Unraveling biotypes of the northern house mosquito, Culex pipiens s.l. (Diptera: Culicidae): molecular differentiation and morphometric analysis.

Geometric morphometrics was used to determine whether geographic isolation could explain differences in wing size and shape between and within continental (27°S to 41°S) and insular (Rapa Nui) populations of Culex pipiens s.s. Linnaeus and their biotypes (f. pipiens and f. molestus). Molecular protocols based on polymorphisms in the second intron of nuclear locus ace-2 (acetylcholinesterase-2) were used to differentiate Cx. pipiens s.s. from Cx. quinquefasciatus Say, and an assay based on polymorphisms in the flanking region of a microsatellite locus (CQ11) was used to identify biotypes. Culex pipiens f. molestus and hybrids shared larval habitats in all continental sites, while Cx. pipiens f. pipiens was found in 5 of the 10 sites. Only biotype molestus was found in Rapa Nui (Easter Island) Pipiens and molestus biotypes occur sympatrically in aboveground locations, and only molestus was found in the underground site (ME). Biotype molestus was dominant in rural locations and preferably anthropophilic. These results agree with the ecological descriptions previously reported for the biotypes of Cx. pipiens s.s. Procrustes ANOVA only showed differences in centroid size between biotypes in females and males and did not show significant differences in wing shape. However, we found significant differences among the geographic areas in the centroid size and wing shape of both females and males. Particularly, the population of Rapa Nui Island had shorter wings than the continental populations. The results highlight the effects of geographic and environmental processes on morphotypes in vector mosquitoes.

Biomarker selection depends on gene function and organ: the case of the cytochrome P450 family genes in freshwater fish exposed to chronic pollution.

Pollution and its effects have been of major concern in recent decades. Many strategies and markers have been developed to assess their effects on biota. Cytochrome P450 (CYP) genes have received significant attention in this context because of their relationship with detoxification and activation of exogenous compounds. While their expression has been identified as a pollution exposure biomarker, in most cases, it has been tested only after acute exposures and for CYP genes associated with exogenous compounds. To elucidate CYP gene expression patterns under chronic pollution exposure, we have used the silverside Basilichthys microlepidotus as a model, which inhabits the Maipo River Basin, a freshwater system with different pollution levels. We performed next-generation RNA sequencing of liver and gill tissues from polluted and non-polluted populations. We found most CYP genes were not dysregulated by pollution, and the seven genes that were present and differentially expressed in liver and gill were mainly downregulated. Three CYP genes associated with exogenous compounds showed differential expression in the gill, while four CYP genes associated with endogenous compounds showed differential expression in the liver. The findings presented here highlight the importance of CYP genes, his family, tissues and his interaction in the context of pollution biomarkers use.

Population genomic and biophysical modeling show different patterns of population connectivity in the spiny lobster Jasus frontalis inhabiting oceanic islands.

Knowledge about connectivity between populations is essential for the fisheries management of commercial species. The lobster Jasus frontalis inhabits two oceanic island groups, the Juan Fernández Archipelago and the Desventuradas Islands, separated by 800 km. Since this species is primarily exploited in the Juan Fernández Archipelago, knowledge of the connectivity patterns among islands is foundational for species management. Here, we used variability at single-nucleotide polymorphisms (SNPs) and individual-based modeling (IBM) to estimate the genetic structure and connectivity between J. frontalis populations in these island groups. The variability at 9090 SNPs suggests two genetic populations, one in the Juan Fernández Archipelago and one in the Desventuradas Islands. Furthermore, IBM suggests an asymmetric connectivity pattern, with particles moving from the Juan Fernández Archipelago to the Desventuradas Islands but not vice versa. Since the IBM analysis suggests asymmetric larval movement between the islands, and the genetic analysis indicates isolation between the Juan Fernández Archipelago and the Desventuradas Islands, larval retention mechanisms such as small-scale oceanographic processes or behavior could hinder larval movement between islands. This study highlights the importance of using more than one methodology to estimate population connectivity.

Uniparental and biparental markers unravel invasion pathways, population admixture, and genetic structure in naturalized rainbow trout (Oncorhynchus mykiss).

The present study combined uniparental mtDNA and biparental SNPs to illuminate the invasion and colonization pathways of rainbow trout, Oncorhynchus mykiss, one of the world's most widespread invasive fishes, that has been intensively propagated in Chile, South America. The specific aims of the study were (i) to evaluate potential donor populations, which could be either from the species' native range in North America or from introduced populations in Europe, by comparing mtDNA D-loop/control region haplotypes; and (ii) to assess the factors that have shaped genetic diversity and contemporary genetic structure of rainbow trout populations introduced to Chile through SNP genotyping. The authors comprehensively sampled 24 sites in 12 basins ranging from the High Andean Plateau (Altiplano, 18° S) to northern Patagonia (41° S). Results of the mtDNA data of naturalized trout populations from rivers in the Altiplano (northern Chile) differed from those collected in central and southern Chile, suggesting an origin from North American hatcheries. Naturalized trout populations in central and southern Chile, on the contrary, shared haplotypes with specimens found in European hatcheries. The southern and central Chile populations also contained rare haplotypes, possibly indicating potential spread through aquaculture escapes. Results of the SNP analysis revealed higher allelic richness for trout sampled in sites influenced by commercial aquaculture than sites without commercial aquaculture, likely due to increased admixture between aquaculture broodstock and naturalized trout. The analysis further uncovered some complex patterns of divergent trout populations with low genetic diversity as well as increased relatedness between individuals from isolated sites, suggesting possible local populations. A comprehensive characterization of genetic diversity and structure of rainbow trout should help identify management areas that may augment socioeconomic benefits while preventing the spread and further impacts on biodiversity.

Chromosome Evolution of the Liolaemus monticola (Liolaemidae) Complex: Chromosomal and Molecular Aspects.

Chromosomal rearrangements can directly influence population differentiation and speciation. The Liolaemus monticola complex in Chile is a unique model consisting of several chromosome races arranged in a latitudinal sequence of increasing karyotype complexity from south to north. Here, we compared chromosomal and mitochondrial cytochrome b data from 15 localities across the northern geographic distribution of L. monticola. We expanded the distribution of the previously described Multiple Fissions race (re-described as MF2), in the Coastal range between the Aconcagua River and the Petorca River, and described a new Multiple Fissions 1 (MF1) race in the Andean range. Both races present centric fissions in pairs 1 and 2, as well as a pericentric inversion in one fission product of pair 2 that changes the NOR position. Additionally, we detected a new chromosomal race north of the Petorca River, the Northern Modified 2 (NM2) race, which is polymorphic for novel centric fissions in pairs 3 and 4. Our results increase the number of chromosomal races in L. monticola to seven, suggesting a complex evolutionary history of chromosomal rearrangements, population isolation by barriers, and hybridization. These results show the relevant role of chromosome mutations in evolution, especially for highly speciose groups such as Liolaemus lizards.

Spatial and temporal stability in the genetic structure of a marine crab despite a biogeographic break.

Elucidating the processes responsible for maintaining the population connectivity of marine benthic species mediated by larval dispersal remains a fundamental question in marine ecology and fishery management. Understanding these processes becomes particularly important in areas with a biogeographic break and unidirectional water movement along the sides of the break. Based on variability at 4209 single-nucleotide polymorphisms in 234 individuals, we determine the genetic structure, temporal genetic stability, and gene flow among populations of the commercially important mola rock crab Metacarcinus edwardsii in a system in southern Chile with a biogeographic break at latitude 42°S. Specimens were collected at eight sites within its geographic distribution, with collection at four of these sites was performed twice. Using population genetic approaches, we found no evidence of geographic or temporal population differentiation. Similarly, we found no evidence of an effect on gene flow of the biogeographic break caused by the the West Wind Drift Current. Moreover, migration analyses supported gene flow among all sites but at different rates for different pairs of sites. Overall, our findings indicate that M. edwardsii comprises a single large population with high levels of gene flow among sites separated by over 1700 km and demonstrate temporal stability in its genetic structure.

Genetics, Morphometrics and Health Characterization of Green Turtle Foraging Grounds in Mainland and Insular Chile.

Two divergent genetic lineages have been described for the endangered green turtle in the Pacific Ocean, occurring sympatrically in some foraging grounds. Chile has seven known green turtle foraging grounds, hosting mainly juveniles of different lineages. Unfortunately, anthropic factors have led to the decline or disappearance of most foraging aggregations. We investigated age-class/sex structure, morphological variation, genetic diversity and structure, and health status of turtles from two mainland (Bahia Salado and Playa Chinchorro) and one insular (Easter Island) Chilean foraging grounds. Bahia Salado is composed of juveniles, and with Playa Chinchorro, exclusively harbors individuals of the north-central/eastern Pacific lineage, with Galapagos as the major genetic contributor. Conversely, Easter Island hosts juveniles and adults from both the eastern Pacific and French Polynesia. Morphological variation was found between lineages and foraging grounds, suggesting an underlying genetic component but also an environmental influence. Turtles from Easter Island, unlike Bahia Salado, exhibited injuries/alterations probably related to anthropic threats. Our findings point to establishing legal protection for mainland Chile's foraging grounds, and to ensure that the administrative plan for Easter Island's marine protected area maintains ecosystem health, turtle population viability, and related cultural and touristic activities.

Smoke of Capsicum baccatum L. var. baccatum (Solanaceae) repels nymphs of triatoma infestans (Klug) (Hemiptera: Reduviidae) / Humo de capsicum baccatum L. var. baccatum (Solanaceae) repele las ninfas de Triatoma infestans (Klug) (Hemiptera: Reduviidae)

Control of the Chagas disease vector, Triatoma infestans (Klug) (Hemiptera: Reduviidae) with synthetic pesticides in Bolivia has become increasingly inefficient due to the development of resistance in the insects. In the Chaco region of Bolivia, guaraní populations have approached the problem by fumigating their houses with the smoke of native plants. Through interviews and field work with local guides, the main plant used by the guaraníes was collected and later identified as Capsicum baccatumL. var. baccatum (Solanaceae). In choice bioassays, filter papers exposed to the smoke of the plant repelled nymphs of T. infestans. Activity remained significant after storing the exposed filter papers for 9 days. Chemical analysis of smoke and literature data suggested that capsaicinoids present in the smoke were responsible for the repellent effect. The data presented provide a rationale for the use of C. baccatumvar. baccatumto control the Chagas vector bythe guaraní populations.

El control del vector de la enfermedad de Chagas, Triatoma infestans (Klug) (Hemiptera: Reduviidae) con plaguicidas sintéticos en Bolivia se ha vuelto cada vez más ineficiente debido al desarrollo de resistencias en los insectos. En la región del Chaco de Bolivia, las poblaciones guaraníes han abordado el problema fumigando sus casas con el humo de las plantas nativas. A través de entrevistas y trabajo de campo con guías locales, se recogió la principal planta utilizada por los guaraníes y posteriormente se identificó como Capsicum baccatumL. var. baccatum (Solanaceae). En bioensayos selectos, los papeles de filtro expuestos al humo de la planta repelieron a las ninfas de T. infestans. La actividad siguió siendo significativa después de almacenar los papeles de filtro expuestos durante 9 días. El análisis químico del humo y los datos de la literatura sugieren que los capsaicinoides presentes en el humo eran responsables del efecto repelente. Los datos presentados proporcionan una justificación para el uso de C. baccatum var. baccatum para el control del vector Chagas por las poblaciones guaraníes.

Integrating genetics, physiology and morphology to study desert adaptation in a lizard species.

Integration of multiple approaches is key to understand the evolutionary processes of local adaptation and speciation. Reptiles have successfully colonized desert environments, that is, extreme and arid conditions that constitute a strong selective pressure on organisms. Here, we studied genomic, physiological and morphological variations of the lizard Liolaemus fuscus to detect adaptations to the Atacama Desert. By comparing populations of L. fuscus inhabiting the Atacama Desert with populations from the Mediterranean forests from central Chile, we aimed at characterizing features related to desert adaptation. We combined ddRAD sequencing with physiological (evaporative water loss, metabolic rate and selected temperature) and morphological (linear and geometric morphometrics) measurements. We integrated the genomic and phenotypic data using redundancy analyses. Results showed strong genetic divergence, along with a high number of fixed loci between desert and forest populations. Analyses detected 110 fixed and 30 outlier loci located within genes, from which 43 were in coding regions, and 12 presented non-synonymous mutations. The candidate genes were associated with cellular membrane and development. Desert lizards presented lower evaporative water loss than those from the forest. Morphological data showed that desert lizards had smaller body size, different allometry, larger eyeballs and more dorsoventrally compressed heads. Our results suggest incipient speciation between desert and forest populations. The adaptive signal must be cautiously interpreted since genetic drift could also contribute to the divergence pattern. Nonetheless, we propose water and resource availability, and changes in habitat structure, as the most relevant challenges for desert reptiles. This study provides insights of the mechanisms that allow speciation as well as desert adaptation in reptiles at multiple levels, and highlights the benefit of integrating independent evidence.

High levels of connectivity over large distances in the diadematid sea urchin Centrostephanus sylviae.

Most benthic marine invertebrates with sedentary benthic adult phases have planktonic larvae that permit connectivity between geographically isolated populations. Planktonic larval duration and oceanographic processes are vital to connecting populations of species inhabiting remote and distant islands. In the present study, we analyzed the population genetic structure of the sea urchin Centrostephanus sylviae, which inhabits only the Juan Fernández Archipelago and the Desventuradas islands, separated by more than 800 km. For 92 individuals collected from Robinson Crusoe and Selkirk Islands (Juan Fernández Archipelago) and San Ambrosio Island (Desventuradas Islands), 7,067 single nucleotide polymorphisms (SNPs) were obtained. The results did not show a spatial genetic structure for C. sylviae; relative high migration rates were revealed between the islands. An analysis of the water circulation pattern in the area described a predominant northward water flow with periods of inverted flow, suggesting that larvae could move in both directions. Overall, this evidence suggests that C. sylviae comprises a single large population composed of individuals separated by more than 800 km.

Development and Validation of a Multi-Locus PCR-HRM Method for Species Identification in Mytilus Genus with Food Authenticity Purposes.

DNA-based methods using informative markers such as single nucleotide polymorphism (SNPs) are suitable for reliable species identification (SI) needed to enforce compliance with seafood labelling regulations (EU No.1379/2013). We developed a panel of 10 highly informative SNPs to be genotyped by PCR-High resolution melting (HRM) for SI in the Mytilus genus through in silico and in vitro stages. Its fitness for purpose and concordance were assessed by an internal validation process and by the transference to a second laboratory. The method was applicable to identify M. chilensis, M. edulis, M. galloprovincialis and M. trossulus mussels, fresh, frozen and canned with brine, oil and scallop sauce, but not in preserves containing acetic acid (wine vinegar) and tomato sauce. False-positive and negative rates were zero. Sensitivity, expressed as limit of detection (LOD), ranged between 5 and 8 ng/µL. The method was robust against small variations in DNA quality, annealing time and temperature, primer concentration, reaction volume and HRM kit. Reference materials and 220 samples were tested in an inter-laboratory assay obtaining an "almost perfect agreement" (κ = 0.925, p < 0.001). In conclusion, the method was suitable for the intended use and to be applied in the seafood industry.

Genetic diversity in a restricted-dispersal kissing bug: The centre-periphery hypothesis halfway.

The centre-periphery hypothesis (CPH) postulates that populations close to the centre of a species distribution will exhibit higher genetic diversity and lower genetic differentiation than populations located at the edge of the distribution. The centre of a species' distribution might represent an optimum for the environmental factors influencing the species absolute fitness and, therefore, genetic diversity. In species with wide distribution, the geographical variation of biotic and abiotic variables is crucial to understand the underlying mechanisms of the CPH. We evaluated the CPH and specifically tested which environmental variables better explained the patterns of genetic diversity in the kissing bug Mepraia spinolai, one of the main wild vectors of Chagas disease in southern South America, distributed across three Mediterranean climatic ecoregions in Chile. We analysed 2380 neutral single nucleotide polymorphisms to estimate genetic diversity. Mean winter temperature, mean summer temperature, vegetation cover, population abundance, proportion of winged individuals and female abdomen area were measured for each kissing bug population to construct a model. Lower genetic diversity was detected in populations at the edge of the distribution compared to those in the centre. However, genetic differentiation was not higher in the periphery. Genetic diversity was related to climatic and biological variables; there was a positive relationship with mean winter temperature and a negative association with mean summer temperature and body size. These results partially support the CPH and identify biotic (abdomen area) and abiotic (winter/summer temperatures) factors that would affect genetic diversity in this restricted-dispersal species of epidemiological relevance.

Green, yellow or black? Genetic differentiation and adaptation signatures in a highly migratory marine turtle.

Marine species may exhibit genetic structure accompanied by phenotypic differentiation related to adaptation despite their high mobility. Two shape-based morphotypes have been identified for the green turtle (Chelonia mydas) in the Pacific Ocean: the south-central/western or yellow turtle and north-central/eastern or black turtle. The genetic differentiation between these morphotypes and the adaptation of the black turtle to environmentally contrasting conditions of the eastern Pacific region has remained a mystery for decades. Here we addressed both questions using a reduced-representation genome approach (Dartseq; 9473 neutral SNPs) and identifying candidate outlier loci (67 outlier SNPs) of biological relevance between shape-based morphotypes from eight Pacific foraging grounds (n = 158). Our results support genetic divergence between morphotypes, probably arising from strong natal homing behaviour. Genes and enriched biological functions linked to thermoregulation, hypoxia, melanism, morphogenesis, osmoregulation, diet and reproduction were found to be outliers for differentiation, providing evidence for adaptation of C. mydas to the eastern Pacific region and suggesting independent evolutionary trajectories of the shape-based morphotypes. Our findings support the evolutionary distinctness of the enigmatic black turtle and contribute to the adaptive research and conservation genomics of a long-lived and highly mobile vertebrate.

Y chromosome diversity in Aztlan descendants and its implications for the history of Central Mexico.

Native Mexican populations are crucial for understanding the genetic ancestry of Aztec descendants and coexisting ethnolinguistic groups in the Valley of Mexico and elucidating the population dynamics of the prehistoric colonization of the Americas. Mesoamerican societies were multicultural in nature and also experienced significant admixture during Spanish colonization of the region. Despite these facts, Native Mexican Y chromosome diversity has been greatly understudied. To further elucidate their genetic history, we conducted a high-resolution Y chromosome analysis with Chichimecas, Nahuas, Otomies, Popolocas, Tepehuas, and Totonacas using 19 Y-short tandem repeat and 21 single nucleotide polymorphism loci. We detected enormous paternal genetic diversity in these groups, with haplogroups Q-MEH2, Q-M3, Q-Z768, Q-L663, Q-Z780, and Q-PV3 being identified. These data affirmed the southward colonization of the Americas via Beringia and connected Native Mexicans with indigenous populations from South-Central Siberia and Canada. They also suggested that multiple population dispersals gave rise to Y chromosome diversity in these populations.

Age-related anomalies of electrocardiograms in patients from areas with differential Seroprevalence of Chagas disease in Southern Bolivia.

INTRODUCTION: Chagas disease currently affects some 6 million people around the world. At the chronic stage, cardiomyopathy occurs in about 20-30% of infested people. Most prevalence studies have focused on young to adult people due to the drastic consequences of acquiring the pathogen and the possibility to cure the disease at this age; the prevalence of this disease, the effect of patients' sex and the consequences to senescent people have been largely neglected. This study looks to characterize the seroprevalence of Chagas disease and its relation with occurrence of electrocardiographic anomalies associated with sex and age, and to compare rural and urban populations in Bolivia. METHODOLOGY: Seroprevalence of Chagas disease was determined in blood samples and electrocardiograms were performed on seropositive individuals. RESULTS: The rural population showed higher seroprevalence than the urban population (92% and 40%, respectively). The proportion of Chagasic cardiac anomalies in seropositive persons was highest in patients of the 50-59 age group (36%) as compared with the 40-49 (8%) and the ≥60 (17%) age groups. CONCLUSIONS: Higher seroprevalence in rural population was attributable to a higher probability to encounter the vector in rural areas. Increased exposure to infection and to development of the disease symptoms together with increased lethality of the disease as patients age explains the age-related Chagasic electrocardiographic anomalies. Since rural and urban populations showed different reactions under Chagas disease and the rural population was mainly of guaraní stock, the genetic and environmental determinants of the results should be further explored.

Temporal changes in gene expression and genotype frequency of the ornithine decarboxylase gene in native silverside Basilichthys microlepidotus: Impact of wastewater reduction due to implementation of public policies.

Human activity has caused a deterioration in the health and population size of riverine species; thus, public policies have been implemented to mitigate the anthropogenic impacts of water use, watercourse transformation, and pollution. We studied the Maipo River Basin, one of the most polluted with untreated wastewater in Chile, for a period of 12 years (2007-2019). Since the implementation of new public policies, including the operation of a wastewater collector (2012), the Maipo River Basin is currently much less polluted by untreated water than before. To analyze the impact of wastewater reduction in this river basin, we studied the native silverside (Basilichthys microlepidotus), which inhabits both polluted and unpolluted areas of the river basin. Previous studies reported the overexpression of the ornithine decarboxylase (odc) gene, heterozygote deficit, and high frequency of a homozygote odc genotype in silverside populations that inhabit wastewater-polluted sites, suggesting a phenotypic change and genotypic selection in response to pollution. Here, a population affected and another population unaffected by wastewater were studied before and after implementing the wastewater collector. The physicochemical data of water samples, changes in odc expression and microsatellite variability, and odc genotype frequencies were analyzed. The results showed physicochemical changes in the affected site before and after the operation of the wastewater collector. The microsatellite loci showed no changes in either population. The odc expression in the affected site was higher before the operation of the wastewater collector. Significant changes in the genotype frequencies of the odc gene before and after the wastewater collector operation were detected only at the affected site, wherein the homozygous dominant genotype decreased from >59% to <25%. Our results suggest that public policies aimed at mitigating aquatic pollution can indirectly affect both gene expression and genotype frequencies of important functional genes.

Identifying genetic lineages through shape: An example in a cosmopolitan marine turtle species using geometric morphometrics.

The green turtle (Chelonia mydas) is a globally distributed marine species whose evolutionary history has been molded by geological events and oceanographic and climate changes. Divergence between Atlantic and Pacific clades has been associated with the uplift of the Panama Isthmus, and inside the Pacific region, a biogeographic barrier located west of Hawaii has restricted the gene flow between Central/Eastern and Western Pacific populations. We investigated the carapace shape of C. mydas from individuals of Atlantic, Eastern Pacific, and Western Pacific genetic lineages using geometric morphometrics to evaluate congruence between external morphology and species' phylogeography. Furthermore, we assessed the variation of carapace shape according to foraging grounds. Three morphologically distinctive groups were observed which aligned with predictions based on the species' lineages, suggesting a substantial genetic influence on carapace shape. Based on the relationship between this trait and genetic lineages, we propose the existence of at least three distinct morphotypes of C. mydas. Well-defined groups in some foraging grounds (Galapagos, Costa Rica and New Zealand) may suggest that ecological or environmental conditions in these sites could also be influencing carapace shape in C. mydas. Geometric morphometrics is a suitable tool to differentiate genetic lineages in this cosmopolitan marine species. Consequently, this study opens new possibilities to explore and test ecological and evolutionary hypotheses in species with wide morphological variation and broad geographic distribution range.

Selection of suitable reference genes for gene expression analysis in gills and liver of fish under field pollution conditions.

To understand the role of gene expression in adaptive variation, it is necessary to examine expression variation in an ecological context. Quantitative real-time PCR (qPCR) is considered the most accurate and reliable technique to measure gene expression and to validate the data obtained by RNA-seq; however, accurate normalization is crucial. In Chile, the freshwater silverside fish Basilichthys microlepidotus inhabits both polluted and nonpolluted areas, showing differential gene expression related to pollution. In this study, we infer the stability of six potential reference genes (tubulin alpha, hypoxanthine-guanine phosphoribosyltransferase, glyceraldehyde-3-phosphate dehydrogenase, beta-actin, 60S ribosomal protein L13, and 60S ribosomal protein L8) in the gills and liver of silverside individuals inhabiting polluted and nonpolluted areas. To validate the reference genes selected, the most and least stable reference genes were used to normalize two target transcripts, one for each organ. The RefFinder tool was used to analyze and identify the most stably expressed genes. The 60S ribosomal protein L8 gene was ranked as the most stable gene for both organs. Our results show that reference gene selection influences the detection of differences in the expression levels of target genes in different organs and, also highlighting candidate reference genes that could be used in field studies.

Highly Connected Populations and Temporal Stability in Allelic Frequencies of a Harvested Crab from the Southern Pacific Coast.

For marine invertebrates with a benthic adult form and a planktonic larva phase, the connectivity among populations is mainly based on larval dispersal. While an extended larval phase will promote gene flow, other factors such as an intensive fishery and geographical barriers could lead to changes in genetic variability. In this study, the population genetic structure of the commercial crab Metacarcinus edwardsii was analyzed along 700 km of the Chilean coast. The analysis, based on eight microsatellite loci genotyped from megalopae and adult crabs, considered temporal and spatial patterns of genetic variation. The results showed no evidence of spatial patterns in genetic structure, suggesting high connectivity among the sampling sites. The temporal analysis showed no evidence of changes in allele frequencies and no evidence of a recent bottleneck. The lack of spatial structure and allele variation over time could be explained by the interaction of factors such as i) low reproductive variance due to the capability of females to store sperm in the seminal receptacle, which can be used for successive broods, ii) high larval dispersal and iii) high individual reproductive output. Using our data as priors, a genetic modelling approach coincided, predicting this temporal and spatial stability. The same analysis showed that a reduction in population size leads to the loss of genetic variability in populations, as well as of the genetic cohesiveness between populations, pointing out the importance management for species under exploitation, such as M. edwardsii.

The complete mitochondrial genome of the endemic and threatened killifish Orestias ascotanensis Parenti, 1984 (Cyprinodontiformes, Cyprinodontidae) from the High Andes.

The killifish Orestias ascotanensis is endemic to the small isolated springs of Ascotán salt pan in the Central High Andes, Chile. Due to small populations, mining activity, and increasing aridity, this species is catalogued in danger of extinction. The complete mitochondrial genome of O. ascotanesis was assembled with an Ion Torrent sequencer (chip 318) that produced 2.61 million of reads. The 16 617 bp of the entire genome consisted of 22 transfer RNAs, 2 ribosomal RNAs, 13 protein-coding genes, and a control region, showing that the gene composition and arrangement match to that reported for most fishes.