Molecular genetics of speciation and human origins.

  title={Molecular genetics of speciation and human origins.},
  author={Francisco Jos{\'e} Ayala and Anan{\'i}as A. Escalante and Colm O'huigin and Jan Klein},
  journal={Proceedings of the National Academy of Sciences of the United States of America},
  volume={91 15},
  • F. Ayala, A. Escalante, J. Klein
  • Published 19 July 1994
  • Biology
  • Proceedings of the National Academy of Sciences of the United States of America
The major histocompatibility complex (MHC) plays a cardinal role in the defense of vertebrates against parasites and other pathogens. In some genes there are extensive and ancient polymorphisms that have passed from ancestral to descendant species and are shared among contemporary species. The polymorphism at the DRB1 locus, represented by 58 known alleles in humans, has existed for at least 30 million years and is shared by humans, apes, and other primates. The coalescence theory of… 

Genetic Structure of the Ancestral Population of Modern Humans

This ancestral population was characterized by an effective size of about 10,000 as estimated from the nucleotide diversity; this size may describe the number of breeding individuals over a long time during the Middle Pleistocene or reflect a speciation bottleneck from an initially larger population at the end of this period.

Mhc Allelic Diversity and Modern Human Origins

A rigorous analysis of allelic genealogies in this gene family cannot be used to justify the claim that the lineage leading to modern humans contained on average at least 100,000 individuals, according to prior assertions.

Recent origin of HLA-DRB1 alleles and implications for human evolution

The coalescence time of alleles within allelic lineages indicates that the effective population size for early hominids (over the last 1 Myr) was approximately 104 individuals, similar to estimates based on other nuclear loci and mitochondrial DMA.

MHC, TSP, and the origin of species: from immunogenetics to evolutionary genetics.

It is argued that the conclusions reached regarding the cichlid fishes apply also to other examples of adaptive radiation, for example that of Darwin's finches, and so provide new insights into the nature of speciation in general.

Genetics and the human lineage

Investigation of mitochondrial DNA, Y-chromosome DNA, and other genetic polymorphisms have shed light on the size of human populations through hominid history, and recent genetic discoveries have contributed to unravelling the phylogenetic history of distinctive human traits.

Molecular evolution and modern human origins

While molecular evolutionists may be fascinated by the features and history of a particular gene or DNA segment, evolutionary anthropologists are often more interested in the activities and history

The Myth of Eve: Molecular Biology and Human Origins: F. J. Ayala

It has been proposed that modern humans descended from a single woman, the "mitochondrial Eve" who lived in Africa 100,000 to 200,000 years ago, and the weight of the evidence is against a population bottleneck before their emergence.

Increased heterozygosity for MHC class II lineages in newborn males

The MHC-mediated prenatal selection of males may be one of the selective events suggested by the very high primary (male-to-female) sex ratio at fertilization reaching close to unity at birth in humans.

Genetics of Modern Human Origins and Diversity

  • J. Relethford
  • Biology
    The International Encyclopedia of Anthropology
  • 2018
Although the genetic data do provide support for the recent African origin model, they also are compatible with the multiregional model and neither model of modern human origins is unequivocally supported to the exclusion of the other.

Rapid Evolution of Major Histocompatibility Complex Class I Genes in Primates Generates New Disease Alleles in Humans via Hitchhiking Diversity

The overrepresentation of a fraction of these hvSNV (hv1SNV) along with hsSNV, as compared to those that appear to have been maintained throughout primate evolution, tends to establish that the majority of the MHC polymorphism is de novo (species specific).



Ancient roots for polymorphism at the HLA-DQa locus in primates ( polymerase chain reaction / evolution / selection )

Most of the polymorphism at the DQa locus in the human species was already present at least 5 million years ago in the ancestral species that gave rise to the chimpanzee, gorilla, and human lineages, but one of the D Qa alleles may have arisen after speciation by recombination between two ancestral alleles.

Calibrating Evolutionary Rates at Major Histocompatibility Complex Loci

The validity of the assumption that accumulation of interspecific differences is believed by many geneticists to proceed with a clock-like regularity within certain taxonomic groups is demonstrated by comparing alleles at the Mhc-DRB and MhC-DQB loci of different primate species.

Allelic diversification at the class II DQB locus of the mammalian major histocompatibility complex.

The use of oligonucleotide primers to amplify, by the polymerase chain reaction, and sequence the polymorphic second exon of the DQB locus from 11 species, indicates that allelic diversification has occurred subsequent to the divergence of hominoids and some haplotype combinations of DQA and DQB alleles are common to several hominoid species and may have been maintained for at least 5 million years.

The origin of MHC class II gene polymorphism within the genus Mus

It is demonstrated that I–Aβ alleles in these two evolutionary groups diverged at least three million years ago and have survived the speciation events leading to several modern Mus species.

Molecular Evolution of the Major Histocompatibility Complex

Conservation versus polymorphism of the MHC in relation to transplantation, immune responses, and autoimmune disease and multiple mutational mechanisms which generate polymorphism at H-2K are compared.

African populations and the evolution of human mitochondrial DNA.

The African origin hypothesis of human mtDNA evolution is supported by two statistical tests and two hypervariable segments of mtDNA were sequenced from 189 people of diverse geographic origin, including 121 native Africans.

Polymorphism and balancing selection at major histocompatibility complex loci.

A model equivalent to overdominance that confers heterozygote advantage is examined and it is demonstrated that the nucleotide substitution rate at the targeted sites relative to that of neutral sites may be much larger than 1.

Pattern of nucleotide substitution at major histocompatibility complex class I loci reveals overdominant selection

Examination of the pattern of nucleotide substitution between polymorphic alleles in the region of the antigen recognition site (ARS) indicates that in ARS the rate of nonsynonymous substitution is significantly higher than that of synonymous substitution in both humans and mice, whereas in other regions the reverse is true.

Shared class II MHC polymorphisms between humans and chimpanzees.

Allelic genealogy under overdominant and frequency-dependent selection and polymorphism of major histocompatibility complex loci.

Consideration of the molecular mechanism of the function of MHC molecules and other biological observations suggest that the most important factor for the maintenance of M HC polymorphism is overdominant selection, but some experiments are necessary to distinguish between the overdominance and frequency-dependent selection hypotheses.