Strong genetic structure and limited connectivity among populations of Clark’s Anemonefish (Amphiprion clarkii) in the centre of marine biodiversity

Abstract

Populations of anemonefish species often show signs of local isolation due limited dispersal potential and oceanographic conditions. Additionally, anthropogenic pressure, such as overharvesting and coral reef exploitation causes reduced population size, eventually leading to local extinction. The understanding of the genetic population structure, as well as the influence of both historical and current connectivity, is required to design effective marine protected area (MPA) networks. In this study, the genetic structure of Clark's Anemonefish (Amphiprion clarkii) populations of the Indo-Malay Archipelago (IMA) is assessed through mitochondrial control region (mtCR) sequences and nuclear microsatellites. Results provided evidence of a significant genetic structure (mtCR: Φst = 0.42039, Φct = 0.63852; microsatellites: Fst = 0.01449, Fct = 0.05199). Genetic breaks were identified among Western (Padang Karimunjawa), Central (Sulawesi, Borneo, Bali, Komodo, Timor), and Eastern (Biak) IMA populations, which matches with patterns obtained for congeneric and other coral reef taxa. Due to the restricted connectivity among these three regions, it is suggested to consider them as separate management areas in the design of MPA networks.

Strong philopatry in an estuarine‐dependent fish

“…Overall, the need for estuarine conditions for spawning and subsequent egg and larval survival (Jenkins et al., 2018 ; Williams et al., 2020 ) is reflected in the overall philopatry we have identified, with connectivity among estuaries most likely a result of adult fish movements. The absence of suitable habitats limiting gene flow has also been found in reef fish, where open water between rocky or coral reefs restricts gene flow and drives population structuring (Ducret et al., 2022 ; Torres‐Hernandez et al., 2022 ). Furthermore, as A. butcheri have been shown to move out of estuarine systems through tagging, telemetry and otolith chemistry (Gillanders et al., 2015 ; Hindell et al., 2008 ; Hoeksema et al., 2006 ), the high genetic structuring found best reflects philopatry (i.e.…”

“…fish, where open water between rocky or coral reefs restricts gene flow and drives population structuring (Ducret et al, 2022;Torres-Hernandez et al, 2022). Furthermore, as A. butcheri have been shown to move out of estuarine systems through tagging, telemetry and otolith chemistry (Gillanders et al, 2015;Hindell et al, 2008;Hoeksema et al, 2006), the high genetic structuring found best reflects philopatry (i.e.…”