Evolutionary demographic models for mortality plateaus

AbstractPopulation persistence is strongly determined by climatic variability. Changes in the patterns of climatic events linked to global warming may alter population dynamics, but their effects may be strongly modulated by biotic interactions. Plant populations interact with each other in such a way that responses to climate of a single population may impact the dynamics of the whole community. In this study, we assess how climate variability affects persistence and coexistence of two dominant plant species in a semiarid shrub community on gypsum soils. We use 9 years of demographic data to parameterize demographic models and to simulate population dynamics under different climatic and ecological scenarios. We observe that populations of both coexisting species may respond to common climatic fluctuations both similarly and in idiosyncratic ways, depending on the yearly combination of climatic factors. Biotic interactions (both within and among species) modulate some of their vital rates, but their effects on population dynamics highly depend on climatic fluctuations. Our results indicate that increased levels of climatic variability may alter interspecific relationships. These alterations might potentially affect species coexistence, disrupting competitive hierarchies and ultimately leading to abrupt changes in community composition.

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A Genealogical Interpretation of Linkage Disequilibrium

Genetics ◽

10.1093/genetics/162.2.987 ◽

2002 ◽

Vol 162 (2) ◽

pp. 987-991 ◽

Cited By ~ 14

Author(s):

Gilean A T McVean

Keyword(s):

Monte Carlo Simulation ◽

Population Structure ◽

Linkage Disequilibrium ◽

Population Bottlenecks ◽

Neutral Model ◽

Demographic Models ◽

Degree Of Association ◽

Different Parts ◽

Direct Correspondence ◽

Coalescence Times

Abstract The degree of association between alleles at different loci, or linkage disequilibrium, is widely used to infer details of evolutionary processes. Here I explore how associations between alleles relate to properties of the underlying genealogy of sequences. Under the neutral, infinite-sites assumption I show that there is a direct correspondence between the covariance in coalescence times at different parts of the genome and the degree of linkage disequilibrium. These covariances can be calculated exactly under the standard neutral model and by Monte Carlo simulation under different demographic models. I show that the effects of population growth, population bottlenecks, and population structure on linkage disequilibrium can be described through their effects on the covariance in coalescence times.

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The Probability of Fixation in Populations of Changing Size

Genetics ◽

10.1093/genetics/146.2.723 ◽

1997 ◽

Vol 146 (2) ◽

pp. 723-733 ◽

Cited By ~ 33

Author(s):

Sarah P Otto ◽

Michael C Whitlock

Keyword(s):

Diffusion Equation ◽

Adaptive Evolution ◽

Process Model ◽

Branching Process ◽

Approximate Solutions ◽

Logistic Growth ◽

Beneficial Mutations ◽

Demographic Models ◽

Deleterious Alleles ◽

Probability Of Fixation

The rate of adaptive evolution of a population ultimately depends on the rate of incorporation of beneficial mutations. Even beneficial mutations may, however, be lost from a population since mutant individuals may, by chance, fail to reproduce. In this paper, we calculate the probability of fixation of beneficial mutations that occur in populations of changing size. We examine a number of demographic models, including a population whose size changes once, a population experiencing exponential growth or decline, one that is experiencing logistic growth or decline, and a population that fluctuates in size. The results are based on a branching process model but are shown to be approximate solutions to the diffusion equation describing changes in the probability of fixation over time. Using the diffusion equation, the probability of fixation of deleterious alleles can also be determined for populations that are changing in size. The results developed in this paper can be used to estimate the fixation flux, defined as the rate at which beneficial alleles fix within a population. The fixation flux measures the rate of adaptive evolution of a population and, as we shall see, depends strongly on changes that occur in population size.

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Evolutionary demographic models reveal the strength of purifying selection on susceptibility alleles to late-onset diseases

Nature Ecology & Evolution ◽

10.1038/s41559-020-01355-2 ◽

2021 ◽

Cited By ~ 1

Author(s):

Samuel Pavard ◽

Christophe F. D. Coste

Keyword(s):

Late Onset ◽

Purifying Selection ◽

Demographic Models

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Demographic Characterization of Anonymous Trace Travel Data

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2526-03 ◽

2015 ◽

Vol 2526 (1) ◽

pp. 19-28 ◽

Cited By ~ 2

Author(s):

Joshua Auld ◽

Abolfazl (Kouros) Mohammadian ◽

Marcelo Simas Oliveira ◽

Jean Wolf ◽

William Bachman

Keyword(s):

Test Data ◽

Large Scale ◽

Travel Demand ◽

Null Model ◽

Demographic Characteristics ◽

Travel Pattern ◽

Data Set ◽

Trace Data ◽

Demographic Models ◽

Pattern Information

Research was undertaken to determine whether demographic characteristics of individual travelers could be derived from travel pattern information when no information about the individual was available. This question is relevant in the context of anonymously collected travel information, such as cell phone traces, when used for travel demand modeling. Determining the demographics of a traveler from such data could partially obviate the need for large-scale collection of travel survey data, depending on the purpose for which the data were to be used. This research complements methodologies used to identify activity stops, purposes, and mode types from raw trace data and presumes that such methods exist and are available. The paper documents the development of procedures for taking raw activity streams estimated from GPS trace data and converting these into activity travel pattern characteristics that are then combined with basic land use information and used to estimate various models of demographic characteristics. The work status, education level, age, and license possession of individuals and the presence of children in their households were all estimated successfully with substantial increases in performance versus null model expectations for both training and test data sets. The gender, household size, and number of vehicles proved more difficult to estimate, and performance was lower on the test data set; these aspects indicate overfitting in these models. Overall, the demographic models appear to have potential for characterizing anonymous data streams, which could extend the usability and applicability of such data sources to the travel demand context.

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Genome diversity in the Neolithic Globular Amphorae culture and the spread of Indo-European languages

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.1540 ◽

2017 ◽

Vol 284 (1867) ◽

pp. 20171540 ◽

Cited By ~ 15

Author(s):

Francesca Tassi ◽

Stefania Vai ◽

Silvia Ghirotto ◽

Martina Lari ◽

Alessandra Modi ◽

...

Keyword(s):

Approximate Bayesian Computation ◽

Cultural Influences ◽

Archaeological Record ◽

Genome Diversity ◽

Early Neolithic ◽

Late Neolithic ◽

Demographic Models ◽

European Languages ◽

Complete Sequences ◽

Approximate Bayesian

It is unclear whether Indo-European languages in Europe spread from the Pontic steppes in the late Neolithic, or from Anatolia in the Early Neolithic. Under the former hypothesis, people of the Globular Amphorae culture (GAC) would be descended from Eastern ancestors, likely representing the Yamnaya culture. However, nuclear (six individuals typed for 597 573 SNPs) and mitochondrial (11 complete sequences) DNA from the GAC appear closer to those of earlier Neolithic groups than to the DNA of all other populations related to the Pontic steppe migration. Explicit comparisons of alternative demographic models via approximate Bayesian computation confirmed this pattern. These results are not in contrast to Late Neolithic gene flow from the Pontic steppes into Central Europe. However, they add nuance to this model, showing that the eastern affinities of the GAC in the archaeological record reflect cultural influences from other groups from the East, rather than the movement of people.

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