Cytoplasmic sex ratio distorters Flashcards
What work did Stouthammer et al. (2010) do on parthenogenesis?
Trichogramma genus of parasitoid wasp carries Wolbachia. Bacteria cause diploidisation of unfertilised eggs by failure of the 1st/2nd mitotic division, causing them to develop as females not males.
In parasitoid wasps of the Asorbara genus, A. tabida can no longer complete oogenesis without Wolbachia. A. japonica without Wolbachia can produce eggs but females no longer produce sex pheromones/have sex, eggs remain unfertilised. This shows co-evolution of the host and cytoplasmic sec ratio distorter during parthenogenesis. Who found this?
Kremer et al. (2009)
What did Stouthammer et al. (2001) find about restoring Wolbachia-induced parthenogenesis?
In Trichogramma kaykai (parasitoid wasp) PSR B chromosome transmitted by males destroys all paternal chromosomes except itself, turning diploid females into haploid males. In Wolbachia-infected pops this bring the sex ratio back to equilibrium.
What did Rigaud et al. (1997) find in Armadillidium vulgare (the woodlouse)?
Feminisation: males are ZZ and females ZW, but Wolbachia prevent differentiation of the androgen gland so the testes cannot develop. This causes genetic males to be functional phenotypic females.
What two ways did Bandi et al. (2001) find that cytoplasmic elements benefit from male killing?
a) Can be horizontally transmitted as well as vertically. Kill dead end male and can migrate into female, e.g. microsporidium protozoa inside mosquitos
b) Benefit clonal relatives as dead males provide a meal for hatched sisters, e.g. Wolbachia inside ladybirds
What did Hornett et al. (2006) find in Hypolimnas bolina butterflies?
Thai and Philippine populations had normal sex ratios whilst Polynesian populations did not, both were infected with Wolbachia. Genetic crosses revealed Thai and Philippine showed male-killing in the F2, indicating a dominant mutation has evolved to prevent male killing.
CMS can be restored by PPR (pentatricopeptide repeat) genes in plants like rice. Who found this?
Touzet and Budar, (2004)
