DOI: 10.5061/dryad.2jm63xt2f
title: Strong nuclear and mitochondrial genetic structure of <em>Mazzaella laminarioides</em> in the southeastern Pacific revealed by intensive sampling

description: In the morphospecies Mazzaella laminarioides, a red alga commonly found
 along Chilean rocky coasts, three genetic lineages, named North, Center,
 and South, presenting distinct levels of genetic divergence, have been
 previously described based on sequences of rbcL and COI. Here, we present
 the results obtained for six nuclear microsatellites and the COI data
 acquired for 29 localities positioned between 28°S and 43°S, which allow
 us to characterize the genetic structure of the species with high
 resolution and to delimit, for the first time, the transition zones
 between the three lineages. Our results reveal clearly defined boundaries
 between the lineages, as well as a marked substructure within each of
 them. The transition zone between the Northern and Central lineages is
 located in a narrow transition around 32°48′S, where dispersal appears to
 be restricted to very local scales, with no evidence of isolation by
 distance (IBD). At the same time, a mosaic of Center and South sampling
 sites is observed in an area extending over some 225 kilometers between
 37°S and 38°S. None of the four transition zones include sites that can be
 defined as a true contact zone, an area where two genetic groups are found
 in sympatry. Population admixture estimated with STRUCTURE detected only a
 few introgressed individuals even when genetic groups are located a few
 kilometers apart. We propose that transitions between lineages reflect a
 combination of historical events and contemporary factors that have
 persistently limited gene flow along the Chilean coast. In particular, the
 transition at 32°48′S (not necessarily associated with obvious physical
 barriers, such as estuaries or sandy beaches) could represent a historical
 genetic break that has been maintained by current hydrodynamic conditions.
 In contrast, the mosaic Center-Sur area at 37°S-38°S could be the product
 of earthquakes, coastal uplift, and subsequent recolonization events.
description: # Strong nuclear and mitochondrial genetic structure of *Mazzaella
 laminarioides* in the southeastern Pacific revealed by intensive sampling
 Dataset DOI: [10.5061/dryad.2jm63xt2f](10.5061/dryad.2jm63xt2f) ##
 Description of the data and file structure #### Microsatellite genotypes
 for *Mazzaella laminarioides* #### File:
 Microsatellites_genotypes_file.xlsx This data file includes multilocus
 genotypic data for individuals of the red alga *Mazzaella laminarioides*,
 sampled at 29 localities along the southeastern Pacific coast of Chile,
 between 28°S and 43°S. The data set consists of genotypes obtained from
 six nuclear microsatellite loci. Each row represents an individual, with
 columns indicating the Region, Sampling site, Cod Site, Individual, and
 the allele sizes for each locus (In the first row are the names of each
 locus). The file is presented in Excel (.xlsx) format. These data were
 used to assess the genetic structure and phylogeographic patterns across
 the species' distribution, as described in the associated article.
 For more information about the data set, sampling, and analysis, please
 contact Marie-Laure Guillemin
 ([marielaure.guillemin@gmail.com](mailto:marielaure.guillemin@gmail.com))
 or Suany Quesada-Calderón
 ([suany.quesada@uach.cl](mailto:suany.quesada@uach.cl)).