Life-history characteristics and climate correlates of dioecious plant species in central southern Australia

First published online: 27 April 2023 OnlinePublContext. The proportion of dioecious species can vary considerably among climates and habitats. However, studies often involve isolated communities or large diverse areas and fail to capture how proportions vary across diverse landscapes. Aims. To identify (1) life-history associations of terrestrial dioecious plant species in central southern Australia, (2) whether proportion of dioecy varies spatially across central southern Australia, and (3) whether proportion of dioecy is correlated with life-history and/or climate factors. Methods. Species growth form, pollination mechanisms and seed-dispersal features were extracted from herbarium databases to determine potential dioecy-linked traits. Distribution data for native terrestrial species in 66 Interim Biogeographical Regionalisation of Australia subregions were extracted from the Australasian Virtual Herbarium to calculate the proportion of total native species richness that are dioecious. Climate data for each subregion were also obtained from Terrestrial Ecology Research Network databases to investigate relationships among climate, life-history traits and dioecy. Key results. Woodiness, abiotic pollination and endozoochory were more prevalent in dioecious than non-dioecious taxa. Proportion of dioecy ranged from 1.7% to 8.5% among subregions and correlated negatively with annual temperature range, January to March rainfall and precipitation seasonality and with average annual daily mean, minimum, maximum and average annual minimum temperature. The highest-ranked models of dioecy incorporated the additive effects of the relative proportion of woody species and either annual temperature ranges, January to March rainfall or average annual daily maximum temperature. Conclusions. Dioecy was associated with woodiness, abiotic pollination and endozoochory, in line with studies of other flora, with the model of stable temperature range and woodiness being the highest-ranked model of dioecy. Implications. Areas with higher proportions of dioecy can be targeted for future investigations into dioecious plant ecology to aid conservation and ecosystem management.J. T. Draper, S. Delean, J. G. Conran, P. Weinstein and B. S. Simpso

Recent speciation and adaptation to aridity in the ecologically diverse Pilbara region of Australia enabled the native tobaccos (Nicotiana; Solanaceae) to colonize all Australian deserts

Over the last 6 million years, the arid Australian Eremaean Zone (EZ) has remained as dry as it is today. A widely accepted hypothesis suggests that the flora and fauna of arid regions were more broadly distributed before aridification began. In Australia, this process started around 20 million years ago (Ma), leading to gradual speciation as the climate became increasingly arid. Here, we use genomic data to investigate the biogeography and timing of divergence of native allotetraploid tobaccos, Nicotiana section Suaveolentes (Solanaceae). The original allotetraploid migrants from South America were adapted to mesic areas of Australia and recently radiated in the EZ, including in sandy dune fields (only 1.2 Ma old), after developing drought adaptations. Coalescent and maximum likelihood analyses suggest that Nicotiana section Suaveolentes arrived on the continent around 6 Ma, with the ancestors of the Pilbara (Western Australian) lineages radiating there at the onset of extreme aridity 5 Ma by locally adapting to these various ancient, highly stable habitats. The Pilbara thus served as both a mesic refugium and cradle for adaptations to harsher conditions, due to its high topographical diversity, providing microhabitats with varying moisture levels and its proximity to the ocean, which buffers against extreme aridity. This enabled species like Nicotiana to survive in mesic refugia and subsequently adapt to more arid conditions. These results demonstrate that initially poorly adapted plant groups can develop novel adaptations in situ, permitting extensive and rapid dispersal despite the highly variable and unpredictable extreme conditions of the EZ

Phylogenomics and the rise of the angiosperms

Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods1,2. A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome3,4. Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins5,6,7. However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes8. This 15-fold increase in genus-level sampling relative to comparable nuclear studies9 provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade

A phenetic study of the relationships of Drymophila R.Br. within the reticulate-veined liliiflorae

Drymophila R.Br. is compared with 50 allegedly related taxa and comparisons are made from phenetic analyses involving 94 characters. The results of MACINF, UPGMA, ADDTREE and PCoA analyses show that Drymophila belongs with Luzuriaga Ruiz et Pavon and Behnia Didr. in the Luzuriagaceae (Asparagales), with affinities to the Geitonoplesiaceae and Phormiaceae in the Asparagales, and the Uvulariaceae in the Liliales. Realignments of family groupings within the Liliiflorae are also discussed

Fossil coryphoid palms from the Eocene of Vancouver, British Columbia

Premise of research: Fossil fan palm fronds are well known from Eocene sites in the United States; however, although they are also known from the Paleogene Huntingdon Formation of British Columbia for over 100 years, these are poorly studied. There are early anecdotal reports of Eocene “Sabal” or Sabalites leaves from the Vancouver area, pollen from Vancouver and the interior of British Columbia, and a single megafossil palm described from the Princeton Chert, indicating past warm climates in the region. Leaves of coryphoid palms (Arecaceae) from British Columbia are described formally here for the first time. Methodology: We analyze morphologically the Eocene palm frond fossils from the Vancouver area (Huntingdon Formation) and the Ashcroft area in British Columbia. Pivotal results: The Sabalites fossil fronds from the Vancouver area represent fan palms (subfamily Coryphoideae, cf. tribe Sabaleae) and are assigned to the new taxon Sabalites dawsonii. These and other Eocene palm fossils from the Pacific Northwest demonstrate that—based on prior paleoclimate analyses—coryphoid palms were growing under paleotemperatures close to their modern cold limits. Palm fossils reported from near Ashcroft are not Arecaceae, as key diagnostic characters are absent. Conclusions: These and comparable palm fossil records, coupled with analyses of paleoclimate, corroborate an early Paleogene origin of temperate climate adaptation by Coryphoideae, likely as part of the initial Sabaleae and Trachycarpeae diversifications.David R. Greenwood and John G. Conra

Thysanotus racemoides (Asparagales: Asparagaceae), a new species from South Australia and western Victoria

The new species Thysanotus racemoides Sirisena, T.D.Macfarl. & Conran, from South Australia and western Victoria, is described and distinguished from the previously conspecific T. juncifolius (Salisb.) J.H.Willis & Court, by the presence of sessile subterminal umbels and relatively longer anthers and perianth segments. The revised distribution of T. juncifolius is New South Wales and eastern Victoria. Descriptions, photographic plates and a map are provided for the new species and T. juncifolius. The key in the Flora of Australia is amended to accommodate the new species.Udani M. Sirisena, Terry D. Macfarlane, and John G. Conra

An early Miocene ant (subfam. Amblyoponinae) from Foulden Maar: the first fossil Hymenoptera from New Zealand

The ant subfamily Amblyoponinae is presently represented in New Zealand by one endemic species in the cosmopolitan genus Stigmatomma and an introduced Australian species of Amblyopone. The fossil record of the group is restricted to two species of Stigmatomma from late Eocene Baltic Amber. Here, we describe the third fossil record, an Amblyopone-like specimen from the early Miocene of Otago, southern New Zealand, based on a winged male that resembles the extant A. australis Erichson in size, general habitus and characters of wing venation, but also shares features with the African amblyoponine genus Zymmer. This represents the first fossil record of Amblyoponinae from the Southern Hemisphere and the first example of Hymenoptera among the few pre-Quaternary insect fossils known from New Zealand. It suggests a long history of Amblyoponinae in New Zealand and Australia.Uwe Kaulfuss, Anthony C. Harris, John G. Conran & Daphne E. Le

A new Miocene fern (Palaeosorum: Polypodiaceae) from New Zealand bearing in situ spores of Polypodiisporites

A new species of fossil fern with in situ spores, Palaeosorum waipiata (Polypodiaceae), is described and figured for a microsoroid fern frond from earliest Miocene sediments in Otago, New Zealand. The fertile frond from the Foulden Maar fossil Lagerstätte is pinnatifid with deep narrow lobes with entire margins and bears circular sori without indusia in rows on either side of the lobe midrib. Monolete spores associated with the frond are differentiated from similar, widespread dispersed spores of Polypodiisporites radiatus in possessing very small proximal verrucae/granulae around the laesurae and more rounded verrucae and the description of Palaeosorum is expanded to include information about sori and spores. This is the first confident Southern Hemisphere record for a microsoroid fern macrofossil, as well as the first with in situ spores. It is probable that this fern was epiphytic on trees or lithophytic on rocks adjacent to the Miocene maar lake.Uwe Kaulfuss, John G. Conran, Jennifer M. Bannister, Dallas C. Mildenhall and Daphne E. Le

Reproductive niche conservatism in the isolated New Zealand flora over 23 million years

Published 15 October 2014The temporal stability of plant reproductive features on islands has rarely been tested. Using flowers, fruits/cones and seeds from a well-dated (23 Ma) Miocene Lagerstätte in New Zealand, we show that across 23 families and 30 genera of forest angiosperms and conifers, reproductive features have remained constant for more than 20 Myr. Insect-, wind- and bird-pollinated flowers and wind- and bird-dispersed diaspores all indicate remarkable reproductive niche conservatism, despite widespread environmental and biotic change. In the past 10 Myr, declining temperatures and the absence of low-latitude refugia caused regional extinction of thermophiles, while orogenic processes steepened temperature, precipitation and nutrient gradients, limiting forest niches. Despite these changes, the palaeontological record provides empirical support for evidence from phylogeographical studies of strong niche conservatism within lineages and biomes.John G. Conran, William G. Lee, Daphne E. Lee, Jennifer M. Bannister and Uwe Kaulfus