scholarly journals Genetic structure of black rat populations in a rural plague focus in Madagascar

2007 ◽  
Vol 85 (9) ◽  
pp. 965-972 ◽  
Author(s):  
A. Gilabert ◽  
A. Loiseau ◽  
J.-M. Duplantier ◽  
S. Rahelinirina ◽  
L. Rahalison ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Rattus Rattus ◽  
Geographic Distance ◽  
Distribution Area ◽  
Clear Correlation ◽  
Habitat Segregation ◽  
Fine Spatial Scale ◽  
Natural Systems ◽  
Black Rat ◽  
Indoor And Outdoor

The genetic structure of reservoir populations is a key characteristic in understanding the persistence of infectious diseases in natural systems. In the Highlands of Madagascar, where plague has persisted since 1920, the black rat, Rattus rattus (L., 1758), is the sole species acting as a reservoir of the disease. Ecological surveys have shown a clear correlation between the locations of the plague-persistence area in Madagascar (above 800 m elevation) and the distribution area of one endemic plague vector, the flea Synopsyllus fonquerniei , which is found exclusively on rats living outdoors. This clear habitat segregation has led to the suggestion that R. rattus populations in the central highlands are divided into indoor- and outdoor-dwelling populations. Using eight microsatellite markers, we analysed the genetic structure of R. rattus populations living within a human plague focus in relation to habitat and geographic distance. We found that habitat by itself was not a structuring factor, unlike geographic distance. Nevertheless, the significant genotypic differentiation of R. rattus populations that was found at a fine spatial scale might relate to differences in population dynamics between rats in indoor and outdoor habitats.

MODULATION OF TRIGLYCERIDES IN FEMALE RATTUS RATTUS WITH STEROID CONTRACEPTIVE ALGESTONE ACETOPHENIDE (DHPA)

2019 ◽  
Vol 25 (1) ◽  
Author(s):  
ASHOK KUMAR ◽  
ALPANA PARMAR ◽  
ANAND KUMAR BAJPEYEE
Keyword(s):  
Mixed Type ◽  
Rattus Rattus ◽  
Young Female ◽  
Female Rats ◽  
Control Group ◽  
Black Rat ◽  
Long Acting ◽  
Steroid Contraceptive

Young female Black rat (Rattus rattus), were administered monthly long acting steroid contraceptive to induce hypertriglyceridemia. It was observed that by 3 weeks of the second injection of estrogen containing mixed type of contraceptive, female rats developed consistent and frank hyperglyceridemia . TG in the treated rats was 195.8 ± 7.44 mg /100 ml as compared to 91.5 ± 6.27 mg/100ml in plasma of the control group.

Significant genetic differences among Heterodera schachtii populations within and among sugar beet production areas

Nematology ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 165-177 ◽  
Author(s):  
Rasha Haj Nuaima ◽  
Johannes Roeb ◽  
Johannes Hallmann ◽  
Matthias Daub ◽  
Holger Heuer
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Spatial Scales ◽  
Geographic Distance ◽  
Heterodera Schachtii ◽  
Parasitic Nematodes ◽  
Neutral Genetic Variation ◽  
Production Areas

Summary Characterising the non-neutral genetic variation within and among populations of plant-parasitic nematodes is essential to determine factors shaping the population genetic structure. This study describes the genetic variation of the parasitism gene vap1 within and among geographic populations of the beet cyst nematode Heterodera schachtii. Forty populations of H. schachtii were sampled at four spatial scales: 695 km, 49 km, 3.1 km and 0.24 km. DGGE fingerprinting showed significant differences in vap1 patterns among populations. High similarity of vap1 patterns appeared between geographically close populations, and occasionally among distant populations. Analysis of spatially sampled populations within fields revealed an effect of tillage direction on the vap1 similarity for two of four studied fields. Overall, geographic distance and similarity of vap1 patterns of H. schachtii populations were negatively correlated. In conclusion, the population genetic structure was shaped by the interplay between the genetic adaptation and the passive transport of this nematode.

scholarly journals Genetic Structure of Rhynchosporium secalis in Australia

1999 ◽  
Vol 89 (8) ◽  
pp. 639-645 ◽  
Author(s):  
B. A. McDonald ◽  
J. Zhan ◽  
J. J. Burdon
Keyword(s):  
Genetic Structure ◽  
Gene Diversity ◽  
Sampling Site ◽  
Geographic Distance ◽  
South Australia ◽  
Rflp Markers ◽  
Rhynchosporium Secalis ◽  
Fungal Isolates ◽  
Fungal Populations ◽  
Average Gene

Restriction fragment length polymorphism (RFLP) markers were used to determine the genetic structure of Australian field populations of the barley scald pathogen Rhynchosporium secalis. Fungal isolates were collected by hierarchical sampling from five naturally infected barley fields in different geographic locations during a single growing season. Genetic variation was high in Australian R. secalis populations. Among the 265 fungal isolates analyzed, 214 distinct genotypes were identified. Average genotype diversity within a field population was 65% of its theoretical maximum. Nei's average gene diversity across seven RFLP loci was 0.54. The majority (76%) of gene diversity was distributed within sampling site areas measuring ≈1 m2; 19% of gene diversity was distributed among sampling sites within fields; and 5% of gene diversity was distributed among fields. Fungal populations from different locations differed significantly both in allele frequencies and genotype diversities. The degree of genetic differentiation was significantly correlated with geographic distance between populations. Our results suggest that the R. secalis population in Western Australia has a different genetic structure than populations in Victoria and South Australia.

Late-Holocene asynchronous extinction of endemic mammals on the eastern Canary Islands

The Holocene ◽  
2011 ◽  
Vol 22 (7) ◽  
pp. 801-808 ◽  
Author(s):  
Juan Carlos Rando ◽  
Josep Antoni Alcover ◽  
Jacques Michaux ◽  
Rainer Hutterer ◽  
Juan Francisco Navarro
Keyword(s):  
Canary Islands ◽  
Late Holocene ◽  
Middle Age ◽  
Rattus Rattus ◽  
Tyto Alba ◽  
Isolated Populations ◽  
European Contact ◽  
Black Rat ◽  
Local Extinctions ◽  
Ams Dating

The Lava mouse ( Malpaisomys insularis), and the Canarian shrew ( Crocidura canariensis) are endemic of the Eastern Canary Islands and islets. The former is extinct while Canarian shrew survives in the two main islands and two islets. In order to provide insights regarding causes and processes contributing to the extinction of these endemic mammals: (i) we established last occurrence dates for Lava mouse, and first records for two exotic species – House mouse ( Mus musculus) and Black rat ( Rattus rattus) – through direct 14C AMS dating of collagen from bones; (ii) we analysed recent material from Barn owl ( Tyto alba gracilirostris) roosting sites to evaluate its impact on Canarian shrew in the presence of introduced rodents. The new data strongly suggest that the extinction of Lava mouse was the result of an accumulative process of independent disappearances (or ‘local extinctions’) affecting the isolated populations. The timing of the introduction of the Black rat on the main islands (before Middle Age European contact in Lanzarote and after Middle Age European contact in Fuerteventura) matches with the last occurrence dates for the presence of Lava mouse on these islands, and are very probably their cause. The losses of these Lava mouse populations occurred in an asynchronous way, spreading across at least six centuries. On small islands, hyperpredation emerges as the most plausible process to explain the disappearance of the Lava mouse in the absence of rat populations, although stochastic processes can not be definitively excluded.

Introduced predators and cavity-nesting seabirds: unexpected low level of interaction at breeding sites

2008 ◽  
Vol 86 (9) ◽  
pp. 1068-1073 ◽  
Author(s):  
L. Ruffino ◽  
K. Bourgeois ◽  
E. Vidal ◽  
J. Icard ◽  
F. Torre ◽  
...  
Keyword(s):  
Rattus Rattus ◽  
Breeding Cycle ◽  
Mediterranean Islands ◽  
Breeding Sites ◽  
Low Level ◽  
Black Rat ◽  
Cavity Nesting ◽  
Introduced Predators ◽  
Puffinus Yelkouan ◽  
First Time

The mechanisms by which introduced predators and long-lived seabirds interact and even coexist are still poorly known. Here, the interactions between the widely introduced black rat ( Rattus rattus (L., 1758)) and an endemic Mediterranean cavity-nesting seabird, the yelkouan shearwater ( Puffinus yelkouan (Acerbi, 1827)), were for the first time investigated for a set of 60 suitable breeding cavities throughout the entire breeding cycle of this seabird. Our results pointed out that rat visits to cavities were significantly higher when shearwaters had left the colony for their interbreeding exodus. Among the set of suitable breeding cavities, yelkouan shearwaters preferentially selected the deepest and the most winding cavities for breeding. Very few rat visits were recorded at the shearwater-occupied cavities and no predation event was recorded. These intriguing results reveal a low level of interaction between introduced black rats and yelkouan shearwaters, which may have facilitated their long-term coexistence for thousands of years on some Mediterranean islands.

scholarly journals Genetic structure and dispersal patterns of the invasive psocid Liposcelis decolor (Pearman) in Australian grain storage systems

2010 ◽  
Vol 100 (5) ◽  
pp. 521-527 ◽  
Author(s):  
K.M. Mikac ◽  
N.N. FitzSimmons
Keyword(s):  
Genetic Structure ◽  
Isolation By Distance ◽  
Geographic Distance ◽  
Allelic Diversity ◽  
Mantel Test ◽  
Null Alleles ◽  
Dispersal Patterns ◽  
Long Distance ◽  
Population Comparisons ◽  
Low Levels

AbstractMicrosatellite markers were used to investigate the genetic structure among invasive L. decolor populations from Australia and a single international population from Kansas, USA to determine patterns of dispersal. Six variable microsatellites displayed an average of 2.5–4.2 alleles per locus per population. Observed (HO) heterozygosity ranged from 0.12–0.65 per locus within populations; but, in 13 of 36 tests, HO was less than expected. Despite low levels of allelic diversity, genetic structure estimated as θ was significant for all pairwise comparisons between populations (θ=0.05–0.23). Due to suspected null alleles at four loci, ENA (excluding null alleles) corrected FST estimates were calculated overall and for pairwise population comparisons. The ENA-corrected FST values (0.02–0.10) revealed significant overall genetic structure, but none of the pairwise values were significantly different from zero. A Mantel test of isolation by distance indicated no relationship between genetic structure and geographic distance among all populations (r2=0.12, P=0.18) and for Australian populations only (r2=0.19, P=0.44), suggesting that IBD does not describe the pattern of gene flow among populations. This study supports a hypothesis of long distance dispersal by L. decolor at moderate to potentially high levels.

scholarly journals The influence of roads on the fine-scale population genetic structure of the dengue vector Aedes aegypti (Linnaeus)

2021 ◽  
Vol 15 (2) ◽  
pp. e0009139
Author(s):  
Maria Angenica F. Regilme ◽  
Thaddeus M. Carvajal ◽  
Ann–Christin Honnen ◽  
Divina M. Amalin ◽  
Kozo Watanabe
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Aedes Aegypti ◽  
Spatial Scale ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Mosquito Control ◽  
Genetic Admixture ◽  
Fine Spatial Scale ◽  
The Road

Dengue is endemic in tropical and subtropical countries and is transmitted mainly by Aedes aegypti. Mosquito movement can be affected by human-made structures such as roads that can act as a barrier. Roads can influence the population genetic structure of Ae. aegypti. We investigated the genetic structure and gene flow of Ae. aegypti as influenced by a primary road, España Boulevard (EB) with 2000-meter-long stretch and 24-meters-wide in a very fine spatial scale. We hypothesized that Ae. aegypti populations separated by EB will be different due to the limited gene flow as caused by the barrier effect of the road. A total of 359 adults and 17 larvae Ae. aegypti were collected from June to September 2017 in 13 sites across EB. North (N1-N8) and South (S1-S5) comprised of 211 and 165 individuals, respectively. All mosquitoes were genotyped at 11 microsatellite loci. AMOVA FST indicated significant genetic differentiation across the road. The constructed UPGMA dendrogram found 3 genetic groups revealing the clear separation between North and South sites across the road. On the other hand, Bayesian cluster analysis showed four genetic clusters (K = 4) wherein each individual samples have no distinct genetic cluster thus genetic admixture. Our results suggest that human-made landscape features such as primary roads are potential barriers to mosquito movement thereby limiting its gene flow across the road. This information is valuable in designing an effective mosquito control program in a very fine spatial scale.

The ecological impacts of commensal species: black rats, Rattus rattus, at the urban–bushland interface

2015 ◽  
Vol 42 (2) ◽  
pp. 86 ◽  
Author(s):  
Peter B. Banks ◽  
Helen M. Smith
Keyword(s):  
Exotic Species ◽  
Urban Areas ◽  
Rattus Rattus ◽  
Research Priorities ◽  
Ecological Impacts ◽  
Black Rat ◽  
Urban Impacts ◽  
Commensal Species ◽  
Commensal Rodents ◽  
Black Rats

Exotic species have had devastating impacts worldwide and are a major threat to native wildlife. Human commensal species (hereafter commensals) are a special class of exotic species that live largely off the resources associated with human activity. The encroachment of commensals from an urban area into surrounding bushland has been frequently overlooked as an important component of urban impacts, even though human-commensals are common to many urban regions globally. In this review, we present theoretical and empirical evidence for the processes and outcomes occurring when exotic commensal species encroach into native bushland. Specifically we ask when, how and why exotic commensal species encroach into bushland, what determines whether they establish, and what are the ecological consequences. We focus on the black rat, Rattus rattus, arguably the archetypal commensal species with a cosmopolitan distribution and the greatest potential for ecological damage of all the commensal rodents. We expect that the processes that we outline apply to other commensal species more broadly. We argue that commensals are in fact natives of the urban milieu and only become alien when they encroach into peri-urban bushland. We propose that the mechanisms of this encroachment will be different from those of other, non-commensal exotic species because urban areas act as dispersal hubs to overcome many of the barriers of invasion that other exotic species face. We suggest that resource supplementation by urban areas creates a great potential for promoting encroachment, invasion as well as impact. However, biotic and abiotic barriers to invasion are still relevant for commensals, highlighting the need to maintain the integrity of ecosystems and wildlife populations in urban edges so as to prevent commensal incursion. We examine how commensal black rats affect wildlife via three fundamental mechanisms, namely, predation, disease transfer and competition for resources, and also consider their possible positive impacts acting as functional replacements for lost natives. We conclude the review with an outline of research priorities and future directions that are essential for progressing our understanding of the ecology of commensal species.

Sign in / Sign up

Export Citation Format

Share Document