The name is absent

Singh and Singh

the selection pressures operating on males to produce adaptations which may
include behavioral and physiological characteristics of the males as well as
competitive properties of their sperm. This increases the possibility of his
sperm, in the presence of another male, to be used by a female for insemi-
nation of her eggs. Female fitness is also influenced by multiple mating (Pyle
and Gromko, 1978); females can be directly harmed by male adaptations
for sperm competition (Chapman et al., 1995), so females should be under
strong selection to mediate sperm competition. Remating is common in many
species of Drosophila under both field and laboratory conditions (Lefevre
and Jonsson, 1962; Anderson, 1974; Richmond and Ehrman, 1974; Craddock
and Johnson, 1978; Loukas et al., 1981; Markow, 1985; Barbadilla et al., 1991;
Aspi, 1992; Etges and Heed, 1992; Joly and Lachaise, 1993; McRobert et al.,
1997; Price, 1997; Singh and Singh, 1997; Harshman and Clark, 1998). Females
of some Drosophila species have been shown to gain direct benefits from re-
mating (Markow and Ankney, 1984). Female remating frequency is depen-
dent on the amount of sperm stored (Manning, 1962; Gromko et al., 1984;
Gromko and Markow, 1993), components of the male seminal fluid (Chen
et al., 1988; van Vianen and Bijlsma, 1993), levels of nutrition, and the egg-
laying rate (Gromko and Gerhart, 1984; Harshman et al., 1988; Trevitt et al.,
1988; Chapman et al., 1994; Chapman and Partridge, 1996). The frequency
of remating is also influenced by density. Boorman and Parker (1976) sug-
gested that at higher population densities, there is an increase in the inci-
dence of courtship, resulting in a higher frequency of multiple mating in
D. melanogaster. Marks et al. (1988) provided evidence for a positive corre-
lation between population density and remating frequency in the field in the
same species. However, increasing density can also decrease the frequency of
remating in D. melanogaster (Gromko and Gerhart, 1984). Harshman et al.
(1988) reported that the frequency of remating in D. melanogaster was un-
affected by density for some combinations of the fly strains but was reduced
at low relative densities for other combinations. In D. pseudoobscura and
D. persimilis, increasing density increased the frequency of female remating
(Richmond, 1976; Levine et al., 1980; Turner, 1986). In a natural popula-
tion ofD. montana, Aspi and Lankinen (1992) reported that low population
densities at the end of the mating season probably force females to remate
shortly after first mating.

D. ananassae has been extensively used for genetical studies, partic-
ularly population genetics, behavior genetics, and crossing-over by Singh
and his co-workers (for references see reviews by Singh, 1996, 2000). The
results of mating propensity tests in wild-type strains, mutant strains, and
inversion karyotypes and the results of selection experiments have been
used as evidence for genetic control of sexual behavior in D. ananassae
(Singh and Chatterjee, 1986, 1987, 1988a,b; Chatterjee and Singh, 1987,

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