scholarly journals The Behaviour and Ecology of Austrolittorina antipodum and Austrolittorina cincta: Models for Marine Reserve Connectivity Studies

2021 ◽  
Author(s):  
◽  
Jennifer Vander Veur
Keyword(s):  
Gene Flow ◽  
Larval Mortality ◽  
Marine Reserve ◽  
Sex Ratios ◽  
Marine Conservation ◽  
Population Connectivity ◽  
Adult Density ◽  
Population Surveys ◽  
Multiple Peaks ◽  
High Shore

<p>Determining the magnitude of dispersal and connectivity between populations has important implications for marine conservation. Species with limited dispersal capabilities exhibit restricted gene flow leading to isolation and, ultimately, differentiated populations. In this ecological study I investigated the gastropods Austrolittorina antipodum (Philippi, 1847) and Austrolittorina cincta (Quoy and Gaimard, 1833) to determine how ecology and behaviour influence the dispersal and connectivity of these species. The aim of this study was to determine population size and structure, settlement, fecundity, and adult movement rates. Methodologies included: population surveys, deployment of settlement pads and adult density manipulations, dissections, and a tagging study. These elements of a species ecology and behaviour can enhance or restrict population connectivity by: cohort partitioning resulting from habitat requirements, fluctuating settlement due to variable larval mortality or adult densities impacting dispersal, skewed sex ratios and effective populations sizes altering larval production, and adult movement leading to behavioural isolation or facilitating gene flow, along with other possible effects. Population surveys revealed both species had a Vermeij (1972) "type 1 distribution" (shell size increasing from the low to high shore), with the highest density of individuals on the low shore and the majority of mature adults on the high shore. Overall, A. antipodum was 16 times more abundant than A. cincta. Shifts to a smaller mean size of both species, along all shore heights following periods of peak settlement indicates settlers are potentially triggering competitive interactions or ontogenetic migrations in other cohorts.Settlement surveys revealed that peak settlement for Austrolittorina spp. was from February to April, declining at the beginning of March. Multiple peaks in settlement may act as a buffer limiting the potential of stochastic events to hinder dispersal during reproductive seasons. Settlement rates were not affected by adult density in control treatments; however, settlement was higher on pads deployed within adult populations compared to pads deployed adjacent to adult populations, suggesting the presences of adults has some effect on settlement. Fecundity results revealed A. antipodum to have more mature females than A. cincta, with males of both species reaching sexual maturity before females. Sex ratios of both species were skewed towards more females, with effective population sizes that included approximately 88% of each species population. A. antipodum’s larger population may be due to variation between the species' demographics, such as the distribution of mature females and juveniles leading to greater spawning success and juvenile survivorship. Tagging transplant/translocation experiments used to examine movement revealed that both species traveled similar distances. On average A. antipodum traveled 24.1m (±23.5m) and A. cincta traveled 18.7m (±16m) in eight months. There was no evidence of behavioural isolation occurring between low and high shore individuals. The wide ranging movements of adults indicated adults have the potential to maintain population connectivity on small scales. The findings of this study suggest both species facilitate dispersal with multiple peaks in settlement, large effective populations, and high adult mobility. Behavioural variation between the species appears to affect population connectivity, with the distribution of A. antipodum demographics potentially enhancing connectivity.</p>

scholarly journals The Behaviour and Ecology of Austrolittorina antipodum and Austrolittorina cincta: Models for Marine Reserve Connectivity Studies

2021 ◽  
Author(s):  
◽  
Jennifer Vander Veur
Keyword(s):  
Gene Flow ◽  
Larval Mortality ◽  
Marine Reserve ◽  
Sex Ratios ◽  
Marine Conservation ◽  
Population Connectivity ◽  
Adult Density ◽  
Population Surveys ◽  
Multiple Peaks ◽  
High Shore

<p>Determining the magnitude of dispersal and connectivity between populations has important implications for marine conservation. Species with limited dispersal capabilities exhibit restricted gene flow leading to isolation and, ultimately, differentiated populations. In this ecological study I investigated the gastropods Austrolittorina antipodum (Philippi, 1847) and Austrolittorina cincta (Quoy and Gaimard, 1833) to determine how ecology and behaviour influence the dispersal and connectivity of these species. The aim of this study was to determine population size and structure, settlement, fecundity, and adult movement rates. Methodologies included: population surveys, deployment of settlement pads and adult density manipulations, dissections, and a tagging study. These elements of a species ecology and behaviour can enhance or restrict population connectivity by: cohort partitioning resulting from habitat requirements, fluctuating settlement due to variable larval mortality or adult densities impacting dispersal, skewed sex ratios and effective populations sizes altering larval production, and adult movement leading to behavioural isolation or facilitating gene flow, along with other possible effects. Population surveys revealed both species had a Vermeij (1972) "type 1 distribution" (shell size increasing from the low to high shore), with the highest density of individuals on the low shore and the majority of mature adults on the high shore. Overall, A. antipodum was 16 times more abundant than A. cincta. Shifts to a smaller mean size of both species, along all shore heights following periods of peak settlement indicates settlers are potentially triggering competitive interactions or ontogenetic migrations in other cohorts.Settlement surveys revealed that peak settlement for Austrolittorina spp. was from February to April, declining at the beginning of March. Multiple peaks in settlement may act as a buffer limiting the potential of stochastic events to hinder dispersal during reproductive seasons. Settlement rates were not affected by adult density in control treatments; however, settlement was higher on pads deployed within adult populations compared to pads deployed adjacent to adult populations, suggesting the presences of adults has some effect on settlement. Fecundity results revealed A. antipodum to have more mature females than A. cincta, with males of both species reaching sexual maturity before females. Sex ratios of both species were skewed towards more females, with effective population sizes that included approximately 88% of each species population. A. antipodum’s larger population may be due to variation between the species' demographics, such as the distribution of mature females and juveniles leading to greater spawning success and juvenile survivorship. Tagging transplant/translocation experiments used to examine movement revealed that both species traveled similar distances. On average A. antipodum traveled 24.1m (±23.5m) and A. cincta traveled 18.7m (±16m) in eight months. There was no evidence of behavioural isolation occurring between low and high shore individuals. The wide ranging movements of adults indicated adults have the potential to maintain population connectivity on small scales. The findings of this study suggest both species facilitate dispersal with multiple peaks in settlement, large effective populations, and high adult mobility. Behavioural variation between the species appears to affect population connectivity, with the distribution of A. antipodum demographics potentially enhancing connectivity.</p>

When Less Is More: Sex Ratios for the Mass-Rearing of Anastrepha ludens (Diptera: Tephritidae)

2019 ◽  
Author(s):  
G I González-López ◽  
E Solís-Echeverría ◽  
F Díaz-Fleischer ◽  
D Pérez-Staples
Keyword(s):  
Sex Ratio ◽  
Egg Production ◽  
Sex Ratios ◽  
Pupal Stage ◽  
Mass Rearing ◽  
Anastrepha Ludens ◽  
Adult Density ◽  
Genetic Sexing ◽  
Male Harassment ◽  
Less Is More

Abstract Anastrepha ludens (Loew) is one of the most important pests of citrus and mango crops in Mexico. A method used to control this pest is the sterile insect technique, which consists in the mass production, irradiation, and release of insects in affected areas. The production of insects begins with the establishment of colonies to produce eggs, which must be highly fertile to ensure an adequate production of larvae. However, female fecundity and fertility can be affected by adult density and sex ratio, thus an optimal sex ratio in mass-rearing cages must be used. The genetic sexing strain of A. ludens (Tapachula-7) allows the identification of the sex at the pupal stage, making it possible to establish rearing cages with different sex ratios. We determined if different sex ratios have an effect on egg production. Two sex ratios (4♀: 1♂ and 1♀: 1♂) were compared. Fecundity, fertility and survival at different ages were also determined. Higher fertility and fecundity per female were observed at a ratio of 4:1. However, females with higher fecundity had reduced survival probabilities. In conclusion, maintaining colonies with a lower proportion of males in cages ensures a greater fecundity and fertility. Further research is necessary to understand whether results can be attributed to lower male harassment in cages.

A temporal perspective on population structure and gene flow in Atlantic salmon (Salmo salar) in Newfoundland, Canada

2010 ◽  
Vol 67 (2) ◽  
pp. 225-242 ◽  
Author(s):  
Friso P. Palstra ◽  
Daniel E. Ruzzante
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Gene Flow ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Environmental Changes ◽  
Population Connectivity ◽  
Temporal Perspective ◽  
Atlantic Salmon Salmo Salar ◽  
Contemporary Gene Flow

Studying population structure and gene flow patterns on temporal scales facilitates an evaluation of the consequences of demographic, physical, and environmental changes on the stability and persistence of populations. Here, we examine temporal genetic variation within and among Atlantic salmon ( Salmo salar ) rivers in Newfoundland and Labrador, Canada, using samples collected over a period of six decades (1951–2004). Our objective was to evaluate temporal changes in population connectivity associated with the closure of a commercial marine fishery. Despite demographic instability, we find that population structure remained temporally stable over more than 50 years. However, age structure can affect results when not taken into consideration, particularly in populations of large effective size where genetic drift is not strong. Where weak signals of genetic differentiation did not complicate analyses, contemporary migration was often asymmetric, yet low, suggesting patterns of intermittent gene flow. Nevertheless, we find some links between changes in population dynamics and contemporary gene flow. These findings may therefore imply that management decisions impacting the contemporary population dynamics of individual Atlantic salmon rivers can also affect the genetic stability of this species as a whole.

Inferring population connectivity across the range of the purple-crowned fairy-wren (Malurus coronatus) from mitochondrial DNA and morphology: implications for conservation management

2012 ◽  
Vol 60 (3) ◽  
pp. 199 ◽  
Author(s):  
Anja Skroblin ◽  
Robert Lanfear ◽  
Andrew Cockburn ◽  
Sarah Legge
Keyword(s):  
Mitochondrial Dna ◽  
Gene Flow ◽  
Dna Sequences ◽  
Genetic Divergence ◽  
Conservation Management ◽  
Habitat Degradation ◽  
Morphological Difference ◽  
Population Connectivity ◽  
Isolated Populations ◽  
The Impact

Knowledge of population structure and patterns of connectivity is required to implement effective conservation measures for the purple-crowned fairy-wren (Malurus coronatus), a threatened endemic of northern Australia. This study aimed to identify barriers to dispersal across the distribution of M. coronatus, investigate the impact that the recent declines may have on population connectivity, and propose conservation actions to maintain natural patterns of gene flow. Analysis of mitochondrial DNA sequences from 87 M. coronatus identified two phylogenetic clusters that corresponded with the phenotypically defined western (M. c. coronatus) and eastern (M. c. macgillivrayi) subspecies. The genetic divergence between these subspecies was consistent with isolation by a natural barrier to gene flow, and supports their separate conservation management. Within the declining M. c. coronatus, the lack of genetic divergence and only slight morphological difference between remnant populations indicates that populations were recently linked by gene flow. It is likely that widespread habitat degradation and the recent extirpation of M. c. coronatus from the Ord River will disrupt connectivity between, and dynamics within, remnant populations. To prevent further declines, conservation of M. coronatus must preserve areas of quality habitat and restore connectivity between isolated populations.

scholarly journals Integrating Biophysical, Socio-Economic and Governance Principles Into Marine Reserve Design and Management in Mexico: From Theory to Practice

2021 ◽  
Vol 8 ◽  
Author(s):  
Magdalena Précoma-de la Mora ◽  
Nathan J. Bennett ◽  
Stuart Fulton ◽  
Adrian Munguia-Vega ◽  
Cristina Lasch-Thaler ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Gulf Of California ◽  
Marine Reserve ◽  
Marine Conservation ◽  
Lessons Learned ◽  
Reserve Design ◽  
Policy And Practice ◽  
Human Environment ◽  
The Pacific ◽  
Multi Stakeholder

Marine conservation design and fisheries management are increasingly integrating biophysical, socio-economic and governance considerations. Integrative approaches are adopted to achieve more effective, equitable, inclusive, and robust marine policies and practices. This paper describes a participatory process to co-produce biophysical, socio-economic, and governance principles to guide the design and management of marine reserves in three regions of Mexico: the Pacific region of the Baja California Peninsula, the Gulf of California, and the Mexican Caribbean. The process of co-producing the principles included convening a coordination team, reviewing the science, convening multi-stakeholder workshops, developing and communicating the principles with key practitioners and policy makers, and supporting uptake and application to policy and practice. Biophysical principles were related to: habitat representation and risk spreading; protecting critical, special and unique areas; incorporating connectivity; allowing time for recovery; adapting to changes in climate and ocean chemistry; and considering threats and opportunities. Socio-economic principles focused on: integrating the social context, local aspirations, and human-environment interactions; considering economic and non-economic uses, promoting an equitable distribution of costs and benefits, and respecting and maintaining cultural identity and diversity. Governance principles prioritized establishing and ensuring legitimacy and institutional continuity; implementing collaborative and adaptive management; and, promoting effective management. The paper also examines early efforts to implement the principles, next steps to promote further uptake and application in Mexico, and lessons learned from the process. Thus it provides insights into a practical process and a set of principles that are valuable to inform marine conservation and fisheries management processes elsewhere.

scholarly journals Population connectivity across a transboundary conservation network: potential for restoration?

2021 ◽  
Author(s):  
Simon Dures ◽  
Chris Carbone ◽  
Andrew J Loveridge ◽  
Glyn Maude ◽  
Neil Midland ◽  
...  
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Functional Connectivity ◽  
Large Scale ◽  
Population Connectivity ◽  
Sub Saharan Africa ◽  
Likelihood Method ◽  
Mobile Species ◽  
Transboundary Conservation ◽  
Dispersal Distances

Abstract Context: There has been limited research identifying large-scale functional connectivity of wildlife populations across sub-Saharan Africa, despite the increased focus on transboundary conservation networks. Objectives: This study set out to assess the functional connectivity of a highly mobile predator of conservation concern across the Kavango-Zambezi transboundary conservation area (KAZA) and the northern Central Kalahari Game Reserve (CKGR), covering almost 300,000km2 of Botswana, Namibia, Zambia and Zimbabwe.Methods: We analysed the nuclear diversity of 204 individual lions from across the metapopulation using Bayesian and multivariate statistics to assess population structure and recent migration. A maximum-likelihood method was used to determine average male dispersal distances to determine the potential for functional connectivity across the region.Results: The results are consistent with work identifying the existence of ecotypic differences between wetland and dryland lions, but also indicate hierarchical population structure further dividing the population into four geographic clusters; the Okavango Delta, the Central Kalahari, Kafue National Park, and the Hwange-Chobe complex. Analysis of dispersal distances of males suggests that reconnecting the clusters through conservation intervention should be successful in improving gene flow and connectivity across the region. Conclusions: While trans-boundary conservation areas may currently have limited gene flow and connectivity, there is potential for the restoration of functional connectivity via the natural dispersal of highly mobile species. However, the matrix of habitat through which such dispersing animals must traverse must be conducive to their movement and survival, highlighting the importance of land outside protected areas for the preservation of highly mobile animals such as lions.

scholarly journals Population structure and dispersal across small and large spatial scales in a direct developing marine isopod

2020 ◽  
Author(s):  
William S. Pearman ◽  
Sarah J. Wells ◽  
Olin K. Silander ◽  
Nikki E. Freed ◽  
James Dale
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Population Genetic ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Population Connectivity ◽  
Clear Pattern ◽  
Small Spatial Scale ◽  
Cook Strait ◽  
Genetic Break

AbstractMarine organisms generally exhibit one of two developmental modes: biphasic, with distinct adult and larval morphology, and direct development, in which larvae resemble adults. Developmental mode is thought to significantly influence dispersal, with direct developers expected to have much lower dispersal potential. However, in contrast to our relatively good understanding of dispersal and population connectivity for biphasic species, comparatively little is known about direct developers. In this study, we use a panel of 8,020 SNPs to investigate population structure and gene flow for a direct developing species, the New Zealand endemic marine isopod Isocladus armatus. On a small spatial scale (20 kms), gene flow between locations is extremely high and suggests an island model of migration. However, over larger spatial scales (600km), populations exhibit a clear pattern of isolation-by-distance. Because our sampling range is intersected by two well-known biogeographic barriers (the East Cape and the Cook Strait), our study provides an opportunity to understand how such barriers influence dispersal in direct developers. Our results indicate that I. armatus exhibits significant migration across these barriers, and suggests that ocean currents associated with these locations do not present a barrier to dispersal. Interestingly, we do find evidence of a north-south population genetic break occurring between Māhia and Wellington, two locations where there are no obvious biogeographic barriers between them. We conclude that developmental life history largely predicts dispersal in intertidal marine isopods. However, localised biogeographic processes can disrupt this expectation.

scholarly journals Population Genomics and Lagrangian Modeling Shed Light on Dispersal Events in the Mediterranean Endemic Ericaria zosteroides (=Cystoseira zosteroides) (Fucales)

2021 ◽  
Vol 8 ◽  
Author(s):  
Lauric Reynes ◽  
Didier Aurelle ◽  
Cristele Chevalier ◽  
Christel Pinazo ◽  
Myriam Valero ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Population Genomics ◽  
Spatial Scales ◽  
Seawater Temperature ◽  
Marine Species ◽  
Population Connectivity ◽  
Central Process ◽  
Lagrangian Modeling ◽  
Dispersal Events

Dispersal is a central process that affects population growth, gene flow, and ultimately species persistence. Here we investigate the extent to which gene flow occurs between fragmented populations of the deep-water brown algae Ericaria zosteroides (Turner) Greville (Sargassaceae, Fucales). These investigations were performed at different spatial scales from the bay of Marseille (western Provence) to Corsica. As dispersal of zygotes is shown to be limited over distances beyond a few meters, we used a multidisciplinary approach, based on Lagrangian modeling and population genomics to test the hypothesis that drifting of fertile parts of thallus (eggs on fertile branches), mediated by ocean currents, enable occasional gene flow between populations. Therefore we assessed the respective contribution of oceanographic connectivity, geographical isolation, and seawater temperatures to the genetic structure of this species. The genetic structure was assessed using 10,755 neutral SNPs and 12 outlier SNPs genotyped by dd-RAD sequencing in 261 individuals of E. zosteroides. We find that oceanographic connectivity is the best predictor of genetic structure, while differentiation in outlier SNPs can be explained by the depth of populations, as emphasized by the minimum seawater temperature predictor. However, further investigations will be necessary for clarifying how depth drives adaptive genetic differentiation in E. zosteroides. Our analyses revealed that local hydrodynamic conditions are correlated with the very high divergence of one population in the Bay of Marseille. Overall, the levels of gene flow mediated by drifting were certainly not sufficient to counteract differentiation by local genetic drift, but enough to allow colonization several kilometers away. This study stresses the need to consider secondary dispersal mechanisms of presumed low dispersal marine species to improve inference of population connectivity.

scholarly journals Patterns, causes, and consequences of marine larval dispersal

2015 ◽  
Vol 112 (45) ◽  
pp. 13940-13945 ◽  
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.

scholarly journals Quantifying dispersal from hydrothermal vent fields in the western Pacific Ocean

2016 ◽  
Vol 113 (11) ◽  
pp. 2976-2981 ◽  
Author(s):  
Satoshi Mitarai ◽  
Hiromi Watanabe ◽  
Yuichi Nakajima ◽  
Alexander F. Shchepetkin ◽  
James C. McWilliams
Keyword(s):  
Gene Flow ◽  
Pacific Ocean ◽  
Hydrothermal Vent ◽  
Larval Dispersal ◽  
Marine Conservation ◽  
Western Pacific ◽  
Biophysical Model ◽  
Plate Boundaries ◽  
Western Pacific Ocean ◽  
The Western Pacific

Hydrothermal vent fields in the western Pacific Ocean are mostly distributed along spreading centers in submarine basins behind convergent plate boundaries. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing gene flow, diversity, and distributions of vent animals. By combining a biophysical model and deep-profiling float experiments, we quantify potential larval dispersal of vent species via ocean circulation in the western Pacific Ocean. We demonstrate that vent fields within back-arc basins could be well connected without particular directionality, whereas basin-to-basin dispersal is expected to occur infrequently, once in tens to hundreds of thousands of years, with clear dispersal barriers and directionality associated with ocean currents. The southwest Pacific vent complex, spanning more than 4,000 km, may be connected by the South Equatorial Current for species with a longer-than-average larval development time. Depending on larval dispersal depth, a strong western boundary current, the Kuroshio Current, could bridge vent fields from the Okinawa Trough to the Izu-Bonin Arc, which are 1,200 km apart. Outcomes of this study should help marine ecologists estimate gene flow among vent populations and design optimal marine conservation plans to protect one of the most unusual ecosystems on Earth.

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