SMILE

Stochastic Models for the Inference of Life Evolution

Bibtex

@article{lechner_nucleotide_2014,
Author = {Lechner, Sarah and Ferretti, Luca and Schöning,
Caspar and Kinuthia, Wanja and Willemsen, David and
Hasselmann, Martin},
Title = {Nucleotide variability at its limit? {Insights} into
the number and evolutionary dynamics of the
sex-determining specificities of the honey bee {Apis}
mellifera},
Journal = {Molecular Biology and Evolution},
Volume = {31},
Number = {2},
Pages = {272--287},
abstract = {Deciphering the evolutionary processes driving
nucleotide variation in multiallelic genes is limited
by the number of genetic systems in which such genes
occur. The complementary sex determiner (csd) gene in
the honey bee Apis mellifera is an informative example
for studying allelic diversity and the underlying
evolutionary forces in a well-described model of
balancing selection. Acting as the primary signal of
sex determination, diploid individuals heterozygous for
csd develop into females, whereas csd homozygotes are
diploid males that have zero fitness. Examining 77 of
the functional heterozygous csd allele pairs, we
established a combinatorical criteria that provide
insights into the minimum number of amino acid
differences among those pairs. Given a data set of 244
csd sequences, we show that the total number of csd
alleles found in A. mellifera ranges from 53 (locally)
to 87 (worldwide), which is much higher than was
previously reported (20). Using a coupon-collector
model, we extrapolate the presence of in total 116-145
csd alleles worldwide. The hypervariable region (HVR)
is of particular importance in determining csd allele
specificity, and we provide for this region evidence of
high evolutionary rate for length differences exceeding
those of microsatellites. The proportion of amino acids
driven by positive selection and the rate of
nonsynonymous substitutions in the HVR-flanking regions
reach values close to 1 but differ with respect to the
HVR length. Using a model of csd coalescence, we
identified the high originating rate of csd
specificities as a major evolutionary force, leading to
an origin of a novel csd allele every 400,000 years.
The csd polymorphism frequencies in natural populations
indicate an excess of new mutations, whereas signs of
ancestral transspecies polymorphism can still be
detected. This study provides a comprehensive view of
the enormous diversity and the evolutionary forces
shaping a multiallelic gene.},
doi = {10.1093/molbev/mst207},
issn = {1537-1719},
language = {eng},
month = feb,
pmcid = {PMC3907057},
pmid = {24170493},
shorttitle = {Nucleotide variability at its limit?},
year = 2014
}