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41.
The turnip sawfly, Athalia rosae Linnaeus, is a pest on cruciferous crops. Larvae sequester secondary plant compounds, namely glucosinolates, in their haemolymph. When attacked, their integument is easily disrupted and a droplet of haemolymph is exuded ('easy bleeding'). This has been shown to be an effective, chemical-based, defence against invertebrate predators. The efficiency of this proposed defence was tested against a vertebrate predator, using groups of the iguanid lizard Anolis carolinensis Voigt as a model predator. Caterpillars of Pieris rapae Linnaeus and Pieris brassicae Linnaeus served as control prey species that do not sequester glucosinolates. Lizards attacked far fewer sawfly larvae than pierid caterpillars. Several of the sawfly larvae were rejected after an initial attack, demonstrating unpalatability to the lizards, while the Pieris larvae were not rejected. However, P. rapae larvae topically treated with extracts of haemolymph of A. rosae had no deterrent effect on the lizards and no avoidance learning occurred over a period of two weeks. Adult sawflies do not easy bleed but have glucosinolates carried over from the larval stage. Lizards attacked them at a higher rate than larvae and they were never rejected. The results suggest that for the defensive effectiveness of the pest sawfly species against vertebrates the chemical cue is not necessarily sufficient. Movement and colour may be important additional factors triggering the behaviour of vertebrate predators. 相似文献
42.
Fluctuating asymmetry (FA) is claimed both to provide a means of evaluating developmental stability, and to reflect an individual's quality or the stress experienced during development. FA refers to the nondirectional variation between left and right sides, whereas directional asymmetry (DA) refers to a significant directional variation between the sides. We studied four eyespots on the dorsal forewing of the tropical butterfly, Bicyclus anynana. Two of the eyespots were specified by a mutant allele, Spotty, that was fixed in the stock. These eyespots showed higher FA than the two flanking, wild-type eyespots, although they are all formed by the same developmental pathway. We applied artificial selection for lower FA of the novel eyespots in an attempt to increase their developmental stability. There was significant variation present in individual FA in our study. However, this did not change as a result of the artificial selection. Most of the variation in FA can be accounted for by individual differences in developmental stability rather than by the applied selection or by environmental variation. Thus, it was not possible to produce any increased developmental stability of the novel eyespots by selecting for low FA. The estimates of realized heritability for both FA and DA of each eyespot were not significantly different from zero. The results suggest that FA provides little, if any, potential for exploring the mechanistic basis of developmental stability. 相似文献
43.
Fischer K Eenhoorn E Bot AN Brakefield PM Zwaan BJ 《Proceedings. Biological sciences / The Royal Society》2003,270(1528):2051-2056
We use a full factorial design to investigate the effects of maternal and paternal developmental temperature, as well as female oviposition temperature, on egg size in the butterfly Bicyclus anynana. Butterflies were raised at two different temperatures and mated in four possible sex-by-parental-temperature crosses. The mated females were randomly divided between high and low oviposition temperatures. On the first day after assigning the females to different temperatures, only female developmental temperature affected egg size. Females reared at the lower temperature laid larger eggs than those reared at a higher temperature. When eggs were measured again after an acclimation period of 10 days, egg size was principally determined by the prevailing temperature during oviposition, with females ovipositing at a lower temperature laying larger eggs. In contrast to widely used assumptions, the effects of developmental temperature were largely reversible. Male developmental temperature did not affect egg size in either of the measurements. Overall, developmental plasticity and acclimation in the adult stage resulted in very similar patterns of egg size plasticity. Consequently, we argue that the most important question when testing the significance of acclamatory changes is not at which stage a given plasticity is induced, but rather whether plastic responses to environmental change are adaptive or merely physiological constraints. 相似文献
44.
New observations of early and dynamic expression of Notch in developing lepidopteran wings suggests that this signalling pathway may function in defining the central focus that will specify the butterfly eyespot colour pattern. 相似文献
45.
Saccheri IJ Brakefield PM 《Proceedings. Biological sciences / The Royal Society》2002,269(1495):1073-1078
When local populations are genetically differentiated from one another and partially inbred, as typically occurs in subdivided populations, immigrant genomes are predicted to be at a frequency-dependent fitness advantage due to heterosis (hybrid vigour) in their descendants. We tested this prediction with pedigreed laboratory populations of the butterfly Bicyclus anynana and report here on a rapid increase over five generations in the contribution of an initially rare immigrant genome to the local population gene pool. The replicated experimental design, including immigrant controls, demonstrates that the mechanism underlying immigrant genome spread is heterosis, and that the advantage to the immigrant genes is sustained over several generations. Our result suggests that effective migration rates may often be much higher than the numbers of individual migrants assumed by classical population genetics models, with implications for the persistence and evolution of metapopulations. 相似文献
46.
Phylogeny of the Drosophila saltans species group based on combined analysis of nuclear and mitochondrial DNA sequences 总被引:2,自引:0,他引:2
Nucleotide sequences from two nuclear loci, alcohol dehydrogenase and
internal transcribed spacer-1 of the nuclear ribosomal DNA repeats, and two
mitochondrial genes, cytochrome oxidase I and cytochrome oxidase II, were
determined from nine species in the Drosophila saltans species group. The
partition homogeneity test and partitioned Bremer support were used to
measure incongruence between phylogenetic hypotheses generated from
individual partitions. Individual loci were generally congruent with each
other and consistent with the previously proposed morphological hypothesis,
although they differed in level of resolution. Since extreme conflict
between partitions did not exist, the data were combined and analyzed
simultaneously. The total evidence method gave a more resolved and highly
supported phylogeny, as indicated by bootstrap proportions and decay
indices, than did any of the individual analyses. The cordata and elliptica
subgroups, considered to have diverged early in the history of the D.
saltans group, were sister taxa to the remainder of the saltans group. The
sturtevanti subgroup, represented by D. milleri and D. sturtevanti,
occupies an intermediate position in this phylogeny. The saltans and
parasaltans subgroups are sister clades and occupy the most recently
derived portion of the phylogeny. As with previous morphological studies,
phylogenetic relationships within the saltans subgroup were not
satisfactorily resolved by the molecular data.
相似文献
47.
Brakefield PM Liebert TG 《Proceedings. Biological sciences / The Royal Society》2000,267(1456):1953-1957
Populations of Biston betularia in the region of The Netherlands around Leiden and Rotterdam were resampled. A comparison of three sets of data for 1969-1973, 1988 and 1999 enabled a further examination of declines in melanism. Unlike parallel changes for the black carbonaria form of this species in urban regions of Britain, those inThe Netherlands involve substantial changes in frequencies of at least two of the intermediate insularia morphs as well as an increase in the non-melanic typica morph. The darkest of the three insularia morphs has shown a transitory pulse of increased frequency in The Netherlands. The dynamics are discussed in relation to the history of air pollution and to straightforward predictions about selection. 相似文献
48.
Clunes MT Lindsay SL Roussa E Quinton PM Bovell DL 《Journal of molecular histology》2004,35(4):339-345
The localisation of the vacuolar proton pump (V-H+ -ATPase) and the enzyme carbonic anhydrase II (CAII) was investigated in the human eccrine sweat gland employing standard immunohistochemical techniques after antigen retrieval using microwave heat treatment and high pressure. The high-pressure antigen retrieval unmasked the presence of V-H+ -ATPase in the clear cells of the secretory coil, with a distribution similar to that previously observed for CAII. However, the dark cells were unreactive to both antibodies. In addition, heat and high-pressure antigen retrieval demonstrated the presence of CAII in the apical zone of luminal cells of the reabsorptive duct, a location not previously reported. The localisation of V-H+ -ATPase and CAII in the secretory coil clear cells suggests that the formation of HCO3- and H+ by carbonic anhydrase II and the transport of H+ by V-H+ -ATPase may play an role in sweat fluid secretion. Their presence at the apex of the duct cells indicates involvement in ductal ion reabsorption. 相似文献
49.
Practice with sleep makes perfect: sleep-dependent motor skill learning 总被引:24,自引:0,他引:24
Improvement in motor skill performance is known to continue for at least 24 hr following training, yet the relative contributions of time spent awake and asleep are unknown. Here we provide evidence that a night of sleep results in a 20% increase in motor speed without loss of accuracy, while an equivalent period of time during wake provides no significant benefit. Furthermore, a significant correlation exists between the improved performance overnight and the amount of stage 2 NREM sleep, particularly late in the night. This finding of sleep-dependent motor skill improvement may have important implications for the efficient learning of all skilled actions in humans. 相似文献
50.