Life histories predict genetic diversity and population structure within three species of Octopus targeted by small-scale fisheries in Northwest Mexico
- Published
- Accepted
- Subject Areas
- Aquaculture, Fisheries and Fish Science, Conservation Biology, Genetics, Marine Biology
- Keywords
- octopus, fecundity, larval dispersal, planktonic larval duration, Gulf of California, marine connectivity
- Copyright
- © 2017 Domínguez-Contreras et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Life histories predict genetic diversity and population structure within three species of Octopus targeted by small-scale fisheries in Northwest Mexico. PeerJ Preprints 5:e3016v2 https://doi.org/10.7287/peerj.preprints.3016v2
Abstract
The fishery for octopus in Northwest Mexico has increased to over 2,000 tons annually, but to date the specific composition of the catch has been ignored. With at least three main species with varying life histories targeted by artisanal fisheries in the region, lack of information about the distribution of each species and metapopulation size and structure could impede effective fisheries management to avoid overexploitation. Here we tested if different life histories in three species of octopus help to predict observed patterns of genetic diversity, population dynamics, structure and connectivity that could be relevant to the sustainable management of the fishery. We sequenced two mitochondrial genes and genotyped seven nuclear microsatellite loci to identify the distribution of each species in 20 locations from the Gulf of California and the Pacific coast of the Baja California peninsula. We tested four a priori hypothesis derived from population genetic theory based on differences in the fecundity and dispersal potential for each species. We found that the species with low fecundity and without a planktonic larval stage (Octopus bimaculoides) had lower average effective population size and genetic diversity, but higher levels of kinship, population structure, and richness of private alleles, suggesting limited dispersal and high local recruitment. In contrast, two species with higher fecundity and planktonic larvae (O. bimaculatus, O. hubbsorum) showed higher effective population size and genetic diversity, and overall lower kinship and population structure, supporting higher levels of gene flow over a larger geographical scale. Even among the latter, there were differences in the calculated parameters possibly associated with increased connectivity in the species with the longest planktonic larval duration (O. bimaculatus). We consider that O. bimaculoides could be more susceptible to over exploitation of small, isolated populations that could have longer recovery times, and suggest that management should take place within each local population. For the two species with pelagic larvae, management should consider metapopulation structure over larger geographic scales and the directionality and magnitude of larval dispersal between localities driven by ocean currents. The distribution of each species and variations in their reproductive timing should also be considered when establishing marine reserves or seasonal fishing closures.
Author Comment
Version 2 has a minimal change in the abstract. The statement says "We consider that O. bimaculatus could be more susceptible to over exploitation ...", when it should have been "We considered that O. bimaculoides could be more susceptible to over exploitation ..."
Supplemental Information
Hardy-Weinberg equilibrium
Tests of Hardy-Weinberg equilibrium in 20 populations of octopus genotyped at 7 loci. Estimation of exact P-values by the Markov chain method. Parameters: 10,000 dememorization, 1000 batches and 10,000 iterations per batch.
Null allele frequency
Average null allele frequency obtained with FREENA using Expectation Maximization algorithm of Dempster in 20 populations of octopus genotyped at 7 loci.
Correction for null alleles
Correction of FST with and without null alleles estimated with FREENA. Confidence intervals (CI) calculated using 10,000 bootstraps.
Genetic differentiation of Octopus bimaculoides
Genetic differentiation between pairs of localities for Octopus bimaculoides. FST values below the diagonal and F’ST above diagonal.
Genetic differentiation of Octopus hubbsorum
Genetic differentiation between pairs of localities for Octopus hubbsorum. FST below the diagonal significance in bold. F'ST above the diagonal. Shadow area correspond to Pacific Coast.
Genetic differentiation of Octopus bimaculatus
Genetic differentiation between pairs of localities for Octopus bimaculatus. FST below the diagonal. Significance in bold. F'ST above the diagonal. Shadow area correspond to Pacific Coast.
Structure clustering algorithm
Structure clustering algorithm: A) Delta K is the mean of the absolute values, B) mean and standard deviation of Ln probability of data for No. of genetic cluster (K) =1 to 20 and C) bar plot showing the mean individual assignment probabilities among 10 independent replicates of both K = 2 and K = 3.