Abstract
This thesis deals with factors affecting mate choice as well
as with genetic variation in male courtship song in Drosophila
montana. Males, which produced song with a high carrier
frequency, were found to court females, and also to succeed in
their courtship more often than the males producing low frequency
song. Male mating success correlated with the carrier frequency
of his song recorded after, but not before, an "artificial
winter", which suggests that a sexually selected male
trait is sensitive to environmental factors. A high carrier frequency
of male courtship song correlated positively with the survival
rate of the male's progeny from egg to adulthood (indirect
benefit for the female), but not with the fecundity of his mating
partner (no direct benefit for the female).
The heritabilities and the amount of additive and residual
variation in male courtship song characters were measured in two
populations using father-son regression and sib analysis. The songs
of the males from one of these populations were analysed for a
second time after the cold treatment. Most heritability values
were insignificant, largely due to high residual variation. During
the cold treatment, the additive variation increased and the residual
variation decreased in almost all song traits. Increased variation
in sexually selected traits may help the females to exercise selection between
the males during the mating season of the flies in the wild in
spring. This, and the fact that male song gives the female information
about the male's condition/genetic quality suggests
that in this species the evolution of female preferences for male
song characters could have evolved through condition-dependent
viability selection as postulated by "good genes" models.
Variation and inbreeding depression/heterosis were
studied in traits associated with fly reproduction using inbred
D. montana strains. Songs, hydrocarbons and some behavioural traits
of the flies varied significantly between strains. The strain of
both sexes affected female egg-laying, and the female strain, also,
the survival rate of the flies' progeny, in different
intra- and interspecific combinations. Heterosis was found in the
mating propensity of the flies and in the carrier frequency of
the male song. Diallel analysis revealed unidirectional dominance
towards higher carrier frequency. This direction is the same as
the direction of sexual selection exercised by the females of this
species suggesting that sexual selection could be a driving force
in evolution of this song trait.
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:isbn951-42-5191-1 |
| Date | 24 March 1999 |
| Creators | Suvanto, L. (Leena) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © University of Oulu, 1999 |
| Relation | info:eu-repo/semantics/altIdentifier/pissn/0355-3191, info:eu-repo/semantics/altIdentifier/eissn/1796-220X |
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