Large Sampling Effort Research Articles

Patterns and drivers of alien plant invasion in Uruguayan grasslands

AbstractQuestionUnderstanding the patterns of alien plant invasions and their underlying drivers is a key step in conserving the remaining native grasslands of Uruguay. We addressed the level of invasion by considering the four invasive alien plants of these ecosystems, Cynodon dactylon, Eragrostis plana, Senecio madagascariensis and Ulex europaeus, throughout the country.LocationRemnant native grasslands of Uruguay, constituting part of the Río de la Plata grasslands.MethodsExtensive fieldwork was carried out over five years of data collection, including hierarchically randomized observations (around 2000) nested in 137 10 × 10‐km2 squares covering different geomorphological regions. For each invasive alien species, we constructed distribution maps to show their patterns; for the two most abundant, we fitted models to identify the main explanatory variables at different spatial scales.ResultsWe found that 77% of the squares were invaded by at least one target species. The level of invasion varied between regions and target plants. The most abundant invasive alien species were Cynodon dactylon and Senecio madagascariensis; while Eragrostis plana and Ulex europaeus were scarce. Cynodon dactylon cover was related to a set of variables at different spatial scales, including climate, topography and several local community descriptors. Senecio madagascariensis cover was positively associated with grassland fragmentation and anthropic disturbance at the landscape, and a few local descriptors.ConclusionsThe large sampling effort at the country level, with a randomized design, allowed for a reliable assessment of the level of invasion of Uruguayan grasslands and its possible drivers. This is an important step in the design of policies to conserve Uruguay's remaining native grasslands. We suggest that the prevention should focus on the Basaltic Cuestas region, while control and containment should prioritize the eastern and south‐central parts of the country, focusing mainly on Cynodon dactylon management.

Long‐Term Standardized Sampling as a Tool for Evaluating Management Actions: BACI Analysis to Reevaluate Predatory Control of Stunted Crappie with Saugeye

Field evaluations of management manipulations are rarely conducted, in part because they are difficult to design and require large sampling effort. However, many commonly used management approaches have <50% success rate, indicating the need for more research. Herein, we provide a case study illustrating how historic standard sampling data from Oklahoma were used to design robust before–after control–impact study designs to evaluate the effectiveness of stocking saugeye Sander vitreus × S. canadensis as a predatory control for stunted White Crappie Pomoxis annularis populations. Comparing six manipulated lakes with six reference lakes (no saugeye stockings), we found that proportional size distribution, proportional size distribution of preferred‐size fish, and mean length at ages 1 and 2 of White Crappie all improved after stockings, but still fell short of statewide median values. Further, similar improvements in these metrics also occurred in reference lakes, suggesting they were likely caused by regional patterns (flood/drought or temperature effects) rather than management intervention. Thus, we conclude saugeye stockings are not likely to routinely improve stunted White Crappie fisheries. We encourage managers who have historic data to use these data to robustly evaluate management interventions (as illustrated in this study), because our field needs additional information regarding when management interventions will be most effective, versus when they may not have the desired outcome. These historic data sets have considerable utility in providing this type of information. Our case study illustrates the importance of replication and reference lakes to avoid erroneous conclusions in such evaluations.

Large sampling effort is not related to richness and geographic distribution of Cladocera (Crustacea, Branchiopoda) in the Brazilian Savannah

ABSTRACT The Cerrado is home of the headwaters of some important Brazilian basins. Such biome has a high diversity of animal and plant species with a high degree of endemism. This premise is well documented for microcrustaceans of the Superorder Cladocera, although many areas still need sampling. In this context, the objective of the present investigation was to evaluate the geographic distribution and richness of Cladocera in the Cerrado biome. The analyzed data were obtained from the authors database on Brazilian Cladocera and distributed according to the hydrographic regions comprised in the biome. Species distribution models were used to determine the areas with the highest probability of occurrence of Cladocera. We analyzed 125 publications, resulting in 2829 records. In total, we obtained 161 taxa, belonging to 48 genera and seven families. Regarding the Hydrographic Regions, Paraná presented the highest richness, followed by TocantinsAraguaia and São Francisco. Our result indicates that most studies are concentrated in certain areas. Furthermore, the species distribution models indicated that transition areas between biomes have the highest probability of occurrence of genera and families. Our results indicate significant gaps in the knowledge, making it necessary to expand inventories and ecological studies in areas still unsampled.

Association between the severity of histopathological lesions and Mycobacterium avium subspecies paratuberculosis (MAP) molecular diversity in cattle in southern Chile.

The objective was to evaluate the association between the severity of histopathological lesions caused by Mycobacterium avium subspecies paratuberculosis (MAP) infection and the molecular diversity of this pathogen. Blood, ileum, and mesenteric lymph node samples were collected at slaughter, from 1,352 adult cattle [source population 1 (SP1)]. In addition, 42 dairy herds (n = 4,963 cows) were followed for 2 years, and samples from compatible paratuberculosis clinical cases [source population 2 (SP2)] were collected. MAP infection was confirmed using an ELISA test, liquid media culture, and PCR. Isolates were genotyped using five MIRU-VNTR markers. Tissues from confirmed samples were subjected to a histopathological examination. A histopathological severity score (HSS) system was developed and used to grade (0 to 5) the magnitude of lesions caused by MAP. In general, the HSS system assesses the number of foci and degree of macrophage infiltration, together with the presence of multinucleated giant cells (MGCs) and acid-fast bacilli (AFB), in addition to the fusion of the intestinal villi and hyperplasia of the crypts. Despite the large sampling effort, only 79 MAP isolates were successfully genotyped, where 19 different haplotypes were described. A mixed-effect Poisson regression model was used to assess the relationship between haplotypes and HSS values. The model was controlled by animal age, and the farm was used as a random effect. Haplotypes were grouped based on their relative frequency: the most frequent haplotype (group i, 49.4%), the second most frequent haplotype (group ii, 12.7%), and all other haplotypes (group iii, 37.9%). Model outputs indicated that group i had significantly higher HSS values than group iii. In addition, group i was also associated with higher optical density (OD) values of the ELISA test. These results support the existence of differences in pathogenicity between MAP haplotypes. However, results were based on a relatively small sample size; thus, these should be taken with caution. Despite this, study findings suggest that haplotypes would be associated with differences in disease progression, where the dominant haplotype tends to generate more severe lesions, which could be linked to a greater shed of MAP cells than non-dominant haplotypes, increasing their chances of transmission.

Térmitas da Floresta Amazônica: uma lista de espécies do Estado do Acre, Brasil

Abstract The Brazilian state of Acre is located in the southwestern Amazon and it is characterized by a humid tropical forest vegetation that covers plains and mountains. Up to this point, the composition of termite species in the state is not known. The aim of this study was to provide a checklist of termite species or recognizable taxonomic units for the state of Acre. Sampling was conducted through field expeditions at the Serra do Divisor National Park, Chandless State Park, Humaitá Forest Reserve, and Chico Mendes Environmental Park using a standardized rapid termite inventory protocol in the first two areas and active searching collections in the others, without a specific protocol. This study also included occurrence records published in the scientific literature. A total of 128 species and morphospecies of termites were found in Acre, distributed across 59 genera and four families. The most frequently occurring species in Acre was Heterotermes tenuis (Hagen, 1858). The study also identified six new species records for Brazil. The predominant feeding groups were soil-feeders and wood-feeders, as expected from data obtained from surveys in humid tropical forests. Despite the significant number of new records for Acre (112), it is concluded that a larger sampling effort is still required, as many areas of the state have not yet been studied for termites.

Mating Systems of Single Families and Population Genetic Diversity of Endangered Ormosia hosiei in South China.

Ormosia hosiei is a tree species native to China that has been extensively used for ornamental and furniture purposes due to its valued timber. The mating system has substantial impact on genetic diversity and structure of plant natural population. Such information should be considered when planning tree planting for forest restoration. Here we used 12 microsatellite markers and described the mating system of single families and the population genetic diversity of O. hosiei. A high level of genetic diversity was observed in both adults and progenies, although slight differences existed among populations and their progenies, with the expected heterozygosity ranging from 0.763 to 0.794. Overall, O. hosiei displayed a predominantly outcrossed mating. The estimate of multi-locus outcrossing rate (tm) was high with low variations among families, ranged from 0.997 to 1.000. The value of tm-ts, ranged from 0.000 to 0.139, indicated that biparental inbreeding occurred in progenies. Therefore, to obtain a reasonable genetic representation of native tree species and prevent problems associated with inbreeding depression, we suggested effective in situ conservation by replanting seedlings, but seedling production for restoration purposes may require a much larger sampling effort than is currently used. Moreover, it is necessary to conduct further multiple population and multi-year experiments to verify our conclusions.

Spatial distribution of soil δ13C in the central Brazilian savanna

Stable carbon isotope ratios (δ13C) of soil record information regarding C3 and C4 plants at the landscape scale that can be used to document vegetation distribution patterns. The Central Brazilian savanna (locally called the Cerrado) has a substantial potential to develop studies of patterns of dynamics and distribution of soil δ13C, due to its environmental diversity. The purpose of this work was to develop a spatial model of soil δ13C (soil δ13C isoscape) to the Cerrado, based on multiple linear regression analysis, and compare the results with the existing model to obtain greater detail of the soil δ13C distribution. The model used 219 soil samples (0–20 cm depth) and a set of climatic, pedological, topographic, and vegetation correlations. The soil δ13C isoscape model presented amplitude between −29‰ and −13‰, with the highest estimated values in the southern and the lowest values in the northern of the Cerrado. Results indicate that soil δ13C, by reflecting the relative contribution of C3 and C4 species to plant community productivity, served as a proxy indicator of the vegetation history at the landscape scale for the Central Brazilian savanna. Despite the large sampling effort, there are still regions with some gaps that the model could not estimate. However, the soil δ13C isoscape model filled most the existing gaps and provided greater detail of some unique local aspects of the Cerrado.

French Mediterranean and Atlantic populations of the brown algal genus Taonia (Dictyotales) display differences in phylogeny, surface metabolomes and epibacterial communities

Considered as holobiont systems, marine macroalgae and their microbiota constitute functional units displaying a large diversity of interactions. Main factors driving the assembly of epiphytic microbiota, and subsequent interactions with the host, are often associated to environmental differences but also to host taxonomy displaying specific chemical properties. Here, through a large sampling effort focused on the brown algal genus Taonia (Dictyotales) on both the French Mediterranean and Atlantic coasts, we aimed to highlight the relative importance of the effects of environment, host taxonomy and surface metabolome on the epibacterial community of these seaweeds. Phylogenetic analyses revealed two distinct clusters, one grouping only the specimens from the French Mediterranean coasts and the second one composed of samples from Brittany. Both metabarcoding and surface metabolomics revealed clear differences between Mediterranean thalli and those collected in Brittany. Strong environmental differences associated with algae from these two different geographical areas could both be involved in this clustering. For example, oxidative stress due to higher irradiance intensities might induce a higher expression of fucoxanthin in Mediterranean samples, while higher eutrophication levels could explain the higher abundance of Alteromonas spp. on algal samples from Brittany coast. In a lesser extent, genetic differences observed between thalli from these two locations could also influence surface metabolomes and thus host-microbiota interactions.

Effects of oil palm and human presence on activity patterns of terrestrial mammals in the Colombian Llanos

The ability of animals to adjust their behaviour can influence how they respond to environmental changes and human presence. We quantified activity patterns of terrestrial mammals in oil palm plantations and native riparian forest in Colombia to determine if species exhibited behavioural changes depending on the type of habitat and the presence of humans. Despite the large sampling effort (12,403 camera-days), we were only able to examine the activity patterns of ten species in riparian forests and seven species in oil palm plantations, with four species (capybara, giant anteater, lesser anteater and common opossum) being represented by enough records (i.e. n > 20) in both oil palm and forest to allow robust comparisons. Only capybaras showed an apparent change in activity patterns between oil palm plantations and riparian forests, shifting from being crepuscular in forest to predominantly nocturnal inside oil palm plantations. Further, capybaras, giant anteaters and white-tailed deer appeared to modify their activities to avoid human presence inside oil palm plantations by increasing nocturnality (temporal overlap widehat{Delta }ranged from 0.13 to 0.36), whereas jaguarundi had high overlap with human activities [widehat{Delta }=0.85 (0.61–0.90)]. Species pair-wise analysis within oil palm revealed evidence for temporal segregation between species occupying the same trophic position (e.g. foxes and jaguarundi), whereas some predators and their prey (e.g. ocelots and armadillos) had high overlaps in temporal activity patterns as might be expected. Our findings shed light on the potential behavioural adaptation of mammals to anthropogenic landscapes, a feature not captured in traditional studies that focus on measures such as species richness or abundance.

Managing threatened ungulates in logged-primary forest mosaics in Malaysia.

Across the tropics, large-bodied mammals have been affected by selective logging in ways that vary with levels of timber extraction, collateral damage, species-specific traits and secondary effects of hunting, as facilitated by improved access through logging roads. In Peninsular Malaysia, 3.0 million hectares or 61 percent of its Permanent Reserved Forests is officially assigned for commercial selective logging. Understanding how wildlife adapts and uses logged forest is critical for its management and, for threatened species, their conservation. In this study, we quantify the population status of four tropical ungulate species in a large selectively logged forest reserve and an adjacent primary forest protected area. We then conduct finer scale analyses to identify the species-specific factors that determine their occurrence. A combined indirect sign-camera trapping approach with a large sampling effort (2,665 km and 27,780 trap nights surveyed) covering a wide area (560 km2) generated species-specific detection probabilities and site occupancies. Populations of wild boar were widespread across both logged and primary forests, whereas sambar and muntjac occupancy was lower in logged forest (48.4% and 19.2% respectively), with gaur showing no significant difference. Subsequent modelling revealed the importance of conserving lower elevation habitat in both habitat types, particularly <1,000 m asl, for which occupancies of sambar, muntjac and gaur were typically higher. This finding is important because 75 percent (~13,400 km2) of Peninsular Malaysia’s Main Range Forest (Banjaran Titiwangsa) is under 1,000 m asl and therefore at risk of being converted to industrial timber plantations, which calls for renewed thinking around forest management planning.

Species richness and composition of snake assemblages in poorly accessible areas in the Brazilian Amazonia

Abstract: Snakes are a diverse group of terrestrial vertebrates of the order Squamata. Despite that, in the Amazonian biome, information about distribution and identification of snakes is limited when compared to other groups. Additionally, in Amazonia there is a sampling bias towards areas geographically close to urban centers and more densely populated areas. This in turn leads to false distribution gaps in poorly accessible areas of Amazonia. In this article we report the composition of snake assemblages in six areas of the Brazilian Amazonia, based on field sampling conducted over four years using standardized methods. We sampled 70 species from eight families: Typhlopidae (n=1), Leptotyphlopidae (n=1), Anillidae (n=1), Boidae (n=5), Colubridae (n=15), Dipsadidae (n=35), Elapidae (n=7), and Viperidae (n=5). The largest number of species was recorded in the Trombetas River area and the lowest in the Jatapu River area. The total beta diversity was 0.40 and the snake assemblages were structured mainly by replacement (72.5%). The time-limited search was the method that recorded the greatest number of individuals in the studied areas (44.1%) and also the greatest number of species (n=40). However, some species were recorded only by other methods such as interception by pitfall traps with directional fences. Despite the large number of species sampled in the study, no particular area comprised more than 40% of species registered in all the areas, indicating that snakes are poorly detected even with large sampling effort across multiple areas of a species distribution.

Howler monkeys are the reservoir of malarial parasites causing zoonotic infections in the Atlantic forest of Rio de Janeiro.

BackgroundAlthough malaria cases have substantially decreased in Southeast Brazil, a significant increase in the number of Plasmodium vivax-like autochthonous human cases has been reported in remote areas of the Atlantic Forest in the past few decades in Rio de Janeiro (RJ) state, including an outbreak during 2015–2016. The singular clinical and epidemiological aspects in several human cases, and collectively with molecular and genetic data, revealed that they were due to the non-human primate (NHP) parasite Plasmodium simium; however, the understanding of the autochthonous malarial epidemiology in Southeast Brazil can only be acquired by assessing the circulation of NHP Plasmodium in the foci and determining its hosts.MethodologyA large sampling effort was carried out in the Atlantic forest of RJ and its bordering states (Minas Gerais, São Paulo, Espírito Santo) for collecting and examining free-living NHPs. Blood and/or viscera were analyzed for Plasmodium infections via molecular and microscopic techniques.Principal findingsIn total, 146 NHPs of six species, from 30 counties in four states, were tested, of which majority were collected from RJ. Howler monkeys (Alouatta clamitans) were the only species found infected. In RJ, 26% of these monkeys tested positive, of which 17% were found to be infected with P. simium. Importantly, specific single nucleotide polymorphisms–the only available genetic markers that differentiate P. simium from P. vivax–were detected in all P. simium infected A. clamitans despite their geographical origin of malarial foci. Interestingly, 71% of P. simium infected NHPs were from the coastal slope of a mountain chain (Serra do Mar), where majority of the human cases were found. Plasmodium brasilianum/malariae was initially detected in 14% and 25% free-living howler monkeys in RJ and in the Espírito Santo (ES) state, respectively. Moreover, the malarial pigment was detected in the spleen fragments of 50% of a subsample comprising dead howler monkeys in both RJ and ES. All NHPs were negative for Plasmodium falciparum.Conclusions/SignificanceOur data indicate that howler monkeys act as the main reservoir for the Atlantic forest human malarial parasites in RJ and other sites in Southeast Brazil and reinforce its zoonotic characteristics.

Sampling effort and information quality provided by rare and common species in estimating assemblage structure

Abstract Reliable biological assessments are essential to answer ecological and management questions but require well-designed studies and representative sample sizes. However, large sampling effort is rarely possible, because it demands large financial resources and time, restricting the number of sites sampled, the duration of the study and the sampling effort at each site. In this context, we need methods and protocols allowing cost-effective surveys that would, consequently, increase the knowledge about how biodiversity is distributed in space and time. Here, we assessed the minimal sampling effort required to correctly estimate the assemblage structure of stream insects sampled in near-pristine boreal and subtropical regions. We used five methods grouped into two different approaches. The first approach consisted of the removal of individuals 1) randomly or 2) based on a count threshold. The second approach consisted of simplification in terms of 1) sequential removal from rare to common species; 2) sequential removal from common to rare species; and 3) random species removal. The reliability of the methods was assessed using Procrustes analysis, which indicated the correlation between a reduced matrix (after removal of individuals or species) and the complete matrix. In many cases, we found a strong relationship between ordination patterns derived from presence/absence data (the extreme count threshold of a single individual) and those patterns derived from abundance data. Also, major multivariate patterns derived from the complete data matrices were retained even after the random removal of more than half of the individuals. Procrustes correlation was generally high (>0.8), even with the removal of 50% of the species. Removal of common species produced lower correlation than removal of rare species, indicating higher importance of the former to estimate resemblance between assemblages. Thus, we conclude that sampling designs can be optimized by reducing the sampling effort at a site. We recommend that such efforts saved should be redirected to increase the number of sites studied and the duration of the studies, which is essential to encompass larger spatial, temporal and environmental extents, and increase our knowledge of biodiversity.

The importance of protected areas for conservation of bare-faced curassow (Crax fasciolata spix, 1825) (Galliformes: Cracidae) in the São Paulo State, Brazil

Abstract The Bare-faced Curassow Crax fasciolata (Cracidae:Cracinae) is a vulnerable species that was classified as critically endangered by the São Paulo State -Brazil, in 2008. Specialists recommended "searches for areas where there may be a few remaining populations and protection of the last remaining semideciduous forest in the State". Protected areas were investigated in the Cerrado and semideciduous forest in São Paulo State by camera trapping to evaluate the presence of the Bare-faced Curassow. Eight protected areas in Cerrado biome were investigated, but the Bare-faced Curassows was recorded only at Furnas do Bom Jesus State Park (2,069 ha), São Paulo State despite the large sampling effort in larger protected areas such as the Santa Bárbara Ecological Station (2,712 ha) and Jataí Ecological Station (9,074 ha); the largest protected area of Cerrado biome in São Paulo State. This record of C. fasciolata is important for the Conservation Action Plan for the Cracid family and shows the importance of monitoring biodiversity and conserving even relatively small remnants of native vegetation for the conservation of this species.

Implementing a new approach to effective conservation of genetic diversity, with ash (Fraxinus excelsior) in the UK as a case study

Gene conservation programs help safeguard species and tangibly benefit ecological restoration, agriculture, forestry, and horticulture. Here we describe a new method for deciding which and how many populations and individuals to conserve ex situ, and we demonstrate the method by evaluating collections of European Ash (Fraxinus excelsior) for an ongoing seed-banking project, the UK National Tree Seed Project (NTSP). The method uses simulations and geographic distribution data, and does not require (but can utilize) genetic data. We estimate that NTSP collections have captured >90% of all alleles and of locally common alleles. We identified optimal sampling solutions at large and small spatial scales, and for northern isolated vs. southern core populations. We also quantified genetic “points of diminishing returns” with a more precise method than previous studies. This analysis revealed that (for European ash, for a goal of capturing one copy of each allele) an optimal “stopping point” is approximately 35 populations, 10 to 30 trees per population, and 30 seeds per tree. Overall, we conclude that the NTSP protocol of random sampling of at least 15 trees per population from two populations per seed zone is effective. We demonstrated how collectors can adjust the number of populations, individuals and seeds sampled using the concept of “genetic equivalence”, allowing projects to accommodate practical or ecological constraints. Lastly we showed that for a conservation goal of 50 allele copies rather than one copy, a much larger sampling effort is needed (>150 populations). This new approach can be tailored to any species. It is applicable to any seed collection seeking to capture genetic diversity, as well as in situ gene conservation approaches. We emphasize that the ability to quantitatively estimate the outcome of gene conservation activities can help design, justify, or evaluate future programs.

Efficiency of rapid field methods for detecting non-native fish in Eastern Brazilian lakes

Where biodiversity conservation and environmental preservation are significant concerns, rapid assessment and monitoring of the colonization and spread of non-native species are essential for timely decision-making and response. We developed and evaluated the adequacy of a rapid assessment protocol (RAP) for detecting non-native fish species in 74 Eastern Brazilian lakes. The RAP consists of a single field day employing two surveyors to conduct interviews with local sport fishers, visual surveys of fish, angling with lures, and gillnetting. We compared our results with those from separate, intense, large sampling effort (LSE) field surveys. Despite requiring less than 1/100th of the field effort, the RAP was able to detect the presence of most non-native fish species that were reported in the same lakes by LSE surveys. Information from local sport fishers was invaluable, particularly for detecting species that were in low abundance, but was not available for lakes within a forest preserve area. Non-native introductions commonly lead to rapid and widespread invasion and adverse effects on native biota. Our results strongly suggest that the RAP could function as a cost-effective tool for efficiently assessing the presence of non-native fishes in lakes and monitoring their colonization and spread over large geographic areas.

Mating System and Effective Population Size of the Overexploited Neotropical Tree (Myroxylon peruiferum L.f.) and Their Impact on Seedling Production.

The reproductive system of a tree species has substantial impact on genetic diversity and structure within and among natural populations. Such information, should be considered when planning tree planting for forest restoration. Here, we describe the mating system and genetic diversity of an overexploited Neotropical tree, Myroxylon peruiferum L.f. (Fabaceae) sampled from a forest remnant (10 seed trees and 200 seeds) and assess whether the effective population size of nursery-grown seedlings (148 seedlings) is sufficient to prevent inbreeding depression in reintroduced populations. Genetic analyses were performed based on 8 microsatellite loci. M. peruiferum presented a mixed mating system with evidence of biparental inbreeding (t^m-t^s = 0.118). We found low levels of genetic diversity for M. peruiferum species (allelic richness: 1.40 to 4.82; expected heterozygosity: 0.29 to 0.52). Based on Ne(v) within progeny, we suggest a sample size of 47 seed trees to achieve an effective population size of 100. The effective population sizes for the nursery-grown seedlings were much smaller Ne = 27.54-34.86) than that recommended for short term Ne ≥ 100) population conservation. Therefore, to obtain a reasonable genetic representation of native tree species and prevent problems associated with inbreeding depression, seedling production for restoration purposes may require a much larger sampling effort than is currently used, a problem that is further complicated by species with a mixed mating system. This study emphasizes the need to integrate species reproductive biology into seedling production programs and connect conservation genetics with ecological restoration.

A new species of Moniliformis from a Sigmodontinae rodent in Patagonia (Argentina).

The majority of species of Acanthocephala known thus far from South America have been recorded mostly in fish and wild birds. In particular, rodents in Argentina have been poorly studied for acanthocephalans. The genus Abrothrix (Sigmodontinae-Cricetidae) ranges from the Altiplano of southern Peru through the highlands of Bolivia, northern Chile, and Argentina south through Tierra del Fuego. The purpose of this paper was to study Acanthocephala species parasitizing different populations of Abrothrix from Santa Cruz province (Patagonia Argentina). Specimens of Acanthocephala were found in the small intestine of Abrothrix olivaceus, showing values of P 14.7%, IM=2.8, and AM=0.41. All the rodents parasitized were collected in Punta Quilla, Santa Cruz, Argentina. The specimens of Abrothrix longipilis were not parasitized. Moniliformis amini n. sp. is described with features such as the long, cylindrical, and pseudo-segmented body; proboscis receptacle double walled, outer wall with muscle fibers usually arranged spirally, and a combination of several morphometric characters, mainly the very small size of the proboscis receptacle and length of the testes and lemnisci. A marked proportion of arthropods was found in the diet of A. olivaceus, characterizing it as arthropodivorous. Possibly, a larger sampling effort and specific projects dealing with the study of acanthocephalans will shed light on several questions of the rodent-Moniliformis relationship.

Diversity of helminth parasites in aquatic invertebrate hosts in Latin America: how much do we know?

Helminths in aquatic invertebrate hosts have been overlooked in comparison with vertebrate hosts. Therefore, the known diversity, ecology and distribution of these host-parasite systems are very limited in terms of their taxonomic diversity, habitat and geographic regions. In this study we examined the published literature on helminth parasites of aquatic invertebrates from Latin America and the Caribbean (LAC) to identify the state of the knowledge in the region and to identify patterns of helminth diversity. Results showed that 67% of the literature is from Argentina, Mexico and Brazil. We found records for 772 host-parasite associations. Most records relate to medically or economically important hosts. Molluscs were the most studied host group with 377 helminth records (80% trematodes). The lymnaeids and planorbids were the most studied molluscs across LAC. Arthropods were the second most studied host group with 78 helminth records (trematodes 38%, cestodes 24% and nematodes 20%), with shrimps and crabs being the most studied hosts. Host species with the largest number of helminth taxa were those with a larger sampling effort through time, usually in a small country region. No large geographical-scale studies were identified. In general, the knowledge is still too scarce to allow any zoogeographical or helminth diversity generalization, as most hosts have been studied locally and the studies on invertebrate hosts in LAC are substantially uneven among countries.

Out of the Celtic cradle: The genetic signature of European hake connectivity in South-western Europe

Population genetic data of marine genetic resources add up to establish their pattern of connectivity. Such pattern determines the choice of a suitable management strategy to those resources in space and time. This study addresses the pattern of connectivity among European hake grounds upon the largest sampling effort so far developed in this species. Bayesian inference made on multilocus genotypic data provides evidence that a large genetic connectivity exists among Atlantic grounds and is mediated by significant migration rates stepping up from the Celtic Sea towards its adjacent Atlantic grounds. Therefore, the spawning biomass of the northern hake population could play a crucial role at ensuring the sustainability of southern hake fish grounds. The deepest restriction to gene flow was observed at the easternmost side of the Alboran Sea what suggests that the Almeria–Oran Oceanographic Front is an effective barrier keeping apart the two major gene pools so far shown in this species. A molecular clock calibrated for cytochrome b sequences of fishes and applied to the divergence between hake pools (0.3%) suggests that the Atlantic–Mediterranean population split might date back to the Middle Pleistocene (150,000years BP). Complementarily, Bayesian treatments of multilocus genotypes indicate that such barrier to gene flow remains active nowadays. This study shows the upmost interest of future integrative efforts to incorporate population genetic data into current assessment practices, in order to better manage European hake populations and make its exploitation sustainable.