Primary pollinator exclusion has divergent consequences for pollen dispersal and mating in different populations of a bird-pollinated tree

Pollination by nectarivorous birds is predicted to result in different patterns of pollen dispersal and plant mating compared to pollination by insects. We tested the prediction that paternal genetic diversity, outcrossing rate and realized pollen dispersal will be reduced when the primary pollinator group is excluded from bird-pollinated plants. Pollinator exclusion experiments in conjunction with paternity analysis of progeny were applied to Eucalyptus caesia Benth. (Myrtaceae), a predominantly honeyeater-pollinated tree that is visited by native insects and the introduced Apis mellifera (Apidae). Microsatellite genotyping at 14 loci of all adult E. caesia at two populations (n = 580 and 315), followed by paternity analysis of 705 progeny, revealed contrasting results between populations. Honeyeater exclusion did not significantly impact pollen dispersal or plant mating at Mount Caroline. In contrast, at the Chiddarcooping site, the exclusion of honeyeaters led to lower outcrossing rates, a threefold reduction in the average number of sires per fruit, a decrease in intermediate-distance mating and an increase in near-neighbour mating. The results from Chiddarcooping suggest that bird pollination may increase paternal genetic diversity, potentially leading to higher fitness of progeny and favouring the evolution of this strategy. However, further experimentation involving additional trees and study sites is required to test this hypothesis. Alternatively, insects may be effective pollinators in some populations of bird-adapted plants, but ineffective in others.Jack family trust; Australian Research Council, Grant/Award Number: DP140103357; University of Western Australia; Great Southern Development Commission; Holsworth Wildlife Research Endowment—Equity Trustees Charitable Foundation; Wiley Fundamental Ecology Award, Ecological Society of Australia Student Research Awar

Paternity analysis reveals wide pollen dispersal and high multiple paternity in a small 1 isolated population of Eucalyptus caesia (Myrtaceae)

Optimal foraging behaviour by nectavores is expected to result in a leptokurtic pollen dispersal distribution and predominantly near-neighbour mating. However, complex social interactions among nectarivorous birds may result in different mating patterns to those typically observed in insect-pollinated plants. Mating system, realised pollen dispersal and spatial genetic structure were examined in the bird-pollinated Eucalyptus caesia, a species characterised by small, geographically disjunct populations. Nine microsatellite markers were used to genotype an entire adult stand and 181 seeds from 28 capsules collected from 6 trees. Mating system analysis using MLTR revealed moderate to high outcrossing (tm =0.479–0.806) and low estimates of correlated paternity (rp=0.136± s.e. 0.048). Paternity analysis revealed high outcrossing rates (mean = 0.72) and high multiple paternity, with 64 different sires identified for 181 seeds. There was a significant negative relationship between the frequency of outcross mating and distance between mating pairs. Realised mating events were more frequent than expected with random mating for plants o40 m apart. The overall distribution of pollen dispersal distances was platykurtic. Despite extensive pollen dispersal within the stand, three genetic clusters were detected by STRUCTURE analysis. These genetic clusters were strongly differentiated yet geographically interspersed, hypothesised to be a consequence of rare recruitment events coupled with extreme longevity. We suggest that extensive polyandry and pollen dispersal is a consequence of pollination by highly mobile honeyeaters and may buffer E. caesia against the loss of genetic diversity predicted for small and genetically isolated populations.The project was funded by an Australian Research Council Grant to SDH, SLK and RDP (DP140103357) for work on the evolution and conservation consequences of promiscuity in plants pollinated by vertebrates. SDH was also supported by a Discovery Outstanding Researcher Award attached to this grant, and by grants from the Great Southern Development Commission and the Jack Family Trust

The movement ecology of seagrasses

A movement ecology framework is applied to enhance our understanding of the causes, mechanisms and consequences of movement in seagrasses: marine, clonal, flowering plants. Four life-history stages of seagrasses can move: pollen, sexual propagules, vegetative fragments and the spread of individuals through clonal growth. Movement occurs on the water surface, in the water column, on or in the sediment, via animal vectors and through spreading clones. A capacity for long-distance dispersal and demographic connectivity over multiple timeframes is the novel feature of the movement ecology of seagrasses with significant evolutionary and ecological consequences. The space–time movement footprint of different life-history stages varies. For example, the distance moved by reproductive propagules and vegetative expansion via clonal growth is similar, but the timescales range exponentially, from hours to months or centuries to millennia, respectively. Consequently, environmental factors and key traits that interact to influence movement also operate on vastly different spatial and temporal scales. Six key future research areas have been identified

Genetic diversity and structure of the Australian flora

Aim To investigate the relationships between species attributes and genetic parameters in Australian plant species and to determine the associations in relation to predictions from population theory and previous global analyses. Location Continent of Australia. Methods We assembled a dataset of all known population genetic analyses of Australian plants based on neutral markers and catalogued them according to key species attributes, including range, abundance, range disjunction, biome and growth form; and genetic parameters, mean number of alleles per locus, observed and expected heterozygosity and population differentiation. We determined relationships between species attributes and genetic parameters using a maximum‐likelihood, multimodel inference approach. Results We found many associations that were consistent with predictions. Species attributes with greatest effect on genetic diversity were range size, growth form, abundance and biome. The most important attributes influencing genetic differentiation were range disjunction and abundance. We found unexpected results in the effects of biome and growth form on genetic diversity, with greater diversity in the eastern biome of Australia, and lower diversity in shrubs compared to trees. Main conclusions Our analysis of genetic diversity of Australian plants showed associations consistent with predictions based on population genetics theory, with strong effects of range size, abundance and growth form. We identified a striking effect of range disjunction on population genetic differentiation, an effect that has received little attention in the literature. We also found some notable differences to global predictions, which were most likely explained by confounding effects across variables. This highlights that caution is needed when extrapolating trends from global analyses to regional floras. Identifying associations between species attributes and patterns of genetic diversity enables broadscale predictions to facilitate the inclusion of genetic considerations into conservation decision‐making.This research was supported by the joint resources of CSIRO and the Western Australian Department of Parks and Wildlif

A threatened ecological community: Research advances and priorities for Banksia woodlands

The rapid expansion of urban areas worldwide is leading to native habitat loss and ecosystem fragmentation and degradation. Although the study of urbanisation\u27s impact on biodiversity is gaining increasing interest globally, there is still a disconnect between research recommendations and urbanisation strategies. Expansion of the Perth metropolitan area on the Swan Coastal Plain in south-western Australia, one of the world\u27s thirty-six biodiversity hotspots, continues to affect the Banksia Woodlands (BWs) ecosystem, a federally listed Threatened Ecological Community (TEC). Here, we utilise the framework of a 1989 review of the state of knowledge of BWs ecology and conservation to examine scientific advances made in understanding the composition, processes and functions of BWs and BWs\u27 species over the last 30 years. We highlight key advances in our understanding of the ecological function and role of mechanisms in BWs that are critical to the management of this ecosystem. The most encouraging change since 1989 is the integration of research between historically disparate ecological disciplines. We outline remaining ecological knowledge gaps and identify key research priorities to improve conservation efforts for this TEC. We promote a holistic consideration of BWs with our review providing a comprehensive document that researchers, planners and managers may reference. To effectively conserve ecosystems threatened by urban expansion, a range of stakeholders must be involved in the development and implementation of best practices to conserve and maintain both biodiversity and human wellbeing

A framework for the practical science necessary to restore sustainable, resilient, and biodiverse ecosystems

Demand for restoration of resilient, self-sustaining, and biodiverse natural ecosystems as a conservation measure is increasing globally; however, restoration efforts frequently fail to meet standards appropriate for this objective. Achieving these standards requires management underpinned by input from diverse scientific disciplines including ecology, biotechnology, engineering, soil science, ecophysiology, and genetics. Despite increasing restoration research activity, a gap between the immediate needs of restoration practitioners and the outputs of restoration science often limits the effectiveness of restoration programs. Regrettably, studies often fail to identify the practical issues most critical for restoration success. We propose that part of this oversight may result from the absence of a considered statement of the necessary practical restoration science questions. Here we develop a comprehensive framework of the research required to bridge this gap and guide effective restoration. We structure questions in five themes: (1) setting targets and planning for success, (2) sourcing biological material, (3) optimizing establishment, (4) facilitating growth and survival, and (5) restoring resilience, sustainability, and landscape integration. This framework will assist restoration practitioners and scientists to identify knowledge gaps and develop strategic research focused on applied outcomes. The breadth of questions highlights the importance of cross-discipline collaboration among restoration scientists, and while the program is broad, successful restoration projects have typically invested in many or most of these themes. Achieving restoration ecology's goal of averting biodiversity losses is a vast challenge: investment in appropriate science is urgently needed for ecological restoration to fulfill its potential and meet demand as a conservation too

Systematic pattern and evolutionary process in the complex species Persoonia mollis R. BR. (Proteaceae)

The species is one of the most important concepts in organismic biology. There is, however, a long history of disagreement about how to define species and how they arise. All current species concepts are logically and operationally flawed because they rely on prospective narration, or equivalently, they depend upon the future. The solution is to use a species concept that is appropriate to a specific objective. The objective in this thesis was to study the processes producing divergence and ultimately perhaps speciation. It was most appropriate then to define species here as the most inclusive monophyletic group of organisms having the potential for genetic and/or demographic exchangeability. Persoonia mollis R. Br. sens, lat (Proteaceae) is a complex species that offers great opportunity to effectively address unresolved concepts relating to both systematic pattern and evolutionary process at the specific and infra-specific level. Persoonia mollis R.Br. sens, lat was circumscribed and formally revised, and, as here defined, is clearly separated from all other species and constitutes a monophyletic group. A key and description were provided for the nine taxa recognised as subspecies. Five new taxa were described in P. mollis: subsp. maxima, subsp. nectens, subsp. leptophylla, subsp. livens and subsp. budawangensis. Three new combinations were made: P. mollis subsp. caleyi, P. mollis subsp. revoluta and P. mollis subsp. ledifolia. Support for the recognition of these nine infraspecific taxa within P. mollis was found following a multivariate phenetic analysis of morphological variation. Eighty-seven flowering herbarium specimens, collected from throughout the range of P. mollis, were measured for 24 characters incorporating size, shape and pubescence on vegetative and floral parts. These data were analyzed by two ordination procedures, multidimensional scaling (MDS) and canonical variate analysis (CVA). Plots of canonical variate scores against latitude or longitude across subspecies boundaries revealed phenetic homogeneity within subspecies with sharp transitions between subspecies. The geographic variation in morphology within P. mollis can be best described as a mosaic of nine recognisably distinct allopatric or parapatric taxa, where narrow zones of morphological transition separate neighbouring taxa. The breeding system of P. mollis was characterised to firstly assess its importance as a mechanism promoting genotypic diversity and secondly to investigate the modee of control over selective fruit abortion. Fruit quantity and quality was assessed following self- and outcross-pollination manipulations. Twenty percent of outcrossed flowers set fruit, compared to only 1% of flowers fertilized with self-pollen. Fruits produced by self-fertilization were 72% the weight of cross-fertilized fruits. Fruits produced by self-fertilization were significantly fewer in number and lighter than fruits following natural pollination of unmanipulated flowers (17% fruit set), but outcrossed and naturally pollinated fruits were equivalent. Flower to fruit demography suggested that a post-zygotic mechanism may be preferentially selecting the most vigorous genotypes, as ovary abscission occurs mostly between 4 and 30 weeks after pollination regardless of pollen source. Self-pollen tube growth was found to be inhibited within the style, while pollen tubes were found in the ovary for 50% of all outcrossed flowers. These data suggest that a pre-zygotic pseudo self-incompatibility mechanism is the cause of low fruit set following self-pollination. The breeding system of P. mollis was found to promote outbreeding, with an emphasis on flexibility and post-zygotic choice following pre-zygotic pseudo self-incompatibility. Severely restricted gene flow may be a factor contributing to the remarkable amount of morphological variation within P. mollis. The mating system and realized pollen dispersal were studied to assess their effect on gene flow. Mating system parameters were estimated in seven natural populations over two seasons using allozyme electrophoresis. Realized pollen dispersal was measured in two natural populations over two seasons by monitoring the dispersion of a rare allozyme from a known source plant in each population. Single- and multi-locus estimates of outcrossing rate (t) were consistently equal to or greater than one (i.e. complete outcrossing). Realized pollen dispersal distances showed that 99% of the pollen received by given females was donated by males on average within 33m. However, 70% of all pollen dispersal was on average to the paternal plant\u27s immediate neighbour. Genetic neighbourhood sizes due to pollen dispersal alone ranged from 1 to 5 plants, and paternity pool sizes ranged from 4 to 22 plants. These population sizes are small enough to allow genetic differentiation in the absence of selection. However, in contrast to the expectation that small population size leads to biparental inbreeding and reduced heterozygosity compared to Hardy-Weinberg expectations, the mean fixation index (F) of -0.035 indicated a slight excess of heterozygotes in the seed cohort. This apparent paradox could be the result of selection for heterozygous seeds, disassortative mating, or more likely because gene flow through seed dispersal substantially increases the neighbourhood sizes estimated here through pollen dispersal alone. Hierarchical patterns of genetic diversity and gene flow were estimated within P. mollis from allozyme frequency data. The total gene diversity (HT) within P. mollis was extremely low (0.139) compared to an average of 0.310 for 406 plant species. This low gene diversity m a y be typical of the Proteaceae. However, P. mollis was typical in the way its gene diversity was distributed, with 78.3% of the total gene diversity found within populations. Of the 21.7% found among populations, 17.9% was attributed to differences among subspecies and only 3.8% attributed to differences among populations within subspecies. Indirect estimates of gene flow (Nm) among all 18 populations of P. mollis were approximately 1 individual per generation. Estimates of gene flow (Nm) between populations of neighbouring subspecies were generally well in excess of 1. A more detailed comparison of gene flow within and between some neighbouring subspecies revealed only 1 of 4 cases where Nm within subspecies was significantly in excess of Nm between subspecies. However, even for this exception, Nm was still in excess of 1. These results show that P. mollis is morphologically differentiated despite the homogenizing effects of gene flow. Consequently, natural selection rather than genetic drift was inferred to be primarily responsible for the patterns of morphological differentiation within P. mollis. The phylogenetic analysis of conspecific populations is essential for an understanding of historical processes within species such as range expansion, divergence and ultimately speciation. The phylogeny of 18 populations representing all nine subspecies within P. mollis was estimated from allozyme frequency data. Trees were constructed under different models and assumptions. These procedures were maximum likelihood (CONTML), maximum parsimony (FREQPARS), UPGMA , distance Wagner and neighbor joining. Major differences in topology between trees constructed under an assumption of an evolutionary clock (UPGMA) and trees that do not assume equal rates of divergence indicated that evolutionary rates are not equal in different lineages in P. mollis. Of the non-UPGMA trees, the maximum likelihood and maximum parsimony trees produced similar topologies and were the most optimal under the criteria of likelihood (given the model of all change due to drift) and tree length. The major patterns produced included an extremely close congruence between geographic distance between populations and the position of each population on the tree for most populations, the early differentiation of subsp. maxima, the well supported clade of all other P. mollis populations and, within this clade, the split into two clades that although distinct, were weakly differentiated at their base. These trees were consistent with a scenario of range expansion along two distinct lineages in a southern direction. These lineages currently terminate in populations that share a hybrid zone of apparently secondary origin west of the Budawang Range. Hybrid zones provide a unique opportunity to study the processes involved in the differentiation of populations and ultimately speciation. Narrow hybrid zones between P. mollis subsps. revoluta, livens and ledfolia were studied. These zones were associated with ecotones. Gene flow was assessed indirectly from allozyme frequency data. The fitness of hybrids was assessed by fruit set and weight following controlled pollination manipulations across the hybrid zones. The relationship between fitness and the spatial distance between mates was assessed to test for the presence of an optimal outcrossing distance. This was tested for initially at distances of up to 15 k m across the hybrid zones, and in a second experiment involving plants separated naturally by distances of up to 150 km. Unique allozyme markers were tracked from pollen to seed in a manipulated population to determine whether pollinators (bees) discriminate between plants from different subspecies. There was no evidence for restricted gene flow across these zones, as indirect estimates of gene flow were extremely high (average Nm over 8 loci was 19), and pollinators did not discriminate between subspecies. There was no detectable fitness effect following pollination across the hybrid zones and no evidence for optimal outcrossing at these distances as fruit set and weight were not significantly different for different pollen sources. These results indicate that hybrid seeds are neither advantageous nor disadvantageous compared to parental seeds. There was, however, evidence for asymmetric outbreeding depression at distances of 150 km. Conclusions about the role of natural selection in affecting phenotypic variation among populations must first distinguish the variation due to phenotypic plasticity, as only the former is heritable. The extent of phenotypic plasticity within P. mollis was assessed by reciprocal transplant experiments of vegetatively propagated seedlings between 3 pairs of populations of markedly different phenotypes. After 15 months in home or away environments, 10 leaf characters were measured on recently produced leaves from transplants and adults, the adults being the source plants of cuttings. The change in phenotype was assessed by the ordination procedure non-metric multidimensional scaling and by ANOVA . Although there was evidence for plasticity, the diagnostic differences between reciprocal populations were not removed from leaves produced under new conditions. Therefore, the diagnostic differences between these populations appear not to be due to plasticity, but are under heritable control. However, similar experiments with seeds are required to assess the extent of genetic canalization in developing seeds and seedlings