Local Habitat Research Articles

Integrated multi-approaches reveal unique metabolic mechanisms of Vestimentifera to adapt to deep sea.

Vestimentiferan tubeworms are deep-sea colonizers, in which chemoautotrophic symbiosis was first observed. These animals are gutless and depend on endosymbiotic bacteria for organic compound synthesis and nutrition supply. Taxonomically, vestimentiferans belong to Siboglinidae and Annelida. Compared with other siboglinids, vestimentiferans are distinguished by high tolerance of the prevailing hydrogen sulfide in hydrothermal vents, rapid growth in local habitats, and a physical structure consisting of a thick chitinous tube. The metabolic mechanisms contributing to these features remain elusive. Comparative genomics revealed that unlike other annelids, vestimentiferans possessed trehaloneogenesis and lacked gluconeogenesis. Transcriptome and metabolome analyses detected the expression of trehalose-6-phosphate synthase/phosphatase (TPSP), the key enzyme of trehaloneogenesis, and trehalose production in vestimentiferan tissues. In addition to trehaloneogenesis, glycogen biosynthesis evidenced by packed glycogen granules was also found in vestimentiferan symbionts, but not in other Siboglinidae symbionts. Data mining and analyses of invertebrate TPSP revealed that the TPSP in Vestimentifera, as well as Cnidaria, Rotifera, Urochordata, and Cephalochordata, likely originated from Arthropoda, possibly as a result of transposon-mediated inter-phyla gene transfer. This study indicates a critical role of bacterial glycogen biosynthesis in the highly efficient symbiont - vestimentiferan cooperation. This study provides a new perspective for understanding the environmental adaptation strategies of vestimentiferans and adds new insights into the mechanism of metabolic evolution in Metazoa. Video Abstract.

Intra‐ and inter‐specific variability in the temporal trends of butterfly phenology in the Northern Alps

Abstract Large‐scale declines in insect abundances and richness due to climate and land‐use change have been well documented during the past years. These changes are accompanied by shifts in insect phenology towards earlier appearance in spring and prolonged activity periods in late summer and autumn. The magnitude of these responses to climate change might be masked by intra‐ and inter‐specific variability in phenology and trait expression. Here, we used a large data set of museum records of butterflies from the northern Austrian Alps (380 m to >3000 m asl) and ask to which degree does intra‐ and inter‐specific variability in spring and autumn activity and in the numbers of generations affect the temporal trends in phenology during the last 30 years? For the 17 most abundant species, we found phenological variability to strongly differ among species, local habitats and study years. Ubiquitous mobile species were significantly more variable than habitat specialist and sedentary species. Intra‐specific variability was highest in ubiquitous habitat generalist species and increased during the study period. As consequence, seasonal appearance and composition of local butterfly communities are now less predictable than decades ago. It remains unclear whether this trend causes a rewiring of pollinator food webs.

Drivers of Interspecific Spatial Segregation in Two Closely‐Related Seabird Species at a Pan‐Atlantic Scale

ABSTRACTAimEcologically similar species living in sympatry are expected to segregate to reduce the effects of competition where resources are limiting. Segregation from heterospecifics commonly occurs in space, but it is often unknown whether such segregation has underlying environmental causes. Indeed, species could segregate because of different fundamental environmental requirements (i.e., ‘niche divergence’), because competitive exclusion at sympatric sites can force species to either change the habitat use they would have at allopatric sites (i.e., ‘niche displacement’) or to avoid certain areas, independently of habitat (i.e., ‘spatial avoidance’). Testing these hypotheses requires the comparison between sympatric and allopatric sites. Understanding the competitive mechanisms that underlie patterns of spatial segregation could improve predictions of species responses to environmental change, as competition might exacerbate the effects of environmental change.LocationNorth Atlantic and Arctic.TaxaCommon guillemots Uria aalge and Brünnich's guillemots Uria lomvia.MethodsHere, we examine support for these explanations for spatial segregation in two closely‐related seabird species, common guillemots (Uria aalge) and Brünnich's guillemots (U. lomvia). For this, we collated a pan‐Atlantic data set of breeding season foraging tracks from 1046 individuals, collected from 20 colonies (8 sympatric and 12 allopatric). These were analysed with habitat models in a spatially transferable framework to compare habitat preferences between species at sympatric and allopatric sites.ResultsWe found no effect of the distribution of heterospecifics on local habitat preferences of the focal species. We found differences in habitat preferences between species, but these were not sufficient to explain the observed levels of spatial segregation at sympatric sites.Main ConclusionsAssuming we did not omit any relevant environmental variables, these results suggest a mix of niche divergence and spatial avoidance produces the observed patterns of spatial segregation.

Landscape diversity, habitat connectivity, age and size determine the conservation value of limestone quarries for diverse wild bee communities

Abstract Abandoned and even active limestone quarries (excavation sites) can represent important secondary habitats for many species, including wild bees, associated with dry grasslands, which are threatened biodiversity hotspots in Europe. However, is not well understood how interactions between local habitat and landscape characteristics influence the value of limestone quarries for wild bees and how this could guide conservation schemes. We studied how wild bee communities in limestone quarries are affected by landscape variables (connectivity to neighbouring dry grasslands, landscape diversity), local quarry characteristics (area, age, woody vegetation cover, flowering plant species) and their interactions. We surveyed bee communities during 208 transects in 19 quarries in southern Lower Saxony, Germany. In total, we recorded 114 bee species (2360 individuals), including 35 endangered species. High flowering plant species richness positively affected bee abundance and richness. Large quarry area was important for determining the presence of endangered bee species. High levels of woody vegetation cover had a negative effect on bee abundance and richness. Bee abundance and richness can increase with quarry age, but only at sites with moderate woody vegetation cover. We found potentially positive interactions between quarry age and landscape diversity and/or habitat connectivity to neighbouring dry grasslands. In particular, high habitat connectivity ensured stable richness of endangered species in old quarries. Synthesis and applications. Observed negative effects of high woody vegetation cover on bee communities highlight the importance of local management to reduce shrub encroachment and reset successional processes in limestone quarries. Local management is particularly important in old quarries of great ecological value, where the adverse impact of high woody vegetation cover on wild bees appears to be most severe. Large and old quarries with high connectivity to neighbouring dry grasslands are especially valuable for endangered bee species. Therefore, landscape‐scale restoration and conservation of dry grasslands is the most promising approach to promote endangered bee species through enhanced habitat connectivity.

Mapping essential juvenile habitats of exploited marine fish: Complementary insights from a scientific survey-based model, fishers’ knowledge and fisheries-dependent data

In the Bay of Biscay (BoB, Northeast Atlantic), a preexisting habitat suitability model (HSM) fitted on ecological scientific trawl survey data with restricted partial coverage revealed the concentration of Young of the Year (YoY) common sole (Solea solea) on restricted coastal and estuarine nurseries. To extend the nursery map of sole in the BoB to zones where survey data are lacking and fit with the sole population and stock management extent, we crossed HSM, fishers’ ecological knowledge (FEK) and fisheries-based (FB) data. FB and FEK data also complemented knowledge on juvenile sole habitat and seasonal migration. Thirteen fishers with potential knowledge about the YoY sole distribution were directly interviewed. Direct interviews included both information about the location of juveniles and YoY distribution mapping. With good consensus among fishers, FEK allowed the identification of four new areas hosting essential juvenile habitat for the common sole, revealed the accuracy of the HSM model outside the spatial coverage of the ecological survey, and provided spatial refinement. The FB observation data confirmed the locations of the essential juvenile habitats given by FEK and the spatial distributions of YoY densities predicted from the scientific data. In addition, FB confirmed the seasonal migration of YoY sole, which was preliminarily hypothesized from a local and short-term survey-based study. Our results emphasized the local accuracy of FEK. These findings also underlined the interest in combining several sources of data and methods to map essential fish habitats outside areas well covered by ecological scientific surveys, on order to inform future spatial management measures.

Depopulation and Changes in Habitat Type in Rural Areas in Aragón (Spain)

Objective: The study aims to examine recent transformations in rural habitats undergoing depopulation in Aragón, Spain, between 2010 and 2018. It seeks to verify changes in habitat concentration patterns and identify the underlying factors. Theoretical Framework: Drawing upon theories of rural exodus and demographic shifts, the research employs the Colas Index (Colas, 1945) to analyze habitat types—dispersed or concentrated. It recognizes the influence of agricultural changes, service provision challenges, and territorial dynamics on rural settlement patterns (Escolano and de la Riva, 2003; Nuninger et al., 2021). Method: The investigation focuses on depopulated municipalities in Aragón, utilizing a comparative analysis of the Colas Index from 2010 to 2018. Administrative boundaries define the study's territorial units, enabling the quantification of habitat changes and an assessment of their direction. The analysis integrates demographic and settlement dynamics to understand habitat evolution. Results and Discussion: Findings indicate varied habitat transformation processes across municipalities, confirming the heterogeneity of the rural landscape (Pinilla and Sáez, 2017). While transformations are not universal, they challenge the traditional link between depopulation and habitat concentration. The Colas Index proves valuable for characterizing habitat dispersion levels, yet its limitations in concentrated areas are acknowledged. Methodological constraints related to administrative boundaries and the complexity of rural-urban continua are also discussed. Research Implications: This study contributes to a nuanced understanding of depopulation impacts on rural habitats, informing territorial planning and demographic policies. It underscores the need for tailored strategies that consider local habitat variability and the potential for revitalization efforts in select areas. Originality/Value: By highlighting the diversity of habitat transitions amidst depopulation, the research offers fresh insights into rural settlement dynamics. Its value lies in demonstrating that depopulation no longer universally leads to habitat concentration, thus updating the scholarly discourse on rural transformation in Spain.

A decolonial approach to ecological distribution conflicts and the Maya Train in Mexico

A neoliberal development model, frequently at odds with the values of the local Mayan biocultural heritage, has historically prompted the conversion of forests and small-scale agricultural land, mainly in the Yucatan Peninsula. This study analyzes ethnographic data collected in two localities in the peninsula that will be impacted by the Maya Train. Preliminary results based mainly on conducted interviews revealed perceptions regarding daily interactions with the local habitat, the effects of public policy initiatives in the communities, and resistance strategies in response to perceived threats surrounding the project. Through a decolonial lens, the study contributes to understanding how social movements impact policies in the face of the environmental and social pacts of neoliberal development projects, while advancing towards a more ontologically diverse political representation.

Genetic and Habitat Rescue Improve Population Viability in Self-Incompatible Plants.

Habitat fragmentation and the acceleration of environmental change threaten the survival of many plant species. The problem is especially pronounced for plant species with self-incompatibility mating systems, which are obligate outcrossers, thus requiring high mate availability to persist. In such situations, plant populations suffering decreased fitness could be rescued by: (a) improving local habitat conditions (habitat rescue), (b) increasing the number of individuals (demographic rescue), or (c) introducing new genetic variation (genetic rescue). In this study, we used a spatially and genetically explicit individual-based model to approximate the demography of a small (N = 250) isolated self-incompatible population using a timescale of 500 years. Using this model, we quantified the effectiveness of the different types of rescues described above, singly and in combination. Our results show that individual genetic rescue is the most effective type of rescue with respect to improving fitness and population viability. However, we found that introducing a high number of individuals (N > 30) to a small population (N = 50) at the brink of extinction through demographic rescue can also have a positive effect on viability, improving average fitness by 55% compared to introducing a low number of individuals (N = 10) over a long timescale (> 500 years). By itself, habitat rescue showed the lowest effects on viability. However, combining genetic and habitat rescue provided the best results overall, increasing both persistence (> 30%) and mate availability (> 50%). Interestingly, we found that the addition of even a small number of new S alleles (20%) can be highly beneficial to increase mate availability and persistence. We conclude that genetic rescue through the introduction of new S alleles and an increase in habitat suitability is the best management strategy to improve mate availability and population viability of small isolated SI plant populations to overcome the effects of demographic stochasticity and positive density dependence.

Spatial and temporal characterization of Aedes albopictus oviposition activity in candidate urban settings for sterile insect technique testing in La Reunion Island

BackgroundUnderstanding of mosquito spatiotemporal dynamics is central to characterize candidate field sites for the sterile insect technique (SIT) testing, and is critical to the effective implementation and evaluation of pilot sterile male release programs. Here, we present a detailed description of Aedes albopictus (Skuse) egg-laying activity over a 6-year period in urban areas identified as potential SIT testing sites on Reunion Island.MethodWeekly entomological collections using ovitraps were carried out in residential and adjacent uninhabited habitats in two urban areas, Duparc and Bois Rouge, in the municipality of Sainte Marie, Reunion Island. Time-series data incorporating the frequency of positive ovitraps and the total number of eggs/ovitrap recorded each time at each locality during the study period from May 2013 to December 2018 were analyzed with multifaceted statistical approaches including descriptive statistics and spatiotemporal analyses incorporating the role of climatic factors on overall ovitrap productivity.ResultsDuring the ovitrap survey, the proportion of egg-positive ovitraps differed among study sites (χ2 = 50.21, df = 2, P < 0.001), being relatively lower in Duparc (89.5%) than in Bois-Rouges (95.3%) and the adjacent buffer zone (91.2%). Within each neighborhood, Ae. albopictus egg abundance varied by month in a roughly seasonal pattern marked by a single peak occurring more regularly February each year, a decline at the onset of the austral winter in July, followed by a period of lower ovitrap productivity in August and September. Fluctuation in both positivity rate and eggs densities per ovitraps were related to annual and seasonal variations in local temperature and rainfall (P < 0.001 in all cases). The spatial analysis also captured substantial between- and within-habitats heterogeneity, whereby the overall ovitrap productivity was higher in residential areas than in the buffer zone.ConclusionsCollectively, these results reveal that the distribution of Ae. albopictus oviposition activity is shaped by local habitat heterogeneity and seasonal climatic factors. Overall, this study provides baseline insights into the reproductive dynamics of Ae. albopictus, which would assist in planning locally tailored SIT interventions, while addressing concerns related to focal areas of high egg-laying intensity and potential immigration of females from natural areas.

Limited evidence for the influence of the physical structure and floristics of habitat on a boreal forest bird community

Studies conducted at regional and continental scales show that avian richness, community composition, and abundance are associated with variation in the vegetation physical structure and community composition (floristics) within broad habitat types. The relative contributions of physical structure and floristics are contested, and relationships are often taxon-specific. We used 110 microphone arrays deployed across 90 sampling locations and two breeding seasons to survey an avian community in the boreal forest in Labrador, Canada. Our objectives were (1) to describe the avian community of an underrepresented portion of the boreal forest, (2) to estimate the relationships between avian species richness and habitat characteristics, (3) to estimate if species detection at a given location was related to local habitat characteristics, and (4) to investigate the spatial and temporal patterns of the avian community composition. We detected 32 species at our sampling locations; physical structure and floristics were not related to avian species richness, although estimates of richness were higher on warmer days and lower on windier days. Habitat characteristics were associated with the detection of Boreal Chickadee (Poecile hudsonicus), Yellow-rumped Warbler (Setophaga coronata), American Robin (Turdus migratorius), and Black-throated Green Warbler (Setophaga virens). Finally, avian community composition was only moderately consistent among three categorical forest types and between audio sampling periods in two consecutive breeding seasons. Overall, we show that the structural and floristic traits measured at our study site are not related to the detection of most avian species or to species richness.

Differential responses to weather and land‐cover conditions explain spatial variation in winter abundance trends in a migratory bird of conservation concern

Abstract Effective conservation strategies for animal populations require knowledge of relationships between population dynamics and their environmental drivers. However, these processes often vary within animal populations, requiring site‐specific conservation planning. Given limited financial resources, identifying groups of sites with similar population dynamics can help practitioners efficiently implement conservation programs to larger areas. We evaluated spatial patterns and environmental drivers of wintering site trends in a migratory bird of conservation concern, the Greenland white‐fronted goose (Anser albifrons flavirostris). We used latent class analysis to identify trend patterns in 35 years of abundance data among 59 geographically discrete Greenland white‐fronted goose wintering sites. We developed a state‐space abundance model in a Bayesian framework to quantify the effects of weather and land‐cover conditions experienced throughout spring migration, summer breeding, autumn migration and wintering periods on variation in wintering site abundance. We identified two main patterns in Greenland white‐fronted goose abundance trends: northeastern wintering sites declined on average by 3% per year, while southwestern wintering sites declined on average by 14% per year. Differential responses to weather and habitat conditions likely explained variation among groups, as geese at southwestern wintering sites were more negatively affected by harsh weather conditions (e.g. low temperatures and high precipitation on breeding areas) and poor habitat conditions (i.e. low‐quality grasslands and croplands) on wintering areas. Future conservation efforts to improve the suitability and nutritional quality of agricultural areas, especially cereal croplands in autumn and early winter and grasslands in late winter and early spring, could potentially improve local habitat conditions, especially in the southwestern wintering sites where abundance declines were steepest. Synthesis and applications. We demonstrate the potential to delineate animal populations based on spatial patterns in population dynamics using long‐term abundance monitoring data, which are commonly the only available data for conservation practitioners. By grouping sites based on spatial patterns in local abundance trends, we can further test hypotheses about how these groups are differentially affected by changing environmental conditions. This information is important for informing efficient conservation planning over large areas when financial resources are limited.

Формирование вторичного ареала караганы древовидной в лесопарках г. Екатеринбурга

The article is devoted to the analysis of the distribution and features of the ecological and biological confinement of Caragana arborescens Lam. in the forest parks of Yekaterinburg. Caragana plantations have been studied in 14 out of the 15 city forest parks: Kalinovskij, Zheleznodorozhnyj, Karas’ye-Ozerskij, Moskovskij, Nizhne-Isetskij, Sanatornyj, Uktusskij, Shuvakishskij, Yuzhnyj, Shartashskij, named after the Foresters of Russia, Obroshinskij, Central and South-West – on an area of 12,077 hectares based on a standard electronic database. The ontogenesis of the species and its morphological features have been studied in 10 local habitats by the example of 2 forest parks – named after the Foresters of Russia with the largest number of caragana and Uktussky with the minimum. The formation of the secondary area of caragana in the forest parks of Yekaterinburg depends on the presence of generative individuals nearby. The maximum growth area is established in the forest park named after the Foresters of Russia (98.6 ha), the minimum – in the SouthWest (0.4 ha). The area of distribution is determined by the area of plantings that have been carried out in the 1970s and 1980s, which is confirmed by our research in the forest parks. C. arborescens prefers to settle in mixed-herb (67.8 %) and berry (26.8 %) pine forests with a stand density of 0.6–0.7, being a heliosciophyte. The number of caragana trees in the habitats increases with the increase in the density of the stand from 404 to 1359 plants. When the density of the pine stand is 0.3–0.5, the amount of caragana decreases, and at 0.1–0.2 it disappears. The distribution of C. arborescens depends on the age categories and productivity of forest plantations, it grows mainly in mature pine (68.8 %) trees in high-quality (the 2nd quality class – 62.3 %) plantations. In the ontogeneisis of caragana, 2 periods and 6 agerelated conditions have been established, with the pregenirative fraction predominating. The studied habitats are normal, incomplete, but capable of self-maintenance, since under favourable conditions individuals reproduce by self-seeding. The life forms of the caragana tree are formed in open areas as an aeroxylic shrub, and in pine forests as a small tree. The Caragana arborescens introductions in the forest parks of Yekaterinburg are rare and currently pose no biological hazard to forest ecosystems.

Exploring the Drivers Influencing Multidimensional Alpha and Beta Diversity of Macroinvertebrates in Mountain Streams

Understanding the driving mechanisms of diversity across multiple dimensions is a fundamental task in biodiversity conservation. Here, we examined the alpha and beta diversity of macroinvertebrates in the taxonomic, functional, and phylogenetic dimensions in mountain streams of northwestern Hubei Province, China. We also assessed how much local environmental, land use, climatic, and spatial variables affected these diversities. We found that (1) there were generally weak or no correlations of alpha and beta diversity between taxonomic, functional, and phylogenetic dimensions; (2) compared to both functional and phylogenetic beta diversity, which was mainly determined by nestedness, taxonomic beta diversity was mostly molded by turnover and was much higher; and (3) local environmental variables predominantly influenced taxonomic and functional dimensions of alpha and beta diversity, while spatial factors primarily drove phylogenetic dimension. These results suggest that regulating local habitats is crucial for lotic biodiversity conservation efforts, though spatial processes cannot be overlooked. Furthermore, our findings verify the supplemental role of functional and phylogenetic data in enriching insights provided by taxonomic data alone. This underscores the importance of a multidimensional approach for a more nuanced understanding of community assembly mechanisms, which is crucial for efficient ecosystem management and biodiversity conservation.

Epigaeic spiders (Araneae) from three habitats at Stryn, Nordfjord, Western Norway

One year of pitfall sampling in (A) a narrow strip of vegetation (junipers, Rosa sp., small pines) close to a river bank, (B) a cultivated medium humid meadow and (C) a humid deciduous forest (Alnus) with some grass on the ground collected a total of 25, 48 and 32 species, respectively (in total 67 species). Shannon indices of general diversity (ln e) were 1.8, 2.1 and 3.1, respectively. The three sites shared only 9 species, 57% of all species were found in only one locality. Similarity indices were low, especially between loc. A and C. Linyphiidae and Lycosidae were dominant. The latter were scarce in loc. B and C but common at loc. A (Pardosa palustris and P. amentata together comprising 43.5% of total) and net building species more scarce. The local distribution, co-existence, ecological and habitat preferences, seasonal activity and body size of some common species are briefly discussed. For some species, aspects of geographical distribution are discussed.

Survival and Evolutionary Adaptation of Populations Under Disruptive Habitat Change: A Study With Darwinian Cellular Automata.

The evolution of living beings with continuous and consistent progress toward adaptation and ways to model evolution along principles as close as possible to Darwin's are important areas of focus in Artificial Life. Though genetic algorithms and evolutionary strategies are good methods for modeling selection, crossover, and mutation, biological systems are undeniably spatially distributed processes in which living organisms interact with locally available individuals rather than with the entire population at once. This work presents a model for the survival of organisms during a change in the environment to a less favorable one, putting them at risk of extinction, such as many organisms experience today under climate change or local habitat loss or fragmentation. Local spatial structure of resources and environmental quality also impacts the capacity of an evolving population to adapt. The problem is considered on a probabilistic cellular automaton with update rules based on the principles of genetic algorithms. To carry out simulations according to the described model, the Darwinian cellular automata are introduced, and the software has been designed with the code available open source. An experimental evaluation of the behavioral characteristics of the model was carried out, completed by a critical evaluation of the results obtained, parametrically describing conditions and thresholds under which extinction or survival of the population may occur.

Quantification of threats to bats at localized spatial scales for conservation and management.

In a rapidly changing world, where species conservation needs vary by local habitat, concentrated conservation efforts at small spatial scales can be critical. Bats provide an array of value to the ecosystems they inhabit; many bat species are also of conservation concern. San Diego County, California, contains 22 of the 41 bat species that occur in the United States, 16 of which are on conservation watchlists. Thus, management of bat communities in San Diego County is a pressing need. Because bats exploit vast areas of the landscape and historical sampling strategies have shifted over time, a standardized way of prioritizing areas of the landscape for management would provide an integral asset to bat conservation. We leveraged long-term bat community survey data from sampling areas across San Diego County to prioritize areas with the most management need. We calculated two types of scores: species scores and threat scores. Species scores incorporated richness and conservation status, and threat scores included landscape level threats that bats could encounter. We found that urbanization, the presence of artificial lights, and areas sampled on unconserved land were all significantly associated with decreases in species richness. Further, using species and threat scores, each sampling area was placed into one of four conservation categories, in order from greatest to least conservation need, ranging from highest priority (high species score, high threat score) to lowest (low species score, low threat score). Additionally, we focused on sampling areas in which Townsend's big-eared bat (Corynorhinus townsendii) and/or pallid bat (Antrozous pallidus) occurred. These two species are of exceptional conservation concern in San Diego County and across the western United States. We identified urbanization, the presence of artificial lights, and areas sampled on unconserved land as threats that were all significantly associated with the absence of Townsend's big-eared bat, but not pallid bat. The strategy, methodology, and solutions proposed in our study should assist bat conservation and management efforts wherever bats occur, and can be extended to other species that require conservation attention.

Hessische Rhön – mountain grassland, rough grazing and their birds

Hessische Rhön – mountain grassland, rough grazing and their birds The project is particularly dedicated to conservation and development measures for the species-rich mountain grassland and the protection of endangered bird species in open areas of the Hessian low mountain ranges of the Rhön. By implementing different types of landscape maintaining measures in close cooperation with local farmers and municipalities valuable habitats in the Natura 2000 protected area network were substantially improved.

Oyster reefs as habitat for aquatic macrofauna in a Gulf of Mexico estuary: biotic complexity at spatial, ecological, and demographic scales

Oysters are important marine foundation species across the world, particularly in estuaries of the Gulf of Mexico. One important function of oysters in estuaries is the provision of 3-dimensional habitat that is used by a wide range of species. In this study, the biotic diversity of mid-bay intertidal oyster reefs found in a Gulf of Mexico estuary was examined at nested ecological and demographic scales. Fishery-independent data collections made in East Matagorda Bay, Texas, USA, were used to compare community structure and diversity at mid-bay reefs to undifferentiated shoreline habitats. Despite similar diversity metrics, there were differences in community structure that were driven by differences in spatial habitat use by several common species. Below the community scale, demographic differences in spotted seatrout Cynoscion nebulosus habitat use were observed, with smaller and younger individuals found along reefs, and larger and older individuals found along shorelines. This finding was more pronounced for male spotted seatrout in the spring. The observed spatial habitat use patterns at nested ecological scales (community, inter-species, intra-species) highlight the importance of oyster reefs for maintaining diversity in Gulf of Mexico estuaries, and more broadly support the notion that heterogeneity in localized habitats drives biotic diversity at the estuary scale. Conservation of oyster reefs as critical habitat should be considered along with conservation of oysters themselves when balancing the ecological value of oysters against the commercial value of oyster fisheries.

European eel (Anguilla anguilla) survival modeling based on a 22-year capture-mark-recapture survey of a Mediterranean subpopulation.

Since the 1980s, the European eel (Anguilla anguilla) has declined by over 90% in recruitment across its European and North African distribution area. This diadromous fish spawns at sea and migrates into continental waters, where it grows for three to more than 30 years, depending on habitat conditions and location. During their growth, different habitat use tactics can locally influence the life-history traits of eels, including their survival rates. Thus, the spatio-temporal dimension of this species is crucial for management. Based on a rare Mediterranean long-term survey of more than 20 years (2001-2022) in an artificial drainage canal connected to a vast brackish lagoon (the Vaccarès lagoon), we aimed to study the dynamics of one subpopulation's life-history traits. We used Bayesian multistate capture-mark-recapture (CMR) models to assess the temporal variability in survival and abundance at both seasonal and inter-annual scales, considering life-stage structure. High survival rates and low detection probabilities were found for the undifferentiated and female yellow stages. In contrast, female silver eels exhibited lower survival rates and higher capture probabilities. Estimating detection probabilities and survival rates enabled accurate assessment of relative abundance across different life stages and time periods. Our findings indicated a substantial decrease in the abundance of undifferentiated and female yellow eels in the early 2000s, whereas the abundance of female silver eels remained consistently low yet stable throughout the study period. Considering the life stage seemed essential to study the dynamics of the eel during its continental growing period. The present results will provide key elements to propose and implement suitable sustainable environmental management strategies for eel conservation.

Extensive Population Structure Highlights an Apparent Paradox of Stasis in the Impala (Aepyceros melampus).

Impalas are unusual among bovids because they have remained morphologically similar over millions of years-a phenomenon referred to as evolutionary stasis. Here, we sequenced 119 whole genomes from the two extant subspecies of impala, the common (Aepyceros melampus melampus) and black-faced (A. m. petersi) impala. We investigated the evolutionary forces working within the species to explore how they might be associated with its evolutionary stasis as a taxon. Despite being one of the most abundant bovid species, we found low genetic diversity overall, and a phylogeographic signal of spatial expansion from southern to eastern Africa. Contrary to expectations under a scenario of evolutionary stasis, we found pronounced genetic structure between and within the two subspecies with indications of ancient, but not recent, gene flow. Black-faced impala and eastern African common impala populations had more runs of homozygosity than common impala in southern Africa, and, using a proxy for genetic load, we found that natural selection is working less efficiently in these populations compared to the southern African populations. Together with the fossil record, our results are consistent with a fixed-optimum model of evolutionary stasis, in which impalas in the southern African core of the range are able to stay near their evolutionary fitness optimum as a generalist ecotone species, whereas eastern African impalas may struggle to do so due to the effects of genetic drift and reduced adaptation to the local habitat, leading to recurrent local extinction in eastern Africa and re-colonisation from the South.