Moving beyond the current paradigm in marine population connectivity: are adults the missing link?

A central question of marine ecology is, how far do larvae disperse? Coupled biophysical models predict that the probability of successful dispersal declines as a function of distance between populations. Estimates of genetic isolation-by-distance and self-recruitment provide indirect support for this prediction. Here, we conduct the first direct test of this prediction, using data from the well-studied system of clown anemonefish ( Amphiprion percula ) at Kimbe Island, in Papua New Guinea. Amphiprion percula live in small breeding groups that inhabit sea anemones. These groups can be thought of as populations within a metapopulation. We use the x- and y -coordinates of each anemone to determine the expected distribution of dispersal distances (the distribution of distances between each and every population in the metapopulation). We use parentage analyses to trace recruits back to parents and determine the observed distribution of dispersal distances. Then, we employ a logistic model to (i) compare the observed and expected dispersal distance distributions and (ii) determine the relationship between the probability of successful dispersal and the distance between populations. The observed and expected dispersal distance distributions are significantly different ( p < 0.0001). Remarkably, the probability of successful dispersal between populations decreases fivefold over 1 km. This study provides a framework for quantitative investigations of larval dispersal that can be applied to other species. Further, the approach facilitates testing biological and physical hypotheses for the factors influencing larval dispersal in unison, which will advance our understanding of marine population connectivity.

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Not All Larvae Stay Close to Home: Insights into Marine Population Connectivity with a Focus on the Brown Surgeonfish (Acanthurus nigrofuscus)

Journal of Marine Biology ◽

10.1155/2011/518516 ◽

2011 ◽

Vol 2011 ◽

pp. 1-12 ◽

Cited By ~ 33

Author(s):

Jeff A. Eble ◽

Luiz A. Rocha ◽

Matthew T. Craig ◽

Brian W. Bowen

Keyword(s):

Resource Planning ◽

Reef Fishes ◽

Population Connectivity ◽

Genetic Connectivity ◽

Dispersal Ability ◽

Small Range ◽

Long Distance ◽

Larval Recruitment ◽

Marine Population ◽

Acanthurus Nigrofuscus

Recent reports of localized larval recruitment in predominately small-range fishes are countered by studies that show high genetic connectivity across large oceanic distances. This discrepancy may result from the different timescales over which genetic and demographic processes operate or rather may indicate regular long-distance dispersal in some species. Here, we contribute an analysis of mtDNA cytochromebdiversity in the widely distributed Brown Surgeonfish (Acanthurus nigrofuscus;N=560), which revealed significant genetic structure only at the extremes of the range (ΦCT=0.452;P<.001). Collections from Hawaii to the Eastern Indian Ocean comprise one large, undifferentiated population. This pattern of limited genetic subdivision across reefs of the central Indo-Pacific has been observed in a number of large-range reef fishes. Conversely, small-range fishes are often deeply structured over the same area. These findings demonstrate population connectivity differences among species at biogeographic and evolutionary timescales, which likely translates into differences in dispersal ability at ecological and demographic timescales. While interspecific differences in population connectivity complicate the design of management strategies, the integration of multiscale connectivity patterns into marine resource planning will help ensure long-term ecosystem stability by preserving functionally diverse communities.

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Observations of Migrant Exchange and Mixing in a Coral Reef Fish Metapopulation Link Scales of Marine Population Connectivity

Journal of Heredity ◽

10.1093/jhered/est021 ◽

2013 ◽

Vol 104 (4) ◽

pp. 532-546 ◽

Cited By ~ 16

Author(s):

John B. Horne ◽

Lynne van Herwerden ◽

Sheena Abellana ◽

Jennifer L. McIlwain

Keyword(s):

Coral Reef ◽

Reef Fish ◽

Coral Reef Fish ◽

Population Connectivity ◽

Marine Population

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Patterns, causes, and consequences of marine larval dispersal

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1513754112 ◽

2015 ◽

Vol 112 (45) ◽

pp. 13940-13945 ◽

Cited By ~ 76

Author(s):

Cassidy C. D’Aloia ◽

Steven M. Bogdanowicz ◽

Robin K. Francis ◽

John E. Majoris ◽

Richard G. Harrison ◽

...

Keyword(s):

Spatial Scale ◽

Spatial Genetic Structure ◽

Marine Reserve ◽

Local Population ◽

Logistic Models ◽

Strong Relationship ◽

Parentage Analysis ◽

Population Connectivity ◽

Dispersal Kernel ◽

Marine Population

Quantifying the probability of larval exchange among marine populations is key to predicting local population dynamics and optimizing networks of marine protected areas. The pattern of connectivity among populations can be described by the measurement of a dispersal kernel. However, a statistically robust, empirical dispersal kernel has been lacking for any marine species. Here, we use genetic parentage analysis to quantify a dispersal kernel for the reef fish Elacatinus lori, demonstrating that dispersal declines exponentially with distance. The spatial scale of dispersal is an order of magnitude less than previous estimates—the median dispersal distance is just 1.7 km and no dispersal events exceed 16.4 km despite intensive sampling out to 30 km from source. Overlaid on this strong pattern is subtle spatial variation, but neither pelagic larval duration nor direction is associated with the probability of successful dispersal. Given the strong relationship between distance and dispersal, we show that distance-driven logistic models have strong power to predict dispersal probabilities. Moreover, connectivity matrices generated from these models are congruent with empirical estimates of spatial genetic structure, suggesting that the pattern of dispersal we uncovered reflects long-term patterns of gene flow. These results challenge assumptions regarding the spatial scale and presumed predictors of marine population connectivity. We conclude that if marine reserve networks aim to connect whole communities of fishes and conserve biodiversity broadly, then reserves that are close in space (<10 km) will accommodate those members of the community that are short-distance dispersers.

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Dispersal and population connectivity are phenotype dependent in a marine metapopulation

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.1104 ◽

2019 ◽

Vol 286 (1909) ◽

pp. 20191104 ◽

Cited By ~ 4

Author(s):

Emily K. Fobert ◽

Eric A. Treml ◽

Stephen E. Swearer

Keyword(s):

Larval Dispersal ◽

Empirical Distribution ◽

Larval Growth ◽

Poor Quality ◽

Ocean Model ◽

Population Connectivity ◽

Marine Population ◽

Temperate Reef ◽

Temperate Reef Fish ◽

Marine Metapopulation

Larval dispersal is a key process determining population connectivity, metapopulation dynamics, and community structure in benthic marine ecosystems, yet the biophysical complexity of dispersal is not well understood. In this study, we investigate the interaction between disperser phenotype and hydrodynamics on larval dispersal pathways, using a temperate reef fish species, Trachinops caudimaculatus . We assessed the influence of larval traits on depth distribution and dispersal outcomes by: (i) using 24-h depth-stratified ichthyoplankton sampling, (ii) quantifying individual phenotypes using larval growth histories extracted from the sagittal otoliths of individual larvae, and (iii) simulating potential dispersal outcomes based on the empirical distribution of larval phenotypes and an advanced biological-physical ocean model. We found T. caudimaculatus larvae were vertically stratified with respect to phenotype, with high-quality phenotypes found in the bottom two depth strata, and poor-quality phenotypes found primarily at the surface. Our model showed high- and average-quality larvae experienced significantly higher local retention (more than double) and self-recruitment, and travelled shorter distances relative to poor-quality larvae. As populations are only connected when dispersers survive long enough to reproduce, determining how larval phenotype influences dispersal outcomes will be important for improving our understanding of marine population connectivity and persistence.

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