1. Polymorphism Polymorphism at the nucleotide level ranges over at least an order of magnitude within species, and average polymorphism ranges over two orders of magnitude between species. Homo sapiens is among the least polymorphic of all species, with a heterozygous single nucleotide polymorphism (SNP) generally occurring once every 500 to 1000 bp (International […]

Modeling human genetic history

1. Introduction The genetic patterns observed today in the human species are the result of a complex history including population expansions and collapses, migration, colonization, extinction, and admixture events. These events have taken place in different locations and times, sometimes involving populations that have been separated for centuries or millennia. Given that anatomically modern humans […]

Homeobox gene repertoires: implications for the evolution of diversity (Genetics)

1. Introduction With the completion of sequencing the DNA of numerous entire genomes, a comprehensive analysis of gene repertoires in evolutionary perspective becomes possible. Of particular interest are those types of genes that are thought to be responsible for, or contributing to, the evolutionary changes that manifest themselves in the various distinct species. One of […]

Geographic structure of human genetic variation: medical and evolutionary implications

1. Introduction This article is divided into three sections. In the first section we shall describe what we consider the main features of human geographic structure, that is, the fact that, on the average, two individuals living in the same geographic area are genetically more similar than two individuals living in different areas. Some common […]

Studies of human genetic history using the Y chromosome

The human Y chromosome’s raison d’etre is sex (in particular, male sex determination), and this louche connection has made it perhaps the strangest segment of our genome. It is specific to males and constitutively haploid in a diploid organism, and therefore escapes from recombination for most of its length, apart from the two pseudoautosomal regions […]

Studies of human genetic history using mtDNA variation

At fertilization, the genetic contribution of the oocyte to the zygote differs from that of the spermatozoon since the latter does not contribute viable mitochondria. These cytoplasmic organelles harbor numerous copies of a circular genome (~16 570 bp), which is characterized by a much higher evolution rate (10-20 folds) than that of the average nuclear […]

The genetic structure of human pathogens

The contemporary genetic structure and the evolutionary history of human pathogens are important to control and prevention strategies, as well as providing interesting case studies in evolutionary biology. Recently, large-scale DNA sequence data have become available for a wide variety of pathogens, and have revealed a variety of structures as diverse as the pathogens themselves. […]

Genetic signatures of natural selection

1. Introduction Identifying genomic regions involved in the adaptive divergence of closely related species or populations is a major goal of evolutionary genetics research. Adaptations come about through a variety of modes, including global selection for a particular allele, local adaptation, where alternative alleles are favored in different environments, and balancing selection (heterozygote advantage), where […]

Modeling protein evolution (Genetics)

Proteins are the biological macromolecular entities most closely and directly related to organismal function, and knowledge of protein structure and function is critical to understanding biological organization. The evolution of protein sequence is molded by the specific requirements of structure and function, and thus an important avenue for predicting features of protein structure and function […]

The role of gene regulation in evolution (Genetics)

Evolutionary biologists have long sought to understand the genetic basis of evolutionary change. For theoretical reasons, biologists have predicted that mutations affecting the regulation of gene expression, rather than the physical structure of gene products, will play a central role in phenotypic evolution. Recent empirical work has begun to nail down the molecular details underpinning […]