Ecology Of Species Research Articles

Ranging Behavior of Non-Breeding and Breeding Adult White-Tailed Eagles

Space utilization by animals is vital for species ecology but also a valuable predictor of habitat conditions and environment capacity for a given species. We investigated the ranging behavior of the white-tailed eagle, an apex predator experiencing a significant population increase and saturation. Comparing five adult floaters and two breeding males tracked with GPS loggers in Poland for 1–5 years, we observed substantial differences in space utilization. Breeding males occupied approximately 63 to 122 km2 (using 90% kernel density), while floaters ranged over roughly 6000 to 60,000 km2. Breeding males expanded their home ranges during successful breeding, with one male frequently flying 29 km to a foraging site when raising chicks but hardly doing so in other seasons. Both breeding males revisited nests more frequently in April and May (up to seven times daily, typically two to four), exhibiting distinct seasonal daily movement patterns. Floaters had slightly higher daily movement rates with a weak seasonal pattern. We conclude that breeding males’ ranging behavior depended on proximity to optimal foraging sites, while adult floaters engaged in prolonged wandering.

Geographic origin and host’s phylogeny are predictors of the gut mucosal microbiota diversity and composition in Mediterranean scorpionfishes (Scorpaena spp.)

The gut microbiome holds an important role in the health and homeostasis of fishes. However, despite the large diversity and distribution of this vertebrate group, only the intestinal microbiome of a limited number of freshwater and marine fish species has been well characterized to date. In this study, we characterize the gut mucosal microbial communities of three commercially valuable Scorpaena spp. (n=125) by using a comprehensive comparative dataset including 16S rRNA gene amplicon data from four different locations in the Mediterranean Sea. We report that the geographical origin of the individuals influences the diversity and the composition of the gut microbial communities more than the host’s phylogenetic relatedness in this fish group. Moreover, we observe a positive correlation between the composition of the gut microbiota and the phylogenetic distance between the hosts (i.e. phylosymbiosis). Finally, the core microbiota of each species is described both regionally and across the Mediterranean Sea. Only a few bacterial genera appear to be residents of the scorpionfishes’ gut microbiota across the Mediterranean Sea: Photobacterium, Enterovibrio, Vibrio, Shewanella, Epulopiscium, Clostridium sensu stricto 1 and Rombutsia in S. notata, Clostridium sensu stricto 1, Cetobacterium and Rombutsia in S. porcus, and only Clostridium sensu stricto 1 in S. scrofa. This study highlights the importance of investigating the gut microbiome across a species’ geographical range and it suggests this as a general procedure to better characterize the gut microbial ecology of each fish species.

Movement Ecology of Adult Western Corn Rootworm: Implications for Management.

Movement of adult western corn rootworm, Diabrotica virgifera virgifera LeConte, is of fundamental importance to this species' population dynamics, ecology, evolution, and interactions with its environment, including cultivated cornfields. Realistic parameterization of dispersal components of models is needed to predict rates of range expansion, development, and spread of resistance to control measures and improve pest and resistance management strategies. However, a coherent understanding of western corn rootworm movement ecology has remained elusive because of conflicting evidence for both short- and long-distance lifetime dispersal, a type of dilemma observed in many species called Reid's paradox. Attempts to resolve this paradox using population genetic strategies to estimate rates of gene flow over space likewise imply greater dispersal distances than direct observations of short-range movement suggest, a dilemma called Slatkin's paradox. Based on the wide-array of available evidence, we present a conceptual model of adult western corn rootworm movement ecology under the premise it is a partially migratory species. We propose that rootworm populations consist of two behavioral phenotypes, resident and migrant. Both engage in local, appetitive flights, but only the migrant phenotype also makes non-appetitive migratory flights, resulting in observed patterns of bimodal dispersal distances and resolution of Reid's and Slatkin's paradoxes.

Dispersal movements of non‐native and native terrestrial slugs in an urban environment

AbstractAnimal movement varies from undirected dispersal to directed migration. Movement rates may have implications for conservation and resource management, as well as pest control, and they play a key role in invasion success. In slugs, long‐distance dispersal is typically passive, whereas active movement is critical for local dispersal and determines access to resources such as food and shelter. Telemetry has recently been used to study individual slug movements in the wild, whereas movement in arena tests has explored mechanisms of interspecific competition and invasiveness in slugs. Studies that relate the performance of individual slugs in arena tests to their post‐release behavior in nature are lacking. We measured individual short‐term movement speed of commonly occurring native and non‐native slugs of the genera Arion and Limax in arena tests and tracked their post‐release dispersal movements in a garden by PIT telemetry. We demonstrate clear differences in movement behavior among the species, but non‐native slugs did not display higher movement rates than their native congeners. In the arena test, slugs of the genus Limax displayed a higher short‐term speed than slugs of the genus Arion, whereas in the field, individuals of Limax maximus showed lower dispersal rates compared to the other slug species. Moreover, there was a positive correlation between short‐term speed in the arena test and movement in the field among individuals of L. cinereoniger, indicating the possible existence of behavioral syndromes in slugs, which may link movement ecology, animal personality, and the invasion ecology of pest species.

Predator recognition learning by northern redbelly dace Chrosomus eos from a small kettle lake with a dynamic predator community

Predation, and the risk of predation, shape the ecology, behavior, and evolution of many species. Small fishes navigate a perilous landscape of risk in the shallow waters of the littoral zone. Moreover, in small lakes, the predator community can be dynamic due to stochastic colonization and extirpation events. These conditions select for the ability by small fish to acquire recognition of novel predators through associative learning. Chemical cues associated with predation events, such as damage-released chemical cues from conspecifics, and the odor of predators, inform prey of the presence of risk, and facilitate acquired recognition of novel predator odor. Deming Lake, MN, is a small meromictic lake with intermittent connections to neighboring lakes in the watershed. Annual sampling of the littoral fish community between the years 2000 and 2023 reveals a history of colonization and extirpation by relatively large-bodied species such as yellow perch Perca flavescens and pumpkinseed sunfish Lepomis gibbosus. Ice cover data, combined with limnological depth profiles of dissolved oxygen, confirm that dissolved oxygen is limiting during the winter and consistent with the hypothesis that extirpation of large-bodied species in Deming Lake is likely due to winter anoxia. These data set the stage for an experimental demonstration of acquired recognition of the odor of allopatric rock bass Ambloplites rupestris by bass-naïve northern redbelly dace Chrosomus eos from Deming Lake. Rock bass have been absent from Deming Lake since at least the year 2000. Predator-recognition learning allows redbelly dace, and many other small-bodied fishes that face variable predator species over ontogenetic, spatial, and temporal scales, a mechanism to adapt quickly to indicators of predation risk.

Holding in the stream: convergent evolution of suckermouth structures in Loricariidae (Siluriformes)

Suckermouth armoured catfish (Loricariidae) are a highly speciose and diverse freshwater fish family, which bear upper and lower lips forming an oral disc. Its hierarchical organisation allows the attachment to various natural surfaces. The discs can possess papillae of different shapes, which are supplemented, in many taxa, by small horny projections, i.e. unculi. Although these attachment structures and their working mechanisms, which include adhesion and interlocking, are rather well investigated in some selected species, the loricariid oral disc is unfortunately understudied in the majority of species, especially with regard to comparative aspects of the diverse oral structures and their relationship to the ecology of different species. In the present paper, we investigated the papilla and unculi morphologies in 67 loricariid species, which inhabit different currents and substrates. We determined four papilla types and eight unculi types differing by forms and sizes. Ancestral state reconstructions strongly suggest convergent evolution of traits. There is no obvious correlation between habitat shifts and the evolution of specific character states. From handling the structures and from drying artefacts we could infer some information about their material properties. This, together with their shape, enabled us to carefully propose hypotheses about mechanisms of interactions of oral disc structures with natural substrates typical for respective fish species.

State‐dependent estuary stopover boosts juvenile salmon growth: Implications for marine survival

AbstractStopover habitats allow migratory animals to bolster energy stores prior to the resumption of migration, which can increase an individual's likelihood of survival. Carryover effects from prior habitats may mediate stopover behavior: evidence suggests that low‐condition migrants exhibit longer stopovers and attain more growth during stopover than high‐condition individuals. For Pacific salmon (Oncorhynchus spp.), estuaries may be important stopover habitats during juvenile emigration from natal freshwaters to the ocean. Favorable foraging conditions in high‐productivity estuaries could boost growth, and body size at marine entry is generally positively correlated with survival to adulthood. However, the contribution of the estuarine life stage to individual fitness across the salmon life cycle remains poorly understood. Here, we show that body size at freshwater exit mediates estuary stopover behavior by juvenile coho salmon (O. kisutch) and that estuary growth can increase the probability of marine survival. We performed a multiyear mark–recapture study of juvenile coho salmon in the Koeye River and its estuary, located on the Central Coast of British Columbia. We found that stopover duration decreased with increasing body size: small juveniles spent more than three times longer in the estuary than their larger conspecifics. Mean annual estuary growth rates ranged from 0.58 to 0.95 mm/day, and the smallest juveniles grew by nearly 30% in fork length during estuary stopover. Consequently, each out‐migrating juvenile cohort entered the ocean larger and less variable in body size than it was at freshwater exit. Analysis of returning spawners from two juvenile cohorts (2017, 2018) indicated that larger individuals had higher ocean survival rates. Using a simplistic analytical extrapolation, we demonstrate that estuary stopover could increase marine survival: For median‐sized juveniles, growth achieved in the estuary was associated with 39.8% (34.0%–46.2%) higher survival for the 2017 cohort and 39.1% (31.6%–47.0%) higher survival for the 2018 cohort. These results, from a watershed unaltered by intensive logging or development, suggest that growth achieved during estuary stopover can mitigate freshwater carryover effects and buffer size‐selective survival in a changing ocean. More broadly, these findings highlight the importance of state‐dependent use of stopover habitats in the study of migration ecology and conservation of migratory species.

Comunidades de aves acuáticas de la laguna Mar Chiquita (Córdoba, Argentina)

Mar Chiquita is a large inland brackish water body of about 2,000 km2, with a salinity of around 100 °/oo. Its aquatic bird communities were studied throughout a year in three study areas, representative of the main habitat types found in the región. We collected information on species composition and abundance, as well as foraging behaviour, feeding site utilization and stomach contents.
 In total we recorded 55 species. The richest community (both in number o f species and individuals) was found around the Rio Segundo estuary, while the less diverse corresponde to saline ponds near the coast. Summer migrant species (long range neartic migrants) included nine species and accounted for the 21% of the observed birds. Winter visitors included five species and made up 1% of bird numbers. Ecological guilds species composition and patterns of resource utilization are analyzed. They closely resemble those of marine estuarine and intertidal conditions. At present, the main adverse factors for the preservation of the local aviiauna are linked with planned stream regime modifications through dam building, and contamination due to industrialdevelopment along tributary rivers.

Alienated Species and Unsettled Ecologies: Locating “Redneck” Conservation in the Racial Discourse of “Asian” Carp Invasion

Abstract: Science studies scholars identify parallels between anti-immigrant and anti-invasive species rhetoric but have yet to consider how this linked racial discourse of invasion functions as part of a settler colonial project or what alternative forms of conservation arise through this confluence. Looking at this confluence through the lens of settler colonialism and Indigenous studies scholarship demonstrates how a form of environmental practice that I term “redneck” conservation reveals the racial and colonial logics of dominant invasive species discourses and practices. I propose the term alienated species to highlight these interconnections. Further, through a case study of “Asian” carp that explores social media, news media, and popular culture alongside Indigenous approaches, I argue that self-identified “redneck” settlers operationalize this discourse—alongside militaristic, masculinist embodiment—to position the “alien” as a foil against which they define whiteness and nativity while perpetuating Indigenous erasure. In this way, erasures of indigeneity and attacks against Asianness jointly produce the white male settled subject. In contrast, Indigenous communities engage a range of alternative responses to the carp and other alienated species within both formal land management strategies and everyday practices, such as harvesting. These responses reveal an Indigenous ethic of belonging that animates different ways of living on and providing care for the land, including the humans forced to live together.

Functional traits predict species co‐occurrence patterns in a North American Odonata metacommunity

AbstractThe probability of occurrence of a given species in a target locality and assemblage is conditioned not only by environmental/climatic variables but also by the presence of other species (i.e., species co‐occurrence). This framework, already complex in nature, becomes even more complicated if one considers the functional traits of species that, in turn, might influence the structure of metacommunities in various ways. Depending on the ecological and environmental setting, functional similarity (i.e., convergence in morphological and ecological traits) between species might either reduce their co‐occurrence due to high niche overlap driving negative interactions or promote it if the similar traits are associated with local habitat suitability. Similarly, functional divergence might either promote species co‐occurrence by limiting negative interactions through niche separation or reduce it through trait mediated environmental filtering. Therefore, discriminating between these alternative scenarios—predicting whether two species will tend to co‐occur or not based on their traits—is extremely challenging. Here, we develop a novel protocol to tackle the challenge, and we demonstrate its effectiveness by showing that ecological species traits can predict species co‐occurrence in a large dataset of North American Odonata. To this end, we first used the Hierarchical Modeling of Species Communities framework to quantify the pairwise species co‐occurrence after controlling for environmental and climatic factors. Then, we used machine learning to generate models which proved capable of predict accurately the observed co‐occurrence patterns from species functional traits. Our approach offers a generalizable analytical framework with the potential to clarify long‐standing ecological questions.

Effect of straying, reproductive strategies, and ocean distribution on the structure of American shad populations

AbstractThe use of species distribution models has proliferated, providing insights for sustainable management of migratory species in a globally changing environment. However, many of these models are based on statistical relationships developed from historical conditions that may not perform well under changing or even analogous conditions caused by climate change. In this paper, we used a mechanistic species distribution model called GR3D (Global Repositioning Dynamics for Diadromous Fish Distribution) to examine the integrated dynamics of American shad (Alosa sapidissima) populations across their native range along the Eastern U.S. coast, where the species demonstrates latitudinal variations in life histories and reproductive strategies. The initial design of the model was adapted to incorporate region‐specific parameterization to fit the species ecology. Then, a sensitivity analysis was performed to test the influences of uncertain processes regarding American shad distribution at sea, straying and reproduction on key characteristics of the species distribution. The sensitivity analysis showed the influence of the Allee effect (i.e., “depensatory” process) and the homing rate (i.e., fidelity to the breeding sites) on the probability of presence and abundances among catchments and metapopulations estimated by the model. Contrary to the homing rate, the distance of straying did not change the estimated number of metapopulations or abundances. Homing strength, however, was quite influential. The integration of complex migration patterns during the marine phase (i.e., wintering and summering offshore areas) provided more likely estimates of the species' overall distribution. Overall, our study illustrated the utility of incorporating factors governing the large‐scale distribution of migratory species to improve local management.

The social behaviour of the common bottlenose dolphin Tursiops truncatus (Montagu, 1821) in the coastal waters of Lampedusa Island (Strait of Sicily, Italy)

Abstract Research on social structure and residency provides important information on the dynamics of a population, improving knowledge of the species' behaviour and ecology. This study investigated the social network, site fidelity, and residency patterns of common bottlenose dolphins (Tursiops truncatus) off Lampedusa Island. Direct visual detection and photo‐identification methods were used to collect data during 124 boat‐based surveys conducted from 2013 to 2020. A total of 117 groups (mean size 4.5 ± 3.3) were sighted; 73 well‐marked animals were identified, of which 59% were resighted over the years. The estimate of social differentiation was 0.72 (SE = 0.07), suggesting differentiated social groups within the community. Data were somewhat representative of the true social system, as the correlation coefficient was close to 0.4. However, the half‐weight index averaged 0.07 (±0.03), indicating individuals' low tendency to associate. Five social clusters were identified with strong relationships between individuals within each cluster, in which 94% of maximum association indices were ≥0.4. The data also highlighted preferred and avoided associations and stable relationships. The removal of individuals with the highest values of strength and eigenvector centrality from the network did not affect its connectivity, suggesting inherent robustness. Despite the different levels of site fidelity among individuals, the results indicated rather high levels of yearly sighting rate. Temporary migration into and out of the area shown by this study indicates that Lampedusa coastal waters are an important, regularly used bottlenose dolphin habitat. These results suggest extensive ranging behaviour, which implies the need for networking between institutions and organizations from the various states bordering the Strait of Sicily to address conservation efforts and inform regional management of the Mediterranean bottlenose dolphin population.

Macroecological constraints on species' ‘movement profiles’: Body mass does not explain it all

AbstractAimAnimals couple habitats by three types of movement: dispersal, migration, and foraging, which dynamically link populations, communities, and ecosystems. Across these types, movement distances tend to correlate with each other, potentially reflecting allometric scaling with body mass, but ecological and evolutionary species' traits may constrain movement distances and weaken these correlations. Here, we investigate multivariate “movement profiles” to better understand patterns in movement across movement types, with the aim of improving predictions in ecology from populations to ecosystems.LocationGlobal.Time period1945–2019.Major taxa studiedVertebrates.MethodsWe synthesized distances of all three movement types (dispersal, migration, and foraging) across 300+ vertebrate species and investigated how the relationships between movement types and body mass were modified by evolutionary history and trophic guild.ResultsWe found that the strength of relationships between movement types and body mass varied among taxa and trophic guilds, for example, strongly positive for mammals but weak for birds, or positive across trophic guilds for foraging and dispersal but not migration. Notably, movement profiles interacted with the effects of shared evolutionary history and trophic guild to diminish covariance between movement types.Main conclusionsOverall, we find that movement types with distinct ecological consequences (foraging, migration) are often correlated, although some species seem able to overcome biomechanical, evolutionary, and metabolic constraints by reducing correlations among movement types. This integrative assessment of movement can improve ecological prediction by allowing estimation of unobserved movement distances for parameterization of models based on estimation of other movement types.

Biological Aspects of Preferred Fish Species in White Volta at Pwalugu, Ghana: A pre-impoundment Study

The socio-economic benefits derived from impounding rivers are extremely important but the ecological imbalances that are usually created in the process can be devastating. It is therefore imperative to understand some aspects of the biology of fishes before the impoundment of a river. This study was conducted to assess the length-weight relationship, condition factor, feeding, and reproductive ecology of fish species with high local market value. Biometric measurements were obtained from monthly samples of fish at two sites. Specimens were transported to the laboratory for gut and gonad analyses. Auchenoglanis occidentalis, Marcussenius senegalensis and Heterobranchus bidorsalis were the most preferred fish species. All three fish species recorded ‘b’ values less than 3 which implies they exhibited a negative allometric growth. Their condition factors (K) indicated they were in good health since K values were greater than 1. A. occidentalis and H. bidorsalis demonstrated a feeding habit comparable to that of an omnivore, whilst M. senegalensis presented a feeding habit that implied it was an invertivore. M. senegalensis registered the uppermost mean gonado-somatic index (GSI) (2.14 ± 0.83) whereas the highest mean fecundity (495 ± 450.96) was noted in A. occidentalis. This study contributed bio-ecological baseline information about the ichthyofauna prior to the damming of the reservoir in the Pwalugu area of the White Volta.

Pollinator and habitat-mediated selection as potential contributors to ecological speciation in two closely related species.

In ecological speciation, incipient species diverge due to natural selection that is ecologically based. In flowering plants, different pollinators could mediate that selection (pollinator-mediated divergent selection) or other features of the environment that differ between habitats of 2 species could do so (environment-mediated divergent selection). Although these mechanisms are well understood, they have received little rigorous testing, as few studies of divergent selection across sites of closely related species include both floral traits that influence pollination and vegetative traits that influence survival. This study employed common gardens in sites of the 2 parental species and a hybrid site, each containing advanced generation hybrids along with the parental species, to test these forms of ecological speciation in plants of the genus Ipomopsis. A total of 3 vegetative traits (specific leaf area, leaf trichomes, and photosynthetic water-use efficiency) and 5 floral traits (corolla length and width, anther insertion, petal color, and nectar production) were analyzed for impacts on fitness components (survival to flowering and seeds per flower, respectively). These traits exhibited strong clines across the elevational gradient in the hybrid zone, with narrower clines in theory reflecting stronger selection or higher genetic variance. Plants with long corollas and inserted anthers had higher seeds per flower at the Ipomopsis tenuituba site, whereas selection favored the reverse condition at the Ipomopsis aggregata site, a signature of divergent selection. In contrast, no divergent selection due to variation in survival was detected on any vegetative trait. Selection within the hybrid zone most closely resembled selection within the I. aggregata site. Across traits, the strength of divergent selection was not significantly correlated with width of the cline, which was better predicted by evolvability (standardized genetic variance). These results support the role of pollinator-mediated divergent selection in ecological speciation and illustrate the importance of genetic variance in determining divergence across hybrid zones.

Ecological restoration for mega-infrastructure projects: a study based on multi-source heterogeneous data

PurposeThis research aims to propose a model for the complex decision-making involved in the ecological restoration of mega-infrastructure (e.g. railway engineering). This model is based on multi-source heterogeneous data and will enable stakeholders to solve practical problems in decision-making processes and prevent delayed responses to the demand for ecological restoration.Design/methodology/approachBased on the principle of complexity degradation, this research collects and brings together multi-source heterogeneous data, including meteorological station data, remote sensing image data, railway engineering ecological risk text data and ecological restoration text data. Further, this research establishes an ecological restoration plan library to form input feature vectors. Random forest is used for classification decisions. The ecological restoration technologies and restoration plant species suitable for different regions are generated.FindingsThis research can effectively assist managers of mega-infrastructure projects in making ecological restoration decisions. The accuracy of the model reaches 0.83. Based on the natural environment and construction disturbances in different regions, this model can determine suitable types of trees, shrubs and herbs for planting, as well as the corresponding ecological restoration technologies needed.Practical implicationsManagers should pay attention to the multiple types of data generated in different stages of megaproject and identify the internal relationships between these multi-source heterogeneous data, which provides a decision-making basis for complex management decisions. The coupling between ecological restoration technologies and restoration plant species is also an important factor in improving the efficiency of ecological compensation.Originality/valueUnlike previous studies, which have selected a typical section of a railway for specialized analysis, the complex decision-making model for ecological restoration proposed in this research has wider geographical applicability and can better meet the diverse ecological restoration needs of railway projects that span large regions.

Comparative morphology of larvae of Elathous agilis Németh, 2019 and Elathous brucki (Candèze, 1878) (Coleoptera: Elateridae: Dendrometrinae), with notes on their biology and ecology

The click-beetle genus Elathous Reitter, 1890 (Elateridae: Dendrometrinae) contains almost 50 species distributed in the Palaearctic and Nearctic realms. Specimens of this genus are rare in collections, partly due to their largely unknown biology and ecology. Until now, larvae were known only for three species, all of them described decades ago. Due to the intensive fieldwork research by the first author, who found larvae of Elathous agilis Németh, 2019 in Lebanon and Elathous brucki (Candèze, 1878) in Greece, we have an opportunity to describe their morphology for the first time. We compare them with each other and the remaining known larvae of Elathous and related genera. Although we are able to differentiate larvae of all known Elathous species, our limited knowledge on dendrometrine immature stages as well as the genus-level systematics is insufficient to propose a reliable generic diagnosis for Elathous based on the larval morphology. Additionally, we provide updated information on biology and ecology of Elathous species.

Comparative Trophic Levels of Phragmocone-Bearing Cephalopods (Nautiloids, Ammonoids, and Sepiids).

Cephalopods are among many marine animals that through some combination of habit and/or habitat have proven difficult to study, especially understanding their trophic positions in marine communities. Stable isotope analyses have provided powerful tools for discovering quantitative aspects about the ecology and food sources of many cephalopod species. Here, we present new gut content and isotopic data (carbon and nitrogen isotopes) from phragmocone-bearing cephalopods (both ectocochleates, as well as those with internal, hard part buoyancy maintenance apparatuses). To this, we also include observations from baited remote underwater video systems to describe feeding habits and potential prey types to correlate with gut contents analyses. These data come from extant Allonautilus, Nautilus, and Sepia species, as well as from extinct nautiloids and ammonites. Extant nautiloids occupy a different isotopic niche than all other cephalopod groups where such data have been published to date. We conclude that these species are obligate scavengers rather than predators on any living species in their environments. Extant Nautilus and Allonautilus also demonstrate different patterns of functional allometry of nitrogen isotope values over ontogeny than do most other cephalopods (or animals in general), by showing decreasing nitrogen isotope levels during ontogeny. This pattern is shown to be different in Sepia and the yet small number of ammonite cephalopods studied to date, supporting the increasingly accepted view that ammonites were far closer to coleoids in basic biology than nautiloids. Overall, phragmocone-bearing cephalopods appear fundamentally different ecologically than cephalopods without this kind of buoyancy system. Of these groups, nautiloids appear to live a low-energy existence that allows them to subsist on energy-poor food sources, such as crustacean molts, as well as being able to scavenge in low oxygen basins where rare food falls, such as dead fish, remain unobtainable by most other animals.

Population ecology and juvenile density hotspots of thornback ray (Raja clavata) around the Shetland Islands, Scotland.

Elasmobranchs are facing global decline, and so there is a pressing need for research into their populations to inform effective conservation and management strategies. Little information exists on the population ecology of skate species around the British Isles, presenting an important knowledge gap that this study aimed to reduce. The population ecology of thornback ray (Raja clavata) around the Shetland Islands, Scotland, was investigated in two habitats: inshore (50-150 m deep) and shallow coastal (20-50 m deep), from 2011 to 2022, and 2017 to 2022, respectively. Using trawl survey data from the annual Shetland Inshore Fish Survey, the size composition of R. clavata catches was compared between shallow and inshore habitats across 157 trawl sets, and 885 individuals, over the years 2017-2022. Catch per unit effort (CPUE) of R. clavata was significantly higher in shallow than that in inshore areas (ANOVA, F = 72.52, df = 1, 5, p < 0.001). Size composition also significantly differed between the two habitats (analysis of similarities, R = 0.96, p = 0.002), with R. clavata being smaller in shallow areas and juveniles (<60 cm) occurring more frequently. Spatial distribution maps confirmed density hotspots of juveniles in shallow habitats, with repeated use of certain locations consistent over time. The results of this study provide the first evidence for R. clavata using shallow areas for potential nurseries in Shetland, which can inform the IUCN's Important Shark and Ray Area process. Furthermore, this study provides important new population ecology information for R. clavata around Shetland, which may have important conservation implications and be valuable for informing species and fisheries stock assessments in this region.

Species-specific effects of production practices on genetic diversity in plant reintroduction programs.

Plant production practices can influence the genetic diversity of cultivated plant materials and, ultimately, their potential to adapt to a reintroduction site. A common step in the plant production process is the application of seed pretreatment to alleviate physiological seed dormancy and successfully germinate seeds. In production settings, the seeds that germinate more rapidly may be favored in order to fill plant quotas. In this study, we investigated how the application of cold-moist stratification treatments with different durations can lead to differences in the genetic diversity of the propagated plant materials. Specifically, we exposed seeds of three Viola species to two different cold stratification durations, and then we analyzed the genetic diversity of the resulting subpopulations through double-digestion restriction site-associated sequencing (ddRADseq). Our results show that, in two out of three species, utilizing a short stratification period will decrease the genetic diversity of neutral and expressed loci, likely due to the imposition of a genetic bottleneck and artificial selection. We conclude that, in some species, the use of minimal stratification practices in production may jeopardize the adaptive potential and long-term persistence of reintroduced populations and suggest that practitioners carefully consider the evolutionary implications of their production protocols. We highlight the need to consider the germination ecology of target species when selecting the length of dormancy-breaking pretreatments.