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Coral reefs in southeast Florida have experienced severe losses in coral cover and diversity in recent decades, primarily due to disease outbreaks and bleaching events exacerbated by anthropogenic impacts. Subsequent increases in “weedy” coral species like Agaricia spp. and Porites spp. have been observed on many reefs in this region. At the northernmost boundary of the Florida’s Coral Reef, St. Lucie Reef in Martin County has experienced a particularly notable increase in the abundance of Porites astreoides. To identify potential larval sources and P. astreoides population dynamics that may be contributing to observed coral community shifts, we sampled P. astreoides across five locations in southeast Florida from St. Lucie Reef to Fort Lauderdale and assessed population genetic structure using 2bRAD sequencing to generate single-nucleotide polymorphism (SNP) data. We identified high rates of clonality within and among the sample populations. Despite the brooding reproductive strategy of P. astreoides, there were relatively high levels of connectivity among populations and varying levels of genetic structure which correlated with geographic gradients. The genetic diversity and connectivity data reported here for P. astreoides populations in southeast Florida suggest that recent increases in abundance may be driven by high fecundity and long-range dispersal of a few successful genotypes.

There are many large, easy‐to‐observe anseriform birds (ducks, geese, and swans) in northern Australia and New Guinea and they often gather in large numbers. Yet, the structure of their populations and their regional movements are poorly understood. Lack of understanding of population structure limits our capacity to understand source‐sink dynamics relevant to their conservation or assess risks associated with avian‐borne pathogens, in particular, avian influenza for which waterfowl are the main reservoir species. We set out to assess present‐day genetic connectivity between populations of two widely distributed waterfowl in the Australo‐Papuan tropics, magpie goose Anseranas semipalmata (Latham, 1798) and wandering whistling‐duck Dendrocygna arcuata (Horsfield, 1824). Microsatellite data were obtained from 237 magpie geese and 64 wandering whistling‐duck. Samples were collected across northern Australia, and at one site each in New Guinea and Timor Leste. In the wandering whistling‐duck, genetic diversity was significantly apportioned by region and sampling location. For this species, the best model of population structure was New Guinea as the source population for all other populations. One remarkable result for this species was genetic separation of two flocks sampled contemporaneously on Cape York Peninsula only a few kilometers apart. In contrast, evidence for population structure was much weaker in the magpie goose, and Cape York as the source population provided the best fit to the observed structure. The fine scale genetic structure observed in wandering whistling‐duck and magpie goose is consistent with earlier suggestions that the west‐coast of Cape York Peninsula is a flyway for Australo‐Papuan anseriforms between Australia and New Guinea across Torres Strait. There are many large, easy‐to‐observe anseriforms in northern Australia and New Guinea for which the structure of populations and movements between them are poorly understood. We formulated and tested biogeographic models of genetic connectivity between populations of two waterfowl in the Australo‐Papuan tropics, magpie goose Anseranas semipalmata and wandering whistling‐duck Dendrocygna arcuata. In the wandering whistling‐duck, the best model of population structure was New Guinea as the source population for all other populations. In magpie goose, Cape York Peninsula as the source population for all other populations provided the best fit to the observed structure.

The genetic traits of seagrass populations are a crucial aspect of their ecology and evolution, influencing their adaptability and resilience. Here, we studied the genetic diversity, population structure, and connectivity of eighteen Posidonia oceanica meadows extending in the Eastern Mediterranean Sea (Aegean, Ionian and Cretan Seas, Greece), combining twelve microsatellite markers and Lagrangian particle drift modelling. Our findings revealed a strong genetic differentiation between the Ionian Sea and the Aegean and Cretan Seas, suggesting limited genetic exchange between these two groups. High gene flow was observed within the meadows of the Aegean and Cretan Seas, indicating a well-connected group of populations. Notably, populations of the North Aegean Sea displayed the lowest genetic diversity and the highest clonality compared to the rest of the populations. The lack of substantial oceanographic connectivity between Ionian and Aegean/Cretan Sea populations supported their genetic differentiation. However, the Lagrangian simulations did not fully support gene flow patterns in the Aegean Sea, suggesting that in addition to contemporary processes, historical events may have contributed to the formation of the observed genetic pattern. The genetic information provided here can be incorporated into management strategies aimed at identifying suitable areas as management units in conservation efforts and determining meadows that may serve as donor sites in transplantation initiatives.

Seasonal movement of less-immune people from low- to high- transmission regions increase malaria risk and may introduce parasite strains to both areas. This study examined Plasmodium falciparum genetic diversity and connectivity between low-transmission highlands and endemic lowlands in Ethiopia to assess the contribution of seasonal agricultural migration in sustaining transmission. P. falciparum qPCR-positive dried blood spots collected from highland health facilities and lowland agricultural worksites were sequenced using multiplexed amplicon sequencing. Complexity of infection (COI) and infection pairwise relatedness were estimated and used for clustering analysis. Lowland populations (seasonal workers and residents) had higher COI and polyclonal infection rates (mean COI 2.62, 62%, n = 581) than highland residents (mean COI 2.00, 40%, n = 599). Similar expected heterozygosity (He ≈ 0.4) was observed, and P. falciparum infections from worksites showed high genetic connectivity between highland and lowland populations, with extensive parasite sharing, including 27 related clusters in highland cases and 10 in seasonal workers. Integrating parasite genomic data with epidemiological information revealed strong connectivity and low genetic differentiation between these regions linked by seasonal migration. These findings highlight how agricultural mobility likely drives parasite diversity and gene flow, implicating its role in sustaining malaria transmission.

Anadara tuberculosa is a bivalve mollusk common in the mangroves of the Panamanian Pacific, subject to commercial exploitation throughout its distribution area. Fishing pressure, combined with environmental contamination processes, is a factor that can influence the genetic structure of the species. Understanding the genetic aspects of A. tuberculosa is relevant for developing conservation policies; therefore, this study analyzed the genetic diversity, structure, and demographic history of this species in five localities of the Panamanian Pacific using the mitochondrial COI gene. The results revealed high haplotypic (0.93–0.97) and low nucleotide (0.0076–0.0095) diversity with generally low genetic differentiation, although significant structure was detected specifically between Coiba and Isla Cañas. Demographic analyses and a star‐shaped haplotype network indicate a recent population expansion, a signal that was most pronounced in the Chame locality. The low genetic differentiation is attributed to the presence of coastal currents and geographical barriers, which together shape each site and influence larval dispersal and cause some degree of genetic connectivity. This study provides a preliminary genetic baseline that can support the design of site‐specific management actions and periodic genetic monitoring aimed at preserving diversity and contributing to the long‐term sustainability of this essential resource for harvesting communities and the ecological processes occurring in the mangrove ecosystems of the studied localities. Our study analyzed the population genetics of Anadara tuberculosa (concha negra) in five Panamanian Pacific mangrove areas using the mitochondrial COI gene. We found high haplotypic diversity and low nucleotide diversity, a pattern that suggests a recent demographic expansion, which was supported by our neutrality tests and a star‐shaped haplotype network. The results indicate a generally high level of genetic connectivity among populations, with the exception of the Coiba and Isla Cañas populations, which showed significant genetic differentiation likely due to geographic barriers and ocean currents.

Anthropogenic habitat modification often creates barriers to animal movement, transforming formerly contiguous habitat into a patchwork of habitat islands with low connectivity. Roadways are a feature of most landscapes that can act as barriers or filters to migration among local populations. Even small and recently constructed roads can have a significant impact on population genetic structure of some species, but not others. We developed a research approach that combines fine-scale molecular genetics with behavioral and ecological data to understand the impacts of roads on population structure and connectivity. We used microsatellite markers to characterize genetic variation within and among populations of timber rattlesnakes (Crotalus horridus) occupying communal hibernacula (dens) in regions bisected by roadways. We examined the impact of roads on seasonal migration, genetic diversity, and gene flow among populations. Snakes in hibernacula isolated by roads had significantly lower genetic diversity and higher genetic differentiation than snakes in hibernacula in contiguous habitat. Genetic-assignment analyses revealed that interruption to seasonal migration was the mechanism underlying these patterns. Our results underscore the sizeable impact of roads on this species, despite their relatively recent construction at our study sites (7 to 10 generations of rattlesnakes), the utility of population genetics for studies of road ecology, and the need for mitigating effects of roads.

Human activities are inducing substantial modifications to landscapes on a worldwide scale. As a result, a multitude of animal species are forced to adapt and survive within remnants of altered natural habitats rendering them more vulnerable to the impact of genetic drift. The objective of this research is to assess the degree of connectivity among Oligoryzomys flavescens , an orthohantavirus reservoir species, inhabiting two contrasting human-altered environments by means of genome-wide markers. This study was conducted in 16 sites with varying degrees of urbanization in the city of Buenos Aires and the surrounding metropolitan area, and rural localities in Buenos Aires province, Argentina. Genomic DNA was extracted from 93 specimens collected between 2017 and 2019 and a total of 2456 SNPs, obtained through ddRADseq, were analyzed. Urban sites presented more genetic differentiation, cluster structuring, larger number of private alleles and a higher number of kinship relationships than rural sites. Genetic and spatial distances were positively associated in the rural area while no association was detected in the urban one. Furthermore, our analyses detected some degree of differentiation between individuals inhabiting riparian environments of two distinct river basins and typically rural environments further from both basins. Our results suggest that the urban environment imposes greater limitations to gene flow compared to rural areas, probably due to restrictions to dispersal caused by a higher degree of isolation. This information contributes to the understanding of the potential dispersion of hantavirus among rodents and to design prevention measures to reduce the risk of their transmission to humans.

Habitat fragmentation and loss reduce population size and connectivity, which imperils populations. Functional connectivity is key for species persistence in human-modified landscapes. To inform species conservation management, we investigated spatial genetic structure, gene flow and inferred dispersal between twelve breeding sites of the Natterjack toad (Bufo calamita); regionally Red-Listed as Endangered in Ireland. Spatial genetic structure was determined using both Bayesian and non-Bayesian clustering analysis of 13 polymorphic microsatellite loci genotyping 247 individuals. We tested the influence of geographic distance, climate, habitat, geographical features, and anthropogenic pressure on pairwise genetic distances between breeding sites using Isolation-by-distance and Isolation-by-resistance based on least-cost path and circuit theory models of functional connectivity. There was clear spatial structuring with genetic distances increasing with geographic distance. Gene flow was best explained by Isolation-by-resistance models with coniferous forestry plantations, bog, marsh, moor and heath, scrub, anthropogenic presence (Human Influence Index) and rivers (riparian density) identified as habitats with high resistance to gene flow while metapopulation connectivity was enhanced by coastal habitats (beaches, sand dunes and salt marshes) and coastal grassland. Despite substantial declines in census numbers over the past 15 years and its regional status as Endangered, the Natterjack toad population in Ireland retains high genetic diversity. If declines continue, maintaining habitat connectivity to prevent genetic erosion by management of coastal grasslands, pond construction and assisted migration through translocation will be increasingly important.

Aim Seed dispersal plays a key role in shaping the distribution and genetic complexity of seagrass populations and affects their resilience capacity under disturbance. The endemic seagrass Posidonia oceanica is a key component of Mediterranean coastal ecosystems, but knowledge about movement ecology in this species is limited, especially regarding seed movement pathways and dispersal potential. Location Western coast of Sicily (central Mediterranean). Methods Beach‐cast fruits of the Mediterranean seagrass P. oceanica were collected from nine localities along the Western coast of Sicily, along with adult shoots from eight putative donor meadows. We determined pair‐wise genetic differentiation between established meadows and seed cohorts. Genetic assignment tests were used to infer the most likely meadow of origin of individual seeds and were complemented with forward and backward Lagrangian simulations of dispersal. Results A significant genetic differentiation was found between seed pools and the most‐likely meadow of origin. The genetic assignment confirmed that seeds from the same cohort originated from multiple meadows and emphasised the presence of long‐distance‐dispersal (LDD) events (up to hundreds of km). Genetic connectivity appeared to be greater than that predicted by oceanographic simulations, which may reflect the longer temporal scales on which gene flow is shaped, in contrast to contemporary dispersal patterns. Lagrangian simulations highlighted that fruits were physically capable of dispersing beyond the study area and that the north Tunisian coast could be a key source of propagules for the populations studied. Main Conclusions Our study represents a significant step forward in the understanding of P. oceanica movement ecology and could guide meadows' conservation and restoration actions. Our findings are significant in a broader context outside of the research area and could be the basis of similar studies in other regions, especially considering the increasing number of fruiting events recorded across the Mediterranean likely associated with ocean warming.

Reductions in gene flow due to anthropogenic habitat fragmentation are often associated with reduced genetic diversity and increased population structuring in wildlife populations. We assessed fine-scale population structure and landscape factors influencing gene flow in threatened boreal woodland caribou (Rangifer tarandus caribou) based on genotypes for 337 individuals sampled at the southern extent of their distribution in Ontario. The impact of isolation by distance (IBD) and isolation by resistance (IBR) on gene flow was examined using resistance surface optimization and linear mixed-effects modelling. Genetic clustering algorithms failed to identify a biologically meaningful pattern of population substructure, consistent with the observed weak genetic differentiation of individuals across the study area. Although the inferred optimum resistance scenario differed based on the choice of genetic distance metric, roads were consistently included in the top resistance models. While our results support a growing body of evidence indicating a negative influence of roads on gene flow in woodland caribou, future studies are recommended to validate these finding given the conservation implications for this iconic boreal species.