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71.
Abstract In the terrestrial crustacean Armadillidium vulgare, the prolonged presence of males along with females is known to boost female reproductive physiology, and the so-called ‘male-effect’ was best characterized by a significant shortening of the pre-parturial intermoult (PPI) during which oocyte maturation spontaneously takes place. Continuous presence of a male over that period can speed up vitellogenesis and the moulting cycle, so to reduce female PPI by 15–20 days (shortening of 30–40%, in comparison to females reared with other females or in isolation, respectively). In the last investigation on the subject, we revealed that sexual interactions may start much sooner than previously thought in this species, and suggested that the observed ‘male-effect’ may likely result from early mating stimulations. Here we tested the specific effect of controlled mating interactions (one or two mating events at different times) on female PPI. We revealed that male presence for the time (about 2 h) that allowed a single mating to occur was enough to reduce the female intermoult by about 10 days (shortening of 19%, in comparison to females reared in similar conditions but in the absence of a mating interaction). Moreover, results indicate that the earlier and longer the copulations, the stronger the ‘male-effect’. Altogether, the data support the conclusion that A. vulgare females are adjust their reproductive physiology according to the presence/absence and the intensity of male mating stimuli. We place the findings in a broader ecological context, revise the so far prevailing view on the ‘male-effect’, and stress its possible significance in relation to the occurrence of feminising bacteria in this and other terrestrial isopod species. 相似文献
72.
The diet of King Penguins Aptenodytes patagonica at Possession Island was studied in February 1989 by analysis of 20 stomach contents collected from adult birds, just before they fed their single chicks. The mean mass of the samples was 1.84 kg, equivalent to 15% of the unladen adult body-mass. Fish accounted for 99.8% and squids for 0.2% by mass. The main prey were mesopelagic myctophid fish which live in dense shoals and perform a daily vertical migration. Subadults/adults of Electrona carlsbergi and juveniles and subadults/adults of Krefftichthys anderssoni represented 73.7 and 13.4% of the diet by mass, respectively. No difference was found in the diet of male and female King Penguins. Comparison of individual samples suggests that these birds catch a large quantity of fish from only a limited number of shoals. The mean caloric content of the food was 7 kJ/g wet mass. The total energy requirement of each chick during its initial period of growth was estimated to amount to 328,000 kJ, equivalent to 55 kg of food. The rate at which energy was delivered to the chick was calculated to be 50 W during this period. 相似文献
73.
JAN ŠOBOTNÍK GILLES LEPOINT JEAN‐MICHEL MARTIN OLIVIER J. HARDY ALAIN DEJEAN YVES ROISIN 《Ecological Entomology》2011,36(2):261-269
1. In the current ecological classification of termites, four feeding groups (I–IV) are recognised, corresponding to a gradient of decomposition from sound wood to highly mineralised organic matter in the soil. 2. Nitrogen stable isotopes (hereafter δ15N) were used to place termites from French Guiana rainforests along a wood‐soil decomposition gradient, to test (i) whether feeding group assignation based on morphological characters was accurate and actually represented diet specialisation thresholds, and (ii) to what extent the dietary specialization of species is explained by phylogeny (phylogenetic autocorrelation). 3. δ15N values vary over a range of 13‰, suggesting that diet diversification contributes to the high species diversity in French Guiana. δ15N values span a similar interval in all Termitidae subfamilies. Ranges of different subfamilies broadly overlap, although each of them diversified preferentially on one side of the wood‐soil decomposition gradient. Congeneric species share similar feeding habits, whereas distant species tend to feed on distinct substrates. 4. Feeding groups did not completely match stable isotope data: there was no discontinuity between Groups III and IV, and no correlation between anatomical criteria used to distinguish these groups and δ15N values. Nor was there any consistent difference in δ15N values between wood feeders of the families Rhinotermitidae (Group I) and Termitidae (Group II). We also suggest that species feeding outside the wood‐soil gradient should be distinguished for their peculiar feeding requirements. 相似文献
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1. Soil‐feeding termites are abundant and diversified in neotropical forests, where they are among the major decomposers of the soil macrofauna. While niche specialisation along the humification gradient may reduce inter‐specific competition, some species are represented by numerous colonies likely to be involved in intra‐specific competition, but the subterranean nesting habits of most species of soil‐feeding termites make direct observations difficult. 2. The soldierless species Anoplotermes banksi Emerson was studied, which, unlike other Anoplotermes‐group species, builds arboreal nests that can be easily detected. To infer the biological processes driving the spatial distribution of this species, we conducted a 3‐year survey of the dynamics of colonisation of a 1‐ha plot by A. banksi. Ripley's L‐function, detecting aggregation or dispersion at various spatial scales, was used to investigate the distribution pattern of A. banksi nests, as well as the distribution of new and established nests. 3. Only one‐fourth of the nests recorded the first year were still alive after 3 years, highlighting a rapid turnover of the A. banksi nest population. Age classes were differentially affected by mortality, which was higher in young nests than in large, established nests. 4. Established nests were overdispersed at a short range, whereas young nests had a random or clumped distribution. Young nests tended to be overdispersed from established ones and were more abundant in areas with recently dead nests. Dead nests predominantly occurred where A. banksi nests were particularly abundant. Altogether, the present results indicate a negative interaction between neighbouring colonies suggesting intra‐specific competition. 相似文献
77.
Species concepts and the determination of historic gene flow patterns in the Eulemur fulvus (Brown Lemur) complex 总被引:1,自引:0,他引:1
YAEL WYNER ROBIN ABSHER GEORGE AMATO ELEANOR STERLING REBECCA STUMPF YVES RUMPLER ROB DESALLE 《Biological journal of the Linnean Society. Linnean Society of London》1999,66(1):39-56
Eulmur fulvus , a complex comprising six subspecies, is a classic example of species status conferred through evolutionary taxonomy. We used the phylogcnctic species concept as an alternative method to the biological species concept for determining historic patterns of gene flow between the various E. julvus subspecies and for conferring species status. In this paper, we used population aggregation analysis to determine the proper species partitions and cladistic analysis to reconstruct the evolutionary relationships of the different populations in the Eulemur fulvus complex. We sequenced three mtDNA gene regions (d-loop, 12S, and cyt-b) and one nuclear region, casein kinase, for a total of 1247 bases. Through population aggregation analysis, we determined that the E. fulvus complex should be split into three units; one unit supported by six diagnostic sites comprising E.f. albocollans , one unit supported by three diagnostic sites comprising E.f. collaris , and one unit supported by two diagnostic sites comprising the four other subspecies. Although all six subspecies in the E. julvus complex share a common ancestor, we found in our cladistic analysis that E. J. collaris and E. j. albocollans share a common ancestor that more recently split off from the common ancestor of the four other E. fulvus subspecies. 相似文献
78.
79.
FABIEN L. CONDAMINE LAURENT SOLDATI JEAN‐YVES RASPLUS GAEL J. KERGOAT 《Systematic Entomology》2011,36(2):340-361
The genus Blaps is an emblematic group of large flightless beetles adapted to semi‐arid and arid environments. About 230 species have been described in the subgenus Blaps, which is the largest of the four extant subgenera. Within this subgenus, one large group of morphologically homogeneous species is of particular interest, and comprises the species formerly assigned to Seidlitz's division one. Strikingly, almost all species in this group are endemic to the Mediterranean basin, whereas the remaining Blaps species are mostly distributed in Asia. Here we present the first phylogenetic hypothesis for the Mediterranean Blaps and several taxonomic clarifications for the North African species belonging to this group. Based on careful examination of almost all type material and thousands of specimens for all known species and subspecies (initially 65 taxa), seven lectotypes are designated and six new synonymies are established: Blaps heydeni Allard, 1880 = Blaps heydenissp. taciturna Peyerimhoff syn.n. , Blaps emondi Solier = Blaps nitidula Solier syn.n. , Blaps tripolitanica Karsch = Blaps vialattei Peyerimhoff syn.n. , Blaps bifurcata strauchi Reiche = Blaps bifurcata ssp. gridellii Pierre syn.n. , Blaps cognata Solier = Blaps schweinfurhtii Seidlitz syn.n. and Blaps judaeorum Miller = Blaps pharao Seidlitz syn.n. Among the examined material, five species are also new for science and are assigned to extant species group. To infer species relationships, a morphological character matrix was assembled and analysed using both parsimony and probabilistic methods. All analyses yielded a similar and repeatable phylogenetic pattern, which allows us to discuss the systematics of the Mediterranean endemic species, the limit of extant species groups and to clarify the taxonomic status of several ambiguous taxa. We also reveal the existence of a large clade that encompasses the eastern Mediterranean species that are also mostly associated with arid regions. This clade is embedded within a second group that corresponds to western Mediterranean species, which are generally found in semi‐arid regions. Finally, we discuss the relevance of species groups in relation to their geographic distribution. This work represents a first step for further studies in taxonomy, systematics and historical biogeography of Blaps species. 相似文献
80.
PRIN YVES; MALLEIN-GERIN FREDERIC; SIMONET PASCAL 《Journal of experimental botany》1993,44(4):815-820
In situ hybridization of Frankia mRNA with specific probes wasused to localize the strains Arl3 and AcoN24d in Alnus nodulesobtained after inoculation with one or both strains. The probesconsisted of 18-mer oligonucleotides, complementary to strain-specificsequences located within the nif H gene. Sections of nodulesinoculated with only one strain revealed a specific hybridizationbetween the probe and the corresponding Frankia strain mRNA.In sections of dually-inoculated nodules the presence of thestrain AcoN24d in the nodule was clearly shown whereas thoseof the strain Arl3 could not be detected. This suggests thatthe strain Arl3 is less infective than the strain AcoN24d andis not present within the nodule. Key words: Nitrogen fixation, actinorhizae, autoradiography, histochemistry 相似文献