbia and its importance for conservation efforts in the Balkans

The Griffon vulture was once a widespread species across the region of Southeast Europe, but it is now endangered and in some parts is completely extinct. In the Balkan Peninsula the largest Griffon vulture inland population inhabits the territory of Serbia. We present, for the first time, the genetic data of this valuable population that could be a source for future reintroduction programs planned in South-eastern Europe. To characterize the genetic structure of this population we used microsatellite markers from ten loci. Blood samples were collected from 57 chicks directly in the nests during the ongoing monitoring program. We performed a comparative analysis of the obtained data with the existing data from three native populations from French Pyrenees, Croatia, and Israel. We have assessed the genetic differentiation between different native populations and determined the existence of two genetic clusters that differentiate the populations from the Balkan and Iberian Peninsulas. Furthermore, we analysed whether the recent bottleneck events influenced the genetic structure of the populations studied, and we found that all native populations experienced a recent bottleneck event, and that the population of Israel was the least affected. Nevertheless, the parameters of genetic diversity suggest that all analysed populations have retained a similar level of genetic diversity and that the Griffon vulture population from Serbia exhibits the highest value for private alleles. The results of this study suggest that the Griffon vulture populations of the Balkan Peninsula are genetically differentiated from the populations of the Iberian Peninsula, which is an important information for future reintroduction strategies.

Sex determination through X-Y heterogamety in Salix nigra

The development of non-recombining sex chromosomes has radical effects on the evolution of discrete sexes and sexual dimorphism. Although dioecy is rare in plants, sex chromosomes have evolved repeatedly throughout the diversification of angiosperms, and many of these sex chromosomes are relatively young compared to those found in vertebrates. In this study, we designed and used a sequence capture array to identify a novel sex-linked region (SLR) in Salix nigra, a basal species in the willow clade, and demonstrated that this species has XY heterogamety. We did not detect any genetic overlap with the previously characterized ZW SLRs in willows, which map to a different chromosome. The S. nigra SLR is characterized by strong recombination suppression across a 2 MB region and an excess of low frequency alleles, resulting in a low Tajima’s D compared to the remainder of the genome. We speculate that either a recent bottleneck in population size or factors related to positive or background selection generated this differential pattern of Tajima’s D on the X and autosomes. This discovery provides insights into factors that may influence the evolution of sex chromosomes in plants and contributes to a large number of recent observations that underscore their dynamic nature.

A New Viewpoint on Genetic Diversity in Prestice Black-Pied Pig: Did the Breed Suffer from a Bottleneck?

The research was aimed at determination of genetic variability of Prestice Black-Pied (PC) pig breed (Czech national breed and genetic resource) and to evaluate possible presence of recent bottleneck in this closed small pig population. One hundred and eighty of breeding boars were analysed by eleven tetramer Short Tandem Repeats (STR) panel specifically developed for the genotyping of breeding livestock. Despite the fact that appearance of rare alleles, which may be relatively increased after recent bottleneck, was discovered, the heterozygosity excess was not significant. The PC breed has not undergone recent bottleneck and remained at mutation-drift equilibrium.

Population Structure and Genetic Diversity among Isolates of Coccidioides posadasii in Venezuela and Surrounding Regions

ABSTRACT Coccidioides posadasii is a pathogenic fungus that causes coccidioidomycosis in many arid regions of the Americas. One of these regions is bordered by the Caribbean Sea, and the surrounding landscape may play an important role in the dispersion of C. posadasii across South America through southeastern Mexico, Honduras, Guatemala, and Venezuela. Comparative phylogenomic analyses of C. posadasii reveal that clinical strains from Venezuela are genetically distinct from the North American populations found in (i) Arizona and (ii) Texas, Mexico, and the rest of South America (TX/MX/SA). We find evidence for admixture between the Venezuela and the North American populations of C. posadasii in Central America. Additionally, the proportion of Venezuelan alleles in the admixed population decreases as latitude (and distance from Venezuela) increases. Our results indicate that the population in Venezuela may have been subjected to a recent bottleneck and shows a strong population structure. This analysis provides insight into potential for Coccidioides spp. to invade new regions. IMPORTANCE Valley Fever is a fungal disease caused by two species of fungi: Coccidioides immitis and C. posadasii. These fungi are found throughout the arid regions of North and South America; however, our understanding of genetic diversity and disease in South America is limited. In this report, we analyze 10 new genomes of Coccidioides posadasii from regions bordering the Caribbean Sea. We show that these populations are distinct and that isolates from Venezuela are likely a result of a recent bottleneck. These data point to patterns that might be observed when investigating recently established populations.