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R. C. Griffiths S. W. McKechnie J. A. McKenzie 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1982,62(1):89-96
Summary Mother-offspring data for alcohol dehydrogenase genotypes of a vineyard cellar population of D. melanogaster are best explained by a model that allows 21% of females in the population to mate twice with an 83% level of sperm displacement. A population model with multiple mating and sperm displacement is examined theoretically. A formula for the effective population size is derived under this model. Multiple mating increases the effective population size relative to single mating. 相似文献
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Among Australasian populations from above 32.5° latitude there is a significant negative relationship between Gpdh
F frequency and distance from the equator which is not explained by gametic disequilibrium with the linked inversion In(2L)t. This is consistent with the associations reported earlier for Gpdh
F among populations covering comparable latitudes in North America and Europe/Asia. By contrast, Tpi allele frequencies are found to be significantly associated with distance from the equator in Australasia but not North America or Europe/Asia. The Tpi pattern in the different zones is essentially the same as that reported earlier for the Acph polymorphism, which maps only 0.2 cM away from the Tpi locus.There are now ten enzyme polymorphisms in D. melanogaster which have been screened for latitudinal associations in Australasia, North America and Europe/Asia. Allele frequencies at six of these loci show significant relationships with distance from the equator which are consistent across all three zones. These latitudinal associations are more prevalent for Group II than Group I enzymes. Values of genic heterozygosity averaged over the ten polymorphic loci and eleven other monomorphic systems do not vary with latitude but differ substantially between zones. Values of Nei's genetic distance between North American and European/Asian populations calculated from all 21 systems are equivalent to subspecific differences elsewhere in the genus. 相似文献
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The cellar population of Drosophila melanogaster at the Chateau Tahbilk Winery (Victoria, Australia) was perturbed for alcohol dehydrogenase (Adh) gene frequencies. Phenol oxidase (Phox) frequencies were also perturbed and monitored as a control. Subsequent gene frequency changes, together with information on population structure, indicated that selection acted on the chromosome regions of both loci. Adh gene frequencies returned to preperturbation levels in a predictable manner. A model in which the relative fitness of Adh phenotypes was determined by temperature-dependent specific activities of enzymes of Adh genotypes adequately accounts for the rate of gene frequency change at this locus. Thus temperature behaves as a selective agent in modulating Adh gene frequencies in this cellar environment. 相似文献
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For several species of lepidoptera, most of the approximately 350-bp
mitochondrial control-region sequences were determined. Six of these
species are in one genus, Jalmenus; are closely related; and are believed
to have undergone recent rapid speciation. Recent speciation was supported
by the observation of low interspecific sequence divergence. Thus, no
useful phylogeny could be constructed for the genus. Despite a surprising
conservation of control-region length, there was little conservation of
primary sequences either among the three lepidopteran genera or between
lepidoptera and Drosophila. Analysis of secondary structure indicated only
one possible feature in common--inferred stem loops with higher-than-random
folding energies-- although the positions of the structures in different
species were unrelated to regions of primary sequence similarity. We
suggest that the conserved, short length of control regions is related to
the observed lack of heteroplasmy in lepidopteran mitochondrial genomes. In
addition, determination of flanking sequences for one Jalmenus species
indicated (i) only weak support for the available model of insect 12S rRNA
structure and (ii) that tRNA translocation is a frequent event in the
evolution of insect mitochondrial genomes.
相似文献
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Inhibition of amino acid incorporation in vitro by metabolites of 2-acetylaminofluorene and by certain nitroso compounds 总被引:1,自引:0,他引:1
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Thermoregulation in free-ranging Nycteris thebaica (Nycteridae) during winter: No evidence of torpor
Bats are among the most heterothermic mammals, with nearly all species investigated under free-ranging conditions to date exhibiting some degree of daily torpor and/or hibernation. We investigated thermoregulation during late winter by seven Nycteris thebaica in a warm, semi-arid habitat in northern South Africa, using temperature-sensitive transmitters to measure skin temperature (Tskin). Unexpectedly, we found no evidence for any expression of daily torpor or hibernation based on a total of 86 days of data from 7 bats (one male and six females), despite air temperatures as low as ~10 °C. Instead, daytime Tskin was distributed unimodally with most values in the 33–35 °C range, and a minimum Tskin of 28.4 °C at a roost temperature of 24.6 °C. There are several possible reasons why N. thebaica may avoid torpor, including predation in roosts, and the long nightly foraging periods of this species compared to many others. 相似文献
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Across populations of Drosophila melanogaster along the Australian eastern coastline latitudinal clines occur in both heat-knockdown tolerance and hardened heat-knockdown tolerance – low latitude tropical populations being more tolerant. A latitudinal cline also occurs for rates of total protein synthesis following a mild heat stress, with tropical populations having higher rates. Since the control of protein synthesis following heat stress is an important component of the cellular heat-shock response, we hypothesised that the higher rates of synthesis that follow a heat stimulus lead to higher knockdown tolerance and underpins the cline. However, levels of heat-stimulated total protein synthesis have been negatively related to heat-hardening capacity, a somewhat conflicting result. Here we examine the relationship between these physiological and adaptive traits in a set of 40 family lines derived from a hybrid laboratory population established by crossing populations from either end of the latitudinal transect. Among these lines high levels of heat-stimulated total protein synthesis were associated with both low basal and low heat-hardened adult knockdown time, confirming the importance of a negative relationship between protein synthesis and thermal tolerance. This result, when considered along with the directions of the latitudinal clines in protein synthesis and tolerance, suggests that variation in rates of heat-stimulated total protein synthesis is not a factor contributing to the latitudinal cline in heat tolerance. Given the robustness of this negative relationship we discuss possible explanations and future experiments to elucidate how the cellular heat stress response might facilitate increased knockdown tolerance. 相似文献