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When plants establish outside their native range, their ability to adapt to the new environment is influenced by both demography and dispersal. However, the relative importance of these two factors is poorly understood. To quantify the influence of demography and dispersal on patterns of genetic diversity underlying adaptation, we used data from a globally distributed demographic research network comprising 35 native and 18 nonnative populations of Plantago lanceolata Species-specific simulation experiments showed that dispersal would dilute demographic influences on genetic diversity at local scales. Populations in the native European range had strong spatial genetic structure associated with geographic distance and precipitation seasonality. In contrast, nonnative populations had weaker spatial genetic structure that was not associated with environmental gradients but with higher within-population genetic diversity. Our findings show that dispersal caused by repeated, long-distance, human-mediated introductions has allowed invasive plant populations to overcome environmental constraints on genetic diversity, even without strong demographic changes. The impact of invasive plants may, therefore, increase with repeated introductions, highlighting the need to constrain future introductions of species even if they already exist in an area.

ABSTRACT Freshwater ecosystems are among the most threatened globally. Understanding how environmental variables influence the gene flow of freshwater species can help identify landscape features requiring conservation management. We used landscape genetic resistance modelling to assess the influence of climate, topography and vegetation cover on genetic structure and gene flow in platypus (Ornithorhynchus anatinus) in an urban region of south‐east Queensland, Australia. Thirty DNA samples were genotyped using the DArTseq platform, and data were filtered to produce a panel of 5478 neutral single nucleotide polymorphism (SNP) markers. We used fastSTRUCTURE, partial redundancy analysis and maximum likelihood analyses to understand platypus genetic structure and landscape influences on gene flow. Between one and three genetic clusters were detected using fastSTRUCTURE. Partial redundancy analysis identified Topographic Wetness Index and antecedent rainfall as driving genetic differentiation between samples. A maximum likelihood population effects model suggested gene flow was spatially structured by Normalised Difference Vegetation Index at a fine scale (100 m) and antecedent rainfall at a landscape scale (1 km). Thus, less vegetated areas appear to restrict the gene flow of platypus in urban systems. Rainfall, vegetation cover and topographic wetness are also important for maintaining platypus gene flow across landscapes. Our research recommends conservation management through restoration of water flow and riverine vegetation to help maintain platypus connectivity and increase gene flow among populations. [ABSTRACT FROM AUTHOR]

This study surveyed South Australian medical oncologists to capture their perceptions, willingness to participate and perceived barriers and motivations to participation in voluntary assisted dying (VAD) activities. Approximately 70% of surveyed medical oncologists reported familiarity with VAD legislation. Less than half of physicians (39.1%) reported willingness to participate in any VAD activities, and the rate of conscientious objection was 22%. The top barriers to participation were lack of time and uncertainty given no prior experience. These results demonstrate both a low rate of conscientious objection and a low rate of willingness to participate at the point of VAD implementation in South Australia, and identify barriers to participation that are largely logistical. [ABSTRACT FROM AUTHOR]

Spatial isolation is a key driver of population‐level variability in traits and genotypes worldwide. Geographical distance between populations typically increases isolation, but organisms face additional environmental barriers when dispersing between suitable habitat patches. Despite the predicted universal nature of the causes of isolation, global comparisons of isolation effects across taxa and geographic systems are few. We assessed the strength of isolation due to geographic and macroclimatic distance for paired marine island and paired mainland populations within the same species. Our meta‐analysis included published measurements of phenotypic traits and neutral genetic diversity from 1608 populations of 108 plant and animal species at a global scale. As expected, phenotypic differentiation was higher between marine islands than between populations on the mainland, but we found no consistent signal for differences in spatial patterns of neutral genetic diversity between the two systems. Geographic distance had comparatively weak effects on the spatial patterns of phenotypes and neutral genetic diversity. These results suggest that spatial patterns of phenotypic variation are determined by eco‐evolutionary pressures that differ more between islands than between mainland populations, while the spatial variability of neutral genetic diversity might be shaped by rather similar processes in the two systems. Our approach demonstrates that global biodiversity models that include island biology studies may progress our understanding of the interacting effects of spatial habitat structure, geographic‐ and environmental distances on biological processes underlying spatial population variability. We formulate future research directions for empirical tests and global syntheses in the field. [ABSTRACT FROM AUTHOR]

Invasive plants threaten biodiversity worldwide and effective management must control the target invader while conserving biodiversity. Herbicide is often used to control invasive plants, but potential negative impacts on biodiversity have led to spot spraying being recommended over boom spraying to minimize the exposure of nontarget species to chemicals. We examined the influence of herbicide application methods on off‐target plant communities in threatened temperate grasslands of southeastern Australia, where spraying with the broadleaf herbicide fluroxypr is commonly used to control St. John's wort, Hypericum perforatum L. It is well established that fluroxypr effectively controls H. perforatum but few studies have examined its impact on native forbs. A spray drift experiment using water‐sensitive cards indicated that ground surface coverage was higher for spot spraying (91%–99%) than for boom spraying (5%–31%). We established a replicated, 3‐year, before‐after‐control‐impact experiment across 48 1‐m2 quadrats to determine how three herbicide application methods (spot spray, fine boom and coarse boom) affected nontarget native forbs, the group most likely to be affected by broadleaf herbicides. This experiment was conducted in grasslands where H. perforatum was almost absent, so responses would reflect the direct impacts of the chemical, rather than structural changes resulting from removal of the target invader. Spot spraying decreased the probability of occurrence of native leguminous forbs, while increasing the occurrence of exotic leguminous forbs and the richness of all exotic species and exotic annual forbs. Spot spraying reduced the occurrence of the native Desmodium varians and the abundance of the native Chrysocephalum apiculatum. During this 3‐year study, native species appeared to be impacted either directly by fluroxypr or indirectly by increased competition with exotic species. Where herbicide application is deemed crucial in these grasslands, we recommend boom spraying when H. perforatum density is moderate to high. Spot spraying should only be used when the density of H. perforatum is very low. Given the regional variation in H. perforatum density, the spatial scale of invasion, soil depth, and conservation values, we present a decision tree to assist managers in evaluating the costs and benefits of chemical control, indicating situations where alternative or modified methods could be used. [ABSTRACT FROM AUTHOR]