Trophic facilitation in forest restoration: Can Nothofagus trees use ectomycorrhizal fungi of the pioneer shrub Leptospermum?

The benefits of plant-to-plant facilitation in ecological restoration are well recognized, yet the potential for indirect trophic facilitation remains understudied. Nothofagus (southern beech; Nothofagaceae) is an iconic southern hemisphere tree genus that is frequently the focus of ecological restoration efforts. One aspect of Nothofagus ecology that may limit restoration success is the availability of appropriate ectomycorrhizal fungi. It has been suggested that pioneer dual-mycorrhizal hosts such as Leptospermum species (Myrtaceae) could facilitate Nothofagus establishment by providing fungal inoculum, but the capacity for Nothofagus to use Leptospermum ectomycorrhizal fungi is unknown. To investigate potential indirect facilitation, we conducted a common garden pot trial to determine if Nothofagus cliffortioides (mountain beech) can use symbionts from Leptospermum scoparium (manuka) ectomycorrhizal communities. Nothofagus and Leptospermum seedlings were grown in monoculture and mixed pairs with reciprocal "home" and "away" soil fungal inoculum. ITS2 metabarcoding of eDNA from hyphal ingrowth bags revealed that Nothofagus and Leptospermum inoculum contained different ectomycorrhizal fungal communities, but that half of the common ectomycorrhizal taxa identified were found in both soil types, suggesting generalist fungi exist. Nothofagus was able to form associations with some fungal species originating from Leptospermum inoculum, however, probable spore contamination meant that the proportion of root colonization associated with those species was ambiguous. Root ectomycorrhizal colonization rates were positively associated with seedling biomass, and there was some evidence of a home soil inoculum advantage in Nothofagus, but these effects were minor. Additionally, we found evidence that home inoculum provides a protective advantage against drought stress for Leptospermum seedlings. Our results indicate the potential for using Leptospermum to promote Nothofagus establishment in restoration plantings and highlight the possible benefits of considering fungal mutualists in ecological restoration projects.

Phylogenomics and morphology of Celmisiinae (Asteraceae: Astereae): Taxonomic and evolutionary implications.

The tribe Astereae (Asteraceae) includes 36 subtribes and 252 genera, and is distributed worldwide in temperate and tropical regions. One of the subtribes, Celmisiinae Saldivia, has been recently circumscribed to include six genera and ca. 160 species, and is restricted to eastern Australia, New Zealand, and New Guinea. The species show an impressive range of growth habit, from small herbs and ericoid subshrubs to medium-sized trees. They live in a wide range of habitats and are often dominant in subalpine and alpine vegetation. Despite the well-supported circumscription of Celmisiinae, uncertainties have remained about their internal relationships and classification at genus and species levels. This study exploited recent advances in high-throughput sequencing to build a robust multi-gene phylogeny for the subtribe Celmisiinae. The target enrichment Angiosperms353 bait set and the hybpiper-nf and paragone-nf pipelines were used to retrieve, infer, and assemble orthologous loci from 75 taxa representing all the main putative clades within the subtribe. Because of the diploidised ploidy level in Celmisiinae, as well as missing data in the assemblies, uncertainty remains surrounding the inference of orthology detection. However, based on a variety of gene-family sets, coalescent and concatenation-based phylogenetic reconstructions recovered similar topologies. Paralogy and missing data in the gene-families caused some problems, but the estimated phylogenies were well-supported and well-resolved. The phylogenomic evidence supported Celmisiinae and three main clades: the Pleurophyllum clade (Pleurophyllum, Macrolearia and Damnamenia), mostly in the New Zealand Subantarctic Islands, Celmisia of mainland New Zealand and Australia, and Shawia (including 'Olearia pro parte' and Pachystegia) of New Zealand, Australia and New Guinea. The results presented here add to the accumulating support for the Angiosperms353 bait set as an efficient method for documenting plant diversity.

Consistent predictors of microbial community composition across spatial scales in grasslands reveal low context-dependency.

Environmental circumstances shaping soil microbial communities have been studied extensively. However, due to disparate study designs, it has been difficult to resolve whether a globally consistent set of predictors exists, or context-dependency prevails. Here, we used a network of 18 grassland sites (11 of those containing regional plant productivity gradients) to examine (i) if similar abiotic or biotic factors predict both large-scale (across sites) and regional-scale (within sites) patterns in bacterial and fungal community composition, and (ii) if microbial community composition differs consistently at two levels of regional plant productivity (low vs. high). Our results revealed that bacteria were associated with particular soil properties (such as base saturation) and both bacteria and fungi were associated with plant community composition across sites and within the majority of sites. Moreover, a discernible microbial community signal emerged, clearly distinguishing high and low-productivity soils across different grasslands independent of their location in the world. Hence, regional productivity differences may be typified by characteristic soil microbial communities across the grassland biome. These results could encourage future research aiming to predict the general effects of global changes on soil microbial community composition in grasslands and to discriminate fertile from infertile systems using generally applicable microbial indicators.

Correlated evolution in an ectomycorrhizal host-symbiont system.

Mechanisms of diversification in fungi are relatively poorly known. Many ectomycorrhizal symbionts show preference for particular host genera or families, so host-symbiont selection may be an important driver of fungal diversification in ectomycorrhizal systems. However, whether ectomycorrhizal hosts and symbionts show correlated evolutionary patterns remains untested, and it is unknown whether fungal specialisation also occurs in systems dominated by hosts from the same genus. We use metabarcoding of ectomycorrhizal fungi collected with hyphal ingrowth bags from Nothofagus forests across southern New Zealand to investigate host-symbiont specialisation and correlated evolution. We examine how ectomycorrhizal communities differ between host species and look for patterns of host-symbiont cophylogeny. We found substantial differences in ectomycorrhizal communities associated with different host taxa, particularly between hosts from different subgenera (Lophozonia and Fuscospora), but also between more closely related hosts. Twenty-four per cent of fungal taxa tested showed affiliations to particular hosts, and tests for cophylogeny revealed significant correlations between host relatedness and the fungal phylogeny that extended to substantial evolutionary depth. These results provide new evidence of correlated evolution in ectomycorrhizal systems, indicating that preferences among closely related host species may represent an important evolutionary driver for local lineage diversification in ectomycorrhizal fungi.

Zeta diversity differentiates factors driving community assembly of rare and common ectomycorrhizal fungi.

A fundamental goal in community ecology is to understand what factors drive community assembly processes. The factors affecting ectomycorrhizal fungal communities are unknown in many regions, particularly in the southern hemisphere. We investigate community assembly using ITS2 metabarcoding of ectomycorrhizal fungi sampled from 3943 hyphal ingrowth bags buried in 81 Nothofagus forests across New Zealand's South Island. By applying zeta diversity analysis and multisite generalized dissimilarity modelling (MS-GDM) we quantify the effects of 43 biotic and environmental variables on community turnover. Unlike traditional beta diversity analyses that are heavily influenced by rare species, the zeta diversity framework differentiates between factors driving turnover of rare and common species, providing a more complete picture of community dynamics. We found that community assembly was dominated by deterministic rather than stochastic processes and identified ecological factors affecting all taxa, as well as others that were specifically important to rare or common taxa. Soil variables were important drivers of turnover for all species, whereas ground cover variables, forest patch size, precipitation and host tree identity had greater effects on rarer species, and tree size and temperature effects were specific to more common species. Interestingly, the effect of temperature on common species is in line with recent evidence from other Kingdoms, pointing to possible generality, and highlighting the importance of considering common species. Applying these methods to fungi has allowed us to identify the distinct ecological processes that structure rare and common taxa during community assembly. This has important implications for understanding the functional effects of community responses to environmental change.

O-Acylated Flavones in the Alpine Daisy Celmisia viscosa: Intraspecific Variation.

Flavonoids acylated on their core phenolic groups are rare. The Aotearoa New Zealand endemic alpine daisy Celmisia viscosa is widespread, but its flavonoids have not previously been identified. Leaf extracts yielded a series of 8-O-acylated flavones with combinations of 3-methylbutanoate, 2-methylbutanoate, and 2-methylpropanoate groups and one, two, or three O-methyls, all previously unreported. Regiochemistries of 8-(3″-methylbutanoyl)-5-hydroxy-6,7,4'-trimethoxyflavone (5) and 8-(2″-methylbutanoyl)-5,7,4'-trihydroxy-6-methoxyflavone (10) were defined by X-ray crystallography. LC analyses of leaf extracts from the full geographic range of C. viscosa showed intraspecific variation of these flavones: most had high concentrations of trimethoxy 8-O-acylated flavones, but dimethoxy 8-O-acylated flavones were the most abundant flavonoids in two individuals. Three other viscid (sticky leaved) Celmisa species also contained these rare flavones, but four nonviscid Celmisa had none detectable.

Halimane Diterpenes in the Alpine Daisy Celmisia viscosa: Absolute Configuration, 2,6-Dideoxyhexopyran-3-ulosides, Conformational Flexibility, and Intraspecific Variation.

The methyl-migrated bicyclic skeleton of the halimane diterpenes has been found in a wide range of organisms, including flowering plants, liverworts, marine animals, and bacteria. The discovery of halima-1(10),14-dien-13-ol (3) from the Aotearoa New Zealand endemic alpine daisy Celmisia viscosa is now reported. The full configuration was assigned for the first time by X-ray crystallography, enantiomeric to that of a liverwort isolate. The absolute configuration at C-5 of the halimane is opposite to that at C-5 of the labdane epimanool (1) found in some C. viscosa specimens. Two new 2,6-dideoxyhexopyran-3-uloside halimane derivatives (4 and 5) were also found, and the absolute configuration of 5 was determined by 1H NMR analysis of the Mosher esters. Line broadening in the 13C NMR spectra of these halim-1(10)-enes was due to conformational exchange in the decalin ring A, as shown by molecular modeling and DFT calculations. 1H NMR and GC analyses of leaf extracts of individual plants from across the full geographic range of C. viscosa revealed intraspecific variation of diterpenes: 37 samples had halimadienol as the main diterpene in large amounts and 2 specimens had predominantly epimanool, again in large amounts. Three other viscid (sticky leaved) Celmisia species also contained diterpenes, but none was detectable in four nonviscid Celmisia species.

Comparative transcriptome analysis of the wild-type model apomict Hieracium praealtum and its loss of parthenogenesis (lop) mutant.

BACKGROUND: Asexual seed formation (apomixis) has been observed in diverse plant families but is rare in crop plants. The generation of apomictic crops would revolutionize agriculture, as clonal seed production provides a low cost and efficient way to produce hybrid seed. Hieracium (Asteraceae) is a model system for studying the molecular components of gametophytic apomixis (asexual seed reproduction). RESULTS: In this study, a reference transcriptome was produced from apomictic Hieracium undergoing the key apomictic events of apomeiosis, parthenogenesis and autonomous endosperm development. In addition, transcriptome sequences from pre-pollination and post-pollination stages were generated from a loss of parthenogenesis (lop) mutant accession that exhibits loss of parthenogenesis and autonomous endosperm development. The transcriptome is composed of 147,632 contigs, 50% of which were annotated with orthologous genes and their probable function. The transcriptome was used to identify transcripts differentially expressed during apomictic and pollination dependent (lop) seed development. Gene Ontology enrichment analysis of differentially expressed transcripts showed that an important difference between apomictic and pollination dependent seed development was the expression of genes relating to epigenetic gene regulation. Genes that mark key developmental stages, i.e. aposporous embryo sac development and seed development, were also identified through their enhanced expression at those stages. CONCLUSION: The production of a comprehensive floral reference transcriptome for Hieracium provides a valuable resource for research into the molecular basis of apomixis and the identification of the genes underlying the LOP locus.

Importance of including cultural practices in ecological restoration.

Ecosystems worldwide have a long history of use and management by indigenous cultures. However, environmental degradation can reduce the availability of culturally important resources. Ecological restoration aims to repair damage to ecosystems caused by human activity, but it is unclear how often restoration projects incorporate the return of harvesting or traditional life patterns for indigenous communities. We examined the incorporation of cultural use of natural resources into ecological restoration in the context of a culturally important but protected New Zealand bird; among award-winning restoration projects in Australasia and worldwide; and in the peer-reviewed restoration ecology literature. Among New Zealand's culturally important bird species, differences in threat status and availability for hunting were large. These differences indicate the values of a colonizing culture can inhibit harvesting by indigenous people. In Australasia among award-winning ecological restoration projects, <17% involved human use of restored areas beyond aesthetic or recreational use, despite many projects encouraging community participation. Globally, restoration goals differed among regions. For example, in North America, projects were primarily conservation oriented, whereas in Asia and Africa projects frequently focused on restoring cultural harvesting. From 1995 to 2014, the restoration ecology literature contained few references to cultural values or use. We argue that restoration practitioners are missing a vital component for reassembling functional ecosystems. Inclusion of sustainably harvestable areas within restored landscapes may allow for the continuation of traditional practices that shaped ecosystems for millennia, and also aid project success by ensuring community support.

Phenylanthraquinones and flavone-C-glucosides from the disjunct Bulbinella in New Zealand.

The genera Bulbine, Bulbinella and Kniphofia produce phenylanthraquinones and are mostly found in southern Africa, although a disjunct group of Bulbinella species endemic to New Zealand also contain phenylanthraquinones as reported herein. The sub-Antarctic megaherb B. rossii yielded sulphated phenylanthraquinones, including a phenylanthraquinone found to carry a sulphated glycoside substituent, 4'-O-demethylknipholone-4'-ß-D-xylopyranosyl-3″-sulphate. A sensitive HPLC method was used to analyse 5 of the 6 New Zealand Bulbinella species, all of which contained phenylanthraquinones. Leaves and roots had different profiles, but species were not distinct. Roots were rich in sulphated and free phenylanthraquinones (0.27 ± 0.09% dry wt), whereas leaves typically only contained free knipholone (0.14 ± 0.01%). Localisation of phenylanthraquinones to the stele and peel was observed in roots. Two flavone-C-glucosides were found in leaves of Bulbinella.

Patterns in floral traits and plant breeding systems on Southern Ocean Islands.

The harsh climatic conditions and paucity of potential pollinators on Southern Ocean Islands (SOIs; latitude 46°S-55°S) lead to the expectation that anemophily or self-fertilization are the dominant modes of plant sexual reproduction. However, at least some species have showy inflorescences suggesting biotic pollination or dimorphic breeding systems necessitating cross-pollination. This study investigates whether anemophily and self-compatibility are common on SOIs, whether species or genera with these traits are more widespread or frequent at higher latitudes, and whether gender dimorphy is correlated with anemophily, as might occur if reliance on pollinators was a disadvantage. Of the 321 flowering plant species in the SOI region, 34.3 % possessed floral traits consistent with anemophily. Compatibility information was located for 94 potentially self-fertilizing species, of which 92.6 % were recorded as partially or fully self-compatible. Dioecy occurred in 7.1 % of species overall and up to 10.2 % of island floras, but has not clearly arisen in situ. Gynodioecy occurred in 3.4 % of species. The frequency of anemophily and gender dimorphy did not differ between the SOI flora and southern hemisphere temperate reference floras. At the species level, gender dimorphy was positively associated with fleshy fruit, but at the genus level it was associated with occurrence in New Zealand and a reduced regional distribution. Anemophily was more prevalent in genera occurring on subantarctic islands and the proportion of species with floral traits suggestive of biotic pollination was significantly higher on climatically milder, cool temperate islands. These results support the contention that reliance on biotic pollinators has constrained the distribution of species on SOIs; however, it is also clear that the reproductive biology of few SOI species has been studied in situ and many species likely employ a mixed mating strategy combining biotic pollination with self-fertilization.

The New Zealand experience of varroa invasion highlights research opportunities for Australia.

The Varroa mite (Varroa destructor) is implicated as a major disease factor in honey bee (Apis mellifera) populations worldwide. Honey bees are extensively relied upon for pollination services, and in countries such as New Zealand and Australia where honey bees have been introduced specifically for commercial pollinator services, the economic effects of any decline in honey bee numbers are predicted to be profound. V. destructor established in New Zealand in 2000 but as yet, Australia remains Varroa-free. Here we analyze the history of V. destructor invasion and spread in New Zealand and discuss the likely long-term impacts. When the mite was discovered in New Zealand, it was considered too well established for eradication to be feasible. Despite control efforts, V. destructor has since spread throughout the country. Today, assessing the impacts of the arrival of V. destructor in this country is compromised by a paucity of data on pollinator communities as they existed prior to invasion. Australia's Varroa-free status provides a rare and likely brief window of opportunity for the global bee research community to gain understanding of honey bee-native pollinator community dynamics prior to Varroa invasion.

Accessory costs of seed production and the evolution of angiosperms.

Accessory costs of reproduction frequently equal or exceed direct investment in offspring, and can limit the evolution of small offspring sizes. Early angiosperms had minimum seed sizes, an order of magnitude smaller than their contemporaries. It has been proposed that changes to reproductive features at the base of the angiosperm clade reduced accessory costs thus removing the fitness disadvantage of small seeds. We measured accessory costs of reproduction in 25 extant gymnosperms and angiosperms, to test whether angiosperms can produce small seeds more economically than gymnosperms. Total accessory costs scaled isometrically to seed mass for angiosperms but less than isometrically for gymnosperms, so that smaller seeds were proportionally more expensive for gymnosperms to produce. In particular, costs of abortions and packaging structures were significantly higher in gymnosperms. Also, the relationship between seed:ovule ratio and seed size was negative in angiosperms but positive in gymnosperms. We argue that the carpel was a key evolutionary innovation reducing accessory costs in angiosperms by allowing sporophytic control of pre- and postzygotic mate selection and timing of resource allocation. The resulting reduction in costs of aborting unfertilized ovules or genetically inferior embryos would have lowered total reproductive costs enabling early angiosperms to evolve small seed sizes and short generation times.

Flower color influences insect visitation in alpine New Zealand.

Despite a long-standing belief that insect pollinators can select for certain flower colors, there are few experimental demonstrations that free-flying insects choose between natural flowers based on color. We investigated responses of insect visitors to experimental manipulations of flower color in the New Zealand alpine. Native syrphid flies (Allograpta and Platycheirus) and solitary bees (Hylaeus and Leioproctus) showed distinct preferences for visiting certain flower species. These responses were determined, in part, by flower color, as insects also responded to experimental manipulations of visible petal color in 7 out of 11 tests with different combinations of flower species and insect type. When preferences were detected, syrphid flies chose yellow over white petals regardless of flower species, whereas Hylaeus chose white over yellow Ourisia glandulosa. In some cases, the strength and direction of color preference depended on the context of other floral traits, in which case the response usually favored the familiar, normal combination of traits. Syrphid flies also visited in response to floral morphological traits but did not show preference based on UV reflectance. The unusually high preponderance of white flowers in the New Zealand alpine is not explained by complete generalization of flower color choice. Instead, the insect visitors show preferences based on color, including colors other than white, along with other floral traits. Furthermore, they can respond in complex ways to combinations of floral cues, suggesting that traits may act in nonadditive ways in determining pollinator visitation.

Accessory costs of seed production.

Accessory costs of reproduction are those that are necessary to mature a seed, but that do not involve the direct cost of provisioning the seed itself. This study aims to quantify accessory costs in a range of species, and test whether they decrease as a proportion of total reproductive expenditure with increasing seed mass, as might be expected if economies of scale came into play at larger seed sizes. We also test whether accessory costs varied with growth form, pollination mode, and dispersal mode, with the expectation that biotic pollination and dispersal modes should incur greater costs. Reproductive allocation (dry biomass) over one season, was calculated for 14 diclinous angiosperm species. Accessory costs averaged 73% of total reproductive allocation, with the majority spent on packaging and dispersal. Total accessory costs, packaging and dispersal costs, and costs incurred prior to pollination were proportional to direct costs of reproduction in major axis regressions. However, larger seeded species incurred significantly greater costs associated with aborted seeds and fruits, and matured a smaller proportion of ovules. This is consistent with larger seeded species being more selective of the ovules/embryos matured than small-seeded species. Total accessory costs, and proportion of ovules aborted, were also significantly greater for biotically dispersed species, but only due to an association with larger seed masses. Costs associated with abortions were lower for biotically pollinated species, due to a general trend of more ovules per ovary, resulting in greater cost sharing. This study demonstrates that expenditure on items other than seeds accounts for the majority of reproductive allocation in flowering plants. Yet, far more literature exists on seed mass variation than on investment in accessory structures. We found a proportional relationship between accessory costs and seed mass that warrants further investigation within the context of selection on margin returns on investment.

Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?

If snow cover in alpine environments were reduced through climatic warming, plants that are normally protected by snow-lie in winter would become exposed to greater extremes of temperature and solar radiation. We examined the annual course of frost resistance of species of native alpine plants from southern New Zealand that are normally buried in snowbanks over winter (Celmisia haastii and Celmisia prorepens) or in sheltered areas that may accumulate snow (Hebe odora) and other species, typical of more exposed areas, that are relatively snow-free (Celmisia viscosa, Poa colensoi, Dracophyllum muscoides). The frost resistance of these principal species was in accord with habitat: those from snowbanks or sheltered areas showed the least frost resistance, whereas species from exposed areas had greater frost resistance throughout the year. P. colensoi had the greatest frost resistance (-32.5 degrees C). All the principal species showed a rapid increase in frost resistance from summer to early winter (February-June) and maximum frost resistance in winter (July-August). The loss of resistance in late winter to early summer (August-December) was most rapid in P. colensoi and D. muscoides. Seasonal frost resistance of the principal species was more strongly related to daylength than to temperature, although all species except C. viscosa were significantly related to temperature when the influence of daylength was accounted for. Measurements of chlorophyll fluorescence indicated that photosynthetic efficiency of the principal species declined with increasing daylength. Levels of frost resistance of the six principal alpine plant species, and others measured during the growing season, were similar to those measured in tropical alpine areas and somewhat more resistant than those recorded in alpine areas of Europe. The potential for frost damage was greatest in spring. The current relationship of frost resistance with daylength is sufficient to prevent damage at any time of year. While warmer temperatures might lower frost resistance, they would also reduce the incidence of frosts, and the incidence of frost damage is unlikely to be altered. The relationship of frost resistance with daylength and temperature potentially provides a means of predicting the responses of alpine plants in response to global warming.