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Genetic structure and connectivity information can be used to identify biological corridors and prioritize the conservation of areas that help maintain ecosystem integrity. Some marine fish, especially those of commercial interest, have been proposed as suitable indicators to identify potential marine biological corridors due to their high mobility among habitats and socioeconomic importance. In this study, we assessed the genetic structure of lane snapper populations in the Honduran Caribbean to evaluate connectivity and identify potential environmental barriers. Furthermore, we evaluated the genetic characteristics of the lane snapper on a larger spatial scale, including populations across the rest of its distribution range in the western Atlantic, using mtDNA and nuDNA markers. Our results demonstrate a significant genetic diversity of lane snappers in the Honduran Caribbean. Furthermore, despite their high dispersal potential, we observed genetic structuring in lane snapper populations on a larger spatial scale, resulting in the formation of two distinct groups throughout their distribution range: group 1 from Florida, the Gulf of Mexico, Honduras, and Colombia and group 2 from Puerto Rico and Brazil. This genetic differentiation can be attributed to oceanographic barriers such as river plumes and marine currents. These findings have the potential to significantly impact marine conservation and management efforts in the region, both at local and regional scales. It is anticipated that they will not only inform but also elicit a response, driving further action towards effective conservation measures. At a local scale, we recommend that conservation efforts focus on protecting critical habitats. At a regional scale, lane snappers should be included in the management plans of existing marine protected areas necessary to ensure the long-term sustainability of the species and the marine ecosystems in which it resides.

Abstract Natural disturbances can modify extinction-colonization dynamics, driving changes in the genetic diversity and structure of marine populations. Along Chilean coast (36°S, 73°W), a strong hypoxic-upwelling event in 2008, and a mega earthquake-tsunami in 2010 caused mass mortality within the Aphos porosus population, which is a vulnerable species with low dispersal potential. We evaluated the effects of these two major disturbances on the diversity and spatial-temporal genetic structure of Aphos porosus in two neighboring areas that were impacted on different levels (High level: Coliumo Bay; Low level: Itata Shelf). Thirteen microsatellites (from 2008 to 2015) amplified in individuals collected from both locations were used to evaluate the effects of the two disturbances. Results showed that after the strong hypoxic-upwelling event and the mega earthquake-tsunami, Aphos porosus populations exhibited lower genetic diversity and less effective population sizes (Ne

Abstract Background Understanding the mechanisms behind resilience has become more relevant in the last decades, due to the increasing and intensifying disturbances from natural and anthropogenic sources that threaten biodiversity. Evidence from terrestrial populations suggests that resilience increases with genetic diversity. Few studies, however, have evaluated the relationship between genetics and resilience in benthic marine populations. Methods and results For this review, we gathered studies where genetic diversity was the predictor variable, and resilience was the response variable. Twenty-five publications between 2001 and 2018 were included. Thirteen benthic marine species were identified, mainly sea-grass species, among which Zostera marina was the most frequently studied. The relationship between genetic diversity and resilience was variable-dependent. Considering all the analyses (N = 150) in the studies reviewed, 44% reported positive relationships between genetic diversity and resilience capacity. Negative relationships were found in 6%, and no relationship was found in 50%. Positive relationships indicated that genetic diversity increased resistance and recovery capacity after different types of disturbances. Dominance and complementarity were suggested as the underlying mechanism explaining these findings in the few studies that conducted this type of evaluation. Conclusions The results of this review suggest that the relationship between genetic diversity and resilience is mainly positive. However, this relationship relies on how genetic diversity and resiliency were measured, as well as on the biological characteristics of the species under study. This reinforces the importance of acknowledging and maintaining genetic diversity for the conservation of benthic populations in marine ecosystems.

The introduction and establishment of invasive species in regions outside their native range, is one of the major threats for the conservation of ecosystems, affecting native organisms and the habitat where they live in, causing substantial biological and monetary losses worldwide. Due to the impact of invasive species, it is important to understand what makes some species more invasive than others. Here, by simulating populations using a forward-in-time approach combining ecological and single polymorphic nucleotides (SNPs) we evaluated the relation between propagule size (number of individuals = 2, 10, 100, and 1,000), extinction rate (with values 2%, 5%, 10%, and 20%), and initial heterozygosity (0.1, 0.3, and 0.5) on the population survival and maintenance of the heterozygosity of a simulated invasive crab species over 30 generations assuming a single introduction. Our results revealed that simulated invasive populations with initial propagule sizes of 2–1,000 individuals experiencing a high extinction rate (10–20% per generation) were able to maintain over 50% of their initial heterozygosity during the first generations and that under scenarios with lower extinction rates invasive populations with initial propagule sizes of 10–1,000 individuals can survive up to 30 generations and maintain 60–100% of their initial heterozygosity. Our results can help other researchers better understand, how species with small propagule sizes and low heterozygosities can become successful invaders.

Abstract The polychaete Boccardia wellingtonensis is a poecilogonous species that produces different larval types. Females may lay Type I capsules, in which only planktotrophic larvae are present, or Type III capsules that contain planktotrophic and adelphophagic larvae as well as nurse eggs. While planktotrophic larvae do not feed during encapsulation, adelphophagic larvae develop by feeding on nurse eggs and on other larvae inside the capsules and hatch at the juvenile stage. Previous works have not found differences in the morphology between the two larval types; thus, the factors explaining contrasting feeding abilities in larvae of this species are still unknown. In this paper, we use a transcriptomic approach to study the cellular and genetic mechanisms underlying the different larval trophic modes of B. wellingtonensis. By using approximately 624 million high-quality reads, we assemble the de novo transcriptome with 133,314 contigs, coding 32,390 putative proteins. We identify 5221 genes that are up-regulated in larval stages compared to their expression in adult individuals. The genetic expression profile differed between larval trophic modes, with genes involved in lipid metabolism and chaetogenesis over expressed in planktotrophic larvae. In contrast, up-regulated genes in adelphophagic larvae were associated with DNA replication and mRNA synthesis.

Non-native species can have profound implications on the survival of native ones. This is especially true for some invasive crabs, such as the green crab Carcinus maenas, a native species to the Northern Hemisphere that has been introduced into southern Argentina, from where it could expand through Argentina, Chile, and the Antarctic Peninsula. Hence, there is interest in forecasting changes in C. maenas habitat suitability through time to predict if potential future invasions might occur. Here, by using a Species Distribution Model (SDM) approach, we estimated the habitat suitability for C. maenas along southern South America and the Antarctic Peninsula under two future climate-change scenarios. Our results reveal that under current conditions, habitat suitability for C. maenas along the Antarctic Peninsula is null and very restricted in Argentina and Chile. Habitat suitability along the Antarctic Peninsula remained null in the short-term (30 years) and long-term future (80 years), despite the climate-change scenario considered. Surprisingly, when considering future conditions, habitat suitability along the coast of Argentina and Chile decreased and became nil for some currently occupied locations. Thus, the SDM results suggest that climate change could have a negative effect on the habitat suitability of C. maenas leading to potential local extinctions.

Abstract Catastrophic events can have profound effects on the demography of a population and consequently on genetic diversity. The dynamics of postcatastrophic recovery and the role of sexual versus asexual reproduction in buffering the effects of massive perturbations remain poorly understood, in part because the opportunity to document genetic diversity before and after such events is rare. Six natural (purely sexual) and seven cultivated (mainly clonal due to farming practices) populations of the red alga Agarophyton chilense were surveyed along the Chilean coast before, in the days after and 2 years after the 8.8 magnitude earthquake in 2010. The genetic diversity of sexual populations appeared sensitive to this massive perturbation, notably through the loss of rare alleles immediately after the earthquake. By 2012, the levels of diversity returned to those observed before the catastrophe, probably due to migration. In contrast, enhanced rates of clonality in cultivated populations conferred a surprising ability to buffer the instantaneous loss of diversity. After the earthquake, farmers increased the already high rate of clonality to maintain the few surviving beds, but most of them collapsed rapidly. Contrasting fates between sexual and clonal populations suggest that betting on strict clonality to sustain production is risky, probably because this extreme strategy hampered adaptation to the brutal environmental perturbation induced by the catastrophe.

The Western Antarctic Peninsula (WAP) is a hotspot for environmental change and has a strong environmental gradient from North to South. Here, for the first time we used adult individuals of the bivalve Aequiyoldia eightsii to evaluate large-scale spatial variation in the biochemical composition (measured as lipid, protein and fatty acids) and energy content, as a proxy for nutritional condition, of three populations along the WAP: O’Higgins Research Station in the north (63.3°S), Yelcho Research Station in mid-WAP (64.9°S) and Rothera Research Station further south (67.6°S). The results reveal significantly higher quantities of lipids (L), proteins (P), energy (E) and total fatty acids (FA) in the northern population (O’Higgins) (L: 8.33 ± 1.32%; P: 22.34 ± 3.16%; E: 171.53 ± 17.70 Joules; FA: 16.33 ± 0.98 mg g) than in the mid-WAP population (Yelcho) (L: 6.23 ± 0.84%; P: 18.63 ± 1.17%; E: 136.67 ± 7.08 Joules; FA: 10.93 ± 0.63 mg g) and southern population (Rothera) (L: 4.60 ± 0.51%; P: 13.11 ± 0.98%; E: 98.37 ± 5.67 Joules; FA: 7.58 ± 0.48 mg g). We hypothesize these differences in the nutritional condition could be related to a number of biological and environmental characteristics. Our results can be interpreted as a consequence of differences in phenology at each location; differences in somatic and gametogenic growth rhythms. Contrasting environmental conditions throughout the WAP such as seawater temperature, quantity and quality of food from both planktonic and sediment sources, likely have an effect on the metabolism and nutritional intake of this species.

The Antarctic Circumpolar Current (ACC) dominates the open-ocean circulation of the Southern Ocean, and both isolates and connects the Southern Ocean biodiversity. However, the impact on biological processes of other Southern Ocean currents is less clear. Adjacent to the West Antarctic Peninsula (WAP), the ACC flows offshore in a northeastward direction, whereas the Antarctic Peninsula Coastal Current (APCC) follows a complex circulation pattern along the coast, with topographically influenced deflections depending on the area. Using genomic data, we estimated genetic structure and migration rates between populations of the benthic bivalve Aequiyoldia eightsii from the shallows of southern South America and the WAP to test the role of the ACC and the APCC in its dispersal. We found strong genetic structure across the ACC (between southern South America and Antarctica) and moderate structure between populations of the WAP. Migration rates along the WAP were consistent with the APCC being important for species dispersal. Along with supporting current knowledge about ocean circulation models at the WAP, migration from the tip of the Antarctic Peninsula to the Bellingshausen Sea highlights the complexities of Southern Ocean circulation. This study provides novel biological evidence of a role of the APCC as a driver of species dispersal and highlights the power of genomic data for aiding in the understanding of the influence of complex oceanographic processes in shaping the population structure of marine species.

Venezuela es uno de los países con mayor biodiversidad marina. A pesar que posee un alto riesgo de introducción de especies exóticas por su histórica alta actividad turística y transporte marítimo, no cuenta con una revisión actualizada que permita evaluar los principales avances y falencias en el estudio de las invasiones biológicas. El presente trabajo tiene como objetivo revisar el estado actual de las investigaciones en invasiones marinas en Venezuela, identificando las principales temáticas desarrolladas y la tendencia espacial y temporal en la investigación. Por medio de una revisión bibliográfica en diferentes bases de datos científicas, se encontraron un total de 35 artículos publicados entre 1998 y 2018, realizadas principalmente en la costa oriente del país. De las 94 especies reportadas como exóticas o criptogénicas, solo 11 han sido estudiadas bajo el enfoque de invasiones biológicas, siendo la mayoría de los estudios primeros reportes de introducción. A diferencia de la tendencia mundial, el número de investigaciones publicadas en la última década muestra una tendencia negativa, presumiblemente relacionada con la situación sociopolítica del país. El conocimiento actual sobre invasiones biológicas en Venezuela es insuficiente, reflejándose en una notable carencia de información, lo que impediría poder avanzar hacia medidas de prevención o reducción del riesgo para la bioseguridad y conservación marina del país.

Due to climate change, numerous ice bodies have been lost in the West Antarctic Peninsula (WAP). As a consequence, deglaciation is expected to impact the marine environment and its biota at physiological and ecosystem levels. Nuculana inaequisculpta is a marine bivalve widely distributed around Antarctica that plays an important role for ecosystem functioning. Considering that N. inaequisculpta inhabits coastal areas under effect of glacial melt and retreat, impacts on its nutritional condition are expected due to alterations on its physiology and food availability. To test this hypothesis, biochemical composition (lipids, proteins, and fatty acids) and energy content were measured in individuals of N. inaequisculpta collected in a fjord at different distances to the retreating glacier in the WAP. Oceanographic parameters of the top and bottom-water layers (temperature, salinity, dissolved oxygen, and chlorophyll-a) were measured to investigate how the environment changes along the fjord. Results showed that surface oceanographic parameters displayed a lower temperature and dissolved oxygen, but a higher salinity and chlorophyll-a content at nearest compared to farthest sites to the glacier. In contrast, a lower temperature and chlorophyll-a, and a higher salinity and dissolved oxygen was measured in the bottom-water layer toward the glacier. N. inaequisculpta had a higher amount of lipids (17.42 ± 3.24 vs. 12.16 ± 3.46%), protein (24.34 ± 6.12 vs. 21.05 ± 2.46%) and energy content (50.57 ± 6.97 J vs. 39.14 ± 5.80 J) in the farthest compared to the nearest site to the glacier. No differences were found in total fatty acids among all sites. It seems likely that lower individual fitness related to proximity to the glacier would not be related to nutritional quality of sediment food, but rather to food quantity.

The geographical expansion of invasive species depends mainly on its dispersal potential, and the abiotic and biotic factors affecting it. Knowing the invasive dynamic of non-native species, as well as its behavior at different natural or anthropogenic scenarios, is fundamental for planning conservation management policies and control plans. The invasive sea anemone Anemonia alicemartinae in habits from the north (18°S) to the south-central (36°S) coast of Chile and its distribution range has expanded by approximately 1,928 km in the last 50 years. Previous works have proposed that human-mediated southward transport associated with regional-scale maritime activities could explain its rapid spread. To evaluate this hypothesis, we used ecological niche models (ENM) to evaluate the potential colonization of the southernmost area of South America. Additionally, we conducted a post hoc analysis to evaluate the relationship between the prediction of the ENM and human activity measured as the number of landings of ships in ports. The models were built based on presence records of A. alicemartinae, and oceanographic variables. Results showed that sea surface salinity and annual sea surface temperature (variance) are the best predictor variables to explain the distribution of A. alicemartinae. There was a positive and significant relationship between the geographical distribution of the sea anemone predicted by the ENM and the number of landings, as a proxy of anthropogenic activity. The most susceptible areas to invasion were those that showed the highest variability in both oceanographic predictors. These areas included the Biobío region, Chiloé´s inland sea, Aysén, and Chacabuco regions, which together comprise two biogeographical provinces. These results sustain the proposed hypothesis and, overall, the results suggest that along with the characteristics of the life history of A. alicemartinae, oceanographic conditions and maritime transport as vector contribute to the southern range expansion of this invasive cryptogenic species in the Humboldt-current large marine ecosystem.

In marine invertebrates, the modes of development at early stages are related to the type and capacity of larval feeding to achieve growth. Therefore, studying the factors that determine larval feeding strategies can help to understand the diversity of life histories and evolution of marine invertebrates. The polychaete Boccardia wellingtonensis is a poecilogonous species that encapsulates and incubates its offspring. This species produces two types of larvae: (1) larvae that do not feed within the capsule and hatch as planktotrophic larvae (indirect development), and (2) adelphophagic larvae that feed on nurse eggs and other larvae inside the capsule to hatch as advanced larvae or juveniles (direct development). Otherwise, the larval types are indistinguishable at the same stage of development. The non-apparent morphological differences between both types of larvae suggest that other factors are influencing their feeding behavior. This work studied the potential role of the activity of 19 digestive enzymes on the different feeding capacities of planktotrophic and adelphophagic larvae of B. wellingtonensis. Also, differences in larval feeding structures and the larval capacity to feed from intracapsular fluid were evaluated by electron and fluorescence microscopy. Results showed that both types of larvae present similar feeding structures and had the capacity to ingest intracapsular fluid protein. Adelphophagic larvae showed overall the highest activities of digestive enzymes. Significant differences between larval types were observed in nine enzymes related to the use of internal and external nutritional sources. Given that larval feeding is closely related to larval development in species with encapsulation, this work supports that the study of the digestive enzymatic machinery of larvae may contribute to understanding the evolution of developmental modes.

The slipper limpet Crepipatella dilatata, native to Chile and Argentina, was introduced in Spain in 2005. The species was thought to inhabit the region of Rias Bajas, yet recently, putative C. dilatata populations have been documented on the coast of north-central Spain and in the Ebro Delta of the Spanish Mediterranean. Here we undertook a multidisciplinary approach to study the invasion biology of this species. Specifically, two geographically distant populations, one being a successfully established population from O Grove and the other a declining population from Gijon, were studied over the course of four years. Analyses of morphological and developmental traits as well as genetic information confirmed the presence of C. dilatata in these sites. The results revealed polymorphism in anatomical traits and shell shape. Shell shape polymorphism was unevenly distributed among sites and among sexes. Males were monomorphic, while females were polymorphic. Of the female morphotypes encountered, one was absent in the declining population from Gijón. Size at first female maturation and female size were greater in the declining population than in the established population. Reproductive success varied seasonally but not spatially among populations. In the established population, gregariousness was significantly greater; the size when sex changes was found to be plastic and socially controlled. The sex ratio of the declining population was female biased while in the established population the sex ratio changed during the study period from being balanced to being female biased. This change in sex ratio was probably due to higher male mortality. Molecular analyses pointed to the localities of Corral Bay in southern Chile and Puerto Madryn in southern Argentina as potential population sources. The intercontinental import of fresh mussels cultivated in Chilean farms is a likely source of this mussel in Spain. Comparison with available data of native populations of C. dilatata strongly indicate that ecophenotypic plasticity, socially controlled sex change, high gregariousness, increased nurse egg supply to viable larvae during the encapsulated developmental period, later maturation and larger female sizes altogether enhance establishment success of this non-indigenous species. Human-mediated factors like the intraregional mussel trade and transplantation are also likely secondary dispersal mechanisms favouring the spread of this organism.

Non-native ascidians are important members of the fouling community associated with artificial substrata and man-made structures. Being efficient fouling species, they are easily spread by human-mediated transports (e.g., with aquaculture trade and maritime transports). This is exemplified by the ascidian Asterocarpa humilis which displays a wide distribution in the Southern Hemisphere and has been recently reported in the Northern Hemisphere (NW Europe). In continental Chile, its first report dates back from 2000 for the locality of Antofagasta (23°S). Although there was no evidence about the vectors of introduction and spread, nor the source, some authors suggested maritime transport by ship hulls and aquaculture devices as putative introduction pathways and vectors. In the present study, we report for the first time the presence of A. humilis on the hull of an international ship in a commercial port in Concepción bay (36°S), south central Chile. We also found one individual associated to a seashell farm, 70 km far from Concepción bay. Further individuals were subsequently identified within Concepción bay: one juvenile settled upon international harbor pilings and a dozen individuals along aquaculture seashell longlines. For the first specimens sampled, species identification was ascertained using both morphological criteria and molecular barcoding, using the mitochondrial gene cytochrome c oxidase subunit I (COI) and a nuclear gene (ribosomal RNA 18S). The nuclear 18S gene and the mitochondrial gene COI clearly assigned the specimens to A. humilis, confirming our morphological identification. Two haplotypes were obtained with COI corresponding to haplotypes previously obtained with European and Northern Chilean specimens. The present study thus reports for the first time the presence of A. humilis in the Araucanian ecoregion, documenting the apparent expansion of this non-native tunicate in Chile over 2,000 km, spanning over three ecoregions. In addition we reveal the potential implication of the international maritime transport as a vector of spread of this species along the Eastern Pacific coast, and the putative role of aquaculture facilities in promoting local establishments of non-native tunicates.

The diversity of free-living nematodes in the beaches of two Antarctic islands, King George and Deception islands was investigated. We used morphological and molecular (LSU, and two fragments of SSU sequences) approaches to evaluate 236 nematodes. Specimens were assigned to at least genera using morphology and were assessed for the presence of cryptic speciation. The following genera were identified: Halomonhystera, Litoditis, Enoploides, Chromadorita, Theristus, Oncholaimus, Viscosia, Gammanema, Bathylaimus, Choanolaimus, and Paracanthonchus; along with specimens from the families Anticomidae and Linhomoeidae. Cryptic speciation was identified within the genera Halomonhystera and Litoditis. All of the cryptic species identified live sympatrically. The two cryptic species of Halomonhystera exhibited no significant morphological differences. However, Litoditis species 2 was significantly larger than Litoditis species 1. The utility of molecular data in confirming the identifications of some of the morphologically more challenging families of nematodes was demonstrated. In terms of which molecular sequences to use for the identification of free-living nematodes, the SSU sequences were more variable than the LSU sequences, and thus provided more resolution in the identification of cryptic speciation. Finally, despite the considerable amount of time and effort required to put together genetic and morphological data, the resulting advance in our understanding of diversity and ecology of free-living marine nematodes, makes that effort worthwhile.

Studying the mating system of obligate aquatic organisms that inhabit river ecosystems is important for understanding its evolution as well as the role of biological and environmental factors in modulating population dynamics and species distributional patterns. Here, we studied the reproductive strategy of the Chilean endemic freshwater snail, Chilina dombeiana, in the Biobío River, one of the largest rivers in Chile. This species has a low potential for dispersal given the absence of a free-swimming larval stage (benthic larval development) and given that adults have a low capacity for mobility. We hypothesized that: 1. Females would mate with different males (polyandry) resulting in intrabrood multiple paternity, 2. Individuals from closer sites would be more related than individuals from distant sites, and 3. Male parental contributions would be unevenly distributed within broods. Individuals from three different sites were sampled along the river: upper, mid, and river mouth. In the laboratory, hatching juveniles from a total of 15 broods were collected for paternity analyses. We used microsatellite markers and the programs GERUD and COLONY to determine whether multiple paternity exists and to estimate the contribution of different males to the brood. We found that multiple paternity was very common at all of the sites analyzed with as many as 8 males fertilizing a single female and a mean of 4.2 fathers per brood estimated by COLONY. Sire contribution was skewed to particular males in several broods. In addition, overall relatedness among broods for the three sites ranged from 0.17 to 0.45 with evidence of many half-siblings. Relatedness differed among the three sites. Particularly in upstream sites or in anthropogenically disturbed populations, the high levels of multiple paternity observed in C. dombeiana may be an efficient strategy to avoid inbreeding and prevent the loss of genetic diversity within populations.

Understanding large-scale patterns in reproductive investment and fecundity of marine invertebrates is important for determining the critical environmental variables affecting reproduction and thus, the spatial patterns of population dynamics. However, information on patterns of reproduction of marine invertebrates at large spatial scales are either scarce, or have been conducted by mixing species with contrasting modes of development. Brachyuran crabs are an ideal group to analyze large-scale patterns of reproduction not only because many species are commercially exploited, but also because they show a single mode of larval development and wide distributional ranges. Here, we report latitudinal patterns of reproductive variables in five Brachyuran crab species along the coast of Chile (18-54 ° S): Cancer setosus, Paraxanthus barbiger, Homalaspis plana, Ovalipes trimaculatus, and Taliepus marginatus. Five variables were analyzed: brood weight, fecundity, embryo dry weight, embryo volume, and embryo loss. Comparisons between northern (20 °S), central (29-33 °S) and southern Chile (35-41 ° S) were conducted for C. setosus and between central and southern Chile for the other four species. A total of 378 brooding females were collected and analyzed. Although we did not find a clear and consistent pattern in all reproductive variables in the five crab species analyzed along the coast of Chile, generalizations can be drawn from this study. First, brood weight did not vary between central and southern Chile in most of the species (except P. barbiger). Second, embryo loss did not vary between central and southern Chile in four of the species studied. Third, embryo dry weight tended to increase toward high latitudes in four of the five species. We suggest that the costs associated to oxygen provision to broods may explain some of the patterns found, but other factors need also be consideredEl estudio de los patrones de inversión reproductiva y fecundidad en invertebrados marinos a escalas espaciales grandes es de vital importancia para determinar las variables ambientales críticas que afectan la reproducción, y así poder entender los patrones espaciales de las dinámicas poblacionales. Sin embargo, la información sobre patrones de reproducción en invertebrados marinos a gran escala es escasa, y en algunos casos ha sido generada tomando en cuenta especies con diferentes modos de desarrollo. Los crustáceos braquiuros son un grupo de gran interés para analizar patrones de reproducción a gran escala no solo por la importancia comercial de muchas especies sino también por presentar un único modo de desarrollo larval y un amplio rango de distribución geográfica. En este trabajo reportamos los patrones reproductivos de cinco especies de braquiuros: Cancer setosus, Paraxanthus barbiger, Homalaspis plana, Ovalipes trimaculatus y Taliepus marginatus, a lo largo de la costa de Chile (18-54 ° S). Cinco variables fueron analizadas: peso de la masa de embriones, fecundidad, peso seco del embrión, volumen del embrión y pérdida de embriones. Se realizaron comparaciones entre el norte (20 ° S), centro (29-33 ° S) y sur de Chile (35-41 ° S) para C. setosus, y entre el centro y sur de Chile para las otras cuatro especies. Se recolectaron y analizaron un total de 378 hembras ovígeras. Aunque no detectamos un patrón bien definido para todas las variables reproductivas en las especies analizadas a lo largo de la costa de Chile, emergieron al menos tres generalidades. Primero, en la mayoría de las especies el peso de la masa de embriones no varió entre el centro y sur de Chile (exceptuando P. barbiger). Segundo, la pérdida de embriones no varió entre el centro y sur de Chile en cuatro de las especies estudiadas. Tercero, el peso seco del embrión tendió a aumentar en poblaciones de latitudes altas en cuatro de las especies analizadas. Proponemos que el costo asociado a la provisión de oxígeno a los embriones puede explicar alguno de los patrones encontrados, aunque otros factores necesitan ser considerados

The quantification of the costs associated with parental care of marine invertebrates requires a first and necessary step, which is the identification of the different forms of care exhibited by this group. Among marine invertebrates, provision of oxygen to the aggregation of embryos may be critical, although most evidence on the link between oxygen limitation and parental care is indirect. Species which show active behavior directed at providing oxygen to the brood offer a good model to establish the direct link between behavioural patterns and oxygen provision to the embryos, and to estimate the costs associated with this form of care. In this manuscript, we conducted a review of the current knowledge about oxygen limitation in embryos aggregations of marine invertebrates in general and Brachyuran crabs in particular. Most of the emphasis focuses on recent results on Brachyuran crabs and new information on Ovalipes trimaculatus. The consequences of oxygen limitation on investment in reproduction and clutch size determination are analyzed. Temporal patterns of oxygen availability in the center of embryo masses of Brachyuran crabs are different from other brooding species of marine invertebrates. A cyclic pattern in oxygen partial pressure (PO2) was detected in masses of early stage embryos, and constant, high PO2 in females carrying late stage embryos, for all crab species studied so far. As changes in PO2 in the embryo mass occurred, an increase in oxygen demand by the embryos and an increase in abdominal flapping frequency were detected in all species. Moreover, the rate of increase in the frequency of abdominal flapping between females carrying early and late stage embryos varied among species, depending on oxygen consumption rate of the embryos. In spite of this, embryos of all species experience similar oxygen conditions throughout development. Abdominal flapping seems to be the main behavior used to provide oxygen to the embryos, regardless of the habitat types inhabited by brooding females. Recent studies have shown that ovigerous female crabs consume a substantially higher amount of oxygen than non-brooding females, and suggested that there may be a trade-off between investment in eggs and in ventilation of the embryos. This information supports the need for including the cost of oxygen provision in the estimation of maternal effort. A broad range of possible areas of research are proposed to advance in this direction, concentrating either on marine invertebrates in general, or Brachyuran crabs in particularLa cuantificación de los costos asociados con cuidado parental en invertebrados marinos requiere de un primer paso, muy necesario, cual es la identificación de los diferentes tipos de cuidado parental presentes en este grupo. Entre los invertebrados marinos, la provisión de oxígeno a las agregaciones de embriones es crítica, pero hasta ahora las evidencias que ligan el cuidado maternal con la provisión de oxígeno son indirectas. Las especies que muestran comportamientos activos dirigidos a la provisión de oxígeno a los embriones ofrecen un buen modelo de estudio para establecer la relación entre cuidado maternal y provisión de oxígeno, permitiendo además estimar los costos asociados. En este manuscrito, presentamos una revisión de la información existente sobre limitación de oxígeno en agregaciones de embriones de invertebrados marinos en general, y de braquiuros en particular. El principal énfasis es en resultados recientes sobre Braquiuros y nueva información sobre Ovalipes trimaculatus. Las consecuencias de la limitación de oxígeno sobre inversión en reproducción y determinación del tamaño de la camada son analizadas. Los patrones temporales de disponibilidad de oxígeno en el centro de masas de embriones de Braquiuros difiere de otras especies de invertebrados marinos. Un patrón cíclico de presión parcial de oxígeno (PO2) se observa en masas de embriones tempranos, mientras que niveles altos y constantes de PO2 se han encontrado en hembras con embriones en estadíos tardíos de desarrollo. A medida que ocurren estos cambios en PO2 en la masa de embriones, se detectó un aumento en el consumo de oxígeno de los embriones y en la frecuencia del batido abdominal de las hembras. Este patrón también se pudo observar al comparar la frecuencia del batido abdominal entre especies que muestran diferentes tasas de consumo de sus embriones. A pesar de estas diferencias, los embriones de todas las especies experimentan bajos niveles de PO2 durante fases tempranas del desarrollo y altos niveles de PO2 en estadíos tardíos. En todas las especies el batido abdominal parece ser el principal comportamiento utilizado para proveer oxígeno a los embriones, independientemente del tipo de hábitat utilizado por los adultos. Estudios recientes han mostrado que hembras ovígeras de braquiuros consumen significativamente más oxígeno que las hembras no ovígeras, y sugieren que hay un compromiso entre inversión en huevos e inversión en ventilar esos embriones. Estas evidencias muestran la necesidad de incluir el costo de provisión de oxígeno en la estimación del esfuerzo maternal. Se presenta un amplio rango de posibles líneas de interés para investigar este problema y avanzar en nuestro conocimiento, utilizando como modelos invertebrados marinos en general, y los braquiuros en particular

Sibling cannibalism is commonly observed in marine species. For instance, intrabrood cannibalism has been documented in marine gastropods with direct development, suggesting a relationship between embryo behavior and the evolution of life history strategies. However, there has been little effort to document the factors driving sibling cannibalism in marine species. The kin selection theory suggests that the level of relatedness plays an important role in cannibalism patterns. We examined Crepidula coquimbensis, a marine gastropod that broods and encloses its brooded offspring in capsules. Encapsulated embryos show sibling cannibalism and high levels of intracapsular multiple paternity. Given these features, cannibalistic behavior may be driven by kin-relatedness. To test this hypothesis, we constructed artificial aggregations of embryos to mimic three levels of relatedness: high, medium and low. For each category of aggregation, the cannibalism rate and benefits (i.e. size at hatching of surviving offspring) were estimated. In addition, at the end of embryo development, we performed parentage analyses to determine if cannibalism was associated with the relatedness between cannibal and victim embryos. Our results show that the intensity of sibling cannibalism increased in aggregations characterized by the lowest level of relatedness. There were important benefits of cannibalism in terms of hatching cannibal size. In addition, cannibalism between embryos was not random: the variation in reproductive success between males increased over the course of the experiment and the effective number of fathers decreased. Altogether, these results suggest that polyandry may play an important role in the evolution of sibling cannibalism in C. coquimbensis and that kin selection may operate during early embryonic stages in this species.