Limits...
Nonrandom Wolbachia infection status of Drosophila melanogaster strains with different mtDNA haplotypes.

Nunes MD, Nolte V, Schlötterer C - Mol. Biol. Evol. (2008)

Bottom Line: In Drosophila melanogaster, Wolbachia is quite common but CI is variable, with most of the studies reporting low levels of CI.Consistent with this observation, we found that the acquisition of a Wolbachia infection in a population from Crete was accompanied with an almost complete mtDNA replacement, with the Wolbachia-associated haplotype becoming abundant.Although it is difficult to identify the evolutionary forces causing the global increase of wMel, the parallel sweep of Wolbachia and an mtDNA haplotype suggests a fitness advantage of the Wolbachia infection.

View Article: PubMed Central - PubMed

Affiliation: Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna, Austria.

ABSTRACT
Wolbachia are maternally inherited bacteria, which typically spread in the host population by inducing cytoplasmic incompatibility (CI). In Drosophila melanogaster, Wolbachia is quite common but CI is variable, with most of the studies reporting low levels of CI. Surveying mitochondrial DNA (mtDNA) variation and infection status in a worldwide D. melanogaster collection, we found that the Wolbachia infection was not randomly distributed among flies with different mtDNA haplotypes. This preferential infection of some mtDNA haplotypes could be caused by a recent spread of mtDNA haplotypes associated with the infection. The comparison of contemporary D. melanogaster samples with lines collected more than 50 years ago shows that indeed one haplotype with a high incidence of Wolbachia infection has increased in frequency. Consistent with this observation, we found that the acquisition of a Wolbachia infection in a population from Crete was accompanied with an almost complete mtDNA replacement, with the Wolbachia-associated haplotype becoming abundant. Although it is difficult to identify the evolutionary forces causing the global increase of wMel, the parallel sweep of Wolbachia and an mtDNA haplotype suggests a fitness advantage of the Wolbachia infection.

Show MeSH

Related in: MedlinePlus

Change in infection frequency over 40 generations with different values of H (relative hatch rate from incompatible crosses). With an initial frequency of 5% of Wolbachia-infected individuals, a high CI expression (H ≤ 0.3) is necessary to lead to the observed increase of the infection frequency.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2568037&req=5

fig2: Change in infection frequency over 40 generations with different values of H (relative hatch rate from incompatible crosses). With an initial frequency of 5% of Wolbachia-infected individuals, a high CI expression (H ≤ 0.3) is necessary to lead to the observed increase of the infection frequency.

Mentions: To distinguish between a CI and positive fitness effects mediated increase in Wolbachia infection in the Crete population, we evaluated the parameter range for which the frequency of Wolbachia could increase from 5% to 100%. Interestingly, we found that a relative hatch rate 0.3 or less would be required to capture the increase in Wolbachia infection seen in Crete (fig. 2). Fast-developing males of a given family could in principle express CI levels as high as this (Yamada et al. 2007). However, as the high CI is limited to a very short time interval, a natural population with males of different age classes will have a substantially lower mean CI. Furthermore, in D. simulans, the mating success of older males seems to be higher (Hoffmann et al. 1990; Turelli and Hoffmann 1995). If the same holds true for D. melanogaster, the impact of the “younger male” effect would be even smaller. Consequently, the parallel increase of haplotype 2 with the wMel Wolbachia infection in the Cretan population is most likely the result of a fitness benefit, mediated either through mtDNA or Wolbachia.


Nonrandom Wolbachia infection status of Drosophila melanogaster strains with different mtDNA haplotypes.

Nunes MD, Nolte V, Schlötterer C - Mol. Biol. Evol. (2008)

Change in infection frequency over 40 generations with different values of H (relative hatch rate from incompatible crosses). With an initial frequency of 5% of Wolbachia-infected individuals, a high CI expression (H ≤ 0.3) is necessary to lead to the observed increase of the infection frequency.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2568037&req=5

fig2: Change in infection frequency over 40 generations with different values of H (relative hatch rate from incompatible crosses). With an initial frequency of 5% of Wolbachia-infected individuals, a high CI expression (H ≤ 0.3) is necessary to lead to the observed increase of the infection frequency.
Mentions: To distinguish between a CI and positive fitness effects mediated increase in Wolbachia infection in the Crete population, we evaluated the parameter range for which the frequency of Wolbachia could increase from 5% to 100%. Interestingly, we found that a relative hatch rate 0.3 or less would be required to capture the increase in Wolbachia infection seen in Crete (fig. 2). Fast-developing males of a given family could in principle express CI levels as high as this (Yamada et al. 2007). However, as the high CI is limited to a very short time interval, a natural population with males of different age classes will have a substantially lower mean CI. Furthermore, in D. simulans, the mating success of older males seems to be higher (Hoffmann et al. 1990; Turelli and Hoffmann 1995). If the same holds true for D. melanogaster, the impact of the “younger male” effect would be even smaller. Consequently, the parallel increase of haplotype 2 with the wMel Wolbachia infection in the Cretan population is most likely the result of a fitness benefit, mediated either through mtDNA or Wolbachia.

Bottom Line: In Drosophila melanogaster, Wolbachia is quite common but CI is variable, with most of the studies reporting low levels of CI.Consistent with this observation, we found that the acquisition of a Wolbachia infection in a population from Crete was accompanied with an almost complete mtDNA replacement, with the Wolbachia-associated haplotype becoming abundant.Although it is difficult to identify the evolutionary forces causing the global increase of wMel, the parallel sweep of Wolbachia and an mtDNA haplotype suggests a fitness advantage of the Wolbachia infection.

View Article: PubMed Central - PubMed

Affiliation: Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna, Austria.

ABSTRACT
Wolbachia are maternally inherited bacteria, which typically spread in the host population by inducing cytoplasmic incompatibility (CI). In Drosophila melanogaster, Wolbachia is quite common but CI is variable, with most of the studies reporting low levels of CI. Surveying mitochondrial DNA (mtDNA) variation and infection status in a worldwide D. melanogaster collection, we found that the Wolbachia infection was not randomly distributed among flies with different mtDNA haplotypes. This preferential infection of some mtDNA haplotypes could be caused by a recent spread of mtDNA haplotypes associated with the infection. The comparison of contemporary D. melanogaster samples with lines collected more than 50 years ago shows that indeed one haplotype with a high incidence of Wolbachia infection has increased in frequency. Consistent with this observation, we found that the acquisition of a Wolbachia infection in a population from Crete was accompanied with an almost complete mtDNA replacement, with the Wolbachia-associated haplotype becoming abundant. Although it is difficult to identify the evolutionary forces causing the global increase of wMel, the parallel sweep of Wolbachia and an mtDNA haplotype suggests a fitness advantage of the Wolbachia infection.

Show MeSH
Related in: MedlinePlus