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131.
Interval between reproductive events is an important factor for iteroparous animals because it determines the number of clutches
throughout life. This study examined whether female size, clutch size, shell size and prenuptial molting affected the clutch
interval in the hermit crab Pagurus nigrivittatus. Precopulatory guarding pairs of P. nigrivittatus were sampled in the field and kept in the laboratory until the female extruded eggs. The clutch interval of each female was
assessed as one of two types of relatively “short” and “long” intervals by checking whether the guarded female had eggs and/or
egg cases from the preceding brood or not when the guarding pair was collected. The clutch interval was longer in females
with prenuptial molting than those without molting and these females usually grew larger at the prenuptial molt. This suggests
that female P. nigrivittatus with a long interval might allocate energy into growth at the expense of the number of clutches during the current reproductive
season. The allocation to growth is theoretically predicted to decrease with female size. Gastropod shell size is also known
to affect the reproductive activity in hermit crabs. However, female size did not significantly affect the clutch interval
in P. nigrivittatus, and the effect of gastropod shell size on clutch interval was not consistent with previous empirical studies. These results
may be caused by differences in the gastropod species of shell occupied by the females of P. nigrivittatus. 相似文献
132.
The relationship between species richness and environmental variables may change depending on habitat structure, dispersal ability, species mixing, and community adaptation to the environment. It is crucial to know how these factors regulate the environment-diversity relationship. The land molluscan fauna of the Ogasawara Islands in the West Pacific is an excellent model system to address this question because of the high species endemicity (> 90%), small area, and simple habitat structure of the islands. I examined relationships among indigenous species composition, richness, and habitat condition, and especially productivity and forest moisture on the island of Anijima. Two major communities of snails could be distinguished by detrended correspondence analysis (DCA): one group dominated in a moist habitat with high productivity, and the other group dominated in a dry habitat with low productivity. However, species richness became highest at the intermediate condition between the habitats in which the two snail communities were dominant, so that species richness showed a hump-shaped relationship with moisture and productivity. In contrast, the species richness of the snail community in the moist habitat showed a monotonically positive correlation, and that in the dry habitat showed a monotonically negative correlation with moisture and productivity. Thus, the greater species richness in intermediate moisture and productivity resulted from the ecotone effect or community overlap at the transitional areas, where faunas with different ecologies can meet in a single site. These findings suggest that hump-shaped productivity-diversity relationships in land Mollusca would reflect the ecotone effect as a result of the mixing of species adapted to either fertile habitats or sterile habitats. 相似文献
133.
Platydemus manokwari is a broadly distributed invasive terrestrial flatworm that preys heavily on land snails and has been credited with the demise
of numerous threatened island faunas. We examined whether P. manokwari tracks the mucus trails of land snail prey, investigated its ability to determine trail direction, and evaluated prey preference
among various land snail species. A plastic treatment plate with the mucus trail of a single species and a control plate without
the trail were placed side by side at the exit of cages housing P. manokwari. All trials were then videotaped overnight. The flatworms moved along plates with mucus trails, but did not respond to plates
without trails, blank control (distilled water), or with conspecific flatworm trails. When presented at the midpoint of a
snail mucus trail, the flatworms followed the trail in a random direction. The flatworms showed a preference when choosing
between two plates, each with a mucus trail of different land snail species. Our results suggest that P. manokwari follows snail mucus trails based on chemical cues to increase the chance of encountering prey; however, trail-tracking behavior
showed no directionality. 相似文献
134.
Abiotic degradation of four phthalic acid esters in aqueous phase under
natural sunlight irradiation
Abiotic degradability of four phthalic acid esters (PAEs) in the aquatic phase was evaluated over a wide pH range 5–9. The PAE
solutions in glass test tubes were placed either in the dark and under the natural sunlight irradiation for evaluating the degradation rate
via hydrolysis or photolysis plus hydrolysis, respectively, at ambient temperature for 140 d from autumn to winter in Osaka, Japan.
The e ciency of abiotic degradation of the PAEs with relatively short alkyl chains, such as butylbenzyl phthalate (BBP) and di-nbutyl
phthalate (DBP), at neutral pH was significantly lower than that in the acidic or alkaline condition. Photolysis was considered
to contribute mainly to the total abiotic degradation at all pH. Neither hydrolysis nor photolysis of di-ethylhexyl phthalate (DEHP)
proceeded significantly at any pH, especially hydrolysis at neutral pH was negligible. On the other hand, the degradation rate of diisononyl
phthalate (DINP) catalyzed mainly by photolysis was much higher than those of the other PAEs, and was almost completely
removed during the experimental period at pH 5 and 9. As a whole, according to the half-life (t1=2) obtained in the experiments, the
abiotic degradability of the PAEs was in the sequence: DINP (32–140 d) > DBP (50–360 d), BBP (58–480 d) > DEHP (390–1600 d)
under sunlight irradiation (via photolysis plus hydrolysis). Although the abiotic degradation rates for BBP, DBP, and DEHP are much
lower than the biodegradation rates reported, the photolysis rate for DINP is comparable to its biodegradation rate in the acidic or
alkaline condition. 相似文献
135.
Satoshi SUZUKI Norikazu MATSUMURA Takeshi OHOKA Shun SAKUMA Tomohiro NAKAHATA Masahide ISHIKAWA 《环境科学学报(英文版)》2009
Enzymes fixed on the electrode of biosensor are gradually inactivated and the electrode is discarded after using several times. In order to prepare the stable biosensor, we try to use a stable enzyme from extreme thermophilic bacteria, Thermus thermophilus HB8. It is very important that a stable enzyme from T. thermophilus HB8 is overproduced in Escherichia coli, for the purpose of enough supply of enzyme. Thereby, we determined the important sequence for overexpression of NADH oxidase (nox) gene from T. thermophilus HB8 in E. coli. As a result, it is revealed that ten nucleotides sequence, GAAATTAACT, in the upstream of start codon of nox gene was important for its overexpression in E. coli. 相似文献
136.
γ-Al2O3 coatings were prepared on aluminum-free stainless steel (SUS304) by electrophoretic deposition method. Both X-ray diffraction and scanning electron microscopy were used to study the crystalline structure and morphological features of the coatings. Themo gravimetry-differential termal analysis (TG-DTA) is used to study the thermo-chimerical reaction behavior of coatings. Catalytic activity of coatings is determined by degrading of NOx. The results indicated that the thickness of the coatings onto SUS304 could reach 5 μm without any exfoliation at optimized conditions. Catalytic properties of samples coated by electrophoretic deposition method were highly enhanced as compared with that of samples prepared by the dip coating method. 相似文献
137.
Functions of the major cheliped in pagurid hermit crabs have been studied in fights for shells. The major cheliped often shows
sexual size dimorphism, suggesting that sexual selection favors the development of the male major cheliped. The function of
the major cheliped in male–male competition was examined in Pagurus nigrofascia collected from April to June 2009 on the intertidal rocky shore in southern Hokkaido, Japan (41°N, 140°E). Sexual size dimorphism
of the major cheliped was observed, and precopulatory guarding males had larger major chelipeds than solitary ones. Guarding
males used the major cheliped to deter intruders during competitive interactions. Males without a major cheliped were disadvantaged
even if they were larger than opponents and had ownership. Cheliped size affected the outcomes of contests between similar
sized males. This suggests that the male major cheliped in P. nigrofascia protects mates from competitors and, consequently, enhances male mating success. Sexual selection may favor the development
of the major cheliped in male pagurids. 相似文献
138.
The cuticular surface of sexually mature females of the German cockroach contains a sex pheromone that, upon contact with the male's antennae, elicits a characteristic species-specific courtship behavior. This female-specific pheromone is a blend of several long-chain methyl ketones, alcohols and aldehydes, all derived from prominent cuticular hydrocarbons found in all life stages of this cockroach. We found that contact with the antennae of 5 out of 20 assayed cockroach species elicited courtship behavior in German cockroach males. The heterospecific courtship-eliciting compounds were isolated by behaviorally guided fractionation of the active crude extracts and compared to the native sex pheromone components. We identified two active compounds from the cuticular extract of the Oriental cockroach, Blatta orientalis -- 11-methylheptacosan-2-one and 27-oxo-11-methylheptacosan-2-one; the former compound was confirmed by synthesis and proved to independently stimulate courtship in German cockroach males. These compounds share common features with, but are distinct from, any of the known contact sex pheromone components. This suggests that sex pheromone reception in the male German cockroach is unusually promiscuous, accepting a wide range of compounds that share certain features with its native pheromone, thus resulting in a broad spectrum of behavioral response to other species. We propose that several characteristics of their mating system -- chiefly, absence of closely related species in the anthropogenic environment, resulting in relaxation of selection on sexual communication, and a highly male-biased operational sex ratio -- have driven males to respond with extremely low thresholds to a wide spectrum of related compounds. 相似文献
139.
Kikuchi T Miyazaki S Ohnishi H Takahashi J Nakajima Y Tsuji K 《Die Naturwissenschaften》2008,95(10):963-968
Evolution of caste is a central issue in the biology of social insects. Comparative studies on their morphology so far suggest
the following three patterns: (1) a positive correlation between queen–worker size dimorphism and the divergence in reproductive
ability between castes, (2) a negative correlation among workers between morphological diversity and reproductive ability,
and (3) a positive correlation between queen–worker body shape difference and the diversity in worker morphology. We conducted
morphological comparisons between castes in Pachycondyla luteipes, workers of which are monomorphic and lack their reproductive ability. Although the size distribution broadly overlapped,
mean head width, head length, and scape length were significantly different between queens and workers. Conversely, in eye
length, petiole width, and Weber’s length, the size differences were reversed. The allometries (head length/head width, scape
length/head width, and Weber’s length/head width) were also significantly different between queens and workers. Morphological
examinations showed that the body shape was different between queens and workers, and the head part of workers was disproportionately
larger than that of queens. This pattern of queen–worker dimorphism is novel in ants with monomorphic workers and a clear
exception to the last pattern. This study suggests that it is possible that the loss of individual-level selection, the lack
of reproductive ability, influences morphological modification in ants. 相似文献