Search results for "POPULATION DYNAMICS"
showing 10 items of 281 documents
Detection and Characterization of Wolbachia Infections in Natural Populations of Aphids: Is the Hidden Diversity Fully Unraveled?
2011
Copyright © 2011 Augustinos et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Aphids are a serious threat to agriculture, despite being a rather small group of insects. The about 4,000 species worldwide engage in highly interesting and complex relationships with their microbial fauna. One of the key symbionts in arthropods is Wolbachia, an a-Proteobacterium implicated in many important biological processes and believed to be a potential tool for biological control. Aphids were thought not to harbour W…
Local Recruitment in the Greater Flamingo: A New Approach Using Capture- Mark-Recapture Data
1997
International audience; Although the establishment of new individuals in the breeding component of a population is an essential feature of population regulation, only a few attempts have been made to test biological hypotheses about recruitment. Most previous studies rely on ad hoc calculations or are flawed with unwarranted assumptions about survival. We use a recently developed approach, based on capture-mark-recapture, in which analysis of local recruitment is similar to a time-reversed analysis of survival. The basic data set consists of capture histories viewed in reverse order, with initial capture at year of birth, and subsequent observations corresponding to years when the animal ha…
Lake restoration influences nutritional quality of algae and consequently Daphnia biomass
2020
AbstractFood quality is one of the key factors influencing zooplankton population dynamics. Eutrophication drives phytoplankton communities toward the dominance of cyanobacteria, which means a decrease in the availability of sterols and long-chain polyunsaturated fatty acids (EPA and DHA). The effects of different restoration measures on the nutritional quality of the phytoplankton community and subsequent impacts on zooplankton biomass have rarely been considered. We analyzed the nutritional quality of phytoplankton in the eutrophic Lake Vesijärvi in southern Finland over a 37-year period, and studied the impacts of two restoration measures, biomanipulation and hypolimnetic aeration, on th…
Spatio-temporal dynamics of density-dependent dispersal during a population colonisation
2019
Predicting population colonisations requires understanding how spatio‐temporal changes in density affect dispersal. Density can inform on fitness prospects, acting as a cue for either habitat quality, or competition over resources. However, when escaping competition, high local density should only increase emigration if lower‐density patches are available elsewhere. Few empirical studies on dispersal have considered the effects of density at the local and landscape scale simultaneously. To explore this, we analyze 5 years of individual‐based data from an experimental introduction of wild guppies Poecilia reticulata. Natal dispersal showed a decrease in local density dependence as density at…
Long live the alien: is high genetic diversity a pivotal aspect of crested porcupine (Hystrix cristata) long-lasting and successful invasion?
2016
AbstractStudying the evolutionary dynamics of an alien species surviving and continuing to expand after several generations can provide fundamental information on the relevant features of clearly successful invasions. Here, we tackle this task by investigating the dynamics of the genetic diversity in invasive crested porcupine (Hystrix cristata) populations, introduced to Italy about 1500 years ago, which are still growing in size, distribution range and ecological niche. Using genome-wide RAD markers, we describe the structure of the genetic diversity and the demographic dynamics of theH. cristatainvasive populations and compare their genetic diversity with that of native African populatio…
The genetic prehistory of the Baltic Sea region
2018
Correction: Nature communications 9 (2018), art. no. 1494 doi:10.1038/s41467-018-03872-y While the series of events that shaped the transition between foraging societies and food producers are well described for Central and Southern Europe, genetic evidence from Northern Europe surrounding the Baltic Sea is still sparse. Here, we report genome-wide DNA data from 38 ancient North Europeans ranging from similar to 9500 to 2200 years before present. Our analysis provides genetic evidence that hunter-gatherers settled Scandinavia via two routes. We reveal that the first Scandinavian farmers derive their ancestry from Anatolia 1000 years earlier than previously demonstrated. The range of Mesolit…
Improving risk assessments in conservation ecology
2019
Conservation efforts and management decisions on the living environment of our planet often rely on the results from statistical models. Yet, these models are imperfect and quantification of risk associated with the estimate of management-relevant quantities becomes crucial in providing robust advice. Here we demonstrate that estimates of risk themselves could be substantially biased but by combining data fitting with an extensive simulation–estimation procedure, one can back-calculate the correct values. We apply the method to 627 time series of population abundance across four taxa using the Gompertz state-space model as an example. We find that the risk of large bias in population status…
Parallel paleogenomic transects reveal complex genetic history of early European farmers
2017
In European Neolithic populations, the arrival of farmers prompted admixture with local hunter-gatherers over many centuries, resulting in distinct signatures in each region due to a complex series of interactions. David Reich and colleagues analyse genome-wide data from 180 individuals from the Neolithic and Chalcolithic periods of Hungary, Germany and Spain to study the population dynamics of Neolithization in European prehistory. They examine how gene flow reshaped European populations during the Neolithic period, including pervasive admixture—the interbreeding between previously isolated populations—between groups with different ancestry profiles. In each region, they find that the arri…
Long-term dynamics in microbial eukaryotes communities: a palaeolimnological view based on sedimentary DNA
2016
International audience; Assessing the extent to which changes in lacustrine biodiversity are affected by anthropogenic or climatic forces requires extensive palaeolimnological data. We used high-throughput sequencing to generate time-series data encompassing over 2200 years of microbial eukaryotes (protists and Fungi) diversity changes from the sedimentary DNA record of two lakes (Lake Bourget in French Alps and Lake Igaliku in Greenland). From 176 samples, we sequenced a large diversity of microbial eukaryotes, with a total 16 386 operational taxonomic units distributed within 50 phylogenetic groups. Thus, microbial groups, such as Chlorophyta, Dinophyceae, Haptophyceae and Ciliophora, tha…
The genomic history of Southern Europe
2018
Farming was first introduced to southeastern Europe in the mid-7th millennium BCE - brought by migrants from Anatolia who settled in the region before spreading throughout Europe. However, the dynamics of the interaction between the first farmers and the indigenous hunter-gatherers remain poorly understood because of the near absence of ancient DNA from the region. We report new genome-wide ancient DNA data from 204 individuals-65 Paleolithic and Mesolithic, 93 Neolithic, and 46 Copper, Bronze and Iron Age-who lived in southeastern Europe and surrounding regions between about 12,000 and 500 BCE. We document that the hunter-gatherer populations of southeastern Europe, the Baltic, and the Nor…