The oceanic concordance of phylogeography and biogeography: a case study in Notochthamalus

Abstract

Dispersal and adaptation are the two primary mechanisms that set the range distributions for a population or species. As such, understanding how these mechanisms interact in marine organisms in particular – with capacity for long‐range dispersal and a poor understanding of what selective environments species are responding to – can provide useful insights for the exploration of biogeographic patterns. Previously, the barnacle Notochthamalus scabrosus has revealed two evolutionarily distinct lineages with a joint distribution that suggests an association with one of the two major biogeographic boundaries (~30°S) along the coast of Chile. However, spatial and genomic sampling of this system has been limited until now. We hypothesized that given the strong oceanographic and environmental shifts associated with the other major biogeographic boundary (~42°S) for Chilean coastal invertebrates, the southern mitochondrial lineage would dominate or go to fixation in locations further to the south. We also evaluated nuclear polymorphism data from 130 single nucleotide polymorphisms to evaluate the concordance of the signal from the nuclear genome with that of the mitochondrial sample. Through the application of standard population genetic approaches along with a Lagrangian ocean connectivity model, we describe the codistribution of these lineages through a simultaneous evaluation of coastal lineage frequencies, an approximation of larval behavior, and current‐driven dispersal. Our results show that this pattern could not persist without the two lineages having distinct environmental optima. We suggest that a more thorough integration of larval dynamics, explicit dispersal models, and near‐shore environmental analysis can explain much of the coastal biogeography of Chile.

Fine‐scale hierarchical genetic structure and kinship analysis of the ascidianPyura chilensisin the southeastern Pacific

“…Additionally, the genetic differentiation of Mehuín does not appear to be a product of limited larval dispersal at least at the scale of 40 km because genetic homogeneity was found between the localities of Pilolcura and Chaihuín(Giles et al, 2017) as well as between Mehuín and other localities north of it (unpublished data). Rather, our results indicate the presence of a barrier to gene flow between Mehuín and Pilolcura.Genetic breaks close to 39°S latitude have been reported for other species such as the red alga Mozzarella laminariales(Montecinos et al, 2012), the barnacle Notochthamalus scabrosus(Ewers-Saucedo et al, 2016), and the bivalve Perumytilus purpuratus…”

“…In a study where enzymatic markers were used, weak population structuring of P. chilensis is reported between Puerto Montt (41°S) and two sites to the north, Talcahuano (36°S) and Antofagasta (23°S) (Astorga & Ortiz, 2006 Genetic breaks close to 39°S latitude have been reported for other species such as the red alga Mozzarella laminariales (Montecinos et al, 2012), the barnacle Notochthamalus scabrosus (Ewers-Saucedo et al, 2016), and the bivalve Perumytilus purpuratus (Guiñez et al, 2016). In a study where enzymatic markers were used, weak population structuring of P. chilensis is reported between Puerto Montt (41°S) and two sites to the north, Talcahuano (36°S) and Antofagasta (23°S) (Astorga & Ortiz, 2006 Genetic breaks close to 39°S latitude have been reported for other species such as the red alga Mozzarella laminariales (Montecinos et al, 2012), the barnacle Notochthamalus scabrosus (Ewers-Saucedo et al, 2016), and the bivalve Perumytilus purpuratus (Guiñez et al, 2016).…”

Phylogeography and species distribution modelling reveal the effects of the Pleistocene ice ages on an intertidal limpet from the south‐eastern Pacific

“…The austral region where the break is found is formed by fjords and channels that exhibit important shore-coast gradients in salinity and SST that may exceed the tolerance limits of many species (Camus, 2001;Ib añez, Camus, & Rocha, 2009). Other examples of phylogeographical breaks at this latitude have also been reported in other marine organisms, such as molluscs and barnacles (Ewers-Saucedo et al, 2016;S anchez et al, 2011). This break drove the divergence of the northern and southern lineages of S. lessonii, which are nearly reciprocally monophyletic ( Figure S3.3).…”

Phenotypic plasticity at the edge: Contrasting population‐level responses at the overlap of the leading and rear edges of the geographical distribution of two Scurria limpets

“…On the other hand, an intensified upwelling regime will expose coastal species to demanding physical and chemical ocean conditions, particularly for planktonic larvae (Doney et al, 2012;Waldbusser et al, 2013). It is interesting to note that patellogastropod limpets have short larval durations and the phylogeographical (Ewers-Saucedo et al, 2016;Haye et al, 2014) or biogeographical breaks documented around PLV are chiefly of algae or species with short pelagic larval periods, similar to the rocky shores of the northeastern Pacific (Fenberg et al, 2014;Pelc, Warner, & Gaines, 2009).…”