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Ecological interactions among multiple invaders can aggravate their effects on invaded systems. Many salmonids including rainbow trout Oncorhynchus mykiss and Chinook salmon O. tshawytscha have established naturalized populations and co-occur in rivers worldwide. Predation of eggs and juveniles has been well documented among salmonids in their native range in the Northern Hemisphere. It has been unclear to what extent these interactions exist in invaded rivers of the Patagonia. Here, we report and quantify rainbow trout predation of Chinook salmon eggs in the Cisnes River Basin, southern Chile. We used hook and line angling to sample rainbow trout (n = 80) around salmon spawning areas before, during, and after the spawning season of Chinook salmon. Stomach contents obtained during two consecutive years show consistent evidence that rainbow trout opportunistically prey on Chinook salmon eggs. Salmon eggs occurred in 75 and 50% of the trout stomachs analyzed in 2019 and 2020, respectively. The number of salmon eggs (mean ± SD) per trout stomach ranged between 17.95 ± 24.29 in 2019 and 7.45 ± 12.90 in 2020. We assumed that consumed eggs were primarily non-viable or would have had low probabilities of survival suggesting a synergistic interaction between rainbow trout and Chinook salmon. Our findings provide baseline information that contribute to demographic studies and the management of invasive salmonids in rivers of this region and elsewhere.

Since the last decade, the Chinook salmon has become an invasive species in southern Chilean rivers, affecting their environment and displacing native species due to predation and competition. The socioeconomic valuation of this species is complex, due to its high economic, touristic, and culinary value. The tourism industry and artisanal fishing groups see the salmon as a new common-use resource to be regulated. The Chilean regulatory framework, in turn, has made the presence, danger, and economic importance of the species invisible. This document analyzes the social construction of salmonids according to different interest groups and their interaction with the legal invisibility of this species. Our study delves into a particular group: the artisanal fishermen of La Barra del Toltén, in the Araucania Region, whose main economic activity has been illegal Chinook salmon fishing, pressing for their legalization. This case raises reflections on the perennially complex relationship between nature and society, as well as the management of common problems and common resources.

Nile tilapia belongs to the second most cultivated group of fish in the world, mainly because of its favorable characteristics for production. Genetic improvement programs and domestication process of Nile tilapia may have modified the genome through selective pressure, leaving signals that can be detected at the molecular level. In this work, signatures of selection were identified using genome-wide SNP data, by two haplotype-based (iHS and Rsb) and one FST based method. Whole-genome re-sequencing of 326 individuals from three strains (A, B and C) of farmed tilapia maintained in Brazil and Costa Rica was carried out using Illumina HiSeq 2500 technology. After applying conventional SNP-calling and quality-control filters, ~ 1.3 M high-quality SNPs were inferred and used as input for the iHS, Rsb and FST based methods. We detected several candidate genes putatively subjected to selection in each strain. A considerable number of these genes are associated with growth (e.g. NCAPG, KLF3, TBC1D1, TTN), early development (e.g. FGFR3, PFKFB3), and immunity traits (e.g. NLRC3, PIGR, MAP1S). These candidate genes represent putative genomic landmarks that could be associated to traits of biological and commercial interest in farmed Nile tilapia.

Biological invasions create complex eco- logical and societal issues worldwide. Most of the knowledge about invasions comes only from success- ful invaders, but less is known about which processes determine the differential success of invasions. In this review, we develop a framework to identify the main dimensions driving the success and failure of invaders, including human influences, characteristics of the invader, and biotic interactions. We apply this frame- work by contrasting hypotheses and available evi- dence to explain variability in invasion success for 12 salmonids introduced to Chile. The success of On- corhynchus mykiss and Salmo trutta seems to be influenced by a context-specific combination of their phenotypic plasticity, low ecosystem resistance, and propagule pressure. These well-established invaders may limit the success of subsequently introduced salmonids, with the possible exception of O. tshawyts- cha, which has a short freshwater residency and limited spatial overlap with trout. Although propagule pressure is high for O. kisutch and S. salar due to their intensive use in aquaculture, their lack of success in Chile may be explained by environmental resistance, including earlier spawning times than in their native ranges, and interactions with previously established and resident Rainbow Trout. Other salmonids have also failed to establish, and they exhibit a suite of ecological traits, environmental resistance, and lim- ited propagule pressure that are variably associated with their lack of success. Collectively, understanding

The Southern Darwin’s frog Rhinoderma darwinii is a charismatic, mouth-brooding amphibian endemic to temperate forests of South America with a Vulnerable conservation status according to the IUCN Red List. We developed microsatellite markers from next generation sequence data that will aid genetic monitoring during and after re-introduction efforts. Using bioinformatics we characterized 3,521 perfect microsatellite repeats and designed primers for 35 of them. From these, 23 were polymorphic and amplified reliably. Number of alleles varied between 2 and 15, allele sizes varied between 84 and 299 bp, and observed heterozygosities varied between 0.105 and 0.904. These microsatellites represent a valuable resource to aid recovery of threatened Southern Darwin’s frog populations.