scholarly journals A serial founder effect model for human settlement out of Africa

2008 ◽  
Vol 276 (1655) ◽  
pp. 291-300 ◽  
Author(s):  
Omkar Deshpande ◽  
Serafim Batzoglou ◽  
Marcus W Feldman ◽  
L Luca Cavalli-Sforza
Keyword(s):  
Genetic Diversity ◽  
Founder Effect ◽  
Published Data ◽  
Geographical Patterns ◽  
Effect Model ◽  
Occupied Territories ◽  
Out Of Africa ◽  
Serial Founder Effect ◽  
Parameter Values ◽  
Linear Decay

The increasing abundance of human genetic data has shown that the geographical patterns of worldwide genetic diversity are best explained by human expansion out of Africa. This expansion is modelled well by prolonged migration from a single origin in Africa with multiple subsequent serial founding events. We discuss a new simulation model for the serial founder effect out of Africa and compare it with results from previous studies. Unlike previous models, we distinguish colonization events from the continued exchange of people between occupied territories as a result of mating. We conduct a search through parameter space to estimate the range of parameter values that best explain key statistics from published data on worldwide variation in microsatellites. The range of parameters we use is chosen to be compatible with an out-of-Africa migration at 50–60 Kyr ago and archaeo–ethno–demographic information. In addition to a colonization rate of 0.09–0.18, for an acceptable fit to the published microsatellite data, incorporation into existing models of exchange between neighbouring populations is essential, but at a very low rate. A linear decay of genetic diversity with geographical distance from the origin of expansion could apply to any species, especially if it moved recently into new geographical niches.

scholarly journals Can a linguistic serial founder effect originating in Africa explain the worldwide phonemic cline?

2016 ◽  
Vol 13 (117) ◽  
pp. 20160185 ◽  
Author(s):  
Joaquim Fort ◽  
Joaquim Pérez-Losada
Keyword(s):  
Numerical Simulations ◽  
Range Expansion ◽  
Founder Effect ◽  
Linguistic Diversity ◽  
Unit Area ◽  
Accumulation Rate ◽  
Out Of Africa ◽  
Serial Founder Effect

It has been proposed that a serial founder effect could have caused the present observed pattern of global phonemic diversity. Here we present a model that simulates the human range expansion out of Africa and the subsequent spatial linguistic dynamics until today. It does not assume copying errors, Darwinian competition, reduced contrastive possibilities or any other specific linguistic mechanism. We show that the decrease of linguistic diversity with distance (from the presumed origin of the expansion) arises under three assumptions, previously introduced by other authors: (i) an accumulation rate for phonemes; (ii) small phonemic inventories for the languages spoken before the out-of-Africa dispersal; (iii) an increase in the phonemic accumulation rate with the number of speakers per unit area. Numerical simulations show that the predictions of the model agree with the observed decrease of linguistic diversity with increasing distance from the most likely origin of the out-of-Africa dispersal. Thus, the proposal that a serial founder effect could have caused the present observed pattern of global phonemic diversity is viable, if three strong assumptions are satisfied.

scholarly journals Comment on "Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa"

Science ◽  
2012 ◽  
Vol 335 (6072) ◽  
pp. 1042-1042 ◽  
Author(s):  
T. F. Jaeger ◽  
D. Pontillo ◽  
P. Graff
Keyword(s):  
Founder Effect ◽  
Effect Model ◽  
Serial Founder Effect

scholarly journals Cooperation mitigates diversity loss in a spatially expanding microbial population

2019 ◽  
Author(s):  
Saurabh Gandhi ◽  
Kirill S. Korolev ◽  
Jeff Gore
Keyword(s):  
Genetic Diversity ◽  
Genetic Drift ◽  
Founder Effect ◽  
Growth Dynamics ◽  
Low Density ◽  
Density Region ◽  
Diversity Loss ◽  
High Density Region ◽  
Expanding Population ◽  
Serial Founder Effect

AbstractThe evolution and potentially even the survival of a spatially expanding population depends on its genetic diversity, which can decrease rapidly due to a serial founder effect. The strength of the founder effect is predicted to depend strongly on the details of the growth dynamics. Here, we probe this dependence experimentally using a single microbial species, Saccharomyces cerevisiae, expanding in multiple environments that induce varying levels of cooperativity during growth. We observe a drastic reduction in diversity during expansions when yeast grows non-cooperatively on simple sugars, but almost no loss of diversity when cooperation is required to digest complex metabolites. These results are consistent with theoretical expectations. When cells grow independently from each other, the expansion proceeds as a pulled wave driven by the growth at the low-density tip of the expansion front. Such populations lose diversity rapidly because of the strong genetic drift at the expansion edge. In contrast, diversity loss is substantially reduced in pushed waves that arise due to cooperative growth. In such expansions, the low-density tip of the front grows much more slowly and is often reseeded from the genetically diverse population core. Additionally, in both pulled and pushed expansions, we observe a few instances of abrupt changes in allele fractions due to rare fluctuations of the expansion front and show how to distinguish such rapid genetic drift from selective sweeps.Significance statementSpatially expanding populations lose genetic diversity rapidly because of the repeated bottlenecks formed at the front as a result of the serial founder effect. However, the rate of diversity loss depends on the specifics of the expanding population, such as its growth and dispersal dynamics. We have previously demonstrated that changing the amount of within-species cooperation leads to a qualitative transition in the nature of expansion from pulled (driven by migration at the low density tip) to pushed (driven by migration from the high density region at the front, but behind the tip). Here we demonstrate experimentally that pushed waves, which emerge in the presence of sufficiently strong cooperation, result in strongly reduced genetic drift during range expansions, thus preserving genetic diversity in the newly colonized region.

scholarly journals Comment on "Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa"

Science ◽  
2012 ◽  
Vol 335 (6069) ◽  
pp. 657-657 ◽  
Author(s):  
C.-C. Wang ◽  
Q.-L. Ding ◽  
H. Tao ◽  
H. Li
Keyword(s):  
Founder Effect ◽  
Effect Model ◽  
Serial Founder Effect
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