Low genetic variation and isolation of northern peripheral populations of a red seaweed (Grateloupia lanceola)

Abstract

ABSTRACT1. Marine macroalgae are rarely considered from the point of view of conservation and the assessment of their conservation status is often limited by a lack of appropriate data. The red algae Grateloupia lanceola is a common inhabitant of Atlantic rocky shores along West Africa that also occurs in a small number of enclaves in the north-west Iberian Peninsula (NWIP).2. NWIP populations are notoriously separated from the main range of the species, and were proposed as candidates for inclusion in the regional list of species of conservation concern.3. In an attempt to provide further information to assess the status of these populations, amplified fragment length polymorphism (AFLP) and mitochondrial cytochrome oxidase subunit 2 and subunit 3 gene (cox2-3) sequences were used to investigate their genetic structure in the Iberian Peninsula. In contrast with the absence of variation in the cox2-3 region, AFLP revealed significant genetic differentiation and a clear isolation by distance pattern for samples separated by 100 s to 1000 km along Iberian shores.4. Together with assignment/exclusion tests, these results suggest that G. lanceola has geographically restricted dispersal, and indicate that NWIP sites are probably demographically isolated from other conspecifics. Therefore, it would be a mistake, from a conservation perspective, to assume that these populations may be subsidized by arrivals from distant populations located within the main range of the species.5. On a regional scale, most NWIP sites cluster into a single genetic unit with low genetic variation. Altogether, these results support the listing of NWIP populations of G. lanceola as vulnerable.

Levels and patterns of population genetic diversity in the red seaweedChondrus crispus(Florideophyceae): a direct comparison of single nucleotide polymorphisms and microsatellites

“…The limited dispersal potential associated with the various life‐history stages of red algae (haploid spermatia and diploid carpospores) has generally resulted in patterns of IBD, where restrictions on gene flow mean that geographically proximal populations are more genetically similar than those separated on greater spatial scales. This has been observed previously in the red algal species Ahnfeltiopsis pusilla (Couceiro et al ., ), Gelidium canariense (Bouza et al ., ), Grateloupia lanceola (Maneiro et al ., ), and Mazzaella laminarioides (Faugeron et al ., ), although not in the invasive Asparagopsis taxiformis (Andreakis, Kooistra & Procaccini, ). A recent study on C. crispus using fine‐scale sampling (primarily < 100 m but with replicates across 500 km) also identified potential IBD but highlighted the need to test this further at a range of scales (Krueger‐Hadfield et al ., ).…”

The Importance of Propagule Dispersal in Maintaining Local Populations of Rare Algae on Complex Coastlines: Padina pavonica on the South Coast of England

“…There has been very little progress regarding the conservation status of marine algae [22], although see [23]. Few studies have investigated potential population connectivity of intertidal algae on complex coastlines.…”