Disentangling the genetic and morphological structure of Patella candei complex in Macaronesia (NE Atlantic)

Abstract

The uptake of natural living resources for human consumption has triggered serious changes in the balance of ecosystems. In the archipelagos of Macaronesia (NE Atlantic), limpets have been extensively exploited probably since islands were first colonized. This has led to profound consequences in the dynamics of rocky shore communities. The Patella candei complex includes various subspecies of limpets that are ascribed to a particular archipelago and has been the focus of several taxonomic surveys without much agreement. Under a conservational perspective, we apply morphometric and genetic analyses to test subspecies boundaries in P. candei and to evaluate its current population connectivity throughout Macaronesia (Azores, Madeira, and Canaries). A highly significant genetic break between archipelagos following isolation by distance was detected (F ST = 0.369, p < .001). Contrastingly, significant genetic differentiation among islands (i.e., Azores) was absent possibly indicating ongoing gene flow via larval exchange between populations. Significant shell‐shape differences among archipelagos were also detected using both distance‐based and geometric morphometric analyses. Adaptive processes associated with niche differentiation and strong barriers to gene flow among archipelagos may be the mechanisms underlying P. candei diversification in Macaronesia. Under the very probable assumption that populations of P. candei from each archipelago are geographically and/or ecologically isolated populations, the various subspecies within the P. candei complex may be best thought of as true species using the denomination: P. candei in Selvagens, Patella gomesii in Azores, Patella ordinaria in Madeira, and Patella crenata for Canaries. This would be in agreement with stock delimitation and units of conservation of P. candei sensu latu along Macaronesia.

Major ocean currents may shape the microbiome of the topshell Phorcus sauciatus in the NE Atlantic Ocean

“…Our results partially agreed with this new classification, but microbiome composition showed a separation of Madeira from Selvagens and the Canaries. These results are in accordance with previous microsatellite studies conducted on the intertidal limpet Patella candei complex 54 that evidenced genetic discontinuity between Madeira and Canarian populations. It needs to be taken into account that genetic analysis and biogeographical patterns reflect contrasting time scales, i.e., centuries for microsatellites and geological time in the case of biogeography.…”

“…400 km) and the presence of Selvagens Islands halfway between Madeira and the Canaries. These genetic patterns are mainly explained by large and meso-scale oceanographic conditions 54 , which origin supposedly dates back to geological time scales. An additional plausible explanation on microbiome content may be found in the seasonal variations of the Canary Current.…”

The protection effects of marine protected areas on exploited molluscs from an oceanic archipelago

“…For the MPA on the Selvagens Islands, only P. aspera was considered, since the taxonomy status of P. candei in this region is not fully resolved. According to Faria et al (), it is very probable that P. candei from each Macaronesian archipelago are geographically and/or ecologically isolated populations. Hence, specimens of P. candei from Madeira and Desertas islands are considered in order to diminish the genetic variability among the sampling places.…”

Macaronesia as a Fruitful Arena for Ecology, Evolution, and Conservation Biology

“…The ancestors of most extant Macaronesian lineages had to overcome the long distances that separate the islands from the mainland. Accordingly, many Macaronesian plants (e.g., Patiño et al, 2013;García-Verdugo et al, 2019), lizards (Carranza et al, 2000) and marine molluscs (e.g., Ávila et al, 2012;Faria et al, 2017) show some adaptations to long distance dispersal (LDD). However, there is also evidence from the Azorean flora indicating that many plant species lack traits related to LDD (Heleno and Vargas, 2015), and that species ability to track its climatically suitable areas within an island is not strongly related with LDD syndromes (Leo et al, 2021).…”