首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The effects of single (unilateral) eyestalk ablation on the growth and reproduction of male and female Penaeus canaliculatus (Olivier) were compared with those of unablated (control) individuals. Prawns ≤ 10 mm in carapace length ablated in the premoult stage suffered high mortality. Prawns recognized as immature when ablated always moulted irrespective of their moulting stage; ovaries in females did not become vitellogenic nor did spermatogenesis occur in males. Mature females ablated in the premoult stage underwent moulting while those in the postmoult stage developed mature ovaries. Mature males in the postmoult or intermoult stages took longer to moult than those that were in the premoult stage when ablated. The Von Bertalannfy equations describing growth in P. canaliculatus were as follows: Lt = 25.6 [1−e−0.0756(t−to)]for ablated males; Lt = 25.3 [1−e−0.059(tto)] for unablated males; Lt= 37.2 [1−e−0.048(t−to)] forablated females; Lt = 33.4 [1−e−0.044(tto)] for unablated females. Differences in the growth rates were a result of both the moulting frequency and the increment in size at moult. However, the relative contribution of these two factors to growth varied with sex as well as with size. In both sexes, ablated individuals became sexually mature earlier; females spawned earlier. Although moulting frequency and the total number of spawns were greater for ablated females, the mean number of eggs produced (per spawn as well as total) by unablated females was higher and the mean hatching success was better.  相似文献   

2.
Seven species of bees from the eastern United States, representing four families in the Apoidea, were dissected and examined for nematode associates. Dufour''s glands in females of Halictus ligatus, Augochlora pura mosieri, and Augochlorella gratiosa (Halictidae) from Florida were infested with dauer juveniles of Aduncospiculum halicti (Diplogasteridae). The Dufour''s glands of Colletes thoracicus (Colletidae) females from Maryland were infested with dauer juveniles of a new species of Koerneria sp. (Diplogasteridae), and abdominal glands of females of Andrena alleghaniensis (Andrenidae) from New York were infested with dauer juveniles of another new species of Koerneria. The lateral and median oviducts, Dufour''s glands, and poison sacs in females of Anthophora abrupta (Anthophoridae) from Maryland and Alabama were infested with dauer juveniles of a new species of Bursaphelenchus sp. (Aphelenchoididae). Cross sections of the nematode-infested poison sacs of A. abrupta revealed two types of humoral host defense reactions.  相似文献   

3.
Food and feeding habits of mud crab Scylla olivacea (Herbst, 1896) in Pichavaram mangroves was investigated quantitatively and qualitatively for a period of two years from June 2010 to May 2012. Gut contents from 1737 specimens comprising 843 males and 894 females in the size range between 45 mm and 148 mm were examined. Crustaceans form the predominant food item in a majority of size groups in terms of percentage wet weight and frequency of occurrence, while molluscs showed a preference in few size groups. The other dietary items includes fishes, detritus, mud and sand and miscellaneous. Gut content analysis revealed no significant variation between the quantities of food consumed by both sexes. Feeding intensity was higher in juveniles and subadults of both sexes than that of adults, revealing a greater preference to feed on fast moving prey such as crustaceans and fishes. The results of the present study indicate that S. olivacea in Pichavaram mangroves exhibited a clear preference for crustaceans.  相似文献   

4.
A new occurrence of the onychochilid mollusc Pelecyogyra is reported from the late Floian Landeyran Formation (Apatokephalus incisus Biozone) in the Montagne Noire, southern France, where it is associated with the two tergomyans Carcassonnella courtessolei and Thoralispira laevis, and a mollusc indet. With a low cap-shaped shell. The Montagne Noire specimens compare morphologically with Pelecyogyra fezouataensis from the late Tremadocian Fezouata Formation (Araneograptus murrayi Biozone) in Morocco and are tentatively referred to this species. Each occurrence of Pelecyogyra is from one or two localities only, but separated in time. They differ further in the deeper facies, association with Carcassonnella and Thoralispira, and non-gregarious occurrence in Montagne Noire compared to the shallower facies, lack of other molluscs and gregarious occurrence in the Fezouata Formation. In the Lower Ordovician, Pelecyogyra, Carcassonnella courtessolei, the rare C. vizcainoi and Thoralispira laevis are taxa that occur only in Montage Noire and the Anti-Atlas, while Lesueurilla prima also occurs in the Prague basin of the Czech Republic. Contrary to other faunal elements, like echinoderms and trilobites, these genera seem to have a wide environmental tolerance and are long ranging taxa. The main occurrence of the three key taxa Carcassonnella, Thoralispira and Lesueurilla in the Montagne Noire is in the lower part of the La Maurerie Formation (Taihungshania miqueli acme Zone), while the same taxa appear just slightly later in Morocco (?Cymatograptus protobalticus Biozone). Migration to the Anti-Atlas during the early Floian seems to have been possible during a period of general faunal exchange. Pelecyogyra may either have migrated from the Anti-Atlas to Montagne Noire during the same interval or possibly during the late Floian as indicated by shared faunal elements between these two regions at that time.  相似文献   

5.
Partial sequences of the mitochondrial COI gene of forty eight European and two Turkish population samples of Myzus cerasi from different winter hosts (Prunus spp.) were subjected to phylogenetic analyses. The analysed M. cerasi samples emerged as paraphyletic relative to a Myzus borealis sample used as an out-group, and formed two major clades in neighbor joining, maximum parsimony, maximum likelihood and Bayesian inference trees, corresponding to subspecies living specifically on Prunus avium and P. cerasus. Multivariate discriminant analysis (method of canonical variates) was applied to find out if morphological variation of samples correlated with mitochondrial COI and host plant information. Mean scores on the first two canonical variables clustered samples fully in accordance with their COI haplotypes and host plants confirming the existence of two morphologically similar winter host - specific subspecies of M. cerasi in Europe. No single morphological character enabled satisfactory discrimination between apterous viviparous females of the two subspecies. A three-character linear discriminant function enabled 92.37% correct identification of apterous viviparous females of M. cerasi cerasi (n = 118) and 93.64% of M. cerasi pruniavium (n = 110). A key for the morphological identification of the two subspecies is presented and their taxonomic status is discussed.  相似文献   

6.
The occurrence of Archaeopsittacus sp. (Psittaciformes) in the fossil deposits of Sansan (France) is reported, testifying to a survival of this genus in the Middle Miocene, as Archaeopsittacus verreauxi was described from the Early Miocene of Saint-Gérand-le-Puy (France) and was recorded only from its type locality. The data discussed here indicate the presence of two parrot species from Sansan, as it is the type locality of another parrot species, Pararallus dispar, only known from this locality. The differences between the humeri of these two taxa are described in detail, together with the differences from the other European fossil parrot species. The presence of more than one species of parrot in the same locality is not rare, but in Europe it is recorded in Sansan for the second time. Evidence for parrots also confirms the paleoenvironmental reconstruction of Sansan, as parrots are primarily arboreal species. Archaeopsittacus also represents one of the few common elements between the Early and Middle Miocene European bird assemblages.  相似文献   

7.
8.
Preimaginal development and maturation of females of two laboratory strains originated from two populations of the multicolored Asian ladybird Harmonia axyridis were investigated under laboratory conditions. Females of the autochthonous population from Irkutsk (Siberia) enter diapause under the short day conditions, whereas in females of the invasive population from Sochi (the Caucasus) photoperiodic induction of diapause is weak. The two populations also differ in the proportions of morphs: the population from Sochi is represented only by the morph succinea, whereas the population from Irkutsk is represented by the morphs succinea и axyridis with the predominance of the last one, which in our study was separated into two phenotypes, differed in the degree of melanization. Rearing of adults under the short day (12 h) conditions induced reproductive diapause in females of all the studied morphs and phenotypes of the Irkutsk population, whereas under the long day (18 h) conditions females of the morph succinea showed a slightly lower tendency to diapause. Evidently, the interpopulation differences in the responses regulating the seasonal cycle of the multicolored Asian ladybird are determined by genes that are not involved (or almost not involved) in the determination of the color polymorphism. The interpopulation differences in size and weight were quite substantial, whereas the differences between morphs and phenotypes were statistically significant in only some of our experiments. In combination with the literature data, these results suggest that the genes determining the color polymorphism in H. axyridis may have a pleiotropic effect on other traits including important eco-physiological parameters but this effect is relatively weak and manifests itself only against a particular genetic background and / or under particular environmental conditions.  相似文献   

9.
A new clausidiid copepod was found living in galleries of ghost shrimps Neocallichirus grandimana (Gibbes, 1850) in Natal, Brazil. The new species resembles to Clausidium senegalense Humes, 1957 and Clausidium vancouverense (Haddon, 1912) in the armature of P2–P5 of the female, and shares with Clausidium senegalense similar segmentation and armature of the antenna and maxilla of the female. Nevertheless, it can be easily distinguished from its congeners by the unique characteristics observed in the antenna, maxilliped and first leg of males, as well as by the anal somite, maxillule and maxilliped of the females. This new species extends the group distribution to the Southwest Atlantic and represents the first record of the genus in Brazil. A key for the identification of the species based on females of Clausidium is provided.  相似文献   

10.
Common torpedo Torpedo torpedo (Linnaeus, 1758) is widely distributed in the Mediterranean Sea, especially in southern and northern regions. The species is known throughout the Tunisian coast and entered brackish areas, such as the northeastern Lagoon of Bizerte, where it is commonly captured. Investigations conducted in this latter area showed that males and females sexually matured between 234–285 mm and 245–280 mm total length (TL), respectively. The largest male and female were 403 mm and 435 mm TL, respectively and weighed 721.5 and 1273.5 g, respectively. There was a not significant relationship total mass versus TL between males and females. Conversely, the relationship of liver mass versus TL significantly differed between sexes. The diameter of the largest yolky oocytes ranged between 43 and 47 mm (mean 45.08 ± 0.98)}, while the mass ranged between 29.5 and 37.4 g (mean 31.79 ± 2.20). Near term embryos ranged from 19.34 to 31.28 mm TL (mean: 24.60 ± 4.12) and weighed from 3.9 to 9.0 g (mean 5.97 ± 1.41). Ovarian fecundity ranged from 4 to 36 (mean = 11.60 ± 5.96). Uterine fecundity or litter size ranged from 3 to 13 (mean = 6.36 ± 2.67). Both fecundities showed a positive relationship with TL of females. A chemical balance of development based on mean dry masses of yolky oocytes and near-term embryos was 0.75 and suggested that T. torpedo could be considered as a pure lecithotrophic species. Hepatosomatic index (HSI) and gonadosomatic index (GSI) calculated for females presented significant higher values than those of males. HSI values of males significantly differed differences between juveniles, sub-adults and adults, and in females, HSI values were not significantly different between juveniles and sub-adults and significantly different between sub-adults and adults. The values of male GSI increased with TL of specimens; additionally, they showed significant differences between juveniles and subadults, but not between sub-adults and adults. Monthly mean values of adult male and female HSI significantly varied throughout the year. Monthly mean of females GSI showed significant changes especially from January to April, due to a high vitellogenic activity, GSI decreased from May to August, during this period all yolky oocytes were ovulated, then GSI increased progressively from September. The reproductive cycle lasted one year approximately and gestation period 4 months, while near-term females were captured in August. Vitellogenesis did not proceed in parallel with embryonic development: during ovarian vitellogenic activity, the uteri were empty and in an appearent resting phase, conversely during gestation, the ovaries did not exhibit an appearent activity, by contrast other specimens exhibited a vitellogenic activity during gestation. With special regard to the latter case, it remains difficult to state if these small yolky oocytes were not ovulated, or if they were new oocytes produced immediately after ovulation, both hypothesis remaining suitable.  相似文献   

11.
《Animal behaviour》1986,34(4):998-1006
Experiments were performed to compare homospecific and heterospecific species choice in two closely related species of white-footed mice, Peromyscus californicus and P. eremicus. Both species significantly chose the homospecific stimulus animal. Significant homospecific choice was made by mice from sympatric but not from allopatric populations. Reciprocal cross-fostering between the two species resulted in significant choice for the heterospecific (foster) species by P. eremicus, and random choice by cross-fostered P. californicus. Laboratory-reared controls chose significantly for the homospecific chamber. No significant difference in choice performance was demonstrated between males and females, even when the oestrus stages of the females (both stimulus and test animals) were statistically controlled. A comparison of different test durations and temporal regimes of data collection was performed and 90 min was found to be the most efficient experiment duration with our apparatus.  相似文献   

12.
Reproductive behaviors related to habitat utilization were studied in males of the damsefly,Mnais nawai, which has two male forms, territorial orange-winged males (nawai) and non-territorial pale-orange-winged males (sahoi), at the upper part of a mountain stream where they partiallycoexist with a related species,Mnais pruinosa, which also has two male forms, territorial orange-winged males (esakii) and non-territorial hyaline-winged males (strigata). These two species showed parapatric distribution; the lower part of the stream was occupied byM. nawai, and the upper part byM. pruinosa. In the present study, cross-matings occurred between bothMnais species, although normal intraspecific matings occurred more frequently than cross-matings. Territorial males of both species copulated with conspecific females that entered their territory and guarded the ovipositing females, probably to avoid sperm displacement resulting from subsequent copulations. Severe competition for oviposition sites by territorial males even occurred between the two species. On the other hand, non-territorial males of both species have alternative mating strategies (including several tactics such as sneaking, takeover and interception). The possible benefits from conflict among territorial males of both species is discussed.  相似文献   

13.
The calling activity of virgin Phyllonorycter junoniella (Z.) females under a cycling thermal regime differed from that under constant temperature in the following ways: the percentage of females calling at the morning activity peak was increased; the morning period of calling activity was prolonged; the total period of calling activity of an individual female was increased; an extra peak of activity occurred at the end of the photophase, and females changed the calling pattern during the active period. We assume that the occurrence of two calling peaks and the extension of the calling period might be adaptive for a Ph. junoniella species with a sex ratio strongly shifted towards females (8:1 females:males), as it could lead to an increased proportion of females mated.  相似文献   

14.
One sesquiterpene lactone – 9α-hydroxy-3-deoxyzaluzanin C, three benzopyrans: desmethoxyencecalin (6-acetyl-2,2-dimethylchromene), desacetylripariochromen B and 6-(1-hydroxyethyl)-2,2-dimethylchromene, one coumarin – scopoletin and two eugenol derivatives were isolated from the roots of Tolpis barbata (L.) Gaertn, hitherto unexamined species. In the extract from aerial parts of the plant, five known phenolic compounds, namely: esculin, esculetin, chlorogenic acid (5-CQA), luteolin 7-O-glucoside and 3,5-dicaffeoylquinic acid (3,5-DCQA) were identified as major constituents. Except for the two coumarins – scopoletin and esculetin, which were previously obtained from Tolpis webbii Sch.Bip. and T. proustii Pit., the isolated and identified compounds have not been previously reported as constituents of Tolpis spp. Though benzopyrans were found in numerous species of the Asteraceae, their occurrence in the tribe Cichorieae has not been demonstrated before.  相似文献   

15.
Ma Q  Liu S  Zhuang Z  Lin L  Sun Z  Liu C  Ma H  Su Y  Tang Q 《Gene》2012,493(1):92-104
Growth hormone (GH) is a polypeptide which is an important regulator of development and somatic growth in teleosts, and may be associated with the mechanisms which drive sexual growth dimorphism in the Half-smooth tongue sole (Cynoglossus semilaevis). In this study, the full length gh cDNA was cloned from C. semilaevis by homology cloning and the rapid amplification of cDNA ends polymerase chain reaction (RACE-PCR). The full-length gh cDNA is 826 bp and contains an open reading frame (ORF) of 603 bp encoding a protein of 200 amino acids (AA). The precursor of gh consists of a 17 amino-acid signal peptide followed by a 183 amino-acid mature polypeptide. GH gene sequences obtained from female and male adults consist of 3428 bp and 3371 bp, respectively, each of which includes six exons and five introns, and the difference in the GH gene size was mainly caused by the microsatellites. When 14 tissues from females, normal males and extra-large male adults were analyzed for sex-specific tissue expression, the gh mRNA was found to be predominantly expressed in the pituitary, and the expression levels in females were 3.6 times as much as those in normal males, while the mRNA expression in extra-large males was 1.7 times as much as those in normal males. Sex differences in gh mRNA expression during development were also examined by using a full-sib family of C. semilaevis, and the gh mRNA was detected at all of the 12 time points sampled from 10 to 380 days-old. A significant increase in gh mRNA was detected starting in 80 day old fish and was then followed by a drop to very low levels starting at 230 day old fish. Differential expression indicated that the gh expression level in females was significantly higher than males (P < 0.01) at all of the stages except for 10 days-old. Two microsatellite loci were identified in the second intron of the GH gene. Using these two polymorphic markers to genotype 224 individuals, there was no significant difference between the females and males in the Bohai Sea, the Yellow Sea and the hatchery samples.  相似文献   

16.
Life history parameters of the freshwater chironomid species Kiefferulus calligaster (Kieffer, 1911) were investigated under laboratory conditions, with the use of larval development time and wing length as key features. An index of fitness was derived using these two parameters to represent the fitness of adults as a function of the larval development. Survivorship, deduced from the data on the mortality of larval stages, was related to developmental time as—(survivorship, lx) y = 1.16 ? 0.04 × (days). The larval development time varied between males and females with a minimum of 8 and a maximum of 12 days from first instar larva to eclosion of imagine. The average wing length of adult females was larger than males (3.9 mm ± 0.03 S.E. vs. 3.36 mm ± 0.02 S.E.), for both early and late emerging individuals. The degree of dimorphism between the sexes was prominent for wing length and larval development time. The index of fitness for the early and late emerging adults differed significantly (P < 0.05) in both the sexes.  相似文献   

17.
A statistical method for generating seasonal egg hatching profiles is applied to the brachyuran crabs Uca pugnax (Smith) and U. minax (LeConte) in New Jersey. Calibration experiments quantified the time course of egg development, using serial egg sampling at 1- to 2- day intervals from marked ovigerous females maintained in cages in the field. Egg stage was ranked from 1 to 10, based on morphological changes during development. Equations for predicting the number of days remaining until hatching from egg developmental stage were obtained from the calibration experiments, using stepwise polynomial regression. To cover the reproductive season, three consecutive calibration experiments using 15 or more females were run for U. pugnax; two for U. minax. Significant seasonal differences in the time course of egg development were detected. Weekly collections of females for each species were made; the date of larval release for each ovigerous female was predicted from the proximate calibration equation, yielding weekly hatching profiles. Weekly hatching profiles were summed to obtain seasonal hatching profiles. The average number of broods produced per female over the reproductive season was 1.9 for U. pugnax and 1.6 for U. minax. Hatching peaks for both species were associated with spring tides. The merits of this and other methods used to estimate daily variation in egg hatching of crabs are discussed.  相似文献   

18.
《Insect Biochemistry》1991,21(1):73-79
Females of the German cockroach, Blattella germanica, produce a contact sex pheromone consisting of the methyl ketones 3,11-dimethyl-2-heptacosanone, 3,11-dimethyl-2-nonacosanone, 29-hydroxy- and 29-oxo-3,11-dimethyl-2-nonacosanone. We review evidence in support of the hypothesis that in adult females the hydrocarbon 3,11-dimethylnonacosane is oxidized to the corresponding methyl ketone pheromone. Recent studies on the precursors and directionality of synthesis of the methyl-branched alkane indicate that it is formed by the insertion of methylmalonyl units derived from propionate, isoleucine, valine, methionine and succinate early in chain elongation. The hydrocarbon is then hydroxylated and oxidized at the 2-position to form the methyl ketone pheromone. The in vivo synthesis of pheromone and its accumulation on the cuticle are correlated to the synthesis of juvenile hormone (JH) by the corpora allata (CA) in vitro and to oocyte development, suggesting common regulation by JH of pheromone production as well as other reproductive events. The patterns of pheromone and hydrocarbon production in starved, allatectomized and head-ligated females, as well as in females rescued with hormone-replacement therapy, suggest two mechanisms of regulation of pheromone production: a JH-induced conversion of hydrocarbon to pheromone is related to the CA cycle and to oocyte development, while a JH-independent mechanism, which is probably related to feeding, supplies precursors for hydrocarbon biosynthesis.  相似文献   

19.
The study presents new data on spatial distribution of bark beetle pathogens, on changes in frequency over several years and on their prevalence during different time periods within a year from several locations within the wilderness reserve Dürrenstein (Lower Austria). The occurrence of pathogens was investigated in Ips typographus (during five years), in Pityogenes chalcographus (during two years) and in Ips amitinus (in one year). In total, seven pathogen species could be detected in I. typographus. The most dominant pathogen species were the Ips typographus-Entomopoxvirus (ItEPV), the sporozoan species Gregarina typographi and the microsporidium Chytridiopsis typographi; the latter two pathogen species were recorded every year and at about similar high (G. typographi) or low (C. typographi) rates, the ItEPV in strongly varying rates. The neogregarine Mattesia cf. schwenkei and the two microsporidia Nosema typographi and Unikaryon montanum were found in I. typographus only sporadically and the rhizopodan species Malamoeba scolyti was found once. The number of infected males and females was relatively similar with almost all pathogen species in most of the years except U. montanum, which occurred exclusively in females. Three pathogen species were recorded in P. chalcographus which were Gregarina typographi, Mattesia cf. schwenkei and Chytridiopsis typographi. Two pathogen species were observed in I. amitinus, Gregarina typographi and Chytridiopsis typographi.  相似文献   

20.
We present new morphological data on three Colombian and BolivianInia populations. Analysis of morphometric data strongly suggests thatInia are sexually dimorphic, with males smaller for several variables and more heterogeneous than females. Our morphological data supported that Colombian Amazon males had the greatest total body length as well as greatest fluke values (tip to tip) compared to the males from the Orinoco and Bolivia Rivers. There were also significant differences in females among populations. The two Colombian groups (Amazon and Orinoco basin) presented greater total body length than the Bolivian array, while distance from jaw tip to tip of dorsal fin was greater in the Orinoco basin females than in the other two populations. A Canonic Population Analysis showed that the confidence intervals of the Colombian Amazon and Orinoco males were partially superposed. However, the Bolivian male sample was remarkably differing from these two populations. Two long standing debates exist in the systematic literature onInia: (1) the number of extant species (one,Inia geoffrensis, or twoI. geoffrensis andI. boliviensis) and (2) the number of extant subspecies ofI. geoffrensis (I. geoffrensis geoffrensis, I. geoffrensis humboldtiana andI. geoffrensis boliviensis). Using recent collections of both molecular and morphometric data, we suggest the existence of two distinct species ofInia with no subspecific distinction amongI. geoffrensis populations.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号