scholarly journals First Observations of Long‐Distance Migration in a Large Skate Species, the Winter Skate: Implications for Population Connectivity, Ecosystem Dynamics, and Management

2019 ◽  
Vol 11 (2) ◽  
pp. 202-212 ◽  
Author(s):  
Michael G. Frisk ◽  
Oliver N. Shipley ◽  
Christopher M. Martinez ◽  
Kim A. McKown ◽  
Joshua P. Zacharias ◽  
...  
Keyword(s):  
Population Connectivity ◽  
Ecosystem Dynamics ◽  
Long Distance

scholarly journals Incubation periods impact the spatial predictability of cholera and Ebola outbreaks in Sierra Leone

2020 ◽  
Vol 117 (9) ◽  
pp. 5067-5073 ◽  
Author(s):  
Rebecca Kahn ◽  
Corey M. Peak ◽  
Juan Fernández-Gracia ◽  
Alexandra Hill ◽  
Amara Jambai ◽  
...  
Keyword(s):  
Sierra Leone ◽  
Incubation Period ◽  
Population Connectivity ◽  
Disease Spread ◽  
Long Distance ◽  
Spatial Spread ◽  
Transmission Parameters ◽  
Incubation Periods ◽  
Using Data ◽  
The Impact

Forecasting the spatiotemporal spread of infectious diseases during an outbreak is an important component of epidemic response. However, it remains challenging both methodologically and with respect to data requirements, as disease spread is influenced by numerous factors, including the pathogen’s underlying transmission parameters and epidemiological dynamics, social networks and population connectivity, and environmental conditions. Here, using data from Sierra Leone, we analyze the spatiotemporal dynamics of recent cholera and Ebola outbreaks and compare and contrast the spread of these two pathogens in the same population. We develop a simulation model of the spatial spread of an epidemic in order to examine the impact of a pathogen’s incubation period on the dynamics of spread and the predictability of outbreaks. We find that differences in the incubation period alone can determine the limits of predictability for diseases with different natural history, both empirically and in our simulations. Our results show that diseases with longer incubation periods, such as Ebola, where infected individuals can travel farther before becoming infectious, result in more long-distance sparking events and less predictable disease trajectories, as compared to the more predictable wave-like spread of diseases with shorter incubation periods, such as cholera.

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

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
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.

scholarly journals Incubation periods impact the spatial predictability of outbreaks: analysis of cholera and Ebola outbreaks in Sierra Leone

2019 ◽  
Author(s):  
Rebecca Kahn ◽  
Corey M. Peak ◽  
Juan Fernández-Gracia ◽  
Alexandra Hill ◽  
Amara Jambai ◽  
...  
Keyword(s):  
Infectious Diseases ◽  
Sierra Leone ◽  
Incubation Period ◽  
Population Connectivity ◽  
Disease Spread ◽  
Long Distance ◽  
Spatial Spread ◽  
Transmission Parameters ◽  
Incubation Periods ◽  
The Impact

AbstractForecasting the spatiotemporal spread of infectious diseases during an outbreak is an important component of epidemic response. However, it remains challenging both methodologically and with respect to data requirements as disease spread is influenced by numerous factors, including the pathogen’s underlying transmission parameters and epidemiological dynamics, social networks and population connectivity, and environmental conditions. Here, using data from Sierra Leone we analyze the spatiotemporal dynamics of recent cholera and Ebola outbreaks and compare and contrast the spread of these two pathogens in the same population. We develop a simulation model of the spatial spread of an epidemic in order to examine the impact of a pathogen’s incubation period on the dynamics of spread and the predictability of outbreaks. We find that differences in the incubation period alone can determine the limits of predictability for diseases with different natural history, both empirically and in our simulations. Our results show that diseases with longer incubation periods, such as Ebola, where infected individuals can travel further before becoming infectious, result in more long-distance sparking events and less predictable disease trajectories, as compared to the more predictable wave-like spread of diseases with shorter incubation periods, such as cholera.Significance statementUnderstanding how infectious diseases spread is critical for preventing and containing outbreaks. While advances have been made in forecasting epidemics, much is still unknown. Here we show that the incubation period – the time between exposure to a pathogen and onset of symptoms – is an important factor in predicting spatiotemporal spread of disease and provides one explanation for the different trajectories of the recent Ebola and cholera outbreaks in Sierra Leone. We find that outbreaks of pathogens with longer incubation periods, such as Ebola, tend to have less predictable spread, whereas pathogens with shorter incubation periods, such as cholera, spread in a more predictable, wavelike pattern. These findings have implications for the scale and timing of reactive interventions, such as vaccination campaigns.

scholarly journals High matrix vegetation decreases mean seed dispersal distance but increases long wind dispersal probability connecting local plant populations in agricultural landscapes

2021 ◽  
Author(s):  
Sissi Donna Lozada Gobilard ◽  
Florian Jeltsch ◽  
Jinlei Zhu
Keyword(s):  
Land Use ◽  
Seed Dispersal ◽  
Dispersal Distance ◽  
Population Connectivity ◽  
Agricultural Landscapes ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Vegetation Height ◽  
Positive Effect ◽  
Seed Dispersal Distance

Abstract Background Seed dispersal plays an important role in population dynamics in agricultural ecosystems, but the effects of surrounding vegetation height on seed dispersal and population connectivity on the landscape scale have rarely been studied. Understanding the effects of surrounding vegetation height on seed dispersal will provide important information for land use management in agricultural landscapes to prevent the spread of undesired weeds or enhance functional connectivity. Methods We used two model species, Phragmites australis and Typha latifolia, growing in small natural ponds known as kettle holes, in an agricultural landscape to evaluate the effects of surrounding vegetation height on wind dispersal and population connectivity between kettle holes. Seed dispersal distance and the probability of long-distance dispersal (LDD) were simulated with the mechanistic WALD model under three scenarios of “low”, “dynamic” and “high” surrounding vegetation height. Connectivity between the origin and target kettle holes was quantified with a connectivity index adapted from Hanski and Thomas (1994). Results Our results show that mean seed dispersal distance decreases with the height of surrounding matrix vegetation, but the probability of long-distance dispersal (LDD) increases with vegetation height. This indicates an important vegetation-based trade-off between mean dispersal distance and LDD, which has an impact on connectivity. Conclusions Matrix vegetation height has a negative effect on mean seed dispersal distance but a positive effect on the probability of LDD. This positive effect and its impact on connectivity provide novel insights into landscape level (meta-)population and community dynamics — a change in matrix vegetation height by land use or climatic changes could strongly affect the spread and connectivity of wind-dispersed plants. The opposite effect of vegetation height on mean seed dispersal distance and the probability of LDD should therefore be considered in management and analyses of future land use and climate change effects.

Multinational genetic connectivity identified in western Pacific hawksbill turtles, Eretmochelys imbricata

2018 ◽  
Vol 45 (4) ◽  
pp. 307 ◽  
Author(s):  
Ian Bell ◽  
Michael P. Jensen
Keyword(s):  
Great Barrier Reef ◽  
Conservation Management ◽  
Threat Assessment ◽  
Population Connectivity ◽  
Genetic Connectivity ◽  
Stock Structure ◽  
Barrier Reef ◽  
Long Distance ◽  
Eretmochelys Imbricata ◽  
Management Actions

Context An understanding of the genetic stock structure of wide-ranging marine species is necessary for sound conservation management. Eretmochelys imbricata is Critically Endangered globally, but is among the least studied marine turtles. Reduced population sizes, its long-distance migratory nature between feeding and nesting habitats and poor understanding of its stock structure, biology and anthropogenic impact(s) pose challenges to developing effective conservation strategies for regional conspecifics. Aims Quantification of the population connectivity between specific feeding areas and regional nesting populations is needed for threat assessment and development of mitigation actions. Methods Here, we sequenced the mitochondrial DNA (mtDNA) of 91 immature and adult foraging E. imbricata individuals captured at the Howick Group of islands in the far-northern section of the Great Barrier Reef (nGBR), Queensland, Australia. We used a Bayesian mixed-stock analysis (MSA) approach to determine the contribution of nine regional genetically characterised breeding populations to this feeding aggregation. Key results The MSA estimated that a majority (83%; 95% CI = 70–92%) of feeding E. imbricata had originated from nesting beaches in the Bismarck–Solomon Sea region, whereas only 15% (95% CI = 6–25%) had originated from nGBR rookeries. International reproductive migrations were also corroborated by the return of 18 uniquely numbered titanium flipper tags that had been applied to E. imbricata found foraging in the Howick Group and had swum to rookeries within the Bismarck–Solomon Sea region. These 18 turtles represent 86% of all migration tag–recaptures from the Howick Group. Conclusions We postulate that recent increases in nesting populations within the Solomon Islands may be due to the high level of protection afforded to foraging turtles within the Great Barrier Reef. Implications An understanding of the connectivity between specific feeding areas and nesting populations is necessary to determine threats to animals over their entire life history and, therefore, allow the development of sound conservation management actions.

scholarly journals Faecal metabarcoding reveals pervasive long-distance impacts of garden bird feeding

2021 ◽  
Vol 288 (1951) ◽  
pp. 20210480
Author(s):  
Jack D. Shutt ◽  
Urmi H. Trivedi ◽  
James A. Nicholls
Keyword(s):  
Bird Species ◽  
Urban Ecosystems ◽  
Early Spring ◽  
Supplementary Feeding ◽  
Ecosystem Dynamics ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Long Distance ◽  
Supplementary Food ◽  
The Impact

Supplementary feeding of wildlife is widespread, being undertaken by more than half of households in many countries. However, the impact that these supplemental resources have is unclear, with impacts largely considered to be restricted to urban ecosystems. We reveal the pervasiveness of supplementary foodstuffs in the diet of a wild bird using metabarcoding of blue tit ( Cyanistes caeruleus ) faeces collected in early spring from a 220 km transect in Scotland with a large urbanization gradient. Supplementary foodstuffs were present in the majority of samples, with peanut ( Arachis hypogaea ) the single commonest (either natural or supplementary) dietary item. Consumption rates exhibited a distance decay from human habitation but remained high at several hundred metres from the nearest household and continued to our study limit of 1.4 km distant. Supplementary food consumption was associated with a near quadrupling of blue tit breeding density and a 5-day advancement of breeding phenology. We show that woodland bird species using supplementary food have increasing UK population trends, while species that do not, and/or are outcompeted by blue tits, are likely to be declining. We suggest that the impacts of supplementary feeding are larger and more spatially extensive than currently appreciated and could be disrupting population and ecosystem dynamics.

scholarly journals Faecal metabarcoding reveals pervasive long-distance impacts of garden bird feeding

2021 ◽  
Author(s):  
Jack D Shutt ◽  
Urmi H Trivedi ◽  
James A Nicholls
Keyword(s):  
Bird Species ◽  
Urban Ecosystems ◽  
Early Spring ◽  
Supplementary Feeding ◽  
Ecosystem Dynamics ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Long Distance ◽  
Supplementary Food ◽  
The Impact

AbstractSupplementary feeding of wildlife is widespread, being undertaken by more than half of households in many countries. However, the impact that these supplemental resources have is unclear, with impacts assumed to be restricted to urban ecosystems. We reveal the pervasiveness of supplementary foodstuffs in the diet of a wild bird using metabarcoding of blue tit (Cyanistes caeruleus) faeces collected in early spring from a 220km transect in Scotland with a large urbanisation gradient. Supplementary foodstuffs were present in the majority of samples, with peanut (Arachis hypogaea) the single commonest (either natural or supplementary) dietary item. Consumption rates exhibited a distance decay from human habitation but remained high at several hundred metres from the nearest household and continued to our study limit of 1.4km distant. Supplementary food consumption was associated with a near quadrupling of blue tit breeding density and a five-day advancement of breeding phenology. We show that woodland bird species using supplementary food have increasing UK population trends, while species that don’t, and/or are outcompeted by blue tits, are likely to be declining. We suggest that the impacts of supplementary feeding are larger and more spatially extensive than currently appreciated and could be disrupting population and ecosystem dynamics.

scholarly journals Genomic analyses suggest strong population connectivity over large spatial scales of the commercially important baitworm, Australonuphis teres (Onuphidae)

2020 ◽  
Vol 71 (11) ◽  
pp. 1549
Author(s):  
Amanda Padovan ◽  
Rowan C. Chick ◽  
Victoria J. Cole ◽  
Ludovic Dutoit ◽  
Patricia A. Hutchings ◽  
...  
Keyword(s):  
Gene Flow ◽  
Spatial Scales ◽  
Population Connectivity ◽  
Eastern Coast ◽  
Marine Biodiversity ◽  
Marine Animals ◽  
Long Distance ◽  
South Wales ◽  
Genome Wide ◽  
Eastern Australia

Barriers to dispersal can disrupt gene flow between populations, resulting in genetically distinct populations. Although many marine animals have potential for long-distance dispersal via a planktonic stage, gene flow among populations separated by large geographic distances is not always evident. Polychaetes are ecologically important and have been used as biological surrogates for marine biodiversity. Some polychaete species are used as bait for recreational fisheries, with this demand supporting commercial fisheries for polychaetes to service the retail bait market. However, despite their ecological and economic importance, very little is known about the life history or population dynamics of polychaetes, and few studies have used genetic or genomic approaches to understand polychaete population connectivity. Here, we investigate the population structure of one commonly collected beachworm species used for bait on the eastern coast of Australia, namely, Australonuphis teres, by using genome-wide single-nucleotide polymorphism data. We sampled A. teres from hierarchical nested spatial scales along 900km of the coast in New South Wales. We identified six genetic groups, but there was no clear geographic pattern of distribution. Our results suggest that there is considerable gene flow among the sampled populations. These high-resolution genomic data support the findings of previous studies, and we infer that oceanographic processes promote genetic exchange among polychaete populations in south-eastern Australia.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

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