Dispersal and gene flow in the habitat-forming kelp, Ecklonia radiata: relative degrees of isolation across an east - west coastline

2009 ◽  
Vol 60 (8) ◽  
pp. 802 ◽  
Author(s):  
M. A. Coleman ◽  
B. M. Gillanders ◽  
S. D. Connell
Keyword(s):  
Gene Flow ◽  
Anthropogenic Impacts ◽  
Spatial Scales ◽  
Management Strategies ◽  
South Australia ◽  
Rocky Reef ◽  
Ecklonia Radiata ◽  
Island Populations ◽  
Oceanic Currents ◽  
East West

Characterising patterns of dispersal and gene flow in habitat-forming organisms is becoming a focal concern for conservation and management strategies as anthropogenic impacts drive change in coastal ecosystems. Here, we use six microsatellite markers to characterise dispersal and gene flow across the South Australian distribution of the habitat-forming kelp Ecklonia radiata. Populations of E. radiata on subtidal reefs in South Australia were highly genetically structured on large (100s of km, FST = 0.211) and small (10s of km, FST = 0.042) spatial scales with the extent of differentiation positively correlated with geographic distances among populations. Neither the presence of oceanic currents nor intervening rocky reef habitats appeared to facilitate widespread gene flow. There was a trend for island populations to be more genetically differentiated from those on the mainland and to have slightly greater levels of heterozygosity than mainland populations. Our results show relatively low dispersal and gene flow suggesting that recovery following kelp loss may be slow. Such information not only provides insights into relative rates of recovery, but may also identify which populations may be best used for propagation and restoration efforts.

scholarly journals Contrasting gene flow at different spatial scales revealed by genotyping-by-sequencing in Isocladus armatus, a massively colour polymorphic New Zealand marine isopod

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5462 ◽  
Author(s):  
Sarah J. Wells ◽  
James Dale
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
New Zealand ◽  
Genetic Basis ◽  
Marine Organism ◽  
Spatial Scales ◽  
Genotyping By Sequencing ◽  
Population Connectivity ◽  
Larval Phase ◽  
Island Populations

Understanding how genetic diversity is maintained within populations is central to evolutionary biology. Research on colour polymorphism (CP), which typically has a genetic basis, can shed light on this issue. However, because gene flow can homogenise genetic variation, understanding population connectivity is critical in examining the maintenance of polymorphisms. In this study we assess the utility of genotyping-by-sequencing to resolve gene flow, and provide a preliminary investigation into the genetic basis of CP in Isocladus armatus, an endemic New Zealand marine isopod. Analysis of the genetic variation in 4,000 single nucleotide polymorphisms (SNPs) within and among populations and colour morphs revealed large differences in gene flow across two spatial scales. Marine isopods, which lack a pelagic larval phase, are typically assumed to exhibit greater population structuring than marine invertebrates possessing a biphasic life cycle. However, we found high gene flow rates and no genetic subdivision between two North Island populations situated 8 km apart. This suggests that I. armatus is capable of substantial dispersal along coastlines. In contrast, we identified a strong genetic disjunction between North and South Island populations. This result is similar to those reported in other New Zealand marine species, and is congruent with the presence of a geophysical barrier to dispersal down the east coast of New Zealand. We also found some support for a genetic basis to colouration evidenced by positive FST outlier tests, with two SNPs in particular showing strong association to the expression of a striped morph. Our study provides one of the first population genomic studies of a marine organism in New Zealand, and suggests that genotyping-by-sequencing can be a good alternative to more traditional investigations based on traditional markers such as microsatellites. Our study provides a foundation for further development of a highly tractable system for research on the evolutionary maintenance of CP.

scholarly journals Adaptive Divergence under Gene Flow along an Environmental Gradient in Two Coexisting Stickleback Species

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 435
Author(s):  
Thijs M. P. Bal ◽  
Alejandro Llanos-Garrido ◽  
Anurag Chaturvedi ◽  
Io Verdonck ◽  
Bart Hellemans ◽  
...  
Keyword(s):  
Gene Flow ◽  
Brackish Water ◽  
Environmental Gradient ◽  
Spatial Scales ◽  
Morphological Differentiation ◽  
Genotyping By Sequencing ◽  
Adaptive Divergence ◽  
Linkage Groups ◽  
Closely Related Species ◽  
Genomic Patterns

There is a general and solid theoretical framework to explain how the interplay between natural selection and gene flow affects local adaptation. Yet, to what extent coexisting closely related species evolve collectively or show distinctive evolutionary responses remains a fundamental question. To address this, we studied the population genetic structure and morphological differentiation of sympatric three-spined and nine-spined stickleback. We conducted genotyping-by-sequencing and morphological trait characterisation using 24 individuals of each species from four lowland brackish water (LBW), four lowland freshwater (LFW) and three upland freshwater (UFW) sites in Belgium and the Netherlands. This combination of sites allowed us to contrast populations from isolated but environmentally similar locations (LFW vs. UFW), isolated but environmentally heterogeneous locations (LBW vs. UFW), and well-connected but environmentally heterogenous locations (LBW vs. LFW). Overall, both species showed comparable levels of genetic diversity and neutral genetic differentiation. However, for all three spatial scales, signatures of morphological and genomic adaptive divergence were substantially stronger among populations of the three-spined stickleback than among populations of the nine-spined stickleback. Furthermore, most outlier SNPs in the two species were associated with local freshwater sites. The few outlier SNPs that were associated with the split between brackish water and freshwater populations were located on one linkage group in three-spined stickleback and two linkage groups in nine-spined stickleback. We conclude that while both species show congruent evolutionary and genomic patterns of divergent selection, both species differ in the magnitude of their response to selection regardless of the geographical and environmental context.

scholarly journals Novel approach to enhance coastal habitat and biotope mapping with drone aerial imagery analysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
João Gama Monteiro ◽  
Jesús L. Jiménez ◽  
Francesca Gizzi ◽  
Petr Přikryl ◽  
Jonathan S. Lefcheck ◽  
...  
Keyword(s):  
Anthropogenic Impacts ◽  
Spatial Scales ◽  
Low Cost ◽  
Human Populations ◽  
Coastal Habitat ◽  
Coastal Monitoring ◽  
Monitoring Programs ◽  
Novel Approach ◽  
Aerial Platforms ◽  
Rocky Habitats

AbstractUnderstanding the complex factors and mechanisms driving the functioning of coastal ecosystems is vital towards assessing how organisms, ecosystems, and ultimately human populations will cope with the ecological consequences of natural and anthropogenic impacts. Towards this goal, coastal monitoring programs and studies must deliver information on a range of variables and factors, from taxonomic/functional diversity and spatial distribution of habitats, to anthropogenic stress indicators such as land use, fisheries use, and pollution. Effective monitoring programs must therefore integrate observations from different sources and spatial scales to provide a comprehensive view to managers. Here we explore integrating aerial surveys from a low-cost Remotely Piloted Aircraft System (RPAS) with concurrent underwater surveys to deliver a novel approach to coastal monitoring. We: (i) map depth and substrate of shallow rocky habitats, and; (ii) classify the major biotopes associated with these environmental axes; and (iii) combine data from i and ii to assess the likely distribution of common sessile organismal assemblages over the survey area. Finally, we propose a general workflow that can be adapted to different needs and aerial platforms, which can be used as blueprints for further integration of remote-sensing with in situ surveys to produce spatially-explicit biotope maps.

A framework for the Integrated Assessment of SDG trade-offs in the Sundarbans Biosphere Reserve.

2021 ◽  
Author(s):  
Charlotte Marcinko ◽  
Robert Nicholls ◽  
Tim Daw ◽  
Sugata Hazra ◽  
Craig Hutton ◽  
...  
Keyword(s):  
Environmental Change ◽  
Integrated Assessment ◽  
Spatial Scales ◽  
Strong Dependence ◽  
Management Strategies ◽  
Rural Livelihoods ◽  
Biosphere Reserve ◽  
Integrated Analysis ◽  
Trade Offs ◽  
The Sundarbans

<p>The United Nations Sustainable Development Goals (SDGs) and their corresponding targets are significantly interconnected, with many interactions, synergies and trade-offs between individual goals across multiple temporal and spatial scales.  We propose a framework for the Integrated Assessment Modelling (IAM) of a complex deltaic socio-ecological system in order to analyse such SDG interactions. We focus on the Sundarbans Biosphere Reserve (SBR), India within the Ganges-Brahmaputra-Meghna Delta. It is densely populated with 4.4 million people (2011), high levels of poverty and a strong dependence on rural livelihoods. It is only 50 km from the growing megacity of Kolkata (about 15 million people in 2020). The area also includes the Indian portion of the world’s largest mangrove forest – the Sundarbans – hosting the iconic Bengal Tiger. Like all deltaic systems, this area is subject to multiple drivers of environmental change operating across different scales. The IAM framework is designed to investigate current and future trends in socio-environmental change and explore associated policy impacts, considering a broad range of sub-thematic SDG indicators. Integration is achieved through the soft coupling of multiple sub-models, knowledge and data of relevant environmental and socio-economic processes.  The following elements are explicitly considered: (1) agriculture; (2) aquaculture; (3) mangroves; (4) fisheries; and (5) multidimensional poverty. Key questions that can be addressed include the implications of changing monsoon patterns, trade-offs between agriculture and aquaculture, or the future of the Sundarbans mangroves under sea-level rise and different management strategies, including trade-offs with land use to the north.  The novel high-resolution analysis of SDG interactions allowed by the IAM will provide stakeholders and policy makers the opportunity to prioritize and explore the SDG targets that are most relevant to the SBR and provide a foundation for further integrated analysis.</p>

Genetic Differentiation in Isolated Populations of Hakea carinata (Proteaceae)

1998 ◽  
Vol 46 (6) ◽  
pp. 671 ◽  
Author(s):  
G. J. Starr ◽  
S. M. Carthew
Keyword(s):  
Gene Flow ◽  
Habitat Fragmentation ◽  
Gene Diversity ◽  
South Australia ◽  
Similar Species ◽  
Isolated Populations ◽  
Plant Populations ◽  
Evolutionary Condition ◽  
Private Alleles

Fragmentation of the landscape by human activity has created small, isolated plant populations. Hakea carinata F. Muell. ex Meissner, a sclerophyllous shrub, is common in isolated fragments of vegetation in South Australia. This study investigated whether habitat fragmentation has caused restrictions to gene flow between populations. Gene diversity (HT = 0.317) is average for similar species but little is held within populations (HS = 0.168) and 46.9% of gene diversity is accounted for between populations. Estimates of gene flow are NM = 0.270 (based on FST) and NM = 0.129 (based on private alleles). Populations are substantially selfing (t = 0.111). Small isolated populations appears to be a long-term evolutionary condition in this species rather than a consequence of habitat fragmentation; however, population extinctions are occurring. Conservation will require the reservation of many populations to represent the genetic variation present in the species.

scholarly journals Towards evenly distributed grazing patterns: including social context in sheep management strategies

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2152 ◽  
Author(s):  
Agustina di Virgilio ◽  
Juan Manuel Morales
Keyword(s):  
Social Context ◽  
Management Practices ◽  
Spatial Scales ◽  
Management Strategies ◽  
Domestic Sheep ◽  
Conservation Of Resources ◽  
Landscape Conservation ◽  
Sheep Grazing ◽  
Rangeland Degradation ◽  
Natural Grasslands

Background.A large proportion of natural grasslands around the world is exposed to overgrazing resulting in land degradation and biodiversity loss. Although there is an increasing effort in the promotion of sustainable livestock management, rangeland degradation still occurs because animals’ foraging behaviour is highly selective at different spatial scales. The assessment of the ecological mechanisms modulating the spatial distribution of grazing and how to control it has critical implications for long term conservation of resources and the sustainability of livestock production. Considering the relevance of social interactions on animals’ space use patterns, our aim was to explore the potential effects of including animals’ social context into management strategies using domestic sheep grazing in rangelands as case study.Methods.We used GPS data from 19 Merino sheep (approximately 10% of the flock) grazing on three different paddocks (with sizes from 80 to 1000 Ha) during a year, to estimate resource selection functions of sheep grazing in flocks of different levels of heterogeneity. We assessed the effects of sheep class (i.e., ewes, wethers, and hoggets), age, body condition and time since release on habitat selection patterns.Results.We found that social rank was reflected on sheep habitat use, where dominant individuals (i.e., reproductive females) used more intensively the most preferred areas and low-ranked (i.e., yearlings) used less preferred areas. Our results showed that when sheep grazed on more heterogeneous flocks, grazing patterns were more evenly distributed at all the paddocks considered in this study. On the other hand, when high-ranked individuals were removed from the flock, low-ranked sheep shifted their selection patterns by increasing the use of the most preferred areas and strongly avoided to use less preferred sites (i.e., a highly selective grazing behaviour).Discussion.Although homogenization and segregation of flocks by classes are common practices to increase flock productivity, we are proposing an alternative that employs behavioural interactions in heterogeneous flocks to generate more evenly distributed grazing patterns. This practice can be combined with other practices such as rotational grazing and guardian dogs (to decrease mortality levels that may be generated by sheep grazing on more risky habitats). This does not imply any modifications of livestock stocking rates and densities or any additional investments for labour and materials. Considering livestock behaviour is critical for the design of sustainable management practices that balance landscape conservation and livestock productivity.

scholarly journals A synthesis of scale-dependent ecology of the endangered mountain caribou in British Columbia, Canada

Rangifer ◽  
2008 ◽  
Vol 28 (1) ◽  
pp. 33
Author(s):  
Robert Serrouya ◽  
Bruce N. McLellan ◽  
Clayton D. Apps ◽  
Heiko U. Wittmer
Keyword(s):  
British Columbia ◽  
Rangifer Tarandus ◽  
Spatial Scales ◽  
Management Strategies ◽  
Population Level ◽  
Limiting Factors ◽  
Conservation Strategies ◽  
Integrative Approach ◽  
Rangifer Tarandus Caribou ◽  
Multi Scale

Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou) that live in highprecipitation, mountainous ecosystems of southeastern British Columbia and northern Idaho. The distribution and abundance of these caribou have declined dramatically from historical figures. Results from many studies have indicated that mountain caribou rely on old conifer forests for several life-history requirements including an abundance of their primary winter food, arboreal lichen, and a scarcity of other ungulates and their predators. These old forests often have high timber value, and understanding mountain caribou ecology at a variety of spatial scales is thus required to develop effective conservation strategies. Here we summarize results of studies conducted at three different spatial scales ranging from broad limiting factors at the population level to studies describing the selection of feeding sites within seasonal home ranges of individuals. The goal of this multi-scale review is to provide a more complete picture of caribou ecology and to determine possible shifts in limiting factors across scales. Our review produced two important results. First, mountain caribou select old forests and old trees at all spatial scales, signifying their importance for foraging opportunities as well as conditions required to avoid alternate ungulates and their predators. Second, relationships differ across scales. For example, landscapes dominated by roads and edges negatively affect caribou survival, but appear to attract caribou during certain times of the year. This juxtaposition of fine-scale behaviour with broad-scale vulnerability to predation could only be identified through integrated multi-scale analyses of resource selection. Consequently we suggest that effective management strategies for endangered species require an integrative approach across multiple spatial scales to avoid a focus that may be too narrow to maintain viable populations. Abstract in Norwegian / Sammendrag:Skala-avhengig økologi og truet fjellvillrein i Britisk ColumbiaFjellvillreinen i de nedbørsrike fjellområdene i sørøstre Britisk Columbia og nordlige Idaho som er en truet økotype av skogsreinen (Rangifer tarandus caribou), har blitt kraftig redusert både i utbredelse og antall. Mange studier har vist at denne økotypen er avhengig av vinterføden hengelav i gammel barskog hvor det også er få andre klovdyr og dermed få predatorer. Slik skog er også viktige hogstområder, og å forstå økologien til fjellvillreinen i forskjellige skaleringer er derfor nødvendig for å utvikle forvaltningsstrategier som kan berge og ta vare på denne reinen. Artikkelen gir en oversikt over slike arbeider: fra studier av begrensende faktorer på populasjonsnivå til studier av sesongmessige beiteplasser på individnivå. Hensikten er å få frem et mer helhetlig perspektiv på fjellvillreinen og finne hvordan de begrensende faktorene varierer etter skaleringen som er benyttet i studiet. Oversikten vår frembragte to viktige resultater; 1) Uansett skalering så velger dyrene gammel skog og gamle trær. 2) Dyrenes bruk av et område kan variere med benyttet skalering, for eksempel vil landskap utbygd med veier og hogstflater være ufordelaktig for overlevelsen, men synes likevel å kunne tiltrekke fjellvillreinen til visse tider av året. Forholdet mellom atferd ut fra fin-skalering og stor-skalering sårbarhet hva gjelder predasjon, ville kun blitt avdekket ved flere-skaleringsanalyse av hvordan ressursene benyttes. Ut fra dette foreslår vi at forvaltningsstrategier for truete bestander som eksempelvis fjellvillreinen, må baseres på tilnærminger ut fra ulike skaleringer for å hindre at et for snevert perspektiv kan begrense muligheten for vedvarende levedyktighet.

scholarly journals Population Genetics of the Red Rock Lobster,  Jasus edwardsii

2021 ◽  
Author(s):  
◽  
Luke Thomas
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
New Zealand ◽  
Genetic Differentiation ◽  
Microsatellite Markers ◽  
Rocky Reef ◽  
Rock Lobster ◽  
Wide Range ◽  
Jasus Edwardsii ◽  
Polymorphic Microsatellite

<p>Understanding patterns of gene flow across a species range is a vital component of an effective fisheries management strategy. The advent of highly polymorphic microsatellite markers has facilitated the detection of fine-scale patterns of genetic differentiation at levels below the resolving power of earlier techniques. This has triggered the wide-spread re-examination of population structure for a number of commercially targeted species. The aims of thesis were to re-investigate patterns of gene flow of the red rock lobster Jasus edwardsii throughout New Zealand and across the Tasman Sea using novel microsatellite markers. Jasus edwardsii is a keystone species of subtidal rocky reef system and supports lucrative export markets in both Australia and New Zealand. Eight highly polymorphic microsatellite markers were developed from 454 sequence data and screened across a Wellington south coast population to obtain basic diversity indices. All loci were polymorphic with the number of alleles per locus ranging from 6-39. Observed and expected heterozygosity ranged from 0.563-0.937 and 0.583-0.961, respectively. There were no significant deviations from Hardy-Weinberg equilibrium following standard Bonferroni corrections. The loci were used in a population analysis of J. edwardsii that spanned 10 degrees of latitude and stretched 3,500 km across the South Pacific. The analysis rejected the null-hypothesis of panmixia based on earlier mDNA analysis and revealed significant population structure (FST=0.011, RST=0.028) at a wide range of scales. Stewart Island was determined to have the highest levels of genetic differentiation of all populations sampled suggesting a high degree of reproductive isolation and self-recruitment. This study also identified high levels of asymmetric gene flow from Australia to New Zealand indicating a historical source-sink relationship between the two countries. Results from the genetic analysis were consistent with results from oceanographic dispersal models and it is likely that the genetic results reflect historical and contemporary patterns of Jasus edwardsii dispersal and recruitment throughout its range.</p>

Assessing population sustainability and response to fishing in terms of aggregation structure for greenlip abalone (Haliotis laevigata) fishery management

2004 ◽  
Vol 61 (2) ◽  
pp. 247-259 ◽  
Author(s):  
Natalie A Dowling ◽  
Stephen J Hall ◽  
Richard McGarvey
Keyword(s):  
Egg Production ◽  
Fishery Management ◽  
Management Strategies ◽  
South Australia ◽  
Fertilization Success ◽  
Adult Density ◽  
Demographic Feature ◽  
Data Set ◽  
Functional Relationships ◽  
Aggregation Size

The greenlip abalone (Haliotis laevigata) population in Waterloo Bay, South Australia, has undergone collapse and fishery closure twice since 1978. A rich data set, including survey measures of degree of spatial aggregation, has been gathered over that time and provides a unique opportunity to identify factors accounting for persistence or collapse, an issue that is of significance to abalone fisheries worldwide. Statistical analyses of fishery and survey data were undertaken to infer functional relationships between catch, effort, recruitment, adult density, and extent of aggregation. Catch rates were hyperstable, an observation consistent with the targeting of large aggregations. Statistical analysis of recruitment showed a significant year effect, implying an environmental signal, and suggested that aggregation size impacts fertilization success. Aggregation size grew under closure, suggesting an impact of fishing on this demographic feature. Aggregative behaviour appears to be critical for subpopulation sustainability. Fishery collapse may be triggered by depletion of larger abalone aggregations by heavy fishing, resulting in declines in fertilized egg production. When heavy fishing coincides with unfavourable environmental conditions, recruitment may be insufficient to sustain the subpopulation. If aggregation is similarly critical for other subpopulations, management strategies could be adapted according to the extent of aggregation in each subpopulation.

Testing the effects of durability (shell thickness) on species over-representation in death assemblages, a taphonomic baseline for conservation paleobiology

2021 ◽  
Author(s):  
Adam Tomašových ◽  
Susan M. Kidwell
Keyword(s):  
Southern California ◽  
Anthropogenic Impacts ◽  
Spatial Scales ◽  
Organic Content ◽  
Time Averaging ◽  
Shell Size ◽  
Interspecific Differences ◽  
Conservation Paleobiology ◽  
Death Assemblages ◽  
Species Abundances

&lt;p&gt;Differences in the taxonomic or functional composition of living and death assemblages is a key means of identifying the magnitude and drivers of past ecological changes in conservation paleobiology, especially when assessing the effects of anthropogenic impacts. However, such live-dead differences in species abundances can arise not only from ecological (stochastic or deterministic) changes in abundance over the duration of time averaging but also from interspecific differences in the postmortem durability of skeletal remains or from the lifespan of the individuals. Here, we attempt to directly incorporate the effects of durability on species abundances in death assemblages by modeling dead abundance as a function of species&amp;#8217; durability traits and using abundances in living assemblages as a prior. Species inferred to be negatively affected by anthropogenic impacts should be over-represented in death assemblages relative to their abundance in death assemblages predicted by the durability model (rather than just relative to their abundance in living assemblages). Using species-level durability trait data for bivalves (shell size, thickness, mineralogy, shell organic content, and life habit) from the southern California shelf, we find that, among these traits, valve thickness correlates consistently positively and at multiple spatial scales with the log of the dead:live ratio of species abundances, and accounts for ~20-30% of live-dead mismatch. Using this benchmark for the discordance that might be taphonomic in origin, we confirm that the over-representation of epifaunal suspension-feeders and siphonate deposit-feeders in death assemblages of the southern California shelf owes in fact to their ecological decline in recent centuries, even when accounting for their greater durability.&lt;/p&gt;

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