Mitochondrial lineages in Notochthamalus scabrosus as indicators of coastal recruitment and interactions

Abstract

A significant genetic cline has previously been identified along the Chilean coast in the barnacle Notochthamalus scabrosus. Samples from the previous study, spanning 800 km, were not able to show whether the southern lineage ultimately goes to fixation at higher latitudes. In addition to expanding the geographic sampling of this species, locations that were sampled approximately four to five generations ago were resampled for this study, enabling a temporal comparison of the location and strength of the observed cline. Here, we show that although the cline persists as expected, the tremendous changes in observed lineage frequencies near the clinal boundary are indicative of source-sink dynamics that may be associated with a codistributed biogeographic transition zone. We also find that the southern lineage does not increase in frequency in more southern populations, suggesting that this lineage is maintained through a combination of density-dependent interactions and a coastal fitness gradient.

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

“…), or even change considerably from year to year (Laughlin et al. ), suggesting the importance of local habitat and mechanisms associated with larval recruitment for maintaining the biodiversity at a site.…”

“…Isolation of DNA from these tissues proceeded as in Laughlin et al. (). These samples were used for sequencing or haplogroup identification of mitochondrial COI and genotyping of 130 anonymous nuclear single nucleotide polymorphisms (SNP).…”

“…; Laughlin et al. ) [ZL hereafter]. Along the coast of Chile, there are two primary marine biogeographic provinces (defined by taxonomic endemicity) that are considered to broadly overlap – the “Peruvian” Province in the north, with associated taxa found as far south as ~42°S, and the “Magellanic” Province in the south (Fig.…”

“…Indeed, some sites in central Chile where both lineages are found exhibit high variances in lineage frequency suggestive of “sink” dynamics (Laughlin et al. ) seeded from populations upstream in the northward‐flowing Humboldt Current System. By sampling most of the range of N. scabrosus , along with far better sampling of genomic diversity using a set of anonymous SNP markers (Zakas et al.…”

Highly Connected Populations and Temporal Stability in Allelic Frequencies of a Harvested Crab from the Southern Pacific Coast

“…Well-known phylogeographic breaks in the Pacific are located at Point Conception (34.5° N) in California [27], 30–32° S in northern [28] and 42° S in southern Chile [29]. While studies performed in Chile have identified species limited by the break at 30–32° S [30,31], other species did not align with these biogeographic breaks [32,31]. …”