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Genetic variability of red swamp crayfish reveals its invasion process

Patterns of genetic diversity in invasive populations can be modulated by a range of factors acting at different stages of the invasion process, including the genetic composition of the source population(s), the introduction history (e.g. propagule pressure), the environmental suitability of recipient areas, and the features of secondary introductions. The North American red swamp crayfish, Procambarus clarkii, is one of the most widely introduced freshwater species worldwide. It was legally introduced into Spain twice, near the city of Badajoz in 1973 and in the Guadalquivir marshes in 1974. Thereafter the species rapidly colonised almost the entire Iberian Peninsula. Seven nuclear microsatellites were used to describe the genetic diversity and structure of 28 locations distributed across the Iberian Peninsula and to explain the expansion process of the red swamp crayfish. Additionally, the relationship between environmental suitability and genetic diversity of the studied locations were analysed. The red swamp crayfish had a clear spatial genetic structure in the Iberian Peninsula, probably determined by the two independent introduction events in the 1970s, which produced two main clusters separated spatially, one of which was dominant in Portugal and the other in Spain. The human-mediated dispersal process seemed to have involved invasion hubs, hosting highly genetically diverse areas and acting as sources for subsequent introductions. Genetic diversity also tended to be higher in more suitable environments across the Iberian Peninsula. These results showed that the complex and human-mediated expansion of the red swamp crayfish in the Iberian Peninsula has involved several long- and short-distance movements and that both ecological and anthropogenic factors have shaped the genetic diversity patterns resulting from this invasion process. Early detection of potential invasion hubs may help to halt multiple short-distance translocations and thus the rapid expansion of highly prolific invasive species over non-native areas. informacion[at] Acevedo-Limón et al (2020) Historical, human, and environmental drivers of genetic diversity in the red swamp crayfish (Procambarus clarkii) invading the Iberian Peninsula. Freshwater Biology. Doi 10.1111/fwb.13513
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Role of phenology in favoring or limiting biological invasions

Role of phenology in favoring or limiting biological invasions

Climate similarity favors biological invasion, but a match between seasonality in the novel range and the timing of life cycle events of the invader also influences the outcome of species introduction. Yet, phenology effects on invasion success have generally been neglected. Whether a phenological mismatch limits the non-native range of a globally successful invader, the Ring-necked parakeet, in Europe, was studied. Given the latitudes at which parakeets have established across Europe, they breed earlier than expected based on breeding dates from their native Asian range. Moreover, comparing the breeding dates of European populations to those of parakeets in Asia, to five native breeding bird species in Europe and to the start of the growing season of four native European trees, the discrepancy between expected and actual breeding phenology is greater in northern Europe. In these northern populations, this temporal mismatch appears to have negative effects on hatching success, and on population growth rates in years that are colder than average. Phenological mismatch also can explain why parakeets from African populations (that are more likely to breed in autumn) have been poor invaders compared to parakeets from Asia. These lines of evidence support the hypothesis that the reproductive phenology of the Ring-necked parakeet can be a limiting factor for establishment and range expansion in colder climates. Results provide growing support for the hypothesis that the match between climate seasonality and timing of reproduction (or other important life cycle events) can affect the establishment success, invasive potential and distribution range of introduced non-native species, beyond the mere effect of climate similarity. informacion[at] Luna et al (2017) Reproductive timing as a constraint on invasion success in the Ring-necked parakeet (Psittacula krameri). Biol Invasions DOI: 10.1007/s10530-017-1436-y