Abstract
Spatial and temporal variation of environmental parameters can affect dispersal, recruitment and population persistence of marine benthic species. Studies including inter-annual comparisons of genetic structure often indicate high/moderate temporal heterogeneity in marine invertebrates, which may be a prevailing pattern. This suggests that temporal studies are necessary to understand the dynamics of marine metapopulations. In this study, we analyzed the spatio-temporal genetic structure of the ascidianPyura chilensis, a low dispersal sessile marine species endemic from the Southeast Pacific coast and highly demanded for human consumption. We sequenced a fragment of the mitochondrial gene Cytochrome Oxidase I (COI) from 1,005 individuals of six locations (30–40 individuals per site and year) spanning a wide latitudinal range (24°–42°S) and sampled over 5 years (2012, 2014, 2015, 2016, and 2017). The genetic structure of COI indicates the presence of three monophyletic lineages (haplogroups 1–3) previously described for the species, being one of them highly divergent and geographically restricted (~39°S, Los Molinos). Considering the whole dataset, a picture of strong spatial differentiation but temporal stability emerged inPyura chilensis.However, detailed studies of the two main lineages revealed important differences in the extent of spatio-temporal variation. Analyses using haplotype frequencies sorted by site and year showed that, for haplogroup 1, genetic variation was explained mainly by differences between sites, while for haplogroup 2 differences between years were prevailing. Haplogroup 3 was restricted to the most southern sites, and also showed inter-annual variability in its frequency. These results point to disparate patterns of genetic differentiation, which may reflect different adaptive scope or variation in reproductive and dispersal features and could be a response to extreme events such as El Niño (2015–2016). This work calls for caution when obtaining general trends in species clearly differentiated in lineages, and prompts instead for separate analyses of sub-specific genetic lineages whenever possible.
Highlights
Marine benthic coastal species inhabit an environment that is variable geographically and temporarily (Menge et al, 2003)
Phylogeographic studies of marine benthic invertebrates have traditionally focused on the spatial genetic structure using one or more molecular markers, revealing that most benthic marine species show genetic structure in their range of distribution, related to different abiotic and biotic features (Weersing and Toonen, 2009; Kelly and Palumbi, 2010; Schiebelhut and Dawson, 2018)
Studies that include inter-annual comparisons indicate that temporal variation in the genetic structure of populations is a prevailing pattern in the marine environment (e.g., Virgilio and Abbiati, 2006; Barshis et al, 2011; Quintero-Galvis et al, 2020)
Summary
Marine benthic coastal species inhabit an environment that is variable geographically and temporarily (Menge et al, 2003). We studied the degree of interannual genetic variation of six local populations of the ascidian Pyura chilensis in the Chilean coast between 24 and 42◦S, covering the southern portion of its geographic range of distribution (from 10 to 44◦S), with 5 years of sampling. This species is a conspicuous and dominant competitor of hard substrates in the Humboldt Current System (Ambler and Cañete, 1991; Valdivia et al, 2005) and a bioengineer species (Castilla et al, 2004) that is widely distributed in the Southeast Pacific coast (Lancellotti and Vásquez, 2000). The data were used to assess the spatial-temporal patterns of genetic diversity in this ecologically and commercially important species
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
