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1.
1. Spiderlings of the crab spider Misumena vatia and nymphs of the ambush bug Phymata americana normally ambush prey in flowers, as do the adults. The immatures of M. vatia are more mobile, by ballooning, than the ambulatory but largely sedentary adult female spiders, but the apterous immatures of P. americana are less mobile than the alate adults. The aim of the work reported here was to investigate how immatures, as compared with adults, select sites from which to ambush their prey. 2. Individual immatures of both species were released in experimental arenas with variously manipulated natural stems: normal, with and without leaves, and with and without flowers of three species of plants. 3. The spiderlings and nymphs showed discriminatory behaviour but not in accordance with optimal foraging in either case. The spiderlings chose more leafy stems than any other kind of stem. For the nymphs, the importance of leaves was less marked, food apparently being more important than shelter. 4. Neither of the predators discriminated among flowering stems of Solidago canadensis, Daucus carota, and Cirsium arvense. 5. In other experiments, in which flowered and deflowered stems were located in two separated groups in the arena and the individual was released in a bare area between the two groups, the spiderlings chose either group as predicted by chance but the nymphs showed a slight preference for the flowered sector. Nevertheless, once in either of the groups, the predators showed similar behaviour in choosing leafy stems more often than other stems. 6. Nymphs of P. americana are much more selective than adults but spiderlings of M. vatia are less selective than adult females. These results appear to accord with the time and energy costs of changing hunting sites, walking being slower than flying or ballooning. 7. The results indicate the need to include other parameters, such as enemy‐free space and time spent in not being able to forage, in the analysis of foraging behaviour.  相似文献   

2.
Aim To analyse the historical biogeography of the lichen genus Chroodiscus using a phenotype‐based phylogeny in the context of continental drift and evolution of tropical rain forest vegetation. Location All tropical regions (Central and South America, Africa, India, Southeast Asia, north‐east Australia). Methods We performed a phenotype‐based phylogenetic analysis and ancestral character state reconstruction of 14 species of the lichen genus Chroodiscus, using paup * and mesquite ; dispersal–vicariance analysis (DIVA) and dispersal–extinction–cladogenesis (DEC) modelling to trace the geographical origin of individual clades; and ordination and clustering by means of pc‐ord , based on a novel similarity index, to visualize the biogeographical relationships of floristic regions in which Chroodiscus occurs. Results The 14 species of Chroodiscus show distinctive distribution patterns, with one pantropical and one amphi‐Pacific taxon and 12 species each restricted to a single continent. The genus comprises four clades. DIVA and DEC modelling suggest a South American origin of Chroodiscus in the mid to late Cretaceous (120–100 Ma), with subsequent expansion through a South American–African–Indian–Southeast Asian–Australian dispersal route and late diversification of the argillaceus clade in Southeast Asia. Based on the abundance of extant taxa, the probability of speciation events in Chroodiscus is shown to be extremely low. Slow dispersal of foliicolous rain forest understorey lichens is consistent with estimated phylogenetic ages of individual species and with average lengths of biological species intervals in fungi (10–20 Myr). Main conclusions The present‐day distribution of Chroodiscus can be explained by vicariance and mid‐distance dispersal through the interconnection or proximity of continental shelves, without the need for recent, trans‐oceanic long‐distance dispersal. Phylogenetic reconstruction and age estimation for Chroodiscus are consistent with the ‘biotic ferry’ hypothesis: a South American origin and subsequent eastward expansion through Africa towards Southeast Asia and north‐eastern Australia via the Indian subcontinent. The present‐day pantropical distributions of many clades and species of foliicolous lichens might thus be explained by eastward expansion through continental drift, along with the evolution of modern rain forests starting 120 Ma, rather than by the existence of a hypothetical continuous area of pre‐modern rain forest spanning South America, Africa and Southeast Asia during the mid and late Cretaceous.  相似文献   

3.
The shrub, Lantana camara L. (Verbenaceae), of tropical American origin, is a serious weed in South Africa and is the target of a biological control programme. The stem-sucking membracid, Aconophora compressa Walker (Homoptera: Membracidae), from Mexico was reported to be very damaging and was therefore imported into South Africa for biology and host range studies. The female partially inserts the eggs into the woody portion of actively growing stems, and guards them against potential predators. Nymphs develop through five instars to the adult stage in about 45 days. The adults and nymphs feed on the sap of stems causing the leaves to wilt, the flowers to abort and the gradual dieback of stems. No-choice experiments showed that adult survival, egg production, and nymphal emergence was high on L. camara, and also on related ornamental and indigenous species. The adult reproductive performance was higher on some indigenous Lippia species than on L. camara. Furthermore, the nymphs developed faster on these indigenous species and high rates of reproductive performance on these non-target species were sustained over several generations. In multiple-choice trials, equal or larger numbers of egg batches were recorded from indigenous Lippia species and the ornamental plant, Aloysia citrodora Palau, than on L. camara. The treehopper, A. compressa, poses an unacceptable threat to indigenous Lippia species and has therefore been rejected as a biocontrol agent for L. camara in Africa.  相似文献   

4.
Nymphs of Stenoscepa sp. feed on leaves of the Ni hyperaccumulator Berkheya coddii at serpentine sites in Mpumalanga Province, South Africa. These sites contain Ni hyperaccumulators, Ni accumulators, and plants with Ni concentrations in the normal range. We conducted studies to: (i) determine the whole-body metal concentration of nymphs (including those starved to empty their guts); (ii) compare Stenoscepa sp. nymphs against other grasshoppers in the same habitat for whole-body metal concentrations; and (iii)compare the suitability of Ni hyperaccumulator and Ni accumulator plants as food sources for Stenoscepa sp. and other grasshoppers. Stenoscepa nymphs had extremely high whole-body Ni concentrations (3 500μg Ni/g). This was partly due to food in the gut, as starved insects contained less Ni (950 pg Ni/g). Stenoscepa nymphs survived significantly better than other grasshoppers collected from either a serpentine or a non-serpentine site when offered high-Ni plants as food. In a host preference test among four Berkheya species (two Ni hyperaccumulators and two Ni accumulators), Stenoscepa sp, preferred leaves of the Ni hyperaccumulator species. A preference experiment using leaves of three Senecio species (of which one species, Senecio coronatus, was represented by both a Ni hyperaccumulator and a Ni accumulator population) showed that Stenoscepa sp. preferred Ni accumulator Senecio coronatus leaves to all other choices. We conclude that Stenoscepa sp. is extremely Ni-tolerant. Stenoscepa sp. nymphs prefer leaves of hyperaccumulator Berkheya species, but elevated Ni concentration alone does not determine their food preference. We suggest that the extremely high whole-body Ni concentration of Stenoscepa nymphs may affect food web relationships in these serpentine communities.  相似文献   

5.
We examined the genetic divergence of Platycerus hongwonpyoi Imura & Choe, 1989 in South Korea using the nuclear wingless (Wg) gene, internal transcribed spacer (ITS) region and mitochondrial cytochrome oxidase subunit I (COI) gene. We found no variation in Wg or ITS. Based on COI, P. hongwonpyoi was split into four well defined and one weakly supported clades, which were inferred to have diverged 2.11–1.33 Ma. The Platycerus hongwonpyoi population size seems to have decreased during the past several tens of thousands of years. The divergence times of major clades of P. hongwonpyoi were comparable with those involved in the speciation of certain Japanese species. Frequent overlapping of different clades at the same sites suggests the occurrence of secondary gene flow following differentiation in South Korea. In conclusion, the genus Platycerus underwent strikingly different divergence patterns in South Korea compared with Japan according to the disparate topographies of these two geographical areas.  相似文献   

6.
Myrmecophytes depend on symbiotic ants (plant‐ants) to defend against herbivores. Although these defensive mechanisms are highly effective, some herbivorous insects can use myrmecophytes as their host‐plants. The feeding habits of these phytophages on myrmecophytes and the impacts of the plant‐ants on their feeding behavior have been poorly studied. We examined two phasmid species, Orthomeria alexis and O. cuprinus, which are known to feed on Macaranga (Euphorbiaceae) myrmecophytes in a Bornean primary forest. Our observations revealed that: (i) each phasmid species relied on two closely‐related myrmecophytic Macaranga species for its host‐plants in spite of their normal plant‐ant symbioses; and (ii) there was little overlap between their host‐plant preferences. More O. cuprinus adults and nymphs were found on new leaves, which were attended by more plant‐ants than mature leaves, while most adults and nymphs of O. alexis tended to avoid new leaves. In a feeding choice experiment under ant‐excluded conditions, O. alexis adults chose a non‐host Macaranga myrmecophyte that was more intensively defended by plant‐ants and was more palatable than their usual host‐plants almost as frequently as their usual host‐plant, suggesting that the host‐plant range of O. alexis was restricted by the presence of plant‐ants on non‐host‐plants. Phasmid behavior that appeared to minimize plant‐ant attacks is described.  相似文献   

7.
With approximately 25 endemic species, the genus Pyrus (pears) is highly diverse in the Caucasus ecoregion. The majority of Caucasian pears inhabit xerophytic open woodlands or similar habitats, to which they display morphological adaptations, such as narrow leaves. The other species, both Caucasian and non‐Caucasian taxa, mainly inhabit mesophytic forests and display broad leaves. Using a representative taxon sampling of Pyrus from the Caucasus, Europe and Asia, we reconstruct phylogenetic relationships in the genus based on multiple plastid regions. We also estimate the divergence times of major clades in Pyrus, reconstruct the evolution of leaf shapes, and discuss the emergence of xeromorphic leaf traits. Our results confirm the monophyly of Pyrus and the existence of two major clades: (a) an E Asian clade with a crown group age of 15.7 (24.02–8.37 95% HPD) My, and (b) a W Eurasian clade that comprises species from Europe, SW Asia and the Caucasus and that displays a slightly younger crown group of 12.38 (19.02–6.41 95% HPD) My. The existing infrageneric classification of Pyrus was found partially incongruent with the inferred phylogenetic trees. Several currently accepted species were not recovered as monophyletic, indicating that current species limits require re‐evaluation. Ancestral character state reconstructions revealed several independent transitions from broad‐ to narrow‐shaped leaves in Pyrus, probably via intermediate‐shaped leaves.  相似文献   

8.
Vegetative anatomical features are poorly known in the South American genus Chrysolaena. In this study, leaves and stems of six Chrysolaena species were described and compared morphologically and anatomically using diaphanization, microtome serial sectioning and scanning electron microscopy. The species differed in leaf epidermis, type of stomata, shape of anticlinal walls of epidermal cells, trichome density, and presence or absence in stems of small air spaces in the cortical parenchyma and of druse‐shaped oxalate crystals. Furthermore, glandular trichomes and three types of non‐glandular trichomes with different number of basal cells were identified on leaves and stems. Collectively, these features proved instrumental to discriminate among the six studied species, suggesting that leaves and stems of Chrysolaena can represent a source for taxonomically useful characters. We also discuss anatomical features in relation to the environmental conditions in the species’ habitats.  相似文献   

9.
Here we describe a new species ofCorydalis sectCorydalis (Fumariaceae), namely C.hirtipes B.U. Oh et J.G. Kim. This species, from the central part of Korea, is clearly distinguished from other species of sectCorydalis by its simple, unicellular hairs that are densely distributed on the stems, peduncles, and petioles. It is also distinctive from its close relative C.albipetala in having ternate leaves, lobate or parted leaflets, dentate or cleft bracts, and broad, fusiform fruits.  相似文献   

10.
Many species only show sexual dimorphism at the age of maturity, such that juveniles typically resemble females. Under these circumstances, estimating accurate age‐specific demographic parameters is challenging. Here, we propose a multievent model parameterization able to estimate age‐dependent survival using capture–recapture data with uncertainty in age and sex assignment of individuals. We illustrate this modeling approach with capture–recapture data from the ring‐necked parakeet Psittacula krameri. We analyzed capture, recapture, and resighting data (439 recaptures/resightings) of 156 ring‐necked parakeets tagged with neck collars in Barcelona city from 2003 to 2016 to estimate the juvenile and adult survival rate. Our models successfully estimated the survival probabilities of the different age classes considered. Survival probability was similar between adults (0.83, 95% CI = 0.77–0.87) and juveniles during their second (0.79, 95% CI = 0.58–0.87) and third winter (0.83, 95% CI = 0.65–0.88). The youngest juveniles (1st winter) showed a slightly lower survival (0.57, 95% CI = 0.37–0.79). Among adults, females showed a slightly higher survival than males (0.87, 95% CI = 0.78–0.93; and 0.80, 95% CI = 0.73–0.86, respectively). These high survival figures predict high population persistence in this species and urge management policies. The analysis also stresses the usefulness of multievent models to estimate juvenile survival when age cannot be fully ascertained.  相似文献   

11.
Host acceptance by gynoparae and winged virginoparae of the bird cherry‐oat aphid Rhopalosiphum padi (L.) is investigated utilizing leaves and aqueous extracts of the primary and secondary hosts, as well as nonhost plants. Gynoparae are specialized to reproduce on bird cherry Prunus padus L., whereas virginoparae reproduce and feed on various grasses. Host acceptance is assessed using levels of reproduction and survival for adults, as well as survival for nymphs. Little is known of host acceptance by nymphs. The data show that gynoparae and winged virginoparae produce nymphs almost exclusively on their host plants, bird cherry and barley leaves, respectively, over 72 h. When tested with aqueous plant extracts, however, gynoparae produce nymphs almost exclusively on bird cherry extract and progeny numbers are found to be similar to those on plant leaves. Few nymphs are produced on artificial diet. By contrast, winged virginoparae produce nymphs on aqueous extracts of barley, bird cherry and bean, as well as on artificial diet. The numbers of nymphs deposited by gynoparae are similar on aqueous extracts of bird cherry leaves collected at different times during the growing season. When extracts from leaves of various Prunus species are tested, only leaves of P. padus and Prunus virginiana stimulate parturition. Oviparae, the sexual female nymphs of gynoparae, survive well for 96 h on both bird cherry and barley leaves but not on bean seedlings, whereas nymphs of winged virginoparae survive well only on barley leaves. They do not survive for 96 h on any plant‐leaf extracts, although they do survive on artificial diet.  相似文献   

12.
13.
The length–weight relationships (LWRs) for four freshwater fish species in catchment area of Geoje‐island, South Korea, were analyzed. Fish samples were collected quarterly using scoop‐nets (5 mm mesh size), casting nets (7 mm mesh size) from 2016 to 2017. LWRs data for three of these species have not yet been listed in FishBase.  相似文献   

14.
The vlei rat Otomys irroratus has a wide distribution in southern Africa with several datasets indicating the presence of two putative species (O. irroratus and O. auratus). In the present study we use mitochrondrial cyt b data (~950 bp) from 98 specimens (including museum material) collected throughout the range of the species to determine the geographical limits of the two recognized species, and we link this to niche modelling to validate these species. Phylogenetic analysis of the DNA sequence data, using maximum parsimony, neighbour joining and Bayesian inference, retrieved two divergent statistically well‐supported clades. Clade A occurs in the Western and Eastern Cape while Clade B occurs in the Free State, KwaZulu‐Natal, Northern Cape and Mpumalanga provinces of South Africa and Zimbabwe. Mean sequence divergence between the two clades (A and B) was 7.0% and between sub‐clades comprising clade B it was 4.8%; the two clades diverged during the Pleistocene. Within Clade A the mean sequence divergence among specimens was 1.91%. Niche modelling revealed that the incipient species occupy distinct bioclimatic niches associated with seasonality of precipitation. Our data allow insightful analysis into the factors that could have led to cladogenesis within this rodent. More significantly, the new data enable us to pinpoint the Eastern Cape province as a contact zone for the divergent species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 192–206.  相似文献   

15.
The composition of the essential oils obtained by hydrodistillation of different parts of Litsea cubeba, including roots, stems, leaves, alabastra (flower buds), flowers, and fruits, were investigated by GC (RI) and GC/MS. The antimicrobial activity of the oils was assessed with disc diffusion and microbroth dilution assays. The results showed large variations in the composition among the different oils. The major components in the oils from roots and fruits, from stems, leaves, and alabastra, and from flowers were citral B (neral), β‐phellandrene, and β‐terpinene, respectively. The inhibition zone (DD) and MIC values for the bacterial strains tested, which were all sensitive to the essential oil of L. cubeba, were in the range of 10.1–35.0 mm and 100–1000 μg/ml, respectively. Hence, the oils of the various parts showed moderate activity against the tested bacteria. This investigation showed that the antibacterial activity of L. cubeba was attributed to the essential oils, thus they can be a potential medicinal resource.  相似文献   

16.
To clarify recruitment patterns of Photinia glabra, which is an evergreen, broad‐leaved, bird‐dispersed tree species, we analyzed spatial distribution in P. glabra recruits at each growth stage and demography of current‐year seedlings with respect to distributions of adults in a warm‐temperate secondary forest, western Japan. Although individuals ≥ 5 cm diameter at breast height (DBH) that had nearly produced fruits showed a random distribution, seedlings (≥ 1 year old, < 10‐cm stem length [SL]), small saplings (10 ≤ SL < 30 cm) and large saplings (≥ 30‐cm SL, < 5‐cm DBH) were clumped and associated with reproductive adults at approximately 2–3‐m scales, nearly equal to their average crown radius. Based on monitoring the demography of current‐year seedlings, emerged seedling density profoundly decreased, and no seedlings survived at longer than an adult's crown scales, with distance‐dependent mortality as a result of disease and herbivory not greatly affecting the current‐year seedling mortality. Thus, aggregated seed dispersal under the crown of adult P. glabra would directly influence the distribution of recruits for P. glabra in this forest. Of the bird‐dispersed tree species in this forest, P. glabra produced the highest amount of fruits during large crop years, and their fruits ripened during the late seasonal period (early January), suggesting that birds might be strongly attracted to these species, in turn leading to seeds being deposited mostly under the tree crowns. We propose that dispersal limitation would occur, even in a bird‐dispersed tree species such as P. glabra, owing to plant–bird interactions in the forest.  相似文献   

17.
A mirid,Eccritotarsus catarinensis(Carvalho), was studied as a potentially damaging natural enemy for water hyacinth, (Eichhornia crassipes(Mart.) Solms-Laub.), in South Africa. In the laboratory, eggs were inserted into the leaf tissue parallel to the leaf surface. The four nymphal instars fed gregariously with the adults mainly on the undersurface of the leaves, causing severe chlorosis at high population levels. The duration of immature stages (egg and nymphs) was approximately 23 days, while the adults survived for approximately 50 days. Favorable biological characteristics ofE. catarinensisincluded a high rate of increase, gregarious habits, long-lived and mobile adults, and several generations per year. Laboratory host range of the mirid was determined by adult choice trials on 67 plant species in 36 families and adult no-choice trials on five species in the Pontederiaceae. Feeding was recorded on all Pontederiaceae tested and oviposition on four of the five species. However, these plant species proved to be inferior hosts forE. catarinensisin comparison to water hyacinth, suggesting thatE. catarinensiswould be an acceptable natural enemy for water hyacinth in South Africa.  相似文献   

18.
The immature stages of Pangaeus (Pangaeus) serripes are described for the first time. Immature stages are illustrated and notes about their biology are included. Morphological features of the legs of the nymphs are associated with the fossorial habit of the Cydninae. Both adults and nymphs have been reared and found feeding on fallen fruits and seeds of several species of figs in Mexico.  相似文献   

19.
20.
Plant disjunctions have provided some of the most intriguing distribution patterns historically addressed by biogeographers. We evaluated the three hypotheses that have been postulated to explain these patterns [vicariance, stepping‐stone dispersal and long‐distance dispersal (LDD)] using Munroa, an American genus of grasses with six species and a disjunct distribution between the desert regions of North and South America. The ages of clades, cytology, ancestral characters and areas of distribution were investigated in order to establish relationships among species, to determine the time of divergence of the genus and its main lineages, and to understand further the biogeographical and evolutionary history of this genus. Bayesian inference recovered the North American M. pulchella as sister species to the rest. Molecular dating and ancestral area analyses suggest that Munroa originated in North America in the late Miocene–Pliocene (7.2 Mya; 8.2–6.5 Mya). Based on these results, we postulate that two dispersal events modelled the current distribution patterns of Munroa: the first from North to South America (7.2 Mya; 8.2–6.5 Mya) and the second (1.8 Mya; 2–0.8 Mya) from South to North America. Arid conditions of the late Miocene–Pliocene in the Neogene and Quaternary climatic oscillations in North America and South America were probably advantageous for the establishment of populations of Munroa. We did not find any relationship between ploidy and dispersal events, and our ancestral character analyses suggest that shifts associated with dispersal and seedling establishment, such as habit, reproductive system, disarticulation of rachilla, and shape and texture of the glume, have been important in these species reaching new areas. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 110–125.  相似文献   

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