Dr. Brante-Ramírez, Antonio

Natural disturbances can modify extinction-colonization dynamics, driving changes in the genetic diversity and structure of marine populations. Along Chilean coast (36°S, 73°W), a strong hypoxic-upwelling event in 2008, and a mega earthquake-tsunami in 2010 caused mass mortality within the Aphos porosus population, which is a vulnerable species with low dispersal potential. We evaluated the effects of these two major disturbances on the diversity and spatial-temporal genetic structure of Aphos porosus in two neighboring areas that were impacted on different levels (High level: Coliumo Bay; Low level: Itata Shelf). Thirteen microsatellites (from 2008 to 2015) amplified in individuals collected from both locations were used to evaluate the effects of the two disturbances. Results showed that after the strong hypoxic-upwelling event and the mega earthquake-tsunami, Aphos porosus populations exhibited lower genetic diversity and less effective population sizes (Ne < 20), as well as asymmetries in migration and spatial-temporal genetic structure. These findings suggest a rise in extinction-recolonization dynamics in local Aphos porosus populations after the disturbances, which led to a loss of local genetic diversity (mainly in Coliumo Bay area impacted the most), and to greater spatial-temporal genetic structure caused by drift and gene flow. Our results suggest that continuous genetic monitoring is needed in order to assess potential risks for Aphos porosus in light of new natural and anthropogenic disturbances.

Background Understanding the mechanisms behind resilience has become more relevant in the last decades, due to the increasing and intensifying disturbances from natural and anthropogenic sources that threaten biodiversity. Evidence from terrestrial populations suggests that resilience increases with genetic diversity. Few studies, however, have evaluated the relationship between genetics and resilience in benthic marine populations. Methods and results For this review, we gathered studies where genetic diversity was the predictor variable, and resilience was the response variable. Twenty‑five publications between 2001 and 2018 were included. Thirteen benthic marine species were identified, mainly sea‑grass species, among which Zostera marina was the most frequently studied. The relationship between genetic diversity and resilience was variable‑dependent. Considering all the analyses (N = 150) in the studies reviewed, 44% reported positive relationships between genetic diversity and resilience capacity. Negative relationships were found in 6%, and no relationship was found in 50%. Positive relationships indicated that genetic diversity increased resistance and recovery capacity after different types of disturbances. Dominance and complementarity were suggested as the underlying mechanism explaining these findings in the few studies that conducted this type of evaluation. Conclusions The results of this review suggest that the relationship between genetic diversity and resilience is mainly positive. However, this relationship relies on how genetic diversity and resiliency were measured, as well as on the biological characteristics of the species under study. This reinforces the importance of acknowledging and main‑ taining genetic diversity for the conservation of benthic populations in marine ecosystems.