Genomics insight into the past and present of Antarctic Biodiversity
A tool to assess the fate of a unique ecosystem in a changing world (GAB)
The Antarctic continent is one of the most pristine and isolated by the ocean, bathymetry, climate and geographical barriers resulting from the tectonic and climatic events that began in the Eocene. However, the recent acceleration of climate change and anthropogenic pressures can definitely affect Antarctic biodiversity. The Western sector of the Antarctic Peninsula has been described as one of the areas most affected by climate change, therefore, the possibilities of disturbance of this fragile ecosystem have increased, particularly due to the introduction of species and the loss of native biodiversity. Understanding how Antarctic biodiversity responded to past changes will help us to predict the fate of the Antarctic biota due to anthropogenic climate change. In this context, our proposal constitutes an associative program of researchers from five national institutions, supported by a collaborative network that includes national and international researchers, who work in the Southern Ocean (OA). Our main objective is to understand the historical and contemporary effects of climate change on the diversification, demographic history and adaptation of Antarctic biodiversity (including microorganisms, invertebrates and vertebrates) based on genomic data. Our data analyzes include approximations to establish population genetic structure, phylogeographic patterns and adaptation. In addition, we will combine the genetic results with data from environmental variables to model the ecological niche and therefore the past distribution (last glacial maximum – UMG), present and future of the different operational taxonomic units (species) and their lineages. This information will make it possible to understand the response and resilience of the Antarctic and sub-Antarctic biota during climate change events and, therefore, predict the fate of this unique biogeographical province in the face of anthropogenic changes.
Institutions
International Collaboration Network
Project Goals
Determine rhythms and trends in the diversification of genetic lineages of Antarctic and Subantarctic taxa (Historical Biogeography in the Southern Ocean).
The marked changes in the diversity, structure and composition of invertebrate groups in the SO over the last 34 Myr suggest that this region offers a good insight into macro-evolutionary processes, especially the relationship between speciation and extinction. We will study the historical and recent biogeography of different groups along their distribution in the Southern Ocean including Antarctic regions (Antarctic Peninsula, South Shetland Islands and the Scotia Arc) and Subantarctic regions (Patagonia, Falkland Islands, Marion Island, Crozet Island and Kerguelen, Bouvet and Macquarie Archipelago). For this purpose, we selected several groups including Vertebrates (Marine mammals, birds and fishes) and marine and freshwater invertebrates (Echinoderms, Gastropods, Copepods). We will determine the levels of genetic divergence between congeneric species from different provinces in the SO and, we will estimate the divergence time between the different evolutionary units identified by molecular phylogenies. The information contained in their DNA sequences will permit us to estimate rhythms and trends in the diversification of genetic lineages of Antarctic and Subantarctic taxa.
To evaluate past population dynamics using molecular data and identify potential refuge areas (role of Quaternary glacial cycles in shaping the Antarctic and Subantarctic biodiversity).
Phylogeographic approaches can elucidate the impact of the Quaternary glacial cycles in species along the SO Provinces. We will contrast levels of genetic diversity in the same taxa to determine the patterns of genetic structure among these Provinces. This will allow determining the effects of the Quaternary glacial cycles over the distribution of genetic lineages in these species and it will be possible to estimate whether Antarctic populations remained in refugia along the Antarctic Peninsula during the last glacial event or re-colonized this area after the LGM, from northern Antarctic Islands of the Scotia Arc or even from Subantarctic regions. We will also perform demographic inference analyses in the analyzed species to determine times and modes of population expansion.
To determine the contemporary connectivity pattern of species in relation with their life history traits and their geographic distribution.
We will evaluate the degree of connectivity that exists between taxa within the large oceanographic circulation patterns that characterize the SO. We will evaluate the model of Antarctic and sub-Antarctic rings that suggest the existence of two main disconnected dispersion pathways corresponding to: (1) Antarctic Circumpolar Current that has a clockwise circulation and would connect the sub-Antarctic zones and (2) the Antarctic Coastal Current bordering the margin of the continent and that has a counter-clockwise sense, maintaining the connectivity around Antarctica. In contrast, it is expected that the Antarctic Polar Front will represent a strong barrier for dispersal. Moreover, we will evaluate how life history traits such as developmental mode and potential for rafting in marine invertebrates, benthic versus pelagic habitat for fishes and philopatry for birds and marine mammals.
To evaluate adaptation processes and potential evolutionary responses to climate change.
The adaptive genetic diversity (in CDS) today is result of historical environmental changes such as Pleistocene Climatic Oscillations. Therefore, to species respond to recent climate change is required genetic diversity in specific genes (e.g. thermoregulatory genes in endotherm vertebrates or shell development in mollusks) to occur response to selection and consequently adaptation. We will detect how selective forces have contributed to the diversification of SO biota, taking advantage of strong environmental discontinuities observed across the Polar and sub-Antarctic fronts. Therefore, we will disentangle the distribution of SNP under selection on the genomes (genomic islands) and the function of genes, especially those whose function is to respond to climate change. Since the advent of genomics, the adaptation can be studied directly in the genome at the interspecific and intraspecific level, using different approaches, such as (1) evaluating population differentiation (outlier detection methods), (2) haplotype extended pattern, and (3) the association to the environment variables from each population.
Estimating and forecasting species past, present and future distribution based on macro-environmental features.
Species distributions can be predicted by macroclimatic drivers through modeling techniques (SDM), which inform on the biogeographic ranges and ecophysiological envelopes of the species. Genetic information can be integrated with spatial data to uncover life histories, philopatric effects and population trends. This is especially important within species from the same taxa with different patterns of distribution of genetic diversity, such as lack of population structure along the entire distribution (e.g. chinstrap penguin), or divergent clades for different locations (e.g. Gentoo penguin). Furthermore, SDM can identify ecological thresholds that shape species distribution limits and explain past, present or future capabilities to respond to climate effects, this is particularly relevant for identifying climate change impacts and most vulnerable species.
To depict biogeographical patterns in microorganisms along the Southern Ocean.
We will address an emergent and mainly unresolved issue about the biogeography of microorganisms, involving new methodologies and concepts specific to microbial genomics, differing from previous objectives. We will test classical hypotheses such as (1) the pan-distribution of microbial taxa, sometimes called “every-thing is everywhere” assuming that their enormous dispersal capacity rapidly erases the effects of past evolutionary events and that only contemporary environmental conditions determine their distribution or (2) that the distributions of microbial taxa, like those of macroorganisms, reflect the influences of both past events and contemporary environmental conditions. The first step it will to reduce the huge diversity of microbial ecosystems to focusing on two specific communities of interest for Antarctic ecosystems: methanogenic and denitrifying communities, which are relevant in global biogeochemical cycles and involved in global change processes. On the other hand, because micro and macroorganisms are often involved in close associations that affect each other’s growth, metabolism, and fitness. We will assess how these interactions influence the adaptation, co-evolution and geographic distribution of both organisms along a gradient of Antarctic to sub-Antarctic ecosystems. We propose to evaluate the relationship between host phylogeny (macroorganism) and the phylogeny of its gut microbiota among several biogeographic provinces of the SO.