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1.
In their classic study, Alston and Turner (American Journal of Botany, vol. 50, 159-173, 1963) documented extensive hybridization among four morphologically distinct Baptisia species native to East Texas. While Alston and Turner found putative F1 hybrids in great numbers, they found no evidence of backcrossing. In this study prezygotic and postzygotic reproductive barriers between two of these species, B. leucophaea and B. sphaerocarpa, were investigated and found to be quite weak. Flowering times overlap and bumble bees were observed visiting both species and intermediate hybrids. While pollinator constancy in flights between B. leucophaea and B. sphaerocarpa was moderately strong, significant levels of constancy were not observed in flights involving hybrids and either parental species. Thus, backcrossing was not impeded by pollinator behavior. Further, hybrid pollen was highly stainable (93.5%) and able to effectively set seed in crossing experiments with both parental species. Pollinator behavior was compared in experimental populations with and without hybrid ramets and found to differ between these two treatments. Hybrids were found to facilitate pollinator movement between species. In total, these results suggest that reproductive isolation is not responsible for the rarity of backcrossing in naturally hybridizing B. leucophaea and B. sphaerocarpa populations.  相似文献   

2.
This paper examines the hypothesis that nectar robbing can affect plant reproductive success either positively or negatively. To this end, I investigated various aspects of the pollination ecology of a population of the herb Anthyllis vulneraria subsp. vulgaris in northwest Spain over 5 yr. By observing floral visitors, I found that the most important pollinator species was the long-tongued bee Anthophora acervorum, which accounted for ~45% of recorded insect visits. However, just over 45% of visits were by the nectar-robbing bumble bees Bombus terrestris and B. jonellus. Although the incidence of robbing differed considerably over 5 yr of study, the frequency in every season was very high (66.4-76.5% of robbing) except for 1997 (0% robbing). Despite this high frequency of robbing, robbed flowers had a higher probability of setting fruit than nonrobbed flowers in all years of the study (mean: 82.0 vs. 51.0%; excluding 1997). This increased fruit set in robbed flowers is directly related to bumble bee behavior because the robbers' bodies came into contact with both the anthers and stigmas while robbing. Thus, the robbers effect pollination. These results suggest that the effect of nectar robbers on plant reproductive success is dependent both on the robbers' behavior and on flower/inflorescence structure. The importance of nectar-robbing bumble bees on the reproductive success of A. vulneraria and its yearly high frequency suggest that the relationship between robbers and this plant is part of a successful long-term mutualism.  相似文献   

3.
Cypripedium guttatum was studied in north-west Yunnan at 3490 m a.s.l. The flowers are rewardless 'kettle traps'. The structure of the lip, where pollinators are temporarily kept prisoner, and the method of their capture, are unusual in being Paphiopedilum - rather than Cypripedium -like. The deceptive orchid does not mimic any of the diverse flowers concurrently blooming in the habitat, all being visited by the polylectic pollinators of C. guttatum , viz . Lasioglossum virideglaucum, L. clypeinitens and L. sauterum , besides two additional probable pollinators and four non-pollinating visitors (all Halictidae; three new species). The bees got caught when they tried to climb onto the staminode and their forelegs slid down its slippery downward ridges, causing them to tumble to the pouch bottom. To leave, they had to climb a tunnel leading past the stigma to the anthers where a pollen smear was acquired while extruding themselves from the narrow exit. The similarities with myiophylous Paphiopedilum are discussed in view of the possibility that they may foreshadow evolutionary transitions between melittophily and myiophily found in slipper orchids.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 251–264.  相似文献   

4.
Urban landscapes often expose wildlife populations to enhanced edge effects where the biotic and abiotic attributes of native ecosystems have been significantly altered. While some species may respond favourably to edges, there are likely to be varying negative consequences for many forest‐dependent species. In particular, marsupial gliders are influenced by changes in forest composition and structure near edges due to highly specific feeding and nesting requirements, and a high reliance on tree cover to traverse a landscape. We addressed this problem using the squirrel glider (Petaurus norfolcensis) in the fragmented urban landscape of southeast Queensland, Australia. Analysis of variance was applied to determine differences in habitat resources and structure in relation to glider presence and trap success rates in forest fragment interiors compared with road (minor & major) and residential edge habitats. We postulate that an increased presence of squirrel gliders in sites adjacent to minor road and residential edges may be due to the availability of additional resources and/or varying dispersal opportunities. Conversely, forest fragment interiors contain a higher abundance of nest hollows and large trees, together with a greater floristic species richness providing more reliable seasonal foraging sources, which may explain the greater trap success rates of squirrel gliders in these sites. We conclude that while forest fragment interiors provide habitat suitable for year‐round use by greater numbers of squirrel gliders, the conservation value of some edge habitats that provide additional resources and dispersal opportunities should not be underestimated for forest‐dependent mammals; however, each edge type must be assessed individually.  相似文献   

5.
《Ecological Indicators》2008,8(5):599-613
The invertebrate species index (ISI) is a new biotic index to assess stream health in southeast Queensland, Australia, using benthic macroinvertebrates. The index aims to refine stream monitoring, in particular for eutrophication, as nutrient input is a major stressor of streams in the region. Biotic indices previously used for the region were based on sensitivity scores for macroinvertebrate families and orders, and were valid for all streams across the continent. The ISI is based on species level and tailored to the specific traits of southeast Queensland, thus yielding an increased level of detection of biological change. This will improve monitoring of environmental impact on a regional and local scale. The ISI is a site-specific index calculated as the weighted average (WA) of species’ sensitivity scores (S10), with a species-specific indicator weight (W) and the abundance (A) of each species used as weights. S10 scores for 203 species of benthic macroinvertebrates ranging from 10 (species most sensitive to pollution) to 1 (tolerant of excessive pollution) were derived by means of WA regression and calibration using site scores representing an environmental impact gradient. W measures the indicator strength of the species, and was derived from the weighted standard deviation of the S10. The initial site scores for the WA modeling were derived using canonical correspondence analysis (CCA) to ordinate the sites along a gradient associated with 12 abiotic variables. The data on benthic macroinvertebrates are based on 212 quantitative samples collected in wadeable freshwater streams in southeast Queensland. Two major stream types, (1) small creeks, mainly of uplands and (2) larger streams and rivers of lowlands, were recognised for the region, and for both types the ISI range representing reference condition was established. These reference conditions can be used to establish ecological quality ratios by comparing observed to expected indices and to define ecological quality classes. The ISI is the first biotic index for streams in Australia that uses sensitivity scores and indicator weights for macroinvertebrate species. There is a growing trend in Australia to identify stream macroinvertebrates to species level and to study their specific traits and ecological requirements. The reasons for this are manifold; assessing and monitoring stream health is only one of them. For most regions of Australia, no common ground exists, so far, on how to use species data for stream health assessment. The new biotic index fills this gap for southeast Queensland in providing a standard for the use of species level data in stream health assessment.  相似文献   

6.
Xerospermum intermedium, a fairly common understorey species in the West Malesian lowland dipterocarp forest is androdioecious, with delayed self-compatibility. It flowers annually, and has an extended flowering period, with individuals flowering somewhat asynchronously, presenting small flowers with minimal visual lures. The flowers are visited by an unrestricted array of apparently imprecise opportunistic feeders, predominated by trigonid bees and butterflies. Most of these visitors exhibit low fidelity and forage opportunistically on numerous competing tree species. Presentation of nectar in alternating rhythms between the male and hermaphrodite trees appears to induce pollinator movement between them. Out of such alternating visits between the sexes, a low level of short-range inter-tree pollen transfer by trigonids and butterflies seems to occur. Despite the elaborate system which promotes pollinator movement between the sexes, this species has retained a low level of self-compatibility. The physical barriers to pollinator movement in the understorey, and high interspecific competition for pollinators by a large number of tree species, appear therefore to make it difficult to maintain an obligate outbreeding system. Hence, androdioecism may be one of the explanations for the survival of X. intermedium.  相似文献   

7.
In Australia, the brackish water mosquito Verrallina funerea (Theobald) (Diptera: Culicidae) is a serious pest and vector of Ross River and Barmah Forest viruses in coastal areas in the northeast of the continent. We report on the first extensive evaluation of the efficacy of various pesticides against this species, including laboratory dose-response assays and small plot field trials. In the laboratory, Ve. funerea was susceptible to temephos (Abate 100E) (lethal concentration, 95% endpoint [LC95] of 1.651 ppb), Bacillus thuringiensis subsp. israelensis de Barjac (Bti) (VectoBac 12AS) (LC95 of 0.033 ppm), s-methoprene (ProLink Liquid Larvicide [PLL]) (emergence inhibition, 95% endpoint [EI95] of 2.647 ppb), and technical grade pyriproxyfen (EI95 of 0.227 ppb). In contrast, Ve.funerea was highly refractory to Bacillus sphaericus Neide (VectoLex WG) (LC95 of >855.3 ppm). The survival of adults exposed as larvae to sublethal doses of s-methoprene was reduced for those doses greater than the EI50, although sex ratios were unaffected. Field trials demonstrated that Ve. funerea was susceptible to Bti (VectoBac G at 7 kg/ha) and s-methoprene (ProLink ProSand at 4 kg/ha), with these products giving >99 and >98% control, respectively. We also observed a significant increase in immature mortality in s-methoprene-treated pools, suggesting that s-methoprene field trials based solely on emergence inhibition of pupae may underestimate the efficacy of this insecticide.  相似文献   

8.
The distribution of immature Culicoides Latreille (Diptera: Ceratopogonidae) in the intertidal zone was investigated at Redland Bay near Brisbane, southeast Queensland. The aims of this study were to determine the distribution of Culicoides immatures and to identify environmental factors influencing these distributions. Light trapping of adult midges indicated that C.subimmaculatus Lee & Reye, C.marmoratus (Skuse), C.longior Hagan & Reye, C.henryi Lee & Reye, C.cordiger Macfie, may have been breeding in the study site. Soil sampling on six transects traversing mangrove and salt-marsh revealed the breeding habitats from which immature stages of the first four species were obtained. The elevation, vegetation and soils of positive sites were recorded and analysed for each species of Culicoides. The distribution of intertidal vegetation (mangroves and salt-marsh plants) was compared to MacNae's (1966) system of mangrove zonation for eastern Australia. The distribution of immature Culicoides did not correspond with mangrove zones, but was related to the presence or absence of intertidal vegetation. C.subimmaculatus was closely associated with a particular substrate and the presence of burrowing crabs.  相似文献   

9.
In a primary forest on the Central Plateau of MadagascarPlectranthus vestitus (Lamiaceae) was principally pollinated by the beePachymelus limbatus (Hymenoptera, Anthophoridae). A species ofStylogaster (Diptera, Conopidae) acted as a co-pollinator. Flower — pollinator interactions are described. The bee performed pollination while hovering, a flower-visit lasting onlyc. 0.3 seconds. Floral features such as shape and size of the corolla tube, and the lack of a landing place suggest specialization to hovering anthophorid beepollinators. Floral biology and pollination in the genusPlectranthus are discussed.  相似文献   

10.
The seasonal chronology of the events of the reproductive cycle, and changes in the structure and function of the primary and accessory organs of the male bent-winged bat, Miniopterus schreibersii, were studied at latitude 37 degrees S in temperate southeastern Australia. The testicular cycle commenced in late spring (November), and sperm appeared in the seminiferous tubules and epididymides in early fall (March). The cycle of the accessory sex gland complex generally paralleled the testicular cycle, reaching maximum hypertrophy at the time of insemination in late fall (April/May). Thereafter, the primary and secondary sex glands (except the ampullary gland) involuted as the animals entered winter torpor. However, a cauda epididymal store of sperm persisted until late spring, and sperm were often observed, as well, in the ampullary gland duct and alveoli throughout winter. This study has confirmed that male Miniopterus differs from other vespertilionids in that accessory gland activity declines following the fall breeding in keeping with the fact that, unlike in other vespertilionids, insemination, ovulation and conception are concurrent events in the fall in this species. The reduced secretory status of the Leydig cells and exceptionally low levels of circulating androgens throughout the year, in combination with the presence of viable epididymidal sperm for most of gestation, are all interesting features of this reproductive cycle.  相似文献   

11.
Abstract: The pollination and reproductive biology of Rauvolfia grandiflora were studied in natural populations in the forest of the Recife Botanical Garden. R. grandiflora is a shrubby species (2 to 5 m), the flowers are hermaphrodite and salverform. The corolla tube is white and the five free lobes of the corolla are flushed with violet. The five stamens are attached to the corolla tube; the anthers are introrse and form a cone situated immediately above the stigmatic head. There is a space between the anthers and the stigmatic head, where the pollen is deposited. The stigmatic head has three functional regions: a) an upper sterile region; b) a median region that produces a sticky substance and c) a lower receptive region, which is located beneath a basal collar. The secondary pollen presentation and the herkogamy mechanisms are discussed. Sugar concentration in nectar was, on average, 31.7%. The pollen viability was 97.4%. R. grandiflora is melittophilous and in the study area was found to be pollinated by only one species of long-tongued bee, Exaerete smaragdina. R. grandiflora was found to be self-incompatible, and the percentage of fruit set under natural conditions was low.  相似文献   

12.

Gorgorhynchoides pseudocarangis n. sp. (Isthmosacanthidae), is described from the intestine of the white trevally Pseudocaranx dentex (Bloch & Schneider) (Carangiformes: Carangidae) collected in Moreton Bay, Queensland, Australia. The new species has a proboscis armature of 27–28 rows of 16–17 hooks. It is most similar morphologically to Gorgorhynchoides bullocki Cable & Marafachisi, 1970 and Gorgorhynchoides gnathanodontos Smales, 2014 but differs from the former in having a longer proboscis with more rows of hooks, ventral hooks 6/7–12 with notched tips and trunk spines which do not extend onto the anterior bulbous swelling, and from the latter in having a longer proboscis, ventral hooks 6/7–12 with notched tips, more circles of trunk spines, larger eggs and a proboscis armature with all hooks lacking manubria. Previous molecular phylogenetic analyses have shown that the genus Serrasentis Van Cleave, 1923 is sister to Gorgorhynchoides Cable & Linderoth, 1963, although some have failed to resolve these two lineages in separate monophyletic clades. We performed novel single-gene and concatenated phylogenetic analyses using cox1 mtDNA, 18S and 28S rDNA gene-sequences, resolving Gorgorhynchoides and Serrasentis in monophyletic sister clades and demonstrating that Gorgorhynchoides pseudocarangis n. sp. is phylogenetically distinct from related species for which molecular sequence data are available. We view the previous amendment of the Isthmosacanthidae to include the genera Golvanorhynchus Noronha, Fabio & Pinto, 1987, Gorgorhynchoides, Isthmosacanthus Smales 2014 and Serrasentis, and the transfer of the family to the Polymorphida, as the most satisfactory classification at present, although additional molecular evidence would provide greater stability.

  相似文献   

13.
A first study of the pollination biology of a Mediterranean Aristolochia species in its natural habitat is presented. In all, 183 flowers of Aristolochia pallida Willd. were investigated, which in total contained 73 arthropods, dominated by two groups of Diptera, black fungus gnats (Sciaridae representing 37%) and scuttle flies (Phoridae representing 19%), respectively. However, only Phoridae are regarded as potential pollinators, since pollen has been found exclusively on the body of these insects. All Phoridae belong to the genus Megaselia and are recognised as three morpho-species. The measurements of flower and insect dimensions suggest that size is an important constraint for successful pollination: (a) the insects must have a definitive size for being able to enter the flower and (b) must be able to get in touch with the pollen. Only very few insect groups found in A. pallida fulfil these size requirements. However, size alone is not a sufficient filter as too many fly species of the same size might be trapped but not function as pollinators. Instead, specific attraction is required as otherwise pollen is lost. Since all trapped Phoridae are males, a chemical attraction (pheromones) is proposed as an additional constraint. Since the flowers are protogynous, the record of Megaselia loaded with pollen found in a flower during its female stage proves that this insect must have had visited at least one different flower during its male stage before. Further on, this observation provides strong evidence that the flowers are cross-pollinated. All these factors indicate a highly specialised pollination of A. pallida by Megaselia species.  相似文献   

14.
Indian siris, Albizia lebbeck (L.) Benth. (Fabaceae: Mimosoideae) has significant importance to human beings for its multipurpose use. Insects play a crucial role in the pollination biology of flowering plants. In the current study, we studied the pollination biology of A. lebbeck with special reference to insect floral visitors. The effectiveness of floral visitors was investigated in term of visitation frequency, visitation rate and pollen load during 2012 and 2013. In the second experiment, effect of pollinators on yield of A. lebbeck was studied in open and cage pollination experiments. Floral visitor fauna of A. lebbeck included eight-bees, two wasps, two flies, and two butterflies species. Among them, Apis dorsata, Apis florea, Amegilla cingulata, and Nomia oxybeloides had maximum abundance ranging from 349–492, 339–428, 291–342 and 235–255 numbers of individuals, respectively during two flowering seasons. A. dorsata had the highest visitation frequency (6.44 ± 0.49–8.78 ± 0.48 visits/flower/5min) followed by Amegilla cingulata (6.03 ± 0.43–7.99 ± 0.33 visits/flower/5min) and A. florea (3.61 ± 0.31–4.44 ± 0.18 visits/flower/5min). A. dorsata, N. oxybeloides, and Amegilla cingulata had the highest visitation rates (18.904 ± 1.53–11.43 ± 1.17 flower visited/min) and pollen load (15333 ± 336.22–19243 ± 648.45 pollen grains). The open pollinated flowers had significantly higher capsule weight (4.97 ± 0.21 g), seed weight (1.04 ± 0.05 g), seed numbers per pod (9.80 ± 0.34) and seed germination percentage (84.0 ± 1.78%) as compared to caged flowers. The results suggested bees especially A. dorsata, N. oxybeloides and Amegilla cingulata could be effective pollinators of A. lebbeck.  相似文献   

15.
The Darling Downs is an extremely arable district in south eastern Queensland that has lost the majority of its native vegetation cover to agriculture. Vegetation references from land survey charts produced during the late 19th and early 20th century aided the reconstruction of the original vegetation patterns in the Darling Downs. Nearly 5000 references to vegetation were located for the study area and formed the basis of a vegetation map. The survey plans contain reference to seventy-three plant names which could generally be aligned to existing species, the majority of which are trees. The surveyors also referred to vegetation structure with terms such as 'open', 'shrubby' and 'dense'. The ambiguous use of some references and the lack of adequate coverage of surveyor's charts for some sections of the study area did not allow for the production of an accurate and comprehensive map using the survey record in isolation. An iterative process evolved where (i) a working map of the vegetation was produced from the survey record; (ii) the map was ground-truthed with existing remnants and ambiguities in surveyors' terminology clarified; (iii) for gaps in the record, hypotheses concerning eradicated vegetation were erected from knowledge of the environmental correlates of existing remnants; and (iv) these hypotheses were tested from areas where the survey record is comprehensive. Some vegetation types cannot be distinguished reliably on the basis of their physical environment and the distinction between these types for mapping was reliant on either the evidence from the survey record or remaining paddock trees. These processes enabled relatively accurate mapping of the pre-European vegetation of the study area at 1:100,000 scale. Comparison of the survey record and the vegetation of existing remnants suggests that overstorey composition and understorey density have changed little during European management within remnants.  相似文献   

16.
Proteaceae are most diverse in southern Africa and Australia, especially in the south-western portions of these regions. Most genera have some species in flower at all times of the year, although generally there is a preponderance of species that flower between late winter and early summer. The one genus that is an exception to this generalization is Banksia, which either has approximately the same percentage of species in flower at various times of the year (southwestern Australia) or peaks in autumn (southeastern Australia). Within particular communities, opportunities for hybridization among congeneric species are minimized by staggered flowering times, different pollen vectors and/or various incompatibility mechanisms. Birds, mammals and arthropods have been identified as visitors to the inflorescences of many Proteaceae. The most common avian visitors to the majority of genera in Australia are honeyeaters, although lorikeets, silvereyes and approximately 40 other species sometimes may be important. Sugarbirds and sunbirds are seen most frequently at inflorescences of Protea, Leucospermum and Mimetes in southern Africa, although they rarely visit other genera. In most cases, avian visitors forage in a manner that permits the acquisition and transfer of pollen. Limited evidence supports the hypothesis that birds are selective in their choice of inflorescences, responding to morphological and/or colour changes and usually visiting those inflorescences that offer the greatest nectar rewards. Arthropods may be equally selective, although it is possible that only the larger moths, bees and beetles are important pollinators, even for those plant species that rely entirely on arthropods for pollen transfer. Mammals are pollen vectors for some Proteaceae, especially those that have geoflorous and/or cryptic inflorescences. In Australia, small marsupials may be the most important mammalian pollinators, although rodents fill this niche in at least some southern African habitats. All but two genera of Proteaceae are hermaphroditic and protandrous, the exceptions being the dioecious southern African genera Aulax and Leucadendron. For hermaphroditic species, the timing of visits by animals to inflorescences is such that they not only acquire pollen from freshly opened flowers but also brush against pollen presenters and stigmas of others that have lost self-pollen and become receptive. Birds and insects (and probably mammals) generally forage in such a way as to facilitate both outcrossing and selfing. Some species are self-compatible, although many require outcrossing if viable seed is to be formed. Regardless of which animals are the major pollen vectors, fruit set is low relative to the number of flowers available, especially in Australian habitats. Functional andromonoecy of the majority of flowers is advanced as the major cause of poor fruit set. The pollination biology and breeding systems of Australian and southern African Proteaceae resemble one another in many ways, partly because of their common ancestry, but also due to convergence. Divergence is less obvious, apart from the dichotomy between dioecious and hermaphroditic genera, and differences in the levels of seed set for Australian and African species. Future studies should concentrate on identifying the most important pollinators for various Proteaceae, the manner in which their visits are integrated with floral development and factors responsible for limiting fruit set.  相似文献   

17.
Abstract: Data on pollination biology constitute important clues for the comprehension of pollen flow and genetic differentiation in plant populations. Pollinator type, availability and behaviour may modify morphological and mating patterns in populations of typically distylous species. This study investigates the pollination biology of four distylous species of Rubiaceae in the Atlantic rain forest, SE Brazil. Data on flowering phenology, floral lifespan, stigmatic receptivity, pollen availability, nectar volume and concentration, and pollinator activity were collected. The species studied flower sequentially throughout the wet season, and produce terminal inflorescences which bear small, tubular, diurnal, nectariferous flowers. Despite these similarities, some of the species studied are pollinated by different groups of pollinators, probably due to their distribution, availability of flowers and corolla length. On the other hand, pollinator specificity does not seem to be so important for distylous species. Long mouthparts, like those of most of the recorded pollinators, may reach lower sexual organs and, together with the self- and intramorph-incompatibilities observed, be sufficient to perform legitimate pollination and maintain levels of intermorph mating.  相似文献   

18.
Genetic structure among disjunct population groups of Pultenaea pauciflora was assessed to determine the evolutionary history of this species as a basis for conservation management strategies. Analysis of individuals from all extant populations using 1737 amplified length polymorphism markers revealed two highly divergent genetic entities with strong geographical structuring. Populations located at Narrogin and Brookton clustered together in Bayesian assignment analysis with every individual optimally placed in a single cluster with complete membership. Genetic differentiation between populations in these two areas was very low. Populations at Boddington were highly divergent from those located at Narrogin and Brookton. All individuals from Boddington populations were optimally placed into a second cluster with complete membership. Populations located at Boddington maintain lower levels of allelic diversity, yet greater levels of mean heterozygosity than populations located at Narrogin and Brookton. The degree of genetic differentiation and different patterns of genetic diversity strongly suggest historical divergence and separate evolutionary influences on the two lineages that occur in different ecological habitat. These Evolutionary Significant Units are likely to represent two cryptic sister taxa in the extant populations currently recognized as P. pauciflora, and the reassessment of taxonomic and conservation status of both lineages is required. © 2013 State of Western Australia. Biological Journal of the Linnean Society © 2013 The Linnean Society of London  相似文献   

19.
20.
Four distinct species ofCortinarius referable to subg.Dermocybe are described from the Cooloola Sand-Mass, Queensland; two are formally recognized asC. alkalivirens, spec. nova andC. chromobasis, spec. nova, whilst notes are provided for the other two. Chemical methods and cladistic studies are applied and indicate a new section of the subgenus is required.Australodermocybe sect. nova is proposed.  相似文献   

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