Population genetics and comparative genomics of Anopheles mosquitoes with different feeding behaviours

AbstractGene duplication creates a second copy of a gene either in tandem to the ancestral locus or dispersed to another chromosomal location. When the ancestral copy of a dispersed duplicate is lost from the genome, it creates the appearance that the gene was “relocated” from the ancestral locus to the derived location. Gene relocations may be as common as canonical dispersed duplications in which both the ancestral and derived copies are retained. Relocated genes appear to be under more selective constraints than the derived copies of canonical duplications, and they are possibly as conserved as single-copy non-relocated genes. To test this hypothesis, we combined comparative genomics, population genetics, gene expression, and functional analyses to assess the selection pressures acting on relocated, duplicated, and non-relocated single-copy genes in Drosophila genomes. We find that relocated genes evolve faster than single-copy non-relocated genes, and there is no evidence that this faster evolution is driven by positive selection. In addition, relocated genes are less essential for viability and male fertility than single-copy non-relocated genes, suggesting that relocated genes evolve fast because of relaxed selective constraints. However, relocated genes evolve slower than the derived copies of canonical dispersed duplicated genes. We therefore conclude that relocated genes are under more selective constraints than canonical duplicates, but are not as conserved as single-copy non-relocated genes.

Download Full-text

Insights from genomic comparisons of genetically monomorphic bacterial pathogens

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2011.0303 ◽

2012 ◽

Vol 367 (1590) ◽

pp. 860-867 ◽

Cited By ~ 77

Author(s):

Mark Achtman

Keyword(s):

Genetic Diversity ◽

Staphylococcus Aureus ◽

Population Genetics ◽

Comparative Genomics ◽

High Throughput ◽

Antibiotic Resistant ◽

Bacterial Diseases ◽

History Of ◽

Low Levels ◽

Historical Accounts

Some of the most deadly bacterial diseases, including leprosy, anthrax and plague, are caused by bacterial lineages with extremely low levels of genetic diversity, the so-called ‘genetically monomorphic bacteria’. It has only become possible to analyse the population genetics of such bacteria since the recent advent of high-throughput comparative genomics. The genomes of genetically monomorphic lineages contain very few polymorphic sites, which often reflect unambiguous clonal genealogies. Some genetically monomorphic lineages have evolved in the last decades, e.g. antibiotic-resistant Staphylococcus aureus , whereas others have evolved over several millennia, e.g. the cause of plague, Yersinia pestis . Based on recent results, it is now possible to reconstruct the sources and the history of pandemic waves of plague by a combined analysis of phylogeographic signals in Y. pestis plus polymorphisms found in ancient DNA. Different from historical accounts based exclusively on human disease, Y. pestis evolved in China, or the vicinity, and has spread globally on multiple occasions. These routes of transmission can be reconstructed from the genealogy, most precisely for the most recent pandemic that was spread from Hong Kong in multiple independent waves in 1894.

Download Full-text