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The introduction of exotic species in aquatic habitats is one of the causes for the amphibian declines observed worldwide. In the 1970s, the red swamp crayfish Procambarus clarkii was introduced in the southwest Iberian Peninsula, where no native crayfish occur. In this study we assess the effect of P. clarkii presence in the breeding site distribution of each of the 13 southwest Iberian amphibians, while simultaneously accounting for the effects of potentially confounding habitat variables, as well as for the effects of the other large aquatic predators in the study area – predatory fish. Amphibian species richness was lower in places where P. clarkii was present than in places without P. clarkii, regardless of fish presence. After accounting for habitat variables and fish, crayfish presence was a negative predictor of the breeding probability for all urodeles (Pleurodeles waltl, Salamandra salamandra, Triturus boscai and T. marmoratus) and for two anurans (Pelobates cultripes and Bufo bufo). The majority of the species affected usually breed in temporary ponds without fish, but that may be colonized by the crayfish. The ongoing expansion of P. clarkii may eventually lead to a growing isolation of amphibian populations and ultimately to local extinctions and a permanent alteration of the amphibian communities in southwest Iberian Peninsula.

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Invasive alien predators can impose strong selection on native prey populations and induce rapid evolutionary change in the invaded communities. However, studies on evolutionary responses to invasive predators are often complicated by the lack of replicate populations differing in coexistence time with the predator, which would allow the determination of how prey traits change during the invasion. The red swamp crayfish Procambarus clarkii has invaded many freshwater areas worldwide, with negative impacts for native fauna. Here, we examined how coexistence time shapes antipredator responses of the Iberian waterfrog (Pelophylax perezi) to the invasive crayfish by raising tadpoles from five populations differing in historical exposure to P. clarkii (30 years, 20 years, or no coexistence). Tadpoles from non-invaded populations responded to the presence of P. clarkii with behavioral plasticity (reduced activity), whereas long-term invaded populations showed canalized antipredator behavior (constant low activity level). Tadpoles from one of the long-term invaded populations responded to the crayfish with inducible morphological defenses (deeper tails), reflecting the use of both constitutive and inducible antipredator defenses against the exotic predator by this population. Our results suggest that, while naive P. perezi populations responded behaviorally to P. clarkii, the strong predation pressure imposed by the crayfish has induced the evolution of qualitatively different antipredator defenses in populations with longer coexistence time. These responses suggest that strong selection by invasive predators may drive rapid evolutionary change in invaded communities. Examining responses of prey species to biological invasions using multiple populations will help us better forecast the impact of invasive predators in natural communities.

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Due to both deliberate and accidental introductions, invasive African Clawed Frog (Xenopus laevis) populations have become established worldwide. In this study, we investigate the geographic origins of invasive X. laevis populations in France and Portugal using the phylogeographic structure of X. laevis in its native South African range. In total, 80 individuals from the whole area known to be invaded in France and Portugal were analysed for two mitochondrial and three nuclear genes, allowing a comparison with 185 specimens from the native range. Our results show that native phylogeographic lineages have contributed differently to invasive European X. laevis populations. In Portugal, genetic and historical data suggest a single colonization event involving a small number of individuals from the south-western Cape region in South Africa. In contrast, French invasive X. laevis encompass two distinct native phylogeographic lineages, i.e., one from the south-western Cape region and one from the northern regions of South Africa. The French X. laevis population is the first example of a X. laevis invasion involving multiple lineages. Moreover, the lack of population structure based on nuclear DNA suggests a potential role for admixture within the invasive French population.

Emerging diseases have been increasingly associated with population declines, with co-infections exhibiting many types of interactions. The chytrid fungus (Batrachochytrium dendrobatidis) and ranaviruses have extraordinarily broad host ranges, however co-infection dynamics have been largely overlooked. We investigated the pattern of co-occurrence of these two pathogens in an amphibian assemblage in Serra da Estrela (Portugal). The detection of chytridiomycosis in Portugal was linked to population declines of midwife-toads (Alytes obstetricans). The asynchronous and subsequent emergence of a second pathogen - ranavirus - caused episodes of lethal ranavirosis. Chytrid effects were limited to high altitudes and a single host, while ranavirus was highly pathogenic across multiple hosts, life-stages and altitudinal range. This new strain (Portuguese newt and toad ranavirus – member of the CMTV clade) caused annual mass die-offs, similar in host range and rapidity of declines to other locations in Iberia affected by CMTV-like ranaviruses. However, ranavirus was not always associated with disease, mortality and declines, contrasting with previous reports on Iberian CMTV-like ranavirosis. We found little evidence that pre-existing chytrid emergence was associated with ranavirus and the emergence of ranavirosis. Despite the lack of cumulative or amplified effects, ranavirus drove declines of host assemblages and changed host community composition and structure, posing a grave threat to all amphibian populations.

The island of Selvagem Grande holds one of the most important colonies Cory's Shearwater (Calonec-tris diomedea) in the Atlantic. Historical records suggest a stable population well in excess of 100,000 pairs. A succession of massacres in 1975 and 1976 dramatically reduced this population to less than 10% of the original numbers. Since 1977 strict protection was enforced and the population started a steady recovery. However, between 1995 and 1998 an alarming decline, of more than 13% of the birds, was reported and concurrently the monitoring work was interrupted. Data from other colonies in the Atlantic and the Mediterranean also indicated significant regional declines , some of which appear to be driven by unsustainable levels of accidental mortality in fishing gear. In order to investigate the persistence of the regressive trend at Selvagem Grande, we carried out a global census of the colony in June 2005. We counted 20,555 occupied nests and estimated the total breeding population at 29,540 pairs. The population still appears to be recovering from the massacres of 1975-1976, at an average rate of about 4.6% per year over the past 25 years. Our data reveal that Selvagem Grande now harbors the largest known Cory's Shearwater colony in the World. Results from this study suggest that this population is not, as yet, suffering from unsustainable fisheries-related mortality, which would be reflected in a decline in numbers. This situation contrasts with that of the Mediterranean, where significant mortality in fishing gear has been linked to shearwater population declines.