Pleistocene expansion, anthropogenic pressure and ocean currents: Disentangling the past and ongoing evolutionary history of Patella aspera Röding, 1798 in the archipelago of Madeira

Aims: Rising sea-level following the Last Glacial Maximum lead to fragmentation of coastal limpet populations between islands of the Archipelago of Madeira. This fragmentation is reinforced by recent heavy exploitation reducing effective population size on Madeira Island. We use the limpet P. aspera to understand how the role of processes at different time scales (i.e. changes in the sea level and overexploitation) can influence the genetic composition of an extant species, relating these processes to reproductive phenology and seasonal shifts in ocean currents. Location: Madeira Island, Porto Santo and Desertas (Archipelago of Madeira, NE Atlantic Ocean). Taxon: The limpet Patella aspera. Methods: Twelve microsatellite genetic markers were used. A power analysis was used to evaluate the power of the microsatellite markers to detect a signal of population differentiation. Long-term past migrations were assessed using a Bayesian Markov Montecarlo approach in the software MIGRATE-n to estimate mutation-scaled migration rates (M = m/μ; m, probability of a lineage immigrating per generation; μ, mutation rate). Two sce narios were evaluated using an Approximate Bayesian Computation (ABC) in the software DIYABC 2.1 (i) Sce nario 1: considered a population scenario from a reduced Ne at time t3 to a higher Ne at time t2; and (ii) Scenario 2 considering a reduction of Ne from a time t3 to a time t2. Results: Colonization of the archipelago by Portuguese settlers six centuries ago probably led to an important decrease in the genetic diversity of the species (Ne). Contemporary gene flow strongly support a pattern of high asymmetric connectivity explained by the reproductive phenology of the species and spatio-temporal seasonal changes in the ocean currents. Spatio-temporal reconstructions using Bayesian methods, including coalescent and Approximate Bayesian Computation (ABC) approaches, suggest changes in the migration patterns from highly symmetric to highly asymmetric connectivity with subtle population differentiation as consequence of post-glacial maximum sea level rise during the Holocene.info:eu-repo/semantics/publishedVersio

A simulation study evaluating how population survival and genetic diversity in a newly established population can be affected by propagule size, extinction rates, and initial heterozygosity

The introduction and establishment of invasive species in regions outside their native range, is one of the major threats for the conservation of ecosystems, affecting native organisms and the habitat where they live in, causing substantial biological and monetary losses worldwide. Due to the impact of invasive species, it is important to understand what makes some species more invasive than others. Here, by simulating populations using a forward-in-time approach combining ecological and single polymorphic nucleotides (SNPs) we evaluated the relation between propagule size (number of individuals = 2, 10, 100, and 1,000), extinction rate (with values 2%, 5%, 10%, and 20%), and initial heterozygosity (0.1, 0.3, and 0.5) on the population survival and maintenance of the heterozygosity of a simulated invasive crab species over 30 generations assuming a single introduction. Our results revealed that simulated invasive populations with initial propagule sizes of 2–1,000 individuals experiencing a high extinction rate (10–20% per generation) were able to maintain over 50% of their initial heterozygosity during the first generations and that under scenarios with lower extinction rates invasive populations with initial propagule sizes of 10–1,000 individuals can survive up to 30 generations and maintain 60–100% of their initial heterozygosity. Our results can help other researchers better understand, how species with small propagule sizes and low heterozygosities can become successful invaders

Data from: Invasive species and postglacial colonization: Their effects on the genetic diversity of a Patagonian fish

The present distribution of Patagonian species is the result of a complex history involving Quaternary refugial populations, Holocene range expansions, and demographic changes occurring during the Anthropocene. Invasive salmonids were introduced in Patagonia during the last century, occupying most rivers and lakes, preying on, and competing with native species, including the fish Galaxias platei. Here we used G. platei as a case study to understand how long-term (i.e. population differentiation during the Holocene) and short-term historical processes (salmonid introductions) affect genetic diversity. Using a suite of microsatellite markers, we found that the number of alleles is negatively correlated with presence of salmonids (short-term processes), with G. platei populations from lakes with salmonids exhibiting significantly lower genetic diversity than populations from lakes without salmonids. Simulations (100 years backwards) showed that this difference in genetic diversity can be explained by a 99% reduction in population size. Allelic richness and observed heterozygosities were also negatively correlated with the presence of salmonids, but also positively correlated with long-term processes linked to Quaternary glaciations. Our results show how different genetic parameters can help identify processes taking place at different scales and their importance in terms of conservation

Genepop 8 microsatellite

Genepop files for 21 Galaxias platei populations with 8 microsatellite markers and 16 Galaxias platei populations with 10 microsatellite markers

Data from: Echoes of a distant time: effects of historical processes on contemporary genetic patterns in Galaxias platei in Patagonia

Interpreting the genetic structure of a metapopulation as the outcome of gene flow over a variety of timescales is essential for the proper understanding of how changes in landscape affect biological connectivity. Here we contrast historical and contemporary connectivity in two metapopulations of the freshwater fish Galaxias platei in northern and southernmost Patagonia where paleolakes existed during the Holocene and Pleistocene, respectively. Contemporary gene flow was mostly high and asymmetrical in the northern system while extremely reduced in the southernmost system. Historical migration patterns were high and symmetric in the northern system and high and largely asymmetric in the southern system. Both systems showed a moderate structure with a clear pattern of isolation by distance (IBD). Effective population sizes were smaller in populations with low contemporary gene flow. An approximate Bayesian computation (ABC) approach suggests a late Holocene colonization of the lakes in the northern system and recent divergence of the populations from refugial populations from east and west of the Andes. For the southern system, the ABC approach reveals that some of the extant G. platei populations most likely derive from an ancestral population inhabiting a large Pleistocene paleolake while the rest derive from a higher-altitude lake. Our results suggest that neither historical nor contemporary processes individually fully explain the observed structure and geneflow patterns and both are necessary for a proper understanding of the factors that affect diversity and its distribution. Our study highlights the importance of a temporal perspective on connectivity to analyse the diversity of spatially complex metapopulations

Short-Term and Long-Term Predictions: Is the Green Crab <i>Carcinus maenas</i> a Threat to Antarctica and Southern South America under a Climate-Change Scenario?

Non-native species can have profound implications on the survival of native ones. This is especially true for some invasive crabs, such as the green crab Carcinus maenas, a native species to the Northern Hemisphere that has been introduced into southern Argentina, from where it could expand through Argentina, Chile, and the Antarctic Peninsula. Hence, there is interest in forecasting changes in C. maenas habitat suitability through time to predict if potential future invasions might occur. Here, by using a Species Distribution Model (SDM) approach, we estimated the habitat suitability for C. maenas along southern South America and the Antarctic Peninsula under two future climate-change scenarios. Our results reveal that under current conditions, habitat suitability for C. maenas along the Antarctic Peninsula is null and very restricted in Argentina and Chile. Habitat suitability along the Antarctic Peninsula remained null in the short-term (30 years) and long-term future (80 years), despite the climate-change scenario considered. Surprisingly, when considering future conditions, habitat suitability along the coast of Argentina and Chile decreased and became nil for some currently occupied locations. Thus, the SDM results suggest that climate change could have a negative effect on the habitat suitability of C. maenas leading to potential local extinctions

Bayesass - Serrano

BayesAss file containing the microsatellite data (16 markers) of the freshwater fish Galaxias platei in the Serrano system in Southern Patagonia

Mantel - Serrano

Geographic and genetic distance for Galaxias platei individuals from the Serrano system. These distance matrices were used for the Mantel test

Bayesass - SanPedro

BayesAss file containing the microsatellite data (14 markers) of the freshwater fish Galaxias platei in the San Pedro system in Northern Patagonia

Migrate - SanPedro

MIGRATE-n file containing the microsatellite data (14 markers) of the freshwater fish Galaxias platei in the San Pedro system in Nothern Patagonia. The parmfile for this run is included in the readme file