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W B Heed

Publications and source records attributed to W B Heed.

7 recordsLinked to original sources
PubMed1992

Remating effects on the genetic structure of female life histories in populations of Drosophila mojavensis.

A quantitative genetic analysis of nine adult fitness components was performed in two populations of cactophilic Drosophila mojavensis under natural conditions of fermenting cactus and ethanol vapour. Female progeny from 18 sires and 36 dams were treated to a range of six exposure periods to males to assess effects of remating frequency on female fitness. Lifetime fecundity increased with increasing male exposure, but longevity showed an intermediate optimum with temporary exposure to males of 2-4 days. Narrow-sense heritabilities were significant for egg production traits while broad-sense heritabilities were significant for longevity-related traits. Positive genetic correlations between components of fitness were expressed among functionally related traits, e.g. longevity was positively correlated with lifetime fecundity, the number of clutches laid, clutch size, and the number of eggs laid per day. Negative genetic correlations were detected between early and late life fecundity suggesting genetic tradeoffs among components of adult fitness.

Animal Nutritional Physiological Phenomena↗
PubMed1991

Four decades of inversion polymorphism in Drosophila pseudoobscura.

We report data that continue the studies of Dobzhansky and others on the frequencies of third-chromosome inversions in natural populations of Drosophila pseudoobscura in North America. The common gene arrangements continue to be present in frequencies similar to those described four decades ago, and the broad geographic patterns also remain unchanged. There is only one pronounced trend over time: the increase in frequency of the Tree Line inversion in Pacific coast populations.

Animals↗
PubMed1977

Extension of longevity in Drosophila mojavensis by environmental ethanol: differences between subraces.

Drosophila mojavensis adults, which breed and feed on necrotic cacti, show an increase in longevity when exposed to atmospheric ethanol. The increase in longevity is accompanied by retention of mature ovarioles and is independent of diet. Differences in longevity among strains from different localities were detected for females. Strains from Arizona and Sonora, Mexico, showed the greatest increase in longevity, while strains from Baja California, Mexico, showed the least increase. These differences may be controlled by the alcohol dehydrogenase locus, the octanol dehydrogenase locus, and modifier genes, because the aduld response is correlated with the frequency of alcohol dehydrogenase alleles, as well as second chromosomal inversions containing the octanol dehydrogenase locus. The longevity response is also consistent with the more uneven distribution and availability of the host plant in Arizona and Sonora, Mexico. Strains from Arizona and Sonora, Mexico, have a high frequency of Adh-S, the allele whose product is heat and pH tolerant. The host plant, organpipe cactus, exhibits extremes in temperature and pH in the same geographic region. Strains from Baja California, Mexico, possess a high frequency of Adh-F, whose product is heat and pH sensitive. The substrate in this region, agria cactus, has moderate temperature and pH extremes and contains relatively high concentrations of isopropanol. Isopropanol is presumable a selective agen favorable to Adh-F. The environmental heterogeneity that is proposed for maintaining the alleles at the alcohol dehydrogenase locus is the interaction of substrate alcohol content with temperature and pH. Substrates that do not contain appreciable amounts of isopropanol and are exposed to high temperatures and exhibit variable pH favor Adh-S, while substrates containing isopropanol and having moderate temperatures and pH favor Adh-F.

Alcohol Oxidoreductases↗
PubMed1973

Allozyme genotype-environment relationships. I. Variation in natural populations of Drosophila pachea.

Remarkable geographic and seasonal uniformities in gene and genotype frequencies were found for four enzyme loci. Principal component analysis revealed two patterns of allele frequency changes in three of the allozyme loci (Est-b, Est-c and Acph) and one pattern in the Mdh-d locus. These patterns accounted for 90% to 100% of the variability at these loci. Significant positive correlations were obtained between several of the components and the variability in the non-saponifiable and alkaloid fractions of the senita cactus host plant. The genetic variance within a single locality (Guaymas, Mexico) was as great as the variance between all localities sampled. This is interpreted as a local founder effect. The temporary nature of the rotting cactus breeding site, the delayed maturation and the differential maturation rate of females and males are three factors proposed to cause forced outbreeding and counter the local founder effect. A combination of selection resulting from a direct interaction of the genotype and the environment, in addition to migration, is proposed to maintain the uniform gene frequencies.

Acid Phosphatase↗
PubMedDate not supplied

Evolution of the mojavensis cluster of cactophilic Drosophila with descriptions of two new species.

The mojavensis cluster of the repleta species group of Drosophila (Drosophilidae: Diptera) consists of three species. One is newly described as D. navojoa. A second species, described here as D. arizonae, replaces D. arizonensis, which has become a junior subjective synonym for D. mojavensis, the third species in the cluster. A phylogeny of the three species is presented, based on chromosomal inversions, morphology, and the ability to produce hybrids. Breakage points are assigned for all inversions, and male genitalia are figured; 186 crosses were made from 225 possible combinations among 15 geographic strains from the southwestern United States, Mexico, and Guatemala. It is confirmed that D. mojavensis and D. arizonae are very closely related and shown that D. navojoa is more distantly related in regard to all criteria. This relationship is supported by the geographical positions of the ancestral gene sequences in each species, which show a sequential northwest movement (D. navojoa----D. arizonae----D. mojavensis) from southern Mexico to southern California and northern Arizona. The relationship is also supported by the fact that D. navojoa breeds in Opuntia cactus, an ancestral behavior, whereas the other two species breed chiefly in Stenocereus cacti, a derived behavior. The possible role of this host plant shift in speciation is discussed.

Animals↗