scholarly journals Neanderthal-Denisovan ancestors interbred with a distantly related hominin

2020 ◽  
Vol 6 (8) ◽  
pp. eaay5483 ◽  
Author(s):  
Alan R. Rogers ◽  
Nathan S. Harris ◽  
Alan A. Achenbach
Keyword(s):  
Population Size ◽  
Effective Size ◽  
Middle Pleistocene ◽  
Modern Humans

Previous research has shown that modern Eurasians interbred with their Neanderthal and Denisovan predecessors. We show here that hundreds of thousands of years earlier, the ancestors of Neanderthals and Denisovans interbred with their own Eurasian predecessors—members of a “superarchaic” population that separated from other humans about 2 million years ago. The superarchaic population was large, with an effective size between 20 and 50 thousand individuals. We confirm previous findings that (i) Denisovans also interbred with superarchaics, (ii) Neanderthals and Denisovans separated early in the middle Pleistocene, (iii) their ancestors endured a bottleneck of population size, and (iv) the Neanderthal population was large at first but then declined in size. We provide qualified support for the view that (v) Neanderthals interbred with the ancestors of modern humans.

scholarly journals Neanderthal-Denisovan ancestors interbred with a distantly-related hominin

2019 ◽  
Author(s):  
Alan R. Rogers ◽  
Nathan S. Harris ◽  
Alan A. Achenbach
Keyword(s):  
Population Size ◽  
Effective Size ◽  
Middle Pleistocene ◽  
Human Populations ◽  
Modern Humans ◽  
Out Of Africa

Previous research has shown that modern Eurasians interbred with their Neanderthal and Denisovan predecessors. We show here that hundreds of thousands of years earlier, the ancestors of Neanderthals and Denisovans interbred with their own Eurasian predecessors—members of a “superarchaic” population that separated from other humans about 2 mya. The superarchaic population was large, with an effective size between 20 and 50 thousand individuals. We confirm previous findings that: (1) Denisovans also interbred with superarchaics, (2) Neanderthals and Denisovans separated early in the middle Pleistocene, (3) their ancestors endured a bottleneck of population size, and (4) the Neanderthal population was large at first but then declined in size. We provide qualified support for the view that (5) Neanderthals interbred with the ancestors of modern humans.One-sentence summaryWe document the earliest known interbreeding between ancient human populations and an expansion out of Africa early in the middle Pleistocene.

A Neutral Model With Fluctuating Population Size and Its Effective Size

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 381-388
Author(s):  
Masaru Iizuka ◽  
Hidenori Tachida ◽  
Hirotsugu Matsuda
Keyword(s):  
Asymptotic Behavior ◽  
Population Size ◽  
Diffusion Model ◽  
Arithmetic Mean ◽  
Harmonic Mean ◽  
Effective Size ◽  
Neutral Model ◽  
Average Heterozygosity ◽  
Special Case ◽  
Concrete Model

Abstract We consider a diffusion model with neutral alleles whose population size is fluctuating randomly. For this model, the effects of fluctuation of population size on the effective size are investigated. The effective size defined by the equilibrium average heterozygosity is larger than the harmonic mean of population size but smaller than the arithmetic mean of population size. To see explicitly the effects of fluctuation of population size on the effective size, we investigate a special case where population size fluctuates between two distinct states. In some cases, the effective size is very different from the harmonic mean. For this concrete model, we also obtain the stationary distribution of the average heterozygosity. Asymptotic behavior of the effective size is obtained when the population size is large and/or autocorrelation of the fluctuation is weak or strong.

scholarly journals Dental evolutionary rates and its implications for the Neanderthal–modern human divergence

2019 ◽  
Vol 5 (5) ◽  
pp. eaaw1268 ◽  
Author(s):  
Aida Gómez-Robles
Keyword(s):  
Divergence Time ◽  
Modern Human ◽  
Evolutionary Rates ◽  
Middle Pleistocene ◽  
Last Common Ancestor ◽  
Modern Humans ◽  
Bayesian Analyses ◽  
Sima De Los Huesos ◽  
Dental Evolution ◽  
Quantitative Analyses

The origin of Neanderthal and modern human lineages is a matter of intense debate. DNA analyses have generally indicated that both lineages diverged during the middle period of the Middle Pleistocene, an inferred time that has strongly influenced interpretations of the hominin fossil record. This divergence time, however, is not compatible with the anatomical and genetic Neanderthal affinities observed in Middle Pleistocene hominins from Sima de los Huesos (Spain), which are dated to 430 thousand years (ka) ago. Drawing on quantitative analyses of dental evolutionary rates and Bayesian analyses of hominin phylogenetic relationships, I show that any divergence time between Neanderthals and modern humans younger than 800 ka ago would have entailed unexpectedly rapid dental evolution in early Neanderthals from Sima de los Huesos. These results support a pre–800 ka last common ancestor for Neanderthals and modern humans unless hitherto unexplained mechanisms sped up dental evolution in early Neanderthals.

Coalescent process with fluctuating population size and its effective size

2004 ◽  
Vol 65 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Akinori Sano ◽  
Akinobu Shimizu ◽  
Masaru Iizuka
Keyword(s):  
Population Size ◽  
Effective Size ◽  
Coalescent Process

scholarly journals On the estimation of ancestral population sizes of modern humans

1997 ◽  
Vol 69 (2) ◽  
pp. 111-116 ◽  
Author(s):  
ZIHENG YANG
Keyword(s):  
Population Size ◽  
Sequence Data ◽  
Divergence Time ◽  
Ancestral Population ◽  
Rate Variation ◽  
Effective Population ◽  
Modern Humans ◽  
Extant Species ◽  
Population Sizes ◽  
Highly Correlated

The theory developed by Takahata and colleagues for estimating the effective population size of ancestral species using homologous sequences from closely related extant species was extended to take account of variation of evolutionary rates among loci. Nuclear sequence data related to the evolution of modern humans were reanalysed and computer simulations were performed to examine the effect of rate variation on estimation of ancestral population sizes. It is found that the among-locus rate variation does not have a significant effect on estimation of the current population size when sequences from multiple loci are sampled from the same species, but does have a significant effect on estimation of the ancestral population size using sequences from different species. The effects of ancestral population size, species divergence time and among-locus rate variation are found to be highly correlated, and to achieve reliable estimates of the ancestral population size, effects of the other two factors should be estimated independently.

scholarly journals EFFECTIVE SIZE OF AUTO-TETRAPLOID POPULATION UNDER PARTIAL SELFING

2015 ◽  
Vol 24 (1) ◽  
pp. 31
Author(s):  
Muhamad Sabran
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Numerical Study ◽  
Effective Size ◽  
Double Reduction ◽  
Effective Population ◽  
Census Size ◽  
Sister Chromatids ◽  
Tetraploid Population ◽  
Arbitrary Rate

Effective population size is defined as the number of breeding individual in an idealized population that would show the same amount of dispersion of allele frequencies under random genetic drift or the same amount of inbreeding as the population under consideration. Effective population size depends on the census size of the population and the mating system. In autotetraploid population, effective population size also depends on the probability of double reduction, i.e., a meiotic event when two sister chromatids end in the same gamete. In this research, we will study the effect of the probability of double reduction on the effective size of autotetraploid population reproduced by partial selfing. The formula for the effective population size was derived by equating the variance of the change in gene frequency in idealized population and its value in the autotetraploid population with arbitrary rate of partial selfing and double reduction. The resulted formula, and numerical study based on the formula, indicated that the effective size decreases by the increase of probability of double reduction and the rate of selfing. When there is complete selfing, however, the effective size is not affected by the probability of double reduction.

scholarly journals Effective size of nonrandom mating populations.

Genetics ◽  
1992 ◽  
Vol 130 (4) ◽  
pp. 909-916 ◽  
Author(s):  
A Caballero ◽  
W G Hill
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Family Size ◽  
Genetic Drift ◽  
Effective Size ◽  
Effective Population ◽  
Gene Frequencies ◽  
Nonrandom Mating ◽  
Sib Mating ◽  
Census Number

Abstract Nonrandom mating whereby parents are related is expected to cause a reduction in effective population size because their gene frequencies are correlated and this will increase the genetic drift. The published equation for the variance effective size, Ne, which includes the possibility of nonrandom mating, does not take into account such a correlation, however. Further, previous equations to predict effective sizes in populations with partial sib mating are shown to be different, but also incorrect. In this paper, a corrected form of these equations is derived and checked by stochastic simulation. For the case of stable census number, N, and equal progeny distributions for each sex, the equation is [formula: see text], where Sk2 is the variance of family size and alpha is the departure from Hardy-Weinberg proportions. For a Poisson distribution of family size (Sk2 = 2), it reduces to Ne = N/(1 + alpha), as when inbreeding is due to selfing. When nonrandom mating occurs because there is a specified system of partial inbreeding every generation, alpha can be substituted by Wright's FIS statistic, to give the effective size as a function of the proportion of inbred mates.

scholarly journals On the effective size of populations with separate sexes, with particular reference to sex-linked genes.

Genetics ◽  
1995 ◽  
Vol 139 (2) ◽  
pp. 1007-1011 ◽  
Author(s):  
A Caballero
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Effective Size ◽  
Effective Population ◽  
Poisson Distributions

Abstract Inconsistencies between equations for the effective population size of populations with separate sexes obtained by two different approaches are explained. One approach, which is the most common in the literature, is based on the assumption that the sex of the progeny cannot be identified. The second approach incorporates identification of the sexes of both parents and offspring. The approaches lead to identical expressions for effective size under some situations, such as Poisson distributions of offspring numbers. In general, however, the first approach gives incorrect answers, which become particularly severe for sex-linked genes, because then only numbers of daughters of males are relevant. Predictions of the effective size for sex-linked genes are illustrated for different systems of mating.

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