Getting here from there: Testing the genetic paradigm underpinning introduction histories and invasion success

Aim To explore the potential of genetic processes and mating systems to influence successful plant invasions, we compared genetic diversity of the highly invasive tropical treelet, Miconia calvescens, in nine invasive populations and three native range populations. Specifically, we tested how genetic diversity is partitioned in native and invaded regions, which have different invasion histories (multiple vs. single introductions). Lastly, we infer how levels of inbreeding in different regions impact invasion success. Location Invaded ranges in the Pacific (Hawaii, Tahiti, New Caledonia) and Australia and native range in Costa Rica. Methods Genetic diversity was inferred by analysing variation at nine microsatellite loci in 273 individuals from 13 populations of M. calvescens. Genetic structure was assessed using amova, isolation by distance (IBD) within regions, a Bayesian clustering approach, and principal coordinates analysis. Results Microsatellite analysis revealed that invaded regions exhibit low levels of allelic richness and genetic diversity with few private alleles. To the contrary, in the native range, we observed high levels of allelic richness, high heterozygosity and 78% of all private alleles. Surprisingly, despite evident genetic bottlenecks in all invasive regions, similarly high levels of inbreeding were detected in both invasive and native ranges (F IS: 0.345 and 0.399, respectively). Bayesian clustering analysis showed a lack of geographical structure in the Pacific and evidence of differing invasion histories between the Pacific and Australia. While Pacific populations are derived from a single introduction to the region, multiple introductions have taken place in Australia from different source regions. Main conclusions Multiple introductions have not resulted in increased genetic diversity for M. calvescens invasions. Moreover, similar inbreeding levels between native and invaded ranges suggests that there is no correlation between levels of inbreeding and levels of standing genetic diversity for M. calvescens. Overall, our results show that neither inbreeding nor low genetic diversity is an impediment to invasion success. © 2011 Blackwell Publishing Ltd

Risk assessment of plastic pollution on marine diversity in the Mediterranean Sea

Plastic marine pollution is an increasing threat to global marine diversity. Quantifying this threat is particularly difficult and complex, especially when evaluating multiple species with different ecological requirements. Here, we examine the semi-enclosed basin of the Mediterranean Sea where the inputs of plastic pollution and its impact on marine diversity are still widely unknown. Eighty-four species from six taxonomic classes were evaluated to assess the risk of ingesting plastic marine debris, integrating inter-specific factors such as plastic exposure rates and life history traits (e.g., motility, habitat, and body size). Species were modelled within a spatial context to identify and estimate their exposure to plastic ingestion across the Mediterranean Sea using literature data, species distribution maps and plastic dispersion models. Our approach identified hotspots for the risk of plastic ingestion across multiple taxa in the Mediterranean Sea, highlighting that coastal species are at higher risk of ingesting plastic in the marine environment than open-sea species. The plastic exposure analysis indicated that species with larger home ranges were more at risk of exposure with increased distances while local species were more likely to be exposed to plastic closer to the centre of their home range location. The approach used in this study can be applied to support management and mitigation efforts throughout the Mediterranean Sea and in other geographic regions to minimize the impact of plastic pollution on marine diversity

Development of microsatellite loci for Cryptocarya mandioccana Meisner (Lauraceae) and their genotyping success in different tissues

<div><p>ABSTRACT Nine polymorphic microsatellite loci were isolated and characterized for Cryptocarya mandioccana Meisner, a tree from the Atlantic Rainforest with seeds dispersed by large animals. The loci were characterized using 48 individuals from two populations and their genotyping success tested in four tissues: leaves from adults and seedlings, and two diaspore maternal tissues. Maternity analyses were also performed on diaspores and leaves from nine adult trees. The number of alleles per locus ranged from nine to 15 and the observed and expected heterozygosities ranged from 0.214 to 0.864 and 0.745 to 0.892, respectively. The loci genotyping success did not significantly differ between tissues and varied from 56 to 96%. The microsatellites showed enough polymorphism to assign the nine adult trees to their diaspores. The successful genotyping in all tissues and identification of mother trees show that the microsatellites are suitable for studies such as spatial genetic structure and maternity analyses.</p></div