Global biodiversity is both declining and being redistributed in response to multiple drivers characterizing the Anthropocene, including synergies between biological invasions and climate change. The Antarctic marine benthos may constitute the last biogeographic realm where barriers (oceanographic currents, climatic gradients) have not yet been broken. Here we report the successful settlement of a cohort of Mytilus cf. platensis in a shallow subtidal habitat of the South Shetland Islands in 2019, which demonstrates the ability of this species to complete its early life stages in this extreme environment. Genetic analyses and shipping records show that this observation is consistent with the dominant vectors and pathways linking southern Patagonia with the Antarctic Peninsula and demonstrates the potential for impending invasions of Antarctic ecosystems.
Shell-shape variation in the Chilean blue mussel
Mytilus chilensis was examined in eight populations
covering the totality of its distribution range,
which represents over 1800 km of latitudinal gradient
in the southeastern Paci¢c. The shell outline
shapes were assessed using elliptic Fourier analysis
followed by canonical variates analysis. Fourier
coe⁄cients showed a highly signi¢cant morphological
variation between the populations studied.
Canonical variates analysis showed a visual association
of the First canonical with convexity of ventral
edge and umbo shape, while the second axis was associated
with shell elongation. Previously described
genetic patterns were marginally congruent with
our morphometric pattern, though geographic distance
had a stronger e¡ect on morphology. Shape
change (elongation) was correlated with latitudinal
clinal variation. The morphometrical analysis proved
to be an important tool for evaluating the components
of shell-shape variation in mussels and to
document association patterns with geographical
and ecological variables. Such patterns are useful to
establish awide ¢eld of work, including sexing, stock
recognition, traceability studies and productive
management in general.FONDECYT-Chile
through project 1050848
Major geologic and climatic changes during the Quaternary exerted a major role in shaping past and contemporary distribution of genetic diversity and structure of aquatic organisms in southern South America. In fact, the northern glacial limit along the Pacific coast, an area of major environmental changes in terms of topography, currents, and water salinity, represents a major biogeographic transition for marine and freshwater species. We used mitochondrial DNA sequences (D-loop) to investigate the consequences of Quaternary glacial cycles over the pattern of genetic diversity and structure of G. maculatus (Pisces: Galaxiidae) along two biogeographical provinces in the Chilean coast. Extreme levels of genetic diversity and strong phylogeographic structure characterize the species suggesting a low amount of influence of the last glacial cycle over its demography. However, we recognized contrasting patterns of genetic diversity and structure between main biogeographical areas here analyzed. Along the Intermediate Area (38°–41° S) each estuarine population constitutes a different unit. In contrast, Magellanic populations (43°–53° S) exhibited low levels of genetic differentiation. Contrasting patterns of genetic diversity and structure recorded in the species between the analyzed biogeographic areas are consistent with the marked differences in abiotic factors (i.e., different coastal configurations, Quaternary glacial histories, and oceanographic regimes) and to inherent characteristics of the species (i.e., salt-tolerance, physiology, and reproductive behavior).
Cáhuil Lagoon in central Chile harbors distinct microbial communities in various solar salterns that are arranged as interconnected ponds with increasing salt concentrations. Here, we report the metagenome of the 3.0- to 0.2-µm fraction of the microbial community present in a crystallizer pond with 34% salinity.
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