PS 35-167 - Isolation-by-distance and isolation-by-oceanography in Maroon Anemonefish (Premnas biaculeatus)

Tuesday, August 16, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

Kyra Fitz

Ph.D. Candidate
Rutgers University, United States

Coauthor(s)

DT

Diane Thompson

University of Arizona, United States
JM

Jun Montes

Visayas State University, Philippines
MP

Malin Pinsky

Rutgers University
New Brunswick, New Jersey, United States

Background/Question/Methods

Obtaining dispersal estimates for a species is key to understanding local adaptation and population dynamics, and to implementing conservation actions. Genetic isolation-by-distance patterns can be used for estimating dispersal, and these patterns are especially useful for marine species in which few other methods are available. In this study, we generate fine-scale estimates of dispersal in a coral reef fish, Premnas biaculeatus. P. biaculeatus is a rare species that only inhabits one type of anemone and is exploited in the aquarium trade. We address the questions: 1) what is the dispersal spread of P. biaculeatus, and does it follow the theoretical prediction of having shorter dispersal than species inhabiting less fragmented habitats?, and 2) are isolation-by-distance patterns or isolation-by-oceanography patterns more relevant for P. biaculeatus dispersal, and does this depend on spatial scale? To evaluate question 1, we genotyped P. biaculeatus at 16 microsatellite loci across 8 sites across 200 km in the central Philippines to generate fine-scale estimates of dispersal. For question 2, we used oceanographic modeling to test for correlations between potential connectivity and genetic distance at multiple spatial scales.

Results/Conclusions

Our research suggests that using isolation-by-distance patterns and effective density can yield robust dispersal estimates at narrow spatial scales (less than 150 km), but that heterogeneous ocean currents can disrupt this pattern across wider spatial scales (greater than 150 km). We found isolation-by-distance patterns in P. biaculeatus across most but not all reefs in the central Philippines, suggesting dispersal probabilities largely decline with geographic distance. We estimated a dispersal spread of around 9 km (95% confidence interval of 2.3-18.4 km), similar but slightly shorter than other anemonefishes. Our results match past theoretical model results predicting shorter dispersal in species with fragmented habitats. Ocean currents explained observed genetic structure in regions that did not follow isolation-by-distance, but currents were less effective for explaining structure in shallow ocean straits. Our findings suggest that networks of closely-spaced marine reserves would be beneficial for P. biaculeatus and would benefit many coral reef species, as most coral reef fish have dispersal spreads of 9 km or higher. Our study demonstrates the utility of combining isolation-by-distance patterns with oceanographic simulations to understand connectivity in marine environments and to guide marine conservation strategies.