scholarly journals Dispersal evolution diminishes the negative density dependence in dispersal

2020 ◽  
Author(s):  
Abhishek Mishra ◽  
Partha Pratim Chakraborty ◽  
Sutirth Dey
Keyword(s):  
Spatial Ecology ◽  
Local Population ◽  
Rapid Evolution ◽  
Spatial Spread ◽  
Dispersal Traits ◽  
Evolution Study ◽  
Negative Density Dependence ◽  
Ecological Importance ◽  
Dispersal Evolution

ABSTRACTIn many organisms, dispersal varies with the local population density. Such patterns of density-dependent dispersal (DDD) are expected to shape the dynamics, spatial spread and invasiveness of populations. Despite their ecological importance, empirical evidence for the evolution of DDD patterns remains extremely scarce. This is especially relevant because rapid evolution of dispersal traits has now been empirically confirmed in several taxa. Changes in DDD of dispersing populations could help clarify not only the role of DDD in dispersal evolution, but also the possible pattern of subsequent range expansion. Here, we investigate the relationship between dispersal evolution and DDD using a long-term experimental evolution study on Drosophila melanogaster. We compared the DDD patterns of four dispersal-selected populations and their non-selected controls. The control populations showed negative DDD, which was stronger in females than in males. In contrast, the dispersal-selected populations showed density-independent dispersal, where neither males nor females exhibited DDD. We compare our results with previous evolutionary predictions that focused largely on positive DDD, and highlight how the direction of evolutionary change depends on the initial DDD pattern of a population. Finally, we discuss the implications of DDD evolution for spatial ecology and evolution.

scholarly journals Negative density-dependent parasitism in a group-living carnivore

2020 ◽  
Vol 287 (1941) ◽  
pp. 20202655
Author(s):  
Gregory F. Albery ◽  
Chris Newman ◽  
Julius Bright Ross ◽  
David W. MacDonald ◽  
Shweta Bansal ◽  
...  
Keyword(s):  
Local Population ◽  
Group Living ◽  
Host Density ◽  
Meles Meles ◽  
Population Variation ◽  
Network Analyses ◽  
Long Term Study ◽  
Negative Density Dependence ◽  
Dilution Effects

Animals living at high population densities commonly experience greater exposure to disease, leading to increased parasite burdens. However, social animals can benefit immunologically and hygienically from cooperation, and individuals may alter their socio-spatial behaviour in response to infection, both of which could counteract density-related increases in exposure. Consequently, the costs and benefits of sociality for disease are often uncertain. Here, we use a long-term study of a wild European badger population ( Meles meles ) to investigate how within-population variation in host density determines infection with multiple parasites. Four out of five parasite taxa exhibited consistent spatial hotspots of infection, which peaked among badgers living in areas of low local population density. Combined movement, survival, spatial and social network analyses revealed that parasite avoidance was the likely cause of this negative density dependence, with possible roles for localized mortality, encounter-dilution effects, and micronutrient-enhanced immunity. These findings demonstrate that animals can organize their societies in space to minimize parasite infection, with important implications for badger behavioural ecology and for the control of badger-associated diseases.

scholarly journals Negative density-dependent parasitism in a group-living carnivore

2020 ◽  
Author(s):  
Gregory F Albery ◽  
Chris Newman ◽  
Julius Bright Ross ◽  
Shweta Bansal ◽  
Christina Buesching
Keyword(s):  
Local Population ◽  
Group Living ◽  
Host Density ◽  
Meles Meles ◽  
Population Variation ◽  
Network Analyses ◽  
Long Term Study ◽  
Negative Density Dependence ◽  
Dilution Effects

AbstractAnimals living at high population densities commonly experience greater exposure to disease, leading to increased parasite burdens. However, social animals can benefit immunologically and hygienically from cooperation, and individuals may alter their socio-spatial behaviour in response to infection, both of which could counteract density-related increases in exposure. Consequently, the costs and benefits of sociality for disease are often uncertain. Here, we use a long-term study of a wild European badger population (Meles meles) to investigate how within-population variation in host density determines infection with multiple parasites. Four out of five parasite taxa exhibited consistent spatial hotspots of infection, which peaked among badgers living in areas of low local population density. Combined movement, survival, spatial, and social network analyses revealed that parasite avoidance was the likely cause of this negative density dependence, with possible roles for localised mortality, encounter-dilution effects, and micronutrient-enhanced immunity. These findings demonstrate that animals can organise their societies in space to minimise parasite infection, with important implications for badger behavioural ecology and for the control of badger-associated diseases.

scholarly journals The implications of vehicle collisions for the Endangered endemic Zanzibar red colobus Piliocolobus kirkii

Oryx ◽  
2021 ◽  
pp. 1-9
Author(s):  
Harry Olgun ◽  
Mzee Khamis Mohammed ◽  
Abbas Juma Mzee ◽  
M. E. Landry Green ◽  
Tim R. B. Davenport ◽  
...  
Keyword(s):  
Road Ecology ◽  
Local Population ◽  
Red Colobus ◽  
Vehicle Collisions ◽  
The Road ◽  
Life History Data ◽  
Natural Predation ◽  
Historical Accounts ◽  
The Impact

Abstract Roads affect wildlife in a variety of negative ways. Road ecology studies have mostly concentrated on areas in the northern hemisphere despite the potentially greater impact of roads on biodiversity in tropical habitats. Here, we examine 4 years (January 2016–December 2019) of opportunistic observations of mammalian roadkill along a road intersecting Jozani-Chwaka Bay National Park, Unguja, Zanzibar. In particular, we assess the impact of collisions on the population of an endemic primate, the Endangered Zanzibar red colobus Piliocolobus kirkii. Primates accounted for the majority of roadkill in this dataset. Monthly rainfall was not associated with roadkill frequency for mammals generally, nor for the Zanzibar red colobus. No single age–sex class of colobus was found dead more often than expected given their occurrence in the local population. The overall effect of roadkill on colobus populations in habitats fragmented by roads is unknown given the lack of accurate, long-term life history data for this species. Our findings suggest that mortality from collisions with vehicles in some groups of colobus is within the range of mortality rates other primates experience under natural predation. Unlike natural predators, however, vehicles do not kill selectively, so their impact on populations may differ. Although a comparison with historical accounts suggests that the installation of speedbumps along the road near the Park's entrance has led to a significant decrease in colobus roadkill, further actions to mitigate the impact of the road could bring substantial conservation benefits.

scholarly journals Timing and severity of immunizing diseases in rabbits is controlled by seasonal matching of host and pathogen dynamics

2015 ◽  
Vol 12 (103) ◽  
pp. 20141184 ◽  
Author(s):  
Konstans Wells ◽  
Barry W. Brook ◽  
Robert C. Lacy ◽  
Greg J. Mutze ◽  
David E. Peacock ◽  
...  
Keyword(s):  
Local Population ◽  
Disease Outbreaks ◽  
Maternal Antibodies ◽  
Timing Of Reproduction ◽  
Demographic Rates ◽  
Pathogen Dynamics ◽  
Rabbit Haemorrhagic Disease ◽  
Seasonal Epidemics ◽  
Haemorrhagic Disease

Infectious diseases can exert a strong influence on the dynamics of host populations, but it remains unclear why such disease-mediated control only occurs under particular environmental conditions. We used 16 years of detailed field data on invasive European rabbits ( Oryctolagus cuniculus ) in Australia, linked to individual-based stochastic models and Bayesian approximations, to test whether (i) mortality associated with rabbit haemorrhagic disease (RHD) is driven primarily by seasonal matches/mismatches between demographic rates and epidemiological dynamics and (ii) delayed infection (arising from insusceptibility and maternal antibodies in juveniles) are important factors in determining disease severity and local population persistence of rabbits. We found that both the timing of reproduction and exposure to viruses drove recurrent seasonal epidemics of RHD. Protection conferred by insusceptibility and maternal antibodies controlled seasonal disease outbreaks by delaying infection; this could have also allowed escape from disease. The persistence of local populations was a stochastic outcome of recovery rates from both RHD and myxomatosis. If susceptibility to RHD is delayed, myxomatosis will have a pronounced effect on population extirpation when the two viruses coexist. This has important implications for wildlife management, because it is likely that such seasonal interplay and disease dynamics has a strong effect on long-term population viability for many species.

Protected Areas: offering security to whom, when and where?

2016 ◽  
Vol 43 (2) ◽  
pp. 172-180 ◽  
Author(s):  
ALICE B. KELLY ◽  
A. CLARE GUPTA
Keyword(s):  
Protected Areas ◽  
Environmental Conditions ◽  
Protected Area ◽  
Spatial Scales ◽  
Local Population ◽  
Well Being ◽  
Economic Context ◽  
Term Management ◽  
Over Time

SUMMARYThis study considers the issue of security in the context of protected areas in Cameroon and Botswana. Though the literature on issues of security and well-being in relation to protected areas is extensive, there has been less discussion of how and in what ways these impacts and relationships can change over time, vary with space and differ across spatial scales. Looking at two very different historical trajectories, this study considers the heterogeneity of the security landscapes created by Waza and Chobe protected areas over time and space. This study finds that conservation measures that various subsets of the local population once considered to be ‘bad’ (e.g. violent, exclusionary protected area creation) may be construed as ‘good’ at different historical moments and geographical areas. Similarly, complacency or resignation to the presence of a park can be reversed by changing environmental conditions. Changes in the ways security (material and otherwise) has fluctuated within these two protected areas has implications for the long-term management and funding strategies of newly created and already existing protected areas today. This study suggests that parks must be adaptively managed not only for changing ecological conditions, but also for shifts in a protected area's social, political and economic context.

scholarly journals Rapid evolution of decreased host susceptibility drives a stable relationship between ultrasmall parasite TM7x and its bacterial host

2018 ◽  
Vol 115 (48) ◽  
pp. 12277-12282 ◽  
Author(s):  
Batbileg Bor ◽  
Jeffrey S. McLean ◽  
Kevin R. Foster ◽  
Lujia Cen ◽  
Thao T. To ◽  
...  
Keyword(s):  
Host Cell ◽  
Rapid Evolution ◽  
Host Population ◽  
Host Cells ◽  
Host Susceptibility ◽  
Bacterial Host ◽  
Narrow Host Range ◽  
Stable Relationship ◽  
Candidate Phyla Radiation

Around one-quarter of bacterial diversity comprises a single radiation with reduced genomes, known collectively as the Candidate Phyla Radiation. Recently, we coisolated TM7x, an ultrasmall strain of the Candidate Phyla Radiation phylum Saccharibacteria, with its bacterial host Actinomyces odontolyticus strain XH001 from human oral cavity and stably maintained as a coculture. Our current work demonstrates that within the coculture, TM7x cells establish a long-term parasitic association with host cells by infecting only a subset of the population, which stay viable yet exhibit severely inhibited cell division. In contrast, exposure of a naïve A. odontolyticus isolate, XH001n, to TM7x cells leads to high numbers of TM7x cells binding to each host cell, massive host cell death, and a host population crash. However, further passaging reveals that XH001n becomes less susceptible to TM7x over time and enters a long-term stable relationship similar to that of XH001. We show that this reduced susceptibility is driven by rapid host evolution that, in contrast to many forms of phage resistance, offers only partial protection. The result is a stalemate where infected hosts cannot shed their parasites; nevertheless, parasite load is sufficiently low that the host population persists. Finally, we show that TM7x can infect and form stable long-term relationships with other species in a single clade of Actinomyces, displaying a narrow host range. This system serves as a model to understand how parasitic bacteria with reduced genomes such as those of the Candidate Phyla Radiation have persisted with their hosts and ultimately expanded in their diversity.

scholarly journals Seasonal activity of Dermacentor reticulatus ticks in the era of progressive climate change in eastern Poland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zbigniew Zając ◽  
Joanna Kulisz ◽  
Aneta Woźniak ◽  
Katarzyna Bartosik ◽  
Adil Khan
Keyword(s):  
Climate Change ◽  
Local Population ◽  
Weather Conditions ◽  
Dermacentor Reticulatus ◽  
Seasonal Activity ◽  
Saturation Deficit ◽  
Annual Basis ◽  
Questing Ticks ◽  
The Mean

AbstractDermacentor reticulatus ticks are one of the most important vectors and reservoirs of tick-borne pathogens in Europe. Changes in the abundance and range of this species have been observed in the last decade and these ticks are collected in areas previously considered tick-free. This may be influenced by progressive climate change. Eastern Poland is an area where the local population of D. reticulatus is one of the most numerous among those described so far. At the same time, the region is characterized by a significant increase in the mean air temperature in recent years (by 1.81 °C in 2020) and a decrease in the average number of days with snow cover (by 64 days in 2020) and in the number of days with frost (by 20 days in 2020) on an annual basis compared to the long-term average. The aim of our research was to investigate the rhythms of seasonal activity and the population size of D. reticulatus in the era of progressive climate change. To this end, questing ticks were collected in 2017–2020. Next, the weather conditions in the years of observation were analyzed and compared with multi-year data covering 30 years preceding the study. The research results show that, in eastern Poland, there is a stable population of D. reticulatus with the peak of activity in spring or autumn (up to a maximum of 359 individuals within 30 min of collection) depending on the year of observation. Ticks of this species may also be active in winter months. The activity of D. reticulatus is influenced by a saturation deficit.

scholarly journals Development of rice pre-breeding resources with blast resistance

2020 ◽  
Vol 224 ◽  
pp. 04020
Author(s):  
Zh M Mukhina ◽  
E G Savenko ◽  
T L Korotenko ◽  
I I Suprun ◽  
O. A. Bragina ◽  
...  
Keyword(s):  
Magnaporthe Grisea ◽  
Blast Resistance ◽  
Local Population ◽  
Rice Varieties ◽  
Germplasm Exchange ◽  
Yield Structure ◽  
Rice Samples ◽  
Breeding Resources

Within the framework of this study, the first Russian-Chinese joint program for development of rice varieties with long-term blast resistance was launched on the basis of rice germplasm exchange and the subsequent comprehensive study of the obtained breeding samples, hybridization of Russian and Chinese varieties with specified traits. The genetic diversity of the Chinese rice samples obtained by exchange was studied by biological and morphological traits of plants, taxonomic belonging to a botanical variety, elements of the yield structure, and resistance to lodging. 31 hybrid combinations (F1) from the crossing of Russian and Chinese varieties were used to obtain the BC1 generation. The technologies of cultivation of isolated rice anthers in vitro have been optimized in relation to Chinese genotypes in order to accelerate the genetic stabilization of breeding material obtained from crossing. Phenotyping of Russian and Chinese breeding samples was carried out on the basis of resistance to the local population of the blast pathogen (Magnaporthe grisea (T.T. Hebert) M.E. Barr)), on natural and artificial infectious backgrounds. DNA identification of genes for blast resistance was carried out for the same breeding samples. Based on the experimental data obtained, promising samples were selected - prototypes of new rice varieties.

scholarly journals La paradoja de mezquites (Prosopis spp.): La invasión de especies o potenciadores de la biodiversidad?

2017 ◽  
pp. 23 ◽  
Author(s):  
Jordan Golubov ◽  
María C. Mandujano ◽  
Luis E. Eguiarte
Keyword(s):  
Keystone Species ◽  
Arid Environments ◽  
Perennial Species ◽  
Semiarid Environments ◽  
High Species Diversity ◽  
Ecological Importance ◽  
Associated Species ◽  
Semi Arid ◽  
Arid And Semiarid

Arid and semi-arid environments contain relatively high species diversity and are subject to intense use, in particular extensive cattle grazing. The expansion of perennial species in to the grasslands decreases the value of the rangeland, because it makes necessary to control the shrubs, which is not practical in the long term. This paper is a bibliographic review of the ecological importance of the Prosopis (mequite) genus. We compiled information on all the species associated to mesquite (ca. 208 genera and 600 species from different taxa) and we propase that it is important to conserve the mesquites in order to maintain the diversity of the other associated species. We also stress the importance of mesquite as a keystone species in the balance of nitrogen and carbon in the arid and semiarid environments soils. We conclude that the conservation of the mesquites is very relevant, in particular in areas where people want to remove them and convert the environment to grasslands.

scholarly journals Further evidence of a cumulative effect of social disadvantage on risk of psychosis

2016 ◽  
Vol 47 (5) ◽  
pp. 913-924 ◽  
Author(s):  
S. A. Stilo ◽  
C. Gayer-Anderson ◽  
S. Beards ◽  
K. Hubbard ◽  
A. Onyejiaka ◽  
...  
Keyword(s):  
Local Population ◽  
Control Sample ◽  
Cumulative Effect ◽  
Social Disadvantage ◽  
Psychiatric Services ◽  
Cumulative Effects ◽  
First Episode ◽  
Increased Risk ◽  
First Contact

BackgroundA growing body of evidence suggests that indicators of social disadvantage are associated with an increased risk of psychosis. However, only a few studies have specifically looked at cumulative effects and long-term associations. The aims of this study are: To compare the prevalence of specific indicators of social disadvantage at, and prior to, first contact with psychiatric services in patients suffering their first episode of psychosis and in a control sample. To explore long-term associations, cumulative effects, and direction of effects.MethodWe collected information on social disadvantage from 332 patients and from 301 controls recruited from the local population in South London. Three indicators of social disadvantage in childhood and six indicators of social disadvantage in adulthood were analysed.ResultsAcross all the domains considered, cases were more likely to report social disadvantage than were controls. Compared with controls, cases were approximately two times more likely to have had a parent die and approximately three times more likely to have experienced a long-term separation from one parent before the age of 17 years. Cases were also more likely than controls to report two or more indicators of adult social disadvantage, not only at first contact with psychiatric services [odds ratio (OR) 9.5], but also at onset of psychosis (OR 8.5), 1 year pre-onset (OR 4.5), and 5 years pre-onset (OR 2.9).ConclusionsGreater numbers of indicators of current and long-term exposure are associated with progressively greater odds of psychosis. There is some evidence that social disadvantage tends to cluster and accumulate.

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