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Honeybees Apis mellifera (European honeybee) and Apis cerana (Asian honeybee) are cosmopolitan, having colonized continents beyond their natural ranges. In tropical Australia, these alien species have recently become sympatric. The environmental and economic impacts of these species when in sympatry remain to be seen; however, any interspecific competition may be of significance. We examined conspecific and heterospecific interactions between honeybees foraging at the nectar- and pollen-providing flowers of Antipogon leptopus (Polygonaceae). We cross-classified 554 encounters by three variables; incoming bee species, resident bee species, and one of four potential responses: (1) incoming defers to resident; (2) incoming procures the flower from resident; (3) incoming and resident share the flower; or (4) both incoming and resident abandon the flower. We also measured aggression and foraging rates of workers at flowers. Both species visited similar numbers of flowers in a foraging bout and spent similar foraging times on individual flowers. Incoming A. mellifera were more likely to procure flowers from resident A. cerana, and incoming A. cerana were more likely to defer to resident A. mellifera. A. mellifera were more aggressive toward heterospecifics than conspecifics, with heterospecifics 4.5 times more likely to provoke an aggressive response. However, no significant difference between conspecific and heterospecific aggression was observed for incoming A. cerana. A. mellifera were less abundant, yet overall more likely to acquire flowers and use aggression to do so. Costs of aggression may help explain the population-scale dominance of A. cerana over A. mellifera in this study. [ABSTRACT FROM AUTHOR]

Background and Aims Olearia flocktoniae is an endangered shrub that was passively translocated from its natural ecosystem, where it has since gone extinct. This study aimed to determine sensitivities vital to populations persisting in human-created areas. Methods Population colonization, longevity and extinction were investigated over 20 years using 133 populations. Seed-bank longevity was determined from germination trials of seeds exhumed from extinct and extant sites via a 10-year glasshouse trial and by in situ sowing experiments. From 27 populations, 98 cohorts were followed and matrix models of transitions from seeds to adults were used to evaluate the intrinsic rate of population growth against disturbance histories. Ten populations (38 cohorts) with different disturbance histories were used to evaluate sensitivities in vital rates. Key Results Most populations had few individuals (∼30) and were transient (<5 years above ground). The intrinsic population growth rate was rarely >1 and all but two populations were extinct at year 20. Seeds were short-lived in situ. Although >1000 seeds per plant were produced annually in most populations, sensitivity analysis showed that the transition to the seed bank and the transition from the seed bank to seedlings are key vulnerabilities in the life-cycle. Conclusions Seedling establishment is promoted by recent disturbance. Increasing the number of disturbance events in populations, even severe disturbances that almost extirpate populations, significantly increases longer-term population persistence. Only populations that were disturbed annually survived the full 20 years of the study. The results show that translocated populations of O. flocktoniae will fail to persist without active management. [ABSTRACT FROM PUBLISHER]

Background and Aims Many aquatic species with stylar polymorphisms have the capacity for clonal and sexual reproduction and are sensitive to the balance of the two reproductive modes when there are a limited number of mating morphs within a population. This study asked how the clonal and sexual reproductive modes perform in populations that contain only a single morph and where fitness gain through sexual reproduction is rare. In clonal aquatic Nymphoides montana, polymorphic populations normally contain two mating morphs in equal frequencies. Populations are sexually fertile and appear to be maintained by pollen transfer between the two partners. However, in a monomorphic population of N. montana where mating opportunities are unavailable, female and male function is impaired and clonality maintains the population. Here, the consequences of intraspecific variation in sexuality were explored between monomorphic and polymorphic N. montana populations in eastern Australia. Methods Comparative measurements of male and female fertility, total dry mass and genotypic diversity using ISSR markers were made between populations with variable sexuality. Key Results and Conclusions Very few seeds were produced in the monomorphic population under natural and glasshouse conditions due to dysfunctional pollen and ovules. Stigma–anther separation was minimal in the monomorphic population, which may be a consequence of the relaxed selective pressures that regulate the maintenance of sexual function. However, clonal reproduction was favoured at the expense of sexual reproduction in the monomorphic population; this may facilitate the establishment of sterility throughout the population via resource reallocation or pleiotropic effects. The ISSR results showed that the monomorphic population was one large, single genotype, unlike the multi-genotypic fertile polymorphic populations. Evolutionary loss of sex in a clonal population in which a mating morph is absent was evident; under these conditions clonal growth may assure reproduction and expand the population via spreading stolons. [ABSTRACT FROM AUTHOR]

Background and Aims Grevillea rhizomatosa is a spreading shrub which exhibits multiple breeding strategies within a narrow area in the fire-prone heathlands of eastern Australia. Reproductive strategies include self-compatibility, self-incompatibility and clonality (with and without sterility). The close proximity of contrasting breeding systems provides an opportunity to explore the evolution of sterility and to compare and contrast the origins of genotypic diversity (recombinant or somatic) against degrees of sexual expression. Methods ISSR markers for 120 band positions (putative loci) were used to compare genetic diversity among five populations at a macro-scale of 5 m between samples (n = 244 shrubs), and at a micro-scale of nearest neighbours for all plants in five 25-m2 quadrats with contrasting fertilities (n = 162 shrubs). Nearest-neighbour sampling included several clusters of connected ramets. Matrix incompatibility (MIC) analyses were used to evaluate the relative contribution of recombination and somatic mutation to genotype diversity. Key Results High levels of genotypic diversity were found in all populations regardless of fertilities (fertile populations, G/N ≥ 0·94; sterile populations, G/N ≥ 0·97) and most sterile populations had a unique genetic profile. Somatic mutations were detected along connected ramets in ten out of 42 ramet clusters. MIC analyses showed that somatic mutations have contributed to diversity in all populations and particularly so in sterile populations. Conclusions Somatic mutations contribute significantly to gene diversity in sterile populations of Grevillea rhizomatosa, the accumulation of which is the likely cause of male and female sterility. High levels of genetic diversity therefore may not always be synonymous with sexual fitness and genetic health. We hypothesize that frequent fires drive selection for clonal reproduction, at the cost of flowering such that sexual functions are not maintained through selection, and the build-up of somatic mutations in meristems results in high genotype diversity at the cost of pollen and ovule fertilities. [ABSTRACT FROM AUTHOR]

Gross CL, Gorrell L, MacDonald MJ & Fatemi M (2010). Honeybees facilitate the invasion of Phyla canescens (Verbenaceae) in Australia – no bees, no seed! Weed Research 50, 364–372. Several environmental weeds rely on the pollination services of introduced bees. The transfer of this knowledge to weed control management has not been fully explored. In part, this may be because it is difficult to quantify the economic impact of environmental weeds. This diminishes the prospects for expensive research and development required for integrated weed management. In this study, we examine the reproductive ecology of Phyla canescens, a species native to South America that is an aggressive agricultural and environmental weed in many parts of the world. We found that P. canescens is self-compatible, but not capable of automatic self-pollination. A vector is required to effect seed set. Field studies showed that 45% of seeds produced through open pollination are viable. Using exclosure cages, we showed that non-native Apis mellifera L. (honeybee) was the primary floral visitor and pollinator. Honeybee abundance was positively correlated with P. canescens abundance. Within the study site of 0.51 ha, almost 500 000 seeds ha−1 would be produced annually, as a result of honeybee pollination. This study shows that a shared evolutionary history is not required for honeybees to be successful pollinators. Facilitation is demonstrated through the obligate need for pollinators and the successful recruitment of the species through seed. Models for the control of feral honeybees in agricultural systems require development. [ABSTRACT FROM AUTHOR]

Plant breeding systems are seldom studied across the breadth of a species' range. For many systems, this precludes an informed assessment of the evolutionary biology of a species, particularly of the factors that shape fecundity. Grevillea rhizomatosa is a threatened species of shrub known only from a 7 × 8 km area and c. 2000 plants in northern New South Wales, Australia. The species reproduces asexually from rhizomatous suckers, and fruit are only produced in a few populations. Over two flowering seasons, we investigated the extent of sexual reproduction and the mechanisms of infertility in five populations that span the range of the species. Seed were produced in three of the five populations. The breeding system varied among populations from obligate outcrossing to facultative outcrossing to fully sterile. Fruit to flower ratios were below 0.13 in the fertile populations but within the range found in other species of Grevillea. Pollinator limitation was not linked to infertility. Stigmatic opening and receptivity were functional in all populations. Interpopulation crosses using fertile pollen failed to recover fertility in an infertile population. A breakdown in female and male fertility mechanisms was found including a fault in the mechanical release of pollen from anthers, <10% viable pollen, and a post-pollen-deposition event that prevents fertile pollen from effecting seed-set. In the infertile populations pollen was not released from anthers, resulting in flowers projecting barren pollen-presenters. Sexually reproducing populations are threatened by the incursion of asexual forms that may be favored by frequent disturbance from wild-fires. [ABSTRACT FROM AUTHOR]

Aim To determine whether life-history characters that affect population persistence (e.g. habit and life span) and those that influence reproductive success (e.g. sexual system and fruit type) are non-randomly correlated with extinction risk (i.e. threat category) in the Australian flora ( c. 19,000 species, of which c. 14% is threatened). To identify patterns that present useful conservation directions. To understand patterns of extinction risk in the Australian flora at a broad scale. Location Continental Australia. Methods A country-wide exploration of four life-history characters in the Australian flora ( n = 18,822 species) was undertaken using reference texts, expert opinion, herbarium records and field work. For each character and threat-category combination, a G-test (using a log-linear model) was performed to test the null hypothesis that the two factors were independent in their effects on count. A generalized linear model (GLM) with a logit link and binomial error distribution was constructed with the proportion of taxa in each extinction risk category as the response variable and the habit, sex and fruit-type characters as explanatory terms. In a separate approach, we investigated patterns across the threat categories of non-endangered extant, endangered, and extinct using a multinomial model. We examined whether or not species-poor genera were more likely to contain threatened or extinct species than species-rich genera. A GLM with a binomial error distribution and logit link function was constructed to obtain a weighted regression on the proportion of species listed as extinct or endangered within a genus versus the log of the size of the genus. We also used a supertree analysis and character tracing to investigate the role of phylogeny on extinction risk. Results We found that the Australian flora is primarily composed of bisexual shrubs with dry-dehiscent fruits. Dioecious breeding systems (separate female and male flowers on separate plants) in many floras are the predominant unisexual system, but in Australia there are unexpectedly high levels of monoecy (separate female and male flowers on the same plant). Within the extinct data set of 31 species we detected a significant departure from that expected for habit but not for life span, sexual system or fruit type. There are significantly fewer trees on the extinct list than expected. This may reflect the greater resilience of trees than of other growth habits to extinction processes as well as the observation time-frame. Within the endangered data set of 450 species we found significant differences in the representation of the observed characters from that expected within sex systems and fruit types. We show that, depending on the life form, unisexual breeding systems can be significantly and positively associated with endangered species compared with non-threatened species. For example, there are more monoecious species than expected by chance among the tree species listed as endangered but fewer among the herbaceous life forms. Threat category was found to be non-randomly clustered in some clades. Main conclusions Life-history characters in certain combinations are predictive of extinction risk. Phylogeny is also an important component of extinction risk. We suggest that specific life-history characters could be used for conservation planning and as an early warning sign for detecting vulnerability in lists of species. [ABSTRACT FROM AUTHOR]

Rainforests in tropical Australia occupy a very small, discontinuous area (<1% of the continent), yet they are floristically diverse (c. 2800 vascular species) with high endemicity. There is a distinctive Gondwanan and autochthonous element, and some of the world's ancestral links to the basal angiosperms are uniquely found here. Tile rainforests can be evergreen or deciduous, but there is a distinct dry season with intermittent drought years. With these characters, the evolutionary pressures on species may be very different to that experienced elsewhere. Sexual systems of 1113 tree species (83 families) from northern Australia were compared with published accounts from the paleo- and neotropics. Hermaphroditic systems dominated all tree floras, and within all floras but Australia dioecy was the most common unisexual system. In tropical Australia, however, significantly more monoecy than dioecy occurred at landscape and community levels. Incorporating phylogeny revealed that sex and fruit types are significantly clustered. The Euphorbiaceae and Sapindaceae contributed c. 50% of the monoecious taxa. Inefficient pollinators (e.g., beetles) may have favored the maintenance of monoecy at the expense of dioecy in the Australian tropics although <1% of the flora has been studied for pollinators and none of the monoecious tree species. [ABSTRACT FROM AUTHOR]

There is much interest in the utility of incorporating a common congener in studies of rare plants, because differences between species may be informative for conservation management. We propose here that it is the similarities between such species and even the parameters in which the rare species is comparatively more successful that can provide much useful information and opportunities. This is a benefit not often recognised within these species' comparisons. Bertya ingramii (Euphorbiaceae) is a threatened shrub known only from two small populations (<70 plants in each) in northern New South Wales, Australia. Both populations are in decline with grazed and senescing individuals and very few seedlings. In contrast, Bertya rosmarinifolia is widespread and was found to produce five-fold more seedlings than B. ingramii. A comparative study of these species involving pre- and post-seed release factors (bud to fruit ratios, flowering synchrony, breeding system, seed-set, seed viability and seed removal rates) was undertaken to determine whether there are key factors that reduce the pre- and post-dispersal reproductive potential in B. ingramii. Both species are monoecious, self-compatible and flower from August to November. In both species female flowers appear first and last, with ca. 8 weeks of intermittent synchrony between female and male flowers. In 1996, B. rosmarinifolia produced more than 100% more fruit than B. ingramii, which in part is due to bud production which is two-fold higher in B. rosmarinifolia. Seeds in both species exhibited ca. 97% viability. Germination treatments (80, 100 °C, scarified and control) revealed that for both species manual scarification produced a higher germination rate than heat or controls. An additional treatment of GA3 improved germination rates of B. ingramii seeds over most non-GA3 treatments, indicating that seeds of B. ingramii contain a conditional dormancy mechanism. Almost 100% of B. ingramii seeds were removed from experimental trays by ants and more B. ingramii seeds were removed than B. rosmarinifolia. To break the extinction vortex in which B. ingramii is involved, we propose human-assisted seed dispersal to safe sites, the augmenting of populations with ex situ germinated seedlings and the exclusion of herbivores from B. ingramii populations. The incorporation of the common congener B. rosmarinifolia was useful because it revealed that it too experienced bud loss to moths and seed removal by ants. Threat abatement for B. ingramii, particularly of moth damage, could be trialled on common B. rosmarinifolia. [ABSTRACT FROM AUTHOR]

Grevillea beadleana (Proteaceae) is an endangered species known from five populations in northern New South Wales, Australia. The reproductive ecology of G. beadleana was compared in two populations with a ten‐fold difference in the number of plants. Grevillea beadleana was found to be self‐compatible in both populations and an examination of pollen viability and stigma maturation revealed that the species is protandrous. Flowering within inflorescences is acropetallous. In the first season plants in the largest population produced approx. ten‐fold more inflorescences than those in the smaller population and, although the number of flowers per inflorescence did not vary significantly between populations the first season, the larger population produced more fruit per inflorescence than the smaller population. However, fruit to flower ratios were less than 0·2 in both seasons and populations. In both populations the number of fruit was significantly greater at the proximal end of the inflorescence, where flowers open first, compared with medial and distal positions. Several bird species were observed visiting flowers, although few birds were recorded foraging at plants in the smaller population. Within both populations, birds tended to make more within‐ than between‐plant visits. Self‐compatibility, acropetally and proximal fruit‐set, combined with the predominantly within‐plant movement of honeyeaters, suggests inbreeding may be common within both populations of G. beadleana. Pollination and fruiting success are discussed for G. beadleana and breeding systems among rare and common taxa in Grevillea are reviewed. [ABSTRACT FROM PUBLISHER]

The article summarizes a study of Jodi Price and colleagues related to the effects of prolonged summer flooding on the weeds of Gwydir Wetlands, New South Wales. The result of the study indicates that the prolonged summer flooding of 1990s, declined the growth of the invasive weed Lippia (Phyla canescens) whereas increased growth was seen in native species, Tall spike-rush. The authors also observed that a winter flood in the Macquarie Marshes did not result in the expansion of Lippia cover.

Lippia ( Phyla canescens: Verbenaceae) is a serious weed of wetlands, riparian zones and floodplains, particularly in eastern Australia where many Ramsar wetlands are threatened by hydrological changes precipitated by soil-accreting lippia mats. Enriched genomic DNA libraries were used to develop nine informative microsatellite markers. These markers will be valuable tools to understand the genetic structure of the lippia populations in different regions throughout the world. [ABSTRACT FROM AUTHOR]

For over 40 years, the names Sesbania benthamiana Domin, S. javanica Miq. and S. sesban (L.) Merr. have been applied to Australian plant specimens. A review of the types assigned to these taxa has resolved that the names S. javanica Miq. and S. sesban (L.) Merr. do not apply to species native to Australia and S. benthamiana has been misapplied. The name S. burbidgei is proposed to account for specimens previously identified as S. sesban and S. muelleri is proposed to account for specimens previously assigned as S. benthamiana. The name S. benthamiana is reapplied to material previously known as S. javanica. [ABSTRACT FROM AUTHOR]