Reduced influence of penile disability on the mating capacity of male staggerer mice]

Most staggerer mutant mice do not mate spontaneously. This deficiency may be attributed to a penile disability (during erection, the penis in extension is directed backward). The main characteristics of this phenomenon and its involvement in the reproduction of the staggerer mutant have been considered in our study. Seventy-four percent (n = 66) of staggerer males presented this temporary abnormality at least once. It appeared when the males were 84 +/- 37-d old (M +/- SD). In most animals the penile abnormality was labile and did not exceed 1 wk duration in 48% (n = 32) of the males. Three males mated in spite of presenting this abnormal erection. Moreover, 25% of males (n = 23) did not present this disability; nevertheless, most of them (91%) still did not reproduce. Other mechanisms are certainly responsible for the inefficient mating. In any case, the influence of penile disability on this deficiency appears to be weak.     

Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.