Brood Size and Sex Ratio Regulation in the Parasitic Wasp Nasonia Vitripennis (Walker) (Hymenoptera: Pteromalidae)

1983 ◽  
Vol 34 (2) ◽  
pp. 123-143 ◽  
Author(s):  
John H. Werren
Keyword(s):  
Sex Ratio ◽  
Brood Size ◽  
Parasitic Wasp ◽  
Nasonia Vitripennis

scholarly journals The comparative biology of second sex ratio evolution within a natural population of a parasitic wasp, Nasonia vitripennis.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 385-396 ◽  
Author(s):  
S H Orzack
Keyword(s):  
Sex Ratio ◽  
Parasitic Wasp ◽  
Comparative Biology ◽  
Significant Heterogeneity ◽  
Regression Analyses ◽  
Nasonia Vitripennis ◽  
Second Sex ◽  
Sex Ratio Adjustment ◽  
Optimality Models ◽  
Isofemale Strains

Abstract Correlation and regression analyses indicate that isofemale strains extracted from a population of the parasitic wasp, Nasonia vitripennis, differ in the fit of their second sex ratios (those produced in previously parasitized hosts) to the predictions of the theory of optimal facultative sex ratio adjustment. Under the theory's simple assumptions about population structure, there is significant heterogeneity of fitnesses among the isofemale strains. The reasons underlying these types of heterogeneity must be understood before we can make statements about the nature of sex ratio evolution in this species. These results suggest that comparative analyses are essential for testing the qualitative predictions of optimality models.

scholarly journals The comparative biology of genetic variation for conditional sex ratio behavior in a parasitic wasp, Nasonia vitripennis.

Genetics ◽  
1991 ◽  
Vol 127 (3) ◽  
pp. 583-599 ◽  
Author(s):  
S H Orzack ◽  
E D Parker ◽  
J Gladstone
Keyword(s):  
Sex Ratio ◽  
Group Size ◽  
Evolutionarily Stable Strategy ◽  
Sex Ratios ◽  
Parasitic Wasp ◽  
Nasonia Vitripennis ◽  
Reasonable Evidence ◽  
Ess Model ◽  
Isofemale Strains ◽  
Evolutionarily Stable

Abstract Using genetic markers, we tracked the sex ratio behavior of individual females of the parasitic wasp, Nasonia vitripennis, in foundress groups of size 1, 2, 4, 8 and 16. Comparison of 12 isofemale strains extracted from a natural population reveals significant between-strain heterogeneity of sex ratios produced in all sizes of foundress group. Under simple assumptions about population structure, this heterogeneity results in heterogeneity of fitnesses. The strains differ in their conditional sex ratio behavior (the sex ratio response of a female to foundress groups of different sizes). Females of some strains produce more males as foundress group size increases (up to size eight). Females of another strain produce more males when not alone but do not respond differentially to group size otherwise. Females of two other strains show no conditional sex ratio behavior. Females of only two strains behave differently in foundress groups of size 8 and 16. Correlation and regression analyses indicate that the strains differ significantly in their fit to the predictions of an evolutionarily stable strategy (ESS) model of conditional sex ratio behavior. Such heterogeneity contradicts the notion that females of this species possess conditonal sex ratio behavior that is optimal in the ESS sense. The results imply that this ESS model is useful but not sufficient for understanding the causal basis of the evolution of this behavior in this species. This is the first report on the sex ratio behavior of individual females in multiple foundress groups in any species of parasitic wasp. Data of this type (and not foundress group or "patch" sex ratios) are essential for testing evolutionary models that predict the sex ratio behaviors of individuals. We suggest that a test for an ESS model include the answers to two important questions: 1) is the model quantitatively accurate? and 2) is there reasonable evidence to indicate that natural selection has caused individuals to manifest the ESS behavior?

scholarly journals Quantitative genetics of sex ratio traits in the parasitic wasp, Nasonia vitripennis.

Genetics ◽  
1994 ◽  
Vol 137 (1) ◽  
pp. 211-220
Author(s):  
S H Orzack ◽  
J Gladstone
Keyword(s):  
Sex Ratio ◽  
Sex Ratios ◽  
Parasitic Wasp ◽  
Genetic Correlations ◽  
Nasonia Vitripennis ◽  
Narrow Sense Heritability ◽  
First Sex ◽  
Second Sex ◽  
Study Population ◽  
Almost All

Abstract We detected significant parent-offspring regressions for the first sex ratio (the sex ratio produced by a female in a fresh host) and the second sex ratio (the sex ratio produced by a female in a previously parasitized host) in the parasitic wasp, Nasonia vitripennis. For both traits, estimates of the narrow-sense heritability range from approximately 0.05 to approximately 0.15 (depending on how the data are analyzed). The study population was derived from isofemale strains created from wasps captured in a single bird nest. The same population exhibited no significant parent-offspring regression for the brood sizes associated with the first and second sex ratios. There may be a significant negative parent-offspring regression for diapause proportion in the first sex ratio broods. The estimates of the genetic correlations between first and second sex ratios are positive although almost all are not significantly different from 0.0. To our knowledge, this study is the first "fine-scale" analysis of genetic variation for sex ratio traits in any species of insect. Such studies are an essential part of the assessment of the validity of claims that sex ratio traits are locally optimal.

Cytogenetic analysis of the paternal sex ratio chromosome of Nasonia vitripennis

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 157-161 ◽  
Author(s):  
Kent M. Reed
Keyword(s):  
Sex Ratio ◽  
Silver Staining ◽  
Organizer Region ◽  
Parasitic Wasp ◽  
Nucleolus Organizer Region ◽  
B Chromosome ◽  
Nucleolus Organizer ◽  
Nasonia Vitripennis ◽  
C Banding ◽  
Paternal Sex Ratio

Paternal sex ratio (PSR) is a B chromosome found in the parasitic wasp Nasonia vitripennis. PSR has a unique etiology in that it destroys the paternal chromosomes of fertilized eggs, resulting in the production of all male families. This study examined structural aspects of PSR including size, C-banding, and silver staining. PSR was found to constitute approximately 5.7% of the genome of carrier males. C-banding confirmed the heterochromatic nature of PSR and the data suggest that PSR remains primarily condensed throughout the cell cycle. Examination of prometaphase spermatocytes revealed a secondary constriction on PSR. The constriction, however, did not stain positive for nucleolus organizer activity. During mitosis, PSR and the pericentromeric regions of the A chromosomes displayed a temporal pattern of silver staining, involving dense precipitation of silver prior to metaphase. This reaction is indicative of a protein complex specific to the heterochromatin of these regions. The implications of these findings to the origin of PSR are discussed.Key words: Nasonia vitripennis, paternal sex ratio, B chromosome, nucleolus organizer region, heterochromatin.

scholarly journals Deletion analysis of the selfish B chromosome, Paternal Sex Ratio (PSR), in the parasitic wasp Nasonia vitripennis.

Genetics ◽  
1993 ◽  
Vol 133 (3) ◽  
pp. 637-648 ◽  
Author(s):  
L W Beukeboom ◽  
J H Werren
Keyword(s):  
Sex Ratio ◽  
Dna Sequences ◽  
Parasitic Wasp ◽  
B Chromosome ◽  
Deletion Analysis ◽  
Functional Domains ◽  
Functional Domain ◽  
Paternal Chromosome ◽  
Nasonia Vitripennis ◽  
Paternal Sex Ratio

Abstract Paternal Sex Ratio (PSR) is a "selfish" B chromosome in the parasitoid wasp Nasonia vitripennis. It is transmitted via sperm, but causes supercondensation and destruction of the paternal chromosomes in early fertilized eggs. Because this wasp has haplodiploid sex determination, the effect of PSR is to convert diploid (female) eggs into haploid (male) eggs that carry PSR. Characterizing its genetic structure is a first step toward understanding mechanisms of PSR action. The chromosome is largely heterochromatic and contains several tandemly repeated DNA sequences that are not present on the autosomes. A deletion analysis of PSR was performed to investigate organization of repeats and location of functional domains causing paternal chromosome destruction. Deletion profiles using probes to PSR-specific repetitive DNA indicate that most repeats are organized in blocks on the chromosome. This study shows that the functional domains of PSR can be deleted, resulting in nonfunctional PSR chromosomes that are transmitted to daughters. A functional domain may be linked with the psr22 repeat, but function may also depend on abundance of PSR-specific repeats on the chromosome. It is hypothesized that the repeats act as a "sink" for a product required for proper paternal chromosome processing. Almost all deletion chromosomes remained either functional of nonfunctional in subsequent generations following their creation. One chromosome was exceptional in that it reverted from nonfunctionality to functionality in one lineage. Transmission rates of nonfunctional deletion chromosomes were high through haploid males, but low through diploid females.

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