Phenotypic fitness effects of the selfish B chromosome, paternal sex ratio (PSR) in the parasitic waspNasonia vitripennis

Abstract

Phenotypic fitness effects of the selfish B chromosome, paternal sex ratio (PSR) in the parasitic wasp Nasonia vitripennis Beukeboom, Leo W. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. (PSR) is an extreme example of a parasitic B chromosome in the parasitoid wasp Nasonia vitripennis. PSR is transmitted through the sperm of carrier males and destroys the other paternal chromosomes in early fertilized eggs. PSR disrupts the normal haplodiploid sex determination in this wasp by converting diploid (female) eggs into haploid (male) eggs that bear PSR. In this study I compare a number of phenotypic fitness aspects of PSR and standard (non-PSR) males. In general, PSR males were as fit as standard males. No significant differences were found in longevity (with one exception), ability to compete for mates and sperm depletion rates. PSR males produced 11-22% larger family sizes and developed slightly faster than standard males. Under conditions of sperm competition, females who mated with both types of males fertilized a constant proportion of eggs with each sperm type over their lifetime. PSR males produced fewer offspring among progenies from doubleinseminated females. Phenotypic fitness effects are believed to play a minor role in determining PSR frequencies in natural populations.

Evolution of Tandemly Repeated Sequences: What Happens at the End of an Array?

“…It is very close to the end of a PSR79 array. PSR79 is a complex tandemly repeated sequence (Eickbush et al 1992), and current deletion studies indicate that it occurs in a localized block on the PSR chromosome (Beukeboom and Werren 1993;McAllister, Beukeboom, and Werren, in preparation). The probability that NATE P18 inserted at the end of a PSR79 array is thus low, suggesting migration of this element toward the end of an array after insertion.…”

“…These published PSR2 repeats presumably represent a random sample of repeats located internally within the array, because they were subcloned and sequenced from four clones, each with 15-to 20-kb inserts consisting entirely of PSR2 repeats. PSR2 sequences on the PSR chromosome are remarkably homogeneous in restriction enzyme digestion patterns, there is no evidence of a higher-order structure in the array, and they are localized in one or a few arrays (Eickbush et al 1992;Beukeboom and Werren 1993; J.H.W., unpublished data). As is evident in the visual comparison of repeats in Fig.…”

“…This nonhomologous recombination would have truncated NATE. Since a large amount of this chromosome appears to be functionally inert (Beukeboom and Werren 1993;McAllister, Beukeboom, and Werren, in preparation), it is reasonable to assume that the rearrangement was not deleterious.…”

“…Three of these tandem repeats (PSR2, PSR18, and PSR22) are classic ''satellite'' DNAs and they apparently evolved specifically on PSR, because they are not present on the autosomes of N. vitripennis or related species (Nur et al 1988;Eickbush et al 1992). The three repeated sequences are approximately 171-214 bp in length (Eickbush et al 1992) and are present in large localized arrays on the PSR chromosome (Beukeboom and Werren 1993). Overall sequence similarity is evident and two palindromes are highly conserved among the sequences, thus it appears that these repetitive sequences are evolutionarily related (Eickbush et al 1992;Reed et al 1994).…”

Hybrid origin of a B chromosome (PSR) in the parasitic wasp Nasonia vitripennis

“…Based upon the geographic distribution of PSR (restricted to western North America in an area of sympatry with the sibling species Nasonia longicornis) and evidence that interspecific cytoplasmic incompatibility results in the generation of de novo chromosomal fragments (Ryan et al 1985;Beukeboom and Werren 1993b), it was proposed that PSR arose as a chromosomal fragment from N. longicornis generated by interspecific hybridization with N. vitripennis. In this paper, a sequence analysis of the retrotransposon NATE is used to examine directly the evolutionary history of the PSR chromosome.…”