Winning by Losing in the Human Genome?

The idea that evolution is led by increasing genetic complexity has, over the years, annealed into the general opinion of geneticists. This increasing complexity is developed through the expensive and slow innovation cycle of gene duplication, mutation, and selection; and so, it seems contrary that a species’ fitness could be improved by losing hard-won genetic capabilities, as has been proposed by the “less is more” hypothesis (Olson, 1999). For that reason, genetic research has traditionally dealt with active genes instead of “broken” ones (or pseudogenes). The lack of a deep knowledge about the genomic significance of adaptive gene losses in mammalian genome evolution explains the important contribution of a recent study in this research area (Zhu et al, 2007). This recent work applied an ingenious method to systematically identify the losses of genes that had been long established in the human lineage over the last 75 million years. A total of 26 well-established genes, inactivated long after their birth, were identified by this analysis, with the identification of 16 previously uncharacterized human pseudogenes. This work completes former studies about pseudogene formation during human origin (Wang et al, 2006), and provides important insights for a better comprehension of this particular genetic phenomenon, in a field scarcely documented until now.

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Rapid Correspondence – Gender Genomics and Equality

In response to the recent publication of the Florida Lancelet’s genome draft in the June 19th issue of Nature (Nature 453:1064-1071), Mark Hauber of the University of Auckland, New Zealand and colleagues here highlight the important and broader issue of gender genomics in this context.

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Rapid Correspondence – Molecular clock debate

The complex issue of mtDNA rate measurement is a topic of hot debate. In the first issue of Heredity this year H-J Bandelt (Heredity 100, 1-2) provided an interesting news and commentary on this topic, discussing the use of simple mtDNA clocks in molecular dating.

Howell et al. here provide a detailed response to Prof Bandelt’s commentary, arguing that mtDNA evolution is not clock-like and that the evidence for time dependent rates should not be dismissed.

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Rapid Correspondence – One-sided evolution or two? A reply to Ennos

A recent News and Commentary published in Heredity (Heredity 100, 3-4) proposed an alternative hypothesis to the ‘pollinator shift’ hypothsis suggested in a letter by Whittall and Hodges published in Nature (Nature 447, 706-709) . Here, Scott Hodges and Justen Whittall provide their response to this.

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Rapid Correspondence – Mitochondrial DNA polymorphism in birds

After reading with interest an article by Berlin et al. (Heredity 99, 389-396) on mitochondiral variability in birds, Anthony Hickey proposes an alternative interpretation to the data showing low mtDNA diversity, which they attributed to Hill-Robertson effects.

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Dispersal estimation: Demystifying Moran’s I

Populations spaced further apart are expected to be more genetically distinct than populations close together. This pattern arises because neighbouring populations exchange genes.

The trend can be used to infer the magnitude of gene flow.

François Rousset has written papers showing how to calculate such estimates but some researchers – especially plant geneticists – use rival methods based on the statistic “Moran’s I”. Rousset explains why his methods are an advance on these alternatives in a recent News and Commentary published in Heredity.

Click here to read the Heredity News and Commentary

Africans in Yorkshire: what’s the big deal?

A genetic survey in the UK by Mark Jobling and colleagues, found a Yorkshireman who carried a globally rare Y chromosome type, described previously in only a few West African individuals. Their report in the European Journal of Human Genetics earlier this year sparked considerable press speculation about the history of African migrations into the UK.

Further information was obtained by enlarging the sample. Y chromosomes and surnames are both passed from father to son, so other men sharing the same rare east-Yorkshire surname as the original man were recruited for their study in the search for additional Y’s. One third of them were also found to carry the African chromosome. Conventional genealogical research was then used to link the participants to two family trees, both dating back to the 1780s in Yorkshire. Does this evidence pin down the date at which an African ancestor arrived in the UK?

Neil Bradman and Mark Thomas are doubtful. They have published a commentary in Heredity asking whether we should be surprised by the discovery of this Y haplotype in Yorkshire at all, given the accepted wisdom that Modern Man originated from Africa. Indeed, is it not more surprising that from a survey of 421 British males, only one carried the rare African Y chromosome?

Post a comment to share your thoughts.

Click here to read the European Journal of Human Genetics article

Click here to read the Heredity News and Commentary