Extent of Protein Polymorphism and the Neutral Mutation Theory

Nei, Masatoshi; Graur, Dan

doi:10.1007/978-1-4615-6974-9_3

Cited by 226 publications

(193 citation statements)

References 176 publications

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“…1), the log likelihood value at n ϭ 10 4 is significantly smaller than that at n ϭ 10 5 or 10 6 . Because n ϭ 10 4 is the ML estimate from the data for the extant human population (x ϭ 0.08% and g ϭ 15-20 years) and the 90% confidence limit ranges from 5,700 to 17,000 (33,34), the rather small value of N reflects the demographic history of past 20,000 generations or 300,000-400,000 years during which Homo erectus dispersed over Eurasia. Thus, there might have been a reduction in N after H. erectus first migrated out of Africa, although the reduction might not be severe as suggested by the long persistence of polymorphism at major histocompatibility complex loci (35).…”

Section: Resultsmentioning

confidence: 99%

Evolution of the primate lineage leading to modern humans: Phylogenetic and demographic inferences from DNA sequences

Takahata

Satta

1997

Proc. Natl. Acad. Sci. U.S.A.

174

143

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To date major divergences that occurred in the primate lineage leading to modern humans and to infer a demographic parameter (effective population size) of the ancestral lineage that existed at each divergence, a maximum likelihood method was applied to autosomal DNA sequence data currently available for pairs of orthologous genes between the human and each of the chimpanzee, gorilla, Old World monkey (OWM), and New World monkey (NWM). A statistical test is carried out to support the assumption that silent substitutions have accumulated in a clock-like fashion over loci between primate taxa or even among sites within a locus. It is shown that the human ancestral lineage became distinct from the NWM 57.5 million years (Myr) ago, the OWM 31 Myr ago, the gorilla 8.0 Myr ago, and the chimpanzee 4.5 Myr ago, and that the effective population size at these divergences was generally much greater than that of modern humans. It is argued that the human ancestral lineage branched off from the NWM and OWM earlier than once thought and that significant demographic changes might have occurred at different evolutionary stages, particularly at the hominid stage.

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Section: Resultsmentioning

confidence: 99%

Evolution of the primate lineage leading to modern humans: Phylogenetic and demographic inferences from DNA sequences

Takahata

Satta

1997

Proc. Natl. Acad. Sci. U.S.A.

174

143

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“…Bottlenecks are therefore thought to be involved in speciation events (e.g. Mayr 1963;Carson 1990;Slatkin 1996), heterozygote de¢ciency in natural populations (Nei & Graur 1984), low levels of genetic variation (Bonnell & Selander 1974;O'Brien et al 1983;Ellegren et al 1996;Groombridge et al 2000), and reduced reproductive function (Wildt et al 1987;Madsen et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Immigration and the ephemerality of a natural population bottleneck: evidence from molecular markers

Keller

Jeffery

Arcese

et al. 2001

Proc. R. Soc. Lond. B

256

234

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Population bottlenecks are often invoked to explain low levels of genetic variation in natural populations, yet few studies have documented the direct genetic consequences of known bottlenecks in the wild. Empirical studies of natural population bottlenecks are therefore needed, because key assumptions of theoretical and laboratory studies of bottlenecks may not hold in the wild. Here we present microsatellite data from a severe bottleneck (95% mortality) in an insular population of song sparrows (Melospiza melodia). The major ¢ndings of our study are as follows: (i) The bottleneck reduced heterozygosity and allelic diversity nearly to neutral expectations, despite non-random survival of birds with respect to inbreeding and wing length. (ii) All measures of genetic diversity regained pre-bottleneck levels within two to three years of the crash. This rapid recovery was due to low levels of immigration. (iii) The rapid recovery occurred despite a coincident, strong increase in average inbreeding. These results show that immigration at levels that are hard to measure in most ¢eld studies can lead to qualitatively very di¡erent genetic outcomes from those expected from mutations only. We suggest that future theoretical and empirical work on bottlenecks and metapopulations should address the impact of immigration.

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“…Most natural populations of plants and animals exhibit high levels of genetic variability [1,2]. The forces maintaining this variation, however, are still poorly understood and are the subject of much debate [3±7].…”

Section: Introductionmentioning

confidence: 99%

Metazoan parasite species richness and genetic variation among freshwater fish species: cause or consequence?

Poulin

Marshall

Spencer

2000

International Journal for Parasitology

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The factors responsible for the maintenance of genetic variation among natural populations remain a mystery. Recent models of host±parasite co-evolution assume that parasites exert frequency-dependent selection on their hosts by favouring rare alleles that may confer resistance against infection. We tested this prediction in a comparative analysis that sought relationships between levels of genetic variation and the number of metazoan parasite species exploiting each host species. We used data on 40 species of North American freshwater ®shes. After controlling for sampling e ort and phylogenetic in¯uences, we found no relationship between genetic polymorphism and parasite species richness among ®sh species. However, we found a marginal negative correlation between parasite species richness and heterozygosity. This result goes against the prediction that increased selective pressure by parasites should be associated with higher levels of genetic variation. Instead, it suggests that parasites may be colonising host species showing low levels of genetic variation with greater success than genetically more variable host species. 7

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Extent of Protein Polymorphism and the Neutral Mutation Theory

Cited by 226 publications

References 176 publications

Evolution of the primate lineage leading to modern humans: Phylogenetic and demographic inferences from DNA sequences

Evolution of the primate lineage leading to modern humans: Phylogenetic and demographic inferences from DNA sequences

Immigration and the ephemerality of a natural population bottleneck: evidence from molecular markers

Metazoan parasite species richness and genetic variation among freshwater fish species: cause or consequence?

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