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In vascular plant systematics there are sometimes conflicts between phenotypic and ecotypic variation and genetic differentiation that challenge species concepts, introduce taxonomic confusion, and create nomenclatural uncertainty. Until a 2014 taxonomic revision that segregated Kunzea ericoides into 10 species, it and K. sinclairii were the only species recognised in New Zealand. A recent DNA microsatellite study failed to support any of the new species, instead revealing biogeographic variation. Here we present the results of a genotyping by sequencing study with 1,361 single nucleotide polymorphisms (SNPs), sampling 48 populations representing four Kunzea species from South Island and southern North Island. The SNP study confirms the microsatellite findings: the two widespread species, K. robusta and K. serotina, are indistinguishable and share northern and southern genotypes with other species; a single metapopulation lineage reflects a national north-to-south clinal pattern; and population differentiation is low and net migration high. A significant isolation by distance pattern was revealed with SNPs. The 2014 revision was explicitly based on the unified species concept, but the primary criterion, that each species represents a separate metapopulation lineage, was not demonstrated. Species recognition was based on morphological and ecological criteria that have proved difficult to apply. Applying the unified species concept and the primary criterion of a single metapopulation genetic lineage, we now recognise just a single New Zealand species, K. ericoides, with other species constituting taxonomic synonyms. In doing so, we distinguish a grey zone of taxonomic uncertainty that reflects incomplete lineage sorting, gene flow coupled with a lack of reproductive isolation, and only partial ecotypic and phenotypic differentiation. As demonstrated in the Kunzea revision, there is considerable phenotypic and ecotypic variation in regional populations that is likely to be of ecological and conservation importance. We suggest informal ecotypes are a better way to recognise this level of variation. [ABSTRACT FROM AUTHOR]

Eco-evolutionary priority effects, in which early arriving taxa pre-empt environmental niches and evolve to exclude or marginalise later arriving taxa, have been claimed to have influenced current vegetation communities in New Zealand. We here critically assess this claim. An examination of the entire New Zealand conifer and angiosperm flora shows that early arriving lineages do not have more species than later arriving lineages, and do not dominate regional species pools. A nationwide forest plot data set shows no influence of lineage age on tree dominance. Woody species with wide latitudinal ranges tend to be older, but plant height and biotically dispersed fruit exert a stronger influence. Range extent is not influenced by lineage age in the alpine zone. The New Zealand studies on which the original claim for eco-evolutionary priority effects is based are flawed as they sample only a small fraction of the flora and plant communities and base their conclusions on a few selected lineages. The large climatic and landscape alterations of the last 50 million years, changes in the type and number of immigrant taxa establishing, and extinction are likely to have been much more influential than arrival times in shaping the extant New Zealand flora. [ABSTRACT FROM AUTHOR]

We present data on sexual systems and associated traits in the New Zealand angiosperm flora and discuss reasons for the anomalously high levels of gender dimorphism in the flora, and the low levels of monoecy in woody species. Along with Hawai’i and New Caledonia, New Zealand has exceptionally high levels of gender dimorphism (19.5% of angiosperm species). The plant traits associated with gender dimorphism (woody growth, small, unspecialised white to yellow-green flowers, abiotic pollination, fleshy fruit) are the same as those in other regions and most gender dimorphic species belong to lineages that were already gender dimorphic on arrival in New Zealand. We attribute the high levels of gender dimorphism to several distinct factors. New Zealand’s evergreen forests have many small trees and understorey shrubs with fleshy fruit and small, open, inconspicuous flowers, a combination characterised by high levels of gender dimorphism elsewhere. Many of these species belong to lineages that migrated from the tropical north, a region with high levels of gender dimorphism. In comparison with many other regions, the New Zealand angiosperm flora has few annuals, and few plants with large, specialised flowers or pollinated by birds, traits elsewhere associated with exceedingly low levels of gender dimorphism. Finally, chance may have played a role through the association of gender dimorphism with rapidly radiating lineages. While the New Zealand angiosperm flora has similar levels of monoecy (14.2%) to other comparable regions, monoecy is exceptionally uncommon in the tree flora (3.4% for strictly monoecious species). However, the endemic Nothofagaceae and introduced woody monoecious species thrive in New Zealand. We suggest it is the lack of temperate sources for monoecious tree species, combined with the difficulty large-fruited monoecious tropical species have in crossing ocean gaps that may be ultimate reason for their failure to establish in greater numbers. [ABSTRACT FROM AUTHOR]

Indigenous plant naming systems and systematic botanical nomenclature involve different methodologies that result in different knowledge systems. Botanical nomenclature provides a single, universal name for a plant based on its taxonomic and evolutionary relationships. Indigenous classifications allow ready identification of plants for particular communities sharing a common language and cultural milieu to which the names are specific. The two systems are independent, but they can profit from mutual comparison, and each should be respected and valued for its distinctive role. A recent proposal argues that indigenous vernacular plant names, being older than those given in colonial circumstances, should have priority over existing botanical names. This suggestion, along with the call for greater use of indigenous languages in specific epithets, is here discussed in relation to the New Zealand flora. We conclude that the proposal would require extensive, complex changes to the International Code of Nomenclature, result in nomenclatural instability, and subject indigenous names to the rules of botanical nomenclature while severing them from their local cultural contexts. We suggest the proposal undermines indigenous naming systems, threatens the integrity of indigenous languages, and would disrupt botanical nomenclature for little benefit. [ABSTRACT FROM AUTHOR]

Kunzea (kānuka) in New Zealand comprises ten endemic species following a recent taxonomic revision, several of which are abundant, widespread and ecologically important as early successional colonisers. The species are difficult to recognise in the field in many areas, some plants appear intermediate between species and it has been argued hybrids are common. Microsatellite markers are used to investigate genetic variation in these ten species. The species are only weakly supported as they are characterised by low differentiation as reported by FST and high allele migration (Nm). FST varied between 0.027 (K. robusta) and 0.084 (K. triregensis). The allopatric K. triregensis and K. salterae had the highest difference in pairwise FST at 0.155 and the sympatric K. robusta and K. serotina the lowest at 0.005. Allele pairwise net migration (Nm) varied between 1.36 (K. triregensis and K. salterae) and 45.24 (K. robusta and K. serotina). The two most widespread species, K. robusta and K. serotina, are genetically indistinguishable and share northern and southern genotypic clusters. Six species or groups of species are recognised in the Structure analysis but these too are characterised by low FST and high allele migration (Nm). Four genotypic clusters shown by Structure analysis are distributed along a north to south latitudinal gradient cutting across species boundaries and corresponding with established biogeographic regions of New Zealand. This provides the strongest pattern of genotypic variation in the study. The weak level of genetic support for the ten Kunzea species, lack of breeding barriers between them, and problems in recognising some of the species in the field, raises questions as to their validity. However, given the ecological, conservation and economic importance of Kunzea, the ten species currently circumscribed should be retained until decisions are made as to how to recognise the variation within the species complex. [ABSTRACT FROM AUTHOR]

It is argued that the greater use of te reo Māori and ta re Moriori languages for naming new taxa in the flora of Aotearoa / New Zealand supports the aspirations of Māori and Te Tiriti o Waitangi. However, using these indigenous languages in botanical nomenclature is more complex than a simplistic 'more is better', and we identify a number of issues requiring consideration. We appraise Waitangi Tribunal claim Wai 262 and Te Tiriti o Waitangi, collaboration at the interface of mātauranga Māori and research science, debate whether iwi are active collaborators or informants, and, crucially, defend the credibility and utility of te reo Māori / ta re Moriori and botanical nomenclatural systems. We conclude that (1) formal botanical nomenclature and (2) te reo and ta re vernacular plant names are independent, complementary, and mutually supportive classifications, each with different purposes and denoting two functional knowledge systems. Our recommendation when naming new taxa is to derive names from botanical Latin terminology. To provide clarity for the application of indigenous languages in naming Aotearoa / New Zealand vascular plants and bryophytes, an assessment of the rules and recommendations in the International Code of Nomenclature (ICN) is presented, including the use of geographical, personal and plant vernacular names as epithets, diacritical signs, hyphens, combinations of different languages, and epithet authorship. For those considering using te reo or ta re names for a new taxon, we present guidelines that address dialogue between scientists and iwi, key aspects of the ICN to consider, and suggestions for maintaining the scientific credibility of nomenclatural practices. A knowledge gap is identified for ethnobotanical folk taxonomy research into vernacular te reo and ta re names, and to document and promote this mātauranga we recommend Māori-led research into etymology, hierarchical structure, cultural relationships, whakapapa, and relationships to botanical names. [ABSTRACT FROM AUTHOR]

Lineage through time plots (LTTs) are often used to explore past patterns of lineage diversification and community assembly. However, as they are based solely on extant species their ability to accurately depict past events can be questioned. Here, simulation models based on neutral processes are used to explore immigration and extinction scenarios to assist with interpretation of LTT plots generated from molecular clock age estimates for a nearly complete set of extant New Zealand vascular plant genera. With significant genus turnover, model simulations yield smooth exponential and linear semi-log LTT plots. Abrupt changes in extinction and immigration rates imposed in the scenarios caused only slight alterations of the curves. The vast majority of New Zealand vascular plant genera derive from trans-oceanic dispersal, and LTT plots generated from divergence dates and fossil data indicate consistently high turnover. Even major geological and climatic events leave minor signatures on LTT plots. Most notably, the maximum Oligocene Marine Transgression (27–22 Ma), when at least 85% of the current landmass was inundated, isn't clearly registered. By themselves, LTT plots shed little light on the biotic effects of climatic or geomorphic change in the remote past and need to be interpreted in the light of fossil and geological data. [ABSTRACT FROM AUTHOR]

Island ecosystems can be severely affected by climate change as they provide limited opportunities for species to track their habitat. Studying the population dynamics of keystone species from these ecosystems can shed a light on climate – ecosystem interactions. Southern beeches are such keystone species in New Zealand with beech forests constituting the most abundant forest cover on the two main islands. Here we use 2.4 kilobase pairs of chloroplast genetic markers from four species of southern beech across their geographic distribution to help elucidate the Pleistocene history of New Zealand forests, and the processes that led to the present-day distribution of southern beech diversity. Broadly concordant phylogeographic patterns were observed across all beech species analysed. The centre of genetic diversity in silver beech was in the northern South Island, with unique haplotypes in the southern South Island, and southern and northern North Island, separated by known 'beech gaps'. Significantly less genetic diversity was evident in the subgenus Fuscospora (red, hard, black/mountain beech). All three species shared a single haplotype in the southern South Island, and a unique haplotype north of the central South Island 'beech gap'. Our study indicates that the present-day distribution of southern beech diversity in New Zealand is largely a result of Plio-Pleistocene environmental changes, with survival in cryptic southern South Island and multiple North Island in situ microrefugia throughout recent glacial cycles. By contrast, the northern South Island was likely the only New Zealand region that supported large (silver) beech populations throughout the Pleistocene. With beech species in New Zealand being keystone forest species, the distribution of the genus throughout the Pleistocene provides a proxy for forest cover at different times. It helps understand the ecological challenges the New Zealand forest fauna and flora were exposed to during the climate oscillations of the ice ages. [ABSTRACT FROM AUTHOR]

A colonisation history for 411 extant genera and 477 lineages of the vascular flora of New Zealand was constructed using the plastid rbcL gene. Molecular clock crown ages suggest that the Eocene-Oligocene transition extinction at 33.9 Ma was critical to the development of the extant flora as few lineages, mostly ferns and conifers, predate this event. Based on crown dates, almost all extant angiosperm lineages have established after the Eocene-Oligocene transition extinction. The Oligocene marine transgression had little discernible impact on the formation of the extant flora, as at the culmination of the inundation (22.0–25.0 Ma) fifty extant lineages of vascular plant were present and another eight lineages originated during this time. The majority of extant species (89%) originated after the end of the Miocene Thermal Optimum at about 15.0 Ma. Nearly 50% of the extant species have evolved during mountain uplift and glaciation of the late Pliocene-Pleistocene (0–4.99 Ma). Therefore, despite a residual contribution from the Eocene, Oligocene and early to mid Miocene periods, the New Zealand vascular flora essentially originated in the late Miocene and after. [ABSTRACT FROM AUTHOR]

Ecosourcing seed of ‘local genetic stock’ for ecological restoration has been practiced in New Zealand for about 50 years. However, we believe that it has become unnecessarily restrictive. Ecosourcing ensures plants used for restoration are adapted to local conditions and maintains current distributional patterns. It also restricts genetic diversity, confines species to their historic range, and reduces the conservation options for threatened species. For example, New Zealand tree species, the life form most frequently used in restoration plantings, have low population genetic differentiation and high net migration of alleles throughout their range. Therefore, very little is gained through restrictive ecosourcing of tree seed. Furthermore, avoidance of the danger of inbreeding depression and widening the scope for closer environmental matching, argues for larger rather smaller source areas. Climate change, extinctions across multiple trophic levels, habitat loss and fragmentation, spread of invasive species, and novel habitats have completely altered the contemporary biotic landscape. Conservation needs to engage with these changes if it is to protect and restore ecosystems. Restrictive ecosourcing is counter-productive as it limits utilising genotypic, phenotypic and ecotypic diversity, and thus the evolutionary potential of indigenous species and ecosystems. It also reduces opportunities to protect biodiversity when populations are small, and limits response to climate change. A new approach is needed. We recommend that phylogeographic patterns and biogeographic boundaries be used to set nine broad ecosourcing regions and, within these regions, phenotypic adaptation to particular environments be used as a guide to seed selection. This more relaxed approach to ecosourcing will improve restoration outcomes through increasing species and genetic diversity, reducing the detrimental effects of inbreeding and promoting the genetic rescue of populations of threatened species. Examples of adopting an eco-evolutionary approach to ecosourcing are provided for the early-successional coloniser Kunzea ericoides and late-successional conifer species. [ABSTRACT FROM AUTHOR]

New Zealand treeline species have low frost tolerance compared to their northern hemi-sphere counterparts, and appear susceptible to out-of-season frosts. However, foliage from high altitude trees is rarely directly measured. This study compares seasonal frost tolerance of mature treeline trees with local temperatures to assess whether frost affects their perfor-mance. Photosystem efficiency and seasonal frost tolerance (temperatures causing 10% and 50% foliage mortality, LT10 and LT50, respectively) were measured on foliage from four native and one exotic species across the treeline ecotone. For all species, photosystem efficiency and frost tolerance were lower in spring and summer than in autumn. Frost tolerance changed with altitude only for exotic Pinus contorta in spring. Spring frosts regularly exceeded LT10 for all species. In all seasons over the last 20 years, the minimum temperature experienced was at least 4 °C wanner than the LT50; however, east of the Main Divide, a 1-in-40 year extreme minimum temperature in summer reached LT50 levels. This study suggests frosts may cause some foliar damage, especially in spring, but the effects of frosts on mature trees are unlikely to control the position of the New Zealand treeline. [ABSTRACT FROM AUTHOR]

A forest biome map for New Zealand is presented, based on the ecosystem process model LINKNZ. Climate surfaces, landforms, slope, and soil types defined 88 933 homogeneous landscape units covering the North and South islands (264 000 km²). Forest development (2000 years) was simulated on each unit with 78 individually parameterized species selected by ecological importance. Forest biomes for the units were assigned by the relative biomass predicted for 21 plant functional types, categorised from the available species. An assessment of model performance against a systematic sample of 559 measured forest plots was satisfactory (dissimilarity index = 0.25). Direct validation was not possible over most of the landscape where native forest has been removed, but performance was sensible against data from 136 pre-deforestation pollen sites (dissimilarity index = 0.20). The modelled biome map reproduced the main characteristics of the current forest distribution in New Zealand and departures from the observed forest distribution were generally explained by omission of whole-stand disturbance effects from simulations. The model reproduced lowland areas of the striking "beech gap" in the west-central zone of the Southern Alps, but not the distribution of Nothofagus species in montane areas of this zone. The most likely explanation supported previous conclusions that the absence was due to a slow reinvasion of Nothofagus after exclusion during the Last Glaciation. Predictions of Nothofagus across some regions of the south-eastern South Island where it was nearly absent before settlement suggested that the ecological knowledge of some competing conifer species was incomplete. [ABSTRACT FROM AUTHOR]