Volcanic oceanic islands are some of the Earth’s most geologically and ecologically dynamic habitats, where continuous volcanic activity and erosion lead to the formation of habitats that drastically change throughout their ontogeny. Shallow-water sandy habitats, specifically, repetitively disappeared and regenerated due to seasonal oceanographic and climatic eustatic sea-level variations. For its inhabitants, these events translate into populations being cyclically removed or passing by drastic reductions in population size, where the outcome often depends on the specific life-history modes of the species, determining their dispersal, colonization potential and, ultimately, their survival ability. Therefore, population genetic patterns of marine shallow-water infaunal species can provide powerful clues of such outcomes, as well as how specific geological and ecological settings determine the genetic structure of the species. We herewith test the population structure of the marine infaunal bivalve Ervilia castanea (Montagu, 1803) in the sandy habitats of the Azores and Madeira Archipelagos (Northeast and Central Atlantic Ocean), by comparing insular populations with conspecifics from the nearest continental shores in mainland Europe. Little to no genetic structure was observed between insular populations with both nuclear microsatellites and the mitochondrial cytochrome c oxidase subunit I. Moreover, deviations in the Hardy-Weinberg Equilibrium of insular populations suggests the exitance of archipelago specific processes. The high dispersal ability of E. castanea combined with the ephemeral nature of oceanic shallow-water sandy habitats likely made each population to be composed of individuals from multiple sources. High prevalence of null alleles, gene duplication hint at the potential occurrence of recent polyploidization events that require further investigation. Moreover, we found evidence of hyperdiversity among the markers used which may constrain the detection of more detailed patterns. We herewith demonstrate the uniqueness of insular environmental settings and inquire further into the evolutionary and biogeographic patterns of marine shallow-water infaunal species from volcanic oceanic islands.

Fragmentation of landscapes is a common impairment of habitats highlighting the need to increase connectivity to support wildlife populations. This study focuses on the Eastern green lizard (Lacerta viridis) and investigates the effectiveness of a species-specific corridor network in a vineyard landscape. Using a non-invasive photographic capture-recapture approach, individual movements were tracked to assess sex-specific patterns and distances covered in adult lizards. The study also provided insight into population parameters such as sex ratio and spatial distribution of the resident green lizard population. Results showed a surplus of male individuals and clustered distributions along the habitats. Both, male and female green lizards use the habitat network, with males covering larger distances. The connectivity structures facilitated the movement of males between habitat sections with some individuals covering distances exceeding 250 m. Hereby, male movement distances correlated with female abundance, which emphasizes the importance of connectivity structures in maintaining population stability. Two parameters correlated to female abundance showed significance in the models. First, the fewer females were detected in a male’s core area, the higher the probability that it migrated a long distance. Secondly, a positive correlation existed between males’ covered distance and female abundance in its entire activity range. Overall, this research highlights the importance of habitat connectivity measures for natural population dynamics through supporting male lizards to migrate in search of females.