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1.
When sexual cannibalism presents a sexual conflict, one expects to find male traits that reduce the risk of cannibalism. In sexually cannibalistic species, selection is thought to have favored the evolution of male approach behaviors that reduce the probability that the female will kill the male. We tested the hypothesis that male mantids change their approach behavior in response to wind to reduce the risk of being noticed by females. Time between detection of the female by the male and mating was shorter under windy than windless conditions. Sexual approach behavior was observed more frequently under windy than windless conditions. Moreover, this behavior was observed more frequently when the female was walking than when the female was not walking under windy conditions. The detection rate of male mantids by females was significantly lower on swaying leaves than on fixed leaves. Our results thus indicate that male mantids were more active in response to wind. Therefore, we suggest that the male's quick approach strategy toward females when the wind is blowing at short range is adaptive in reducing the risk of detection by females.  相似文献   

2.
Defensive behaviour in Ghanaian praying mantids   总被引:1,自引:0,他引:1  
The defensive behaviour of 25 species of praying mantids from Ghana is described. All have camouflage as the primary defence mechanism, either a general resemblance to vegetation, or a specific resemblance to bark, sticks, leaves or grass. Secondary defence mechanisms include running, flying, thanatosis, secretion of fluid from the mouth, startle display and flash colouration. The early instars of several species are ant-mimics. The female Taracbodes afzelii often guards her ootheca and also the young nymphs, and she can distinguish her nymphs from intruding ants which are attacked. Some mantids have a green/brown polymorphism and there is evidence that the frequencies of the two forms vary seasonally. Other mantids are stick, grass or bark mimics, and the possible ways in which the adaptations of these forms have evolved are outlined. The startle display is probably a bluff which protects the mantid to some extent from avian predators. It does not appear to be directed against predaceous mammals. A curious "boxing display" is described from Oxypilus, Anasigerpes and Catasigerpes. It probably functions to space out individuals, not to discourage attacks from predators. The occurrence of this display is used as taxonomic evidence for the close relationship of these three genera.  相似文献   

3.
P. J. S. Olney 《Ibis》1965,107(4):527-532
The food and feeding habits of Shelduck Tadorna tadorna are described, based on the analyses of the viscera of 30 birds collected under special licence, and of 18 birds found dead or dying during the cold weather of 1963, on faecal material from eight incubating birds, on field observations and on the literature. The birds came from a number of different localities and from each month of the year, apart from July.
The mollusc Hydrobia ulvae (Pennant) was found in all 46 birds which contained food, and it is quite obvious, and this is confirmed by the literature and by faecal analyses, that this is the most important food item during much of the year and in many different localities. Other species eaten included the bivalve Macoma balthica , the amphipod Corophium volutator , the ragworm Nereis sp., the alga Enteromorpha , and occasionally the seeds of various plants.
The importance of H. ulvae is examined in the light of its distribution and numbers, which may be a strong controlling factor in concentrating Shelduck in certain areas at certain times of the year.
The feeding behaviour of Shelduck, and a number of other birds, is apparently closely related to the cyclic behaviour pattern of the main food species, H. ulvae .
It seems that Shelduck have a rather fixed type of feeding behaviour which exploits only one feeding niche and therein mainly one food item. Any event (prolonged gales or very cold weather) which prevents the bird from using that niche can be the cause of heavy mortality.  相似文献   

4.
The association of certain sea anemones and hermit crabs is established in different ways according to the species involved. The present study shows that the behaviour patterns of the two partners in associations between Calliactis tricolor (Lesueur) and Dardanus venosus (H. M. Edwards) in the Caribbean are similar to those seen in the Mediterranean C. parasitica and D. arrosor .
Although about half the crabs display an active behaviour pattern in laboratory trials, the anemone frequently settles on shells unaided and most C. tricolor respond to molluscan shells by clinging with their tentacles until the pedal disc can be attached. As a rule it is necessary for the anemone to relax and to cling to the shell if the crab is to be successful in transferring the anemone to its shell.
The behaviour patterns of D. venosus include a distinctive tapping of the edge of the base of C. tricolor after which the anemone is pulled or lifted off and transferred to the shell. An experimenter can also cause the anemone to relax and to detach itself by tapping the edge of the base with plastic rods after the manner of the crab.
The mechanisms by which the tentacles of Calliactis cling to, and by which the base settles upon, shells still remain to be elucidated. The participation of nematocysts in these processes could not be demonstrated in this study.
C. tricolor is found on some other pagurid and non-pagurid crabs in various localities. These associations need to be investigated fully in order that the behaviour patterns of C. tricolor may be correctly interpreted and compared with those of other species of Calliactis .  相似文献   

5.
The laboratory conditions under which the centipedes were kept and their general behaviour are described. No indication of sexual recognition between adult centipedes was found during studies made of encounters between members of the same or opposite sexes. All displayed the same avoiding reaction on the first encounter and later adopted the defence posture by which fatal attacks were prevented. Where attacks were not successfully countered, biting may or may not be accompanied by injection of poison into the wound. These centipedes are not immune to the poison of their own species, therefore, fatalities and cannibalism can result from aggressive encounters.
The mating behaviour of Cormocephalus anceps was witnessed once in early autumn in South Africa. It was preceded by the typical avoiding reaction and defence posture assumed by either sex towards the other, the male being the more dominant. After adopting this posture, a situation which may last a variable length of time, the subsequent stages of mating behaviour were initiated by the male. The courting behaviour could be followed in five sequences which are described in some detail.
The problems of sperm transfer faced by the Arthropoda evolving towards a wholly terrestrial existence and the many modes adopted by this group are considered together with the recent knowledge of the modes of sperm transfer employed by the four orders of Chilopoda.  相似文献   

6.
L Bertholon  P Carbonel 《Bio Systems》1992,28(1-3):179-194
The ontogenetic development of Ruggieria lekkii, Ruggieria triangulata, Ruggieria martinsoni and Chrysocythere ornata (Ostracoda) was investigated on two different continental shelves (Congo and Senegal). For one species, the ontogenetic trajectories obtained through length and height of valves differed considerably in distinct areas. In the first case, trajectories showing well-separated development stages and slight intraspecific variability in length and height were seen. In the second, trajectories showing valves which are difficult to relate to one stage or another and a high intraspecific variability were noted. In the latter, the uncertainties in the determination of the development stages were resolved by using a statistical method. Furthermore, this allowed for the comparison of the variations in ontogenesis (augmentation or reduction in the development), in relation to abiotic (detrital supply and upwelling processes) and biotic ecological factors (faunal density and interspecific competition). Comparisons were also made with ornamental variations observed on Chrysocythere ornata, which are directly linked with bioprecipitation (environmental) conditions. This comparison highlights the role played by abiotic and trophic factors on the developmental variations of ostracods in some continental shelves areas. This work shows that ontogenetic variations depend either on biotic or abiotic factors. They can act in different ways on distinct species and one can be predominant in a particular biota. Once the architectural characters have appeared, their variations no more depend on ontogenetic development. The study of ontogenesis reveals the adaptation capacities of one species in an environment with variable conditions.  相似文献   

7.
We describe the cloning and characterization of eight novel tetranucleotide microsatellite loci in the ornate chorus frog (Pseudacris ornata). We also screened 26 loci from GenBank that were isolated from other Pseudacris species and obtained consistent product from five of these dinucleotide loci. All loci are polymorphic. In our sample of 26 frogs from a natural population, polymorphism ranged from 1 to 22 alleles per locus with expected heterozygosities ranging from 0 to 0.958. These loci enable high-resolution studies of P. ornata. Moreover, cross-species amplification success suggests they will also be useful for other chorus frog species.  相似文献   

8.
Summary Six mantid species (Sphodromantis viridis, Polyspilota aeruginosa, Hierodula unimaculata, Parasphendale agrionia, Mantis religiosa and Empusa pennata) were studied in laboratory feeding experiments. Mantids stalk their prey and pounce on it, grasping it with their forelegs. Only living prey is selected and it is consumed directly after the catch. The predator orients itself optically, and therefore only takes notice of moving prey. The maximum size of prey which mantids can overwhelm is species-specific and depends on the prey type. On average mantids eat crickets of 50% their own body-weight while cockroaches can weigh up to 110%. Feeding experiments with 101 species of potential prey of 21 invertebrate orders showed an average feeding rate of 70% and marked differences among the predators. Polyspilota proved to be the least specialized mantid and Empusa caught the smallest amount of prey. Most of the defence mechanisms which arthropods have developed against their enemies proved to be ineffective against mantids. Neither a hard chitinous exoskeleton nor poisonous substances prevented the mantids from attacking their prey successfully. The protective secretion of the cotton stainer Dysdercus intermedius proved to be effective at least in a few instances. Even though these bugs were killed, the mantids usually refused to eat the abdomen, where the glands that produce the protective secretion are to be found. Thanatosis, as exhibited by the chrysomelid Cassida viridis and by the phasmid Carausius morosus, proved to be the best protection against mantids.  相似文献   

9.
We tested the hypothesis that a generalist arthropod predator, Tenodera sinensis Saussure, could trigger a trophic cascade in an old-field ecosystem. These mantids had relatively weak effects on abundance and biomass of other carnivorous arthropods as a group. The effect of mantids on herbivores was stronger than on carnivores, mainly concentrated in Homoptera and Diptera. Herbivore load was reduced by mantids with the consequence that overall plant biomass (mainly grasses) was increased. Percapita interaction strengths between mantids and other arthropod taxa were, for the most part, weakly negative. Our study demonstrates that a significant trophic cascade can be triggered by a generalist predator even within the framework of a diverse community with relatively diffuse interactions. Received: 13 January 1997 / Accepted: 28 July 1997  相似文献   

10.
Bidimensional and unidimensional maps of amine-containing components extracted from brains of the praying mantis (Stagmatoptera biocellata) were obtained using high-voltage electrophoresis and chromatography, and high-voltage electrophoresis alone.Bidimensional maps from control insects, i.e. animals that did not receive training, showed four distinctive spots and one less intense spot (number 5). On the other hand, bidimensional maps from trained animals, i.e. mantids that were trained not to attack a moving star, showed the same spots 1–4, plus an intense spot (number 5) and an extra componet (number 6).Unidimensional maps from brains of mantids that were trained not to attack a moving star (‘star-group’) showed two extra components in comparison with maps from the control insects. On the other hand, when mantids received training similarto that of the star-group, but using a fly that could not be caught as a stimulus, instead of a mobile star, they did not learn and their maps were similar to those from control mantids.The techniques used in this paper to obtain the maps suggest that they are maps of peptides of low molecular weight. The possible correlation between the appearance of extra spots in the maps and a learning process is discussed.  相似文献   

11.
Crypsis can be either defensive or aggressive in function, and the first evidence that crypsis reduces the probability of being detected by a predator was collected almost a century ago. Crypsis in mantids may reduce the probability that a mantid will be detected by its prey, but no experiments have been carried out to test this idea. We tested the hypothesis that the approach strategy of the mantid Tenodera aridifolia (Stoll) toward prey when the wind is blowing is adaptive. Significantly less time elapsed between the discovery of the prey by the predator and capture action under windy conditions than under windless conditions. Approach behaviors (walking and body swaying) were observed more frequently under windy than under windless conditions. When the wind stopped, mantids became still, and they changed their behavior in response to alternately changing wind conditions. Moreover, the discovery rate of the predator mantids by conspecific prey mantids was significantly lower on swaying leaves than on fixed leaves. The capturing rate of the prey by the mantid was significantly higher under windy conditions than under windless conditions. We suggest that the strategy of approaching prey quickly when the wind blowing is adaptive for reducing the risk of discovery and escape by the prey.  相似文献   

12.
螳螂种群增长制约因素分析   总被引:1,自引:0,他引:1  
在自然界中,螳螂种群数量的增长受到多种因素的制约。作者通过野外调查和实验室饲养观察,以及对国内外相关资料的查阅,对这些主要制约因素逐一进行了分析和归纳。在影响螳螂分布与制约种群数量增长的这些因素中,自然条件中的温度是关键的制约因素,食物、天敌、自残行为、人类活动等是重要的制约因素。  相似文献   

13.
泽蛙、日本林蛙、饰纹姬蛙不同地理居群的核型多样性   总被引:5,自引:0,他引:5  
钱晓薇  朱睦元 《遗传》2000,22(3):144-148
本文研究了温州地区的泽蛙、日本林蛙、饰纹姬蛙的核型,并分析了9个地理居群泽蛙的核型、4个地理居群日本林蛙的核型和3个地理居群饰纹姬蛙的核型。结果表明,不同地理居群的同种蛙均有相同的染色体数和核型模式。泽蛙、日本林蛙都为 2n=26,NF=52,核模式5+8;饰纹姬蛙 2n=24,NF=48,核模式6+6。但同一种蛙的不同地理居群之间在SM数目和顺序、次缢痕或随体的位置等都有所不同,说明不同地理居群的同种蛙的染色体具有丰富的多样性。故保护蛙品种资源多样性,不仅要从整个群体上考虑,而且要针对每个品种(或类群)进行保护。 Abstract:The karyotypes of Rana limmocharis boie,Rana j.Japonica,and Microhyla ornata from Wenzhou were studied.The karyotypes of nine populations of Rana limmocharis boie,four populations of Rana j.Japonica and three populations of Microhyla ornata from different geographical regions were compared.The results demonstrated that the same species of different geographical populations have the same amount of chromosome and karyotypic formulae. Rana limmocharis boie and Rana j.Japonica have 2n=26,NF=52 and 5+8 karyotypic formulae.Microhyla ornata has 2n=24,NF=48 and 6+6 karyotypic formulae.But some dissimilarities were found among them.First,the number and sequence of submetacentric chromosome were different among them,and then the secondary contriction (SC)or satellite (Sat)were also different.It was showed that the chromosomes of same species of different geographical population have diversities.Conservation of frog genetic diversity must be considered of not only the genetic diversity conservation of the total frog population but also that of every frog breed.  相似文献   

14.
Special features of competitive behavioural organization have been revealed during formation and realization of simple feeding and instrumental reflexes elaborated simultaneously in family pairs of marmoset monkeys. In contrast to other anthropoid species, male and female marmosets performed feeding reactions of different levels of complexity with equal efficiency. The differences between male and female marmosets concern the structure of competitive behaviour: males showed more active forms of competition under equal number of the given reinforcement, whereas passive forms of behaviour were more typical in females. The latter produced intensive vocalization in comparison with males. Stabilization of competitive activity was accompanied by the decrease of active forms of competition and by standardization of individual behaviour. The increase in the number of behavioural strategies was observed in family groups under sophisticated experimental conditions.  相似文献   

15.
John M.  Edington M. Ann  Edington 《Ibis》1983,125(1):74-89
A study was made of feeding patterns and antagonistic behaviour amongst 11 common bird species frequenting an abandoned rubber plantation and scrub plot in southern Nigeria.
The examination of feeding patterns involved a comparison of foraging habits and an analysis of the use made by each species of the major vertical and horizontal subdivisions of the habitat. Two species of muscicapid flycatchers showed a striking similarity, both in foraging habits and their use of the major habitat zones. In general, however, species with otherwise similar foraging habits were found to feed in habitat zones which were spatially separated.
A number of these latter species showed antagonistic reactions to one another. However, unlike most reported instances of such behaviour in birds, neither species in the pairs we observed played a consistently dominant role. Dominance was usually shown by whichever individual made most use, for feeding purposes, of the encounter zone.
Under these circumstances it seems possible that interspecific antagonism allows species to adjust to local variations in habitat structure and to capitalise on the temporary absence of potential competitors. In which case it is more appropriate to regard this type of behaviour as an important component in the process of habitat partitioning, rather than to dismiss it as an activity which will ultimately be rendered redundant in the course of evolution.  相似文献   

16.
Lee YH  Lin CP 《Molecular ecology》2012,21(15):3739-3756
Climatic oscillations during the Pleistocene period could have had a profound impact on the origin of tropical species by the alternation of allopatric isolation and interpopulation gene flow cycles. However, whether tropical speciation involves strictly allopatric isolation, or proceeds in the face of homogenizing gene flow, is relatively unclear. Here, we investigated geographical modes of speciation in four closely related Euphaea damselfly species endemic to the subtropical and tropical East Asian islands using coalescent analyses of a multilocus data set. The reconstructed phylogenies demonstrated distinct species status for each of the four species and the existence of two sister species pairs, Euphaea formosa/E. yayeyamana and E. decorata/E. ornata. The species divergence time of the sibling Euphaea damselflies dates back to within the last one Mya of the Middle to Lower Pleistocene. The speciation between the populous E. formosa of Taiwan and the less numerous E. yayeyamana of the Yaeyama islands occurred despite significant bidirectional, asymmetric gene flow, which is strongly inconsistent with a strictly allopatric model. In contrast, speciation of the approximately equal-sized populations of E. decorata of the southeast Asian mainland and E. ornata of Hainan is inferred to have involved allopatric divergence without gene flow. Our findings suggest that differential selection of natural or sexual environments is a prominent driver of species divergence in subtropical E. formosa and E. yayeyamana; whereas for tropical E. decorata and E. ornata at lower latitudes, allopatric isolation may well be a pivotal promoter of species formation.  相似文献   

17.
Most floral nectars are clear as water, and the enigmatic coloured nectar in three endemic plant species in Mauritius has puzzled scientists studying it. One hypothesis about the possible ecological function of coloured nectar is that it serves as a visual signal for pollinators. Recent studies have shown that at least two of the three Mauritian plant species with coloured nectar are visited and pollinated by endemic Phelsuma geckos. We here provide experimental evidence for the visual signal hypothesis by showing that Phelsuma ornata geckos prefer coloured over clear nectar in artificial flowers. In flowering plants, coloured nectar could additionally function as an honest signal that allows pollinators to assert the presence and judge the size of a reward prior to flower visitation, and to adjust their behaviour accordingly, leading to increased pollinator efficiency. Our study provides a first step in understanding this rare and intriguing floral trait.  相似文献   

18.
ABSTRACT .
The previously monotypic Papuan genus Heterochorista Diakonoff, 1952 is revised and twenty-one species are recognized. Nikolaia Diakonoff, 1953 is synonymized, syn.n. with Heterochorista. The following six species are placed in new combination in Heterochorista: Nikolaia melanopsygma Diakonoff, N.inumbrata Diakonoff, N.aperta Diakonoff, Isochorista papuana Diakonoff, I.polysperma Diakonoff and Dicellitis chrysonetha Diakonoff. Thirteen new species are added to Heterochorista: acomata sp.n., rostrata sp.n., trivialis sp.n., ornata sp.n., prisca sp.n., punctulata sp.n., rufulimaculata sp.n., classeyiana sp.n., spinosa sp.n., signata sp.n., fulgens sp.n., nitida sp.n. and aura sp.n. A checklist and a key to species are provided, and adults and male and female genitalia are described and illustrated. The phylogeny of Heterochorista is outlined on the basis of a cladistic character analysis and the genus is referred to the base of the Sparganothini. The apomorphies characterizing this tribe are reviewed with regard to their phylogenetic significance and the relationship between Sparganothini, Archipini and Atterini is briefly discussed.  相似文献   

19.
Trypanosoma pipientis infections were achieved by exposing laboratory-raised bullfrog tadpoles (Rana catesbeiana) to the leech Desserobdella picta that had fed on infected frogs. Likewise, a laboratory-raised snapping turtle (Chelydra serpentina) was infected with Trypanosoma chrysemydis following exposure to infected Placobdella ornata. Transmission of the trypanosomes by these leeches constitutes new vector records for the parasites. The biology of D. picta and P. ornata suggests that they are more important in transmitting these flagellates than the species of leech previously reported as vectors.  相似文献   

20.
During the period 1964 – 1966 biological studies were conducted of two black rhinoeeros Diceros bicornis L. populations in northern Tanzania. One population occupies the caldera of Ngorongoro and the other the area in the vicinity of Olduvai Gorge. Detailed records were made of each rhinoeeros observatson and 182 individuais were seen in the two study areas during the three-year period.
The black rhinoeeros is a very sedentary species, and the size of the home range is governed by several factors which are described in the^text. The home range of an immature rhinoeeros is larger than that of an adult individual. The adult rhinoeeros, especially the male, is essentially a solitary animal, but immatures frequently join up with a companion.
Activity patterns are described and illustrated, and are similar in the two study areas. Behaviour of the species follows welldefined patterns, and territorial behaviour is uncommon. Vocal communication in the species is described. The significance of dung piles, used regularly by the species, is considered and the results of experiments iflsing faecal samples are described. Relations with two carnivores are discussed.
The recruztment rates of the two populations are almost identical, i.e. 7.0% at Ngorongoro and 7.2% at Olduvai. Various reproductive characteris-tics affecting recruitment rates, such as age at maturity, gestation period and interval between successive calves are described using records obtained from zoological gardens and from field observations.
The results of the studies indIcate that the rhinoeeros population of the Ngorongoro Conservation Area is considerably higher than was formerly believed. The future of the species in the area appears favourable, providing its habitats are not destroyed through encroaching cultivation.  相似文献   

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