Australian Arid Zone Research Articles

Boom-bust population dynamics drive rapid genetic change

Increasing environmental threats and more extreme environmental perturbations place species at risk of population declines, with associated loss of genetic diversity and evolutionary potential. While theory shows that rapid population declines can cause loss of genetic diversity, populations in some environments, like Australia's arid zone, are repeatedly subject to major population fluctuations yet persist and appear able to maintain genetic diversity. Here, we use repeated population sampling over 13 y and genotype-by-sequencing of 1903 individuals to investigate the genetic consequences of repeated population fluctuations in two small mammals in the Australian arid zone. The sandy inland mouse (Pseudomys hermannsburgensis) experiences marked boom-bust population dynamics in response to the highly variable desert environment. We show that heterozygosity levels declined, and population differentiation (FST) increased, during bust periods when populations became small and isolated, but that heterozygosity was rapidly restored during episodic population booms. In contrast, the lesser hairy-footed dunnart (Sminthopsis youngsoni), a desert marsupial that maintains relatively stable population sizes, showed no linear declines in heterozygosity. These results reveal two contrasting ways in which genetic diversity is maintained in highly variable environments. In one species, diversity is conserved through the maintenance of stable population sizes across time. In the other species, diversity is conserved through rapid genetic mixing during population booms that restores heterozygosity lost during population busts.

Applying two remotely-sensed methods for monitoring grazing impacts in the Australian arid zone

Objective monitoring methods that reliably identify grazing impact are required for long-term sustainable management in the arid rangelands. In Australia such methods must contend with highly unpredictable rainfall and large paddocks incorporating spatially complex land types with differing grazing preferences. Retrospective analysis of data collected following very dry and very wet periods removes vegetation dynamics generated by lesser rainfall events and should increase our ability to separate grazing effects from seasonal variability. Two remote-sensing methods were tested for their capacity to quantify trends over 30 years in vegetation-cover dynamics on a pastoral lease in central Australia with a history of heavy grazing. Following destocking by 2002, one section became a conservation reserve and another transitioned to a research station. During drought, the Dynamic Reference Cover Method (DRCM) showed that ground-cover deficit was less negative on both areas towards the end of the study. This improvement was attributable to increased ground cover after removal of grazing, followed by a reduced, but variable, grazing intensity on the research station and the spread of an introduced palatable perennial grass. Ground-cover response following rainfall was highest in 2011. Likewise, increased ground cover meant that the percentage Cover Production Loss (%CPL) index, calculated using grazing gradient methods (GGMs), was considerably less than a decade earlier following similar rainfall. Results from an associated recovery index (R) were inconclusive. Landscape heterogeneity potentially affected calculation of cover deficit using DRCM but, because heterogeneity was stable over time, reported change between dry years reliably indicated a trend owing to grazing. Interpreting trend from successive %CPL values in wet periods was complicated on the research station by altered waterpoint locations being superimposed on pre-existing degradation; however, the method should be effective in large paddocks with stable waterpoint locations. Despite their limitations, both methods can assist in objectively judging the long-term sustainability of grazing practices in contrasting seasonal conditions.

Phylogenetic placement and description of Ngaliadessus humphreysi gen. et sp. nov., Watts & Villastrigo (Coleoptera: Dytiscidae), a subterranean diving beetle from the Ngalia Basin in central Australia

AbstractThe largest diversity in the world of subterranean diving beetles (Dytiscidae) has been discovered in underground waters of the Australian arid zone. The majority of species are from the Dytiscidae genera Limbodessus Guignot, 1939 (Bidessini) and Paroster Sharp, 1882 (Hydroporini) and are distributed within two major regions: calcrete islands of central Western Australia and the Ngalia Basin of the Northern Territory. Here, we use an integrative approach based on morphological and molecular analyses to describe Ngaliadessus humphreysi gen. et sp. nov. Watts & Villastrigo representing a new genus and species of stygobiotic Bidessini collected from a single well in the Ngalia Basin. Phylogenetic analyses using whole mitochondrial genome, Histone 3 and 18S rRNA data, representing a comprehensive coverage of Bidessini genera, support the distinction of the genus and species as a separate evolutionary lineage sister to the Australasian genus Limbodessus and the widely distributed genus Allodessus Guignot, 1953. Our study further confirms that the Ngalia Basin, containing 13 subterranean dytiscid species from four distinct genera, is one of the most speciose areas within the world's most diverse hotspot of subterranean diving beetles.

Activity of tjakura (great desert skinks) at burrows in relation to plant cover and predators.

Increased predation where ground cover is reduced after severe wildfire is increasingly implicated as a factor causing decline of vulnerable prey populations. In arid central Australia, one species detrimentally affected by repeated wildfire is the great desert skink or tjakura (Liopholis kintorei), a distinctive lizard of the central Australian arid zone that constructs and inhabits multi-entranced communal burrows. We aimed to test whether tjakura or predator activity at burrow entrances varied with cover and how tjakura respond to predator presence. Using time-lapse photography, we monitored tjakura and predator activity at the largest entrance of 12 burrows ranging from high (>70%) to low (<50%) cover and at multiple entrances of two other burrows. Overall activity did not vary between burrows with high and low cover. Within burrow systems tjakura were more active at sparsely vegetated entrances, often sitting wholly or partly inside the burrow. However, consistent between and within burrow systems, skinks spent proportionally more time fully outside where cover was higher. Predators-mostly native-were detected at most burrows, with no apparent relationship between predator activity and cover. Skinks also did not appear to modify their activity in response to predator visits. Our results indicate that tjakura may spend more time outside burrow entrances when cover is higher but there was no direct evidence that this related to perceived or real predation risk. Differences in food availability, thermoregulatory opportunities and opportunities for ambush foraging associated with differences in vegetation cover or composition are other factors likely to be important in determining the activity of tjakura at burrows. Our research demonstrates the usefulness of camera traps for behavioural studies of ectothermic burrowing animals. The complex relationships between tjakura activity and vegetation cover thereby revealed, suggest outcomes of fire-mediated habitat change on predator-prey interactions are not easily predictable.

Morphological and environmental variation within Hibiscus krichauffianus (Malvaceae), and the recognition of two new species, H. verecundus and H. calcareus

The velvet-leaf hibiscus, Hibiscus krichauffianus F.Muell. (Malvaceae subfamily Malvoideae), is predominantly associated with sand dunes in the Australian arid zone but the name is presently also applied to plants occurring in different habitats on the southern edge of the range, and in disjunct locations in Western Australia and eastern Queensland. We investigated the morphological and environmental variation within H. krichauffianus throughout the geographic range. As a result, we have identified two new species, H. verecundus McLay &amp; Albr. and H. calcareus McLay &amp; Albr.; coined a phrase name, H. sp. Belele (D.W.Goodall 3417) for a putative new taxon; and recircumscribed H. krichauffianus. We also assessed material collected when the protologue of H. krichauffianus was published in the late 1850s and selected a lectotype from the original material identified.

Breeding patterns in an Australian arid-zone landbird community

In 1990–1994, over nine survey periods, we recorded a total of 684 breeding attempts deriving from 51 species in a landbird community in arid north-western New South Wales. We investigated whether breeding effort was related to regular seasonal patterns (spring vs winter) or to irregular fluctuations in rainfall (pre-drought vs drought vs isolated thunderstorm vs above-average rainfall post-drought). The total breeding effort and number of species breeding in the study area were not correlated with the numbers of individuals or species present at a given time. The overall breeding effort was influenced primarily by season but was modified by rainfall. Spring breeding predominated but the timing and magnitude of the breeding efforts of different movement groups (residents, nomads and migrants) and dietary groups varied. Within these groups, there were inconsistencies between individual species. Residents bred mainly in spring but only in low numbers during the drought. Some resident species with relatively stable food supplies also bred, though to a lesser extent, in winter. Residents did not respond to the breaking of the drought with prolonged or aseasonal breeding. The breeding of nomads appeared to follow rainfall more closely. The greatest nesting effort by nomads occurred in the spring after the drought broke, possibly because of a peak in the availability of foods suitable for the nomads at this time. The uncertainty and extremes of the arid-zone environment are now being exacerbated by ongoing anthropogenic climate change, which is likely to severely impact the breeding efforts of arid-zone birds.

Use of nesting resources in an Australian arid-zone landbird community

We investigated the use of nesting resources in a landbird community in the arid zone near Peery Lake, northwestern New South Wales. Over a 3.5-year period (1990–1994), which encompassed pre-drought, drought and post-drought conditions, we recorded 504 active nests and 51 breeding species, including open- (45% of all breeding species), hollow- (27%), mud- (8%), ground- (8%) and tunnel-nesters (4%), and species that nested both in the open and in hollows (8%). Almost 90% of observed nests were located in run-on habitats – major creeklines and minor creeklines. Forty-two species nested in, and 24 species nested only in, run-on habitats. Only 23 species nested in the much more extensive surrounding run-off habitats, but the nests of six species were located only in run-off areas. Most nests (90%) were located in plants, all of which were perennials, with 408 nests in live plants and 47 nests in dead plants. The live plants included 20 tree and shrub species ≥0.5 m tall and 4 subshrub and grass species &lt;0.5 m tall. Most (88%) nests in perennial plants were in trees &gt;4 m tall but often low down in the tree (only 47% of all nests in perennial plants were at heights &gt;4 m). Different bird species favoured different plant species. Favoured trees included River Red Gum Eucalyptus camaldulensis for hollow-nesters, and Whitewood Atalaya hemiglauca and Black Box Eucalyptus largiflorens for open- and mud-nesters. Though fewer nests were located in plants &lt;4 m tall, they were in a wider variety of plant species (16 species) than the larger number of nests in plants &gt;4 m tall (14 plant species). Some nomadic species nested in low vegetation which, though perennial, died back and was unavailable in dry times. To support the nesting requirements of all birds, and to retain the diversity of arid-zone birds, the floristic and structural diversity of perennial plants needs to be maintained. This will be difficult to achieve if the current pattern of ongoing, incremental loss of trees and shrubs continues in the arid zone, particularly as the rate of loss is likely to be exacerbated by the impacts of climate change.

Regional‐scale partitioning of transmission losses and groundwater recharge using satellite estimates of actual evapotranspiration in an arid environment

AbstractRivers in arid regions often rely on flow generated from wetter regions upstream, leading to high transmission losses of downstream flows. These transmission losses support a range of ecosystems, but partitioning the volume of the transmission losses across the floodplain, riparian zone and in‐channel is difficult. This study presents a methodology relying primarily on multi‐decade satellite remotely sensed actual evapotranspiration estimates to partition these losses. The method was applied to the ~40,000 km2 floodplain of Cooper Creek in the central Australian arid zone, where first, the alluvial landscape was classified based on actual evapotranspiration rates, and second, both regional‐ (i.e., for the entire floodplain) and local‐scale (i.e., for each waterhole) water balances were calculated to partition these losses. Regional‐scale results estimated that 82% of transmission losses occurred on the floodplain, 13% in the riparian zone and 5% from open water in the river channel and waterholes. These results showed that a refinement of the conceptual model of recharge from the waterholes is necessary as vast areas of the riparian zone are likely to be accessing a shallow freshwater lens rather than a discrete freshwater lens below the permanent waterholes. This method can be used in other data‐poor arid river systems as it uses globally accessible data sources.

Life history characteristics and alarm calling in Australian arid-zone birds

ABSTRACT In prey species, it is often the case that individuals give alarms when they are threatened. In birds, such signals are frequently vocal signals that alert conspecifics to the presence of a threat. The responses to these calls by receivers may include fleeing to cover or approaching to mob the predator. Although most birds do give alarm calls when threatened, not all species do. We used Australian arid-zone bird species (n = 171) to test the hypothesis that alarm calling behaviour is determined by ecological, behavioural, and morphological characteristics. Eighty-nine percent of birds analysed possessed an alarm call, highlighting the prevalence of this behaviour. Our study found three variables – number of food types eaten, mobility, and breeding system – that were associated with predicting alarm calling behaviour in these species. The correspondence of alarm calling with these key life history attributes provides insight into benefits of having alarm calls and the evolutionary processes that have given rise to this behaviour.

Has the Australian Endemic Grey Falcon the Most Extreme Dietary Specialization among all Falco Species?

Simple SummaryThe diet of an animal is one of the most informative aspects of how it interacts with its environment. A clear understanding of a species’ diet is, therefore, crucial for conservation considerations. The Grey Falcon is a rare and threatened raptor, found only in Australia’s vast arid and semi-arid zone. Its diet is subject to dispute, therefore, we studied, through direct observation during more than 17 years of fieldwork, the food that these birds ingested. We found that Grey Falcons of all ages fed almost exclusively on birds. No other food type was ever taken with any regularity. Our results suggest strongly that the Grey Falcon, throughout the year, throughout its life, and across its vast distribution, feeds almost exclusively on birds. We compared our results with the diets of the other species in the genus (Falco) and found that the Grey Falcon’s diet is the most extreme, more so than the diet of even those falcon species that are commonly considered to take exclusively birds, such as the Peregrine Falcon. Our evolutionary explanation of the unique dietary specialization of the Grey Falcon takes into account aspects of the species’ environment and relative prey availability.A clear understanding of a species’ diet is crucial in understanding its spatio-temporal dynamics, and is, therefore, pertinent to conservation considerations. The diet of the Grey Falcon (Falco hypoleucos), a rare and threatened predator endemic to the Australian arid and semi-arid zone, is subject to diverging assertions; therefore, we studied its diet through direct observation of food ingestion during more than 17 years of fieldwork across the species’ distribution. We found that Grey Falcons of all ages fed almost exclusively on a single type of food, namely, birds, and non-avian food items never constituted a substantial portion of any individual’s diet. The extraordinary circumstances that were associated with the ingestion of non-avian food suggest strongly that, across its vast distribution, throughout the year, and throughout its life, the Grey Falcon feeds almost exclusively on birds. Further, we compared the diets of all Falco species and found that the dietary specialization is most extreme in the Grey Falcon, more so than even in the Taita (F. fasciinucha) and Peregrine Falcons (F. peregrinus). Based on aspects of the species’ environment and relative prey availability, we offer an evolutionary explanation of the apparently unique dietary specialization of the arid-adapted Grey Falcon.

Assessing soil corrosivity along feral-proof fencing in the Australian Arid Zone and the development of a new soil corrosivity index

Feral-proof fencing plays a fundamental role in many wildlife conservation programs. The gradual deterioration of metal infrastructure (such as fencing) through contact with a corrosive soil environment is a complex and global issue. This paper aims to classify and map areas of low, moderate and high soil corrosivity risk along fence boundaries in the southern part of the Arid Recovery nature reserve in South Australia. This risk mapping will assist with the management of feral-proof fencing and serve as a model for understanding soil corrosion in arid environments. Maghemite and akagenéite were the dominant corrosion products formed on Arid Recovery fencing and are thought to be ineffective at reducing corrosion on exposed wires due to their high porosity and poor adherence to metal surfaces. On their own, soil pH, soil salinity, soil texture, soil carbonate content, soil chloride content, and soil sulfur content were all poorly correlated with the extent of fence corrosion damage observed at field sites (R2 < 0.2 and p > 0.05). The widely used American Water Works Association 10-Point Corrosion Index (C105) significantly underestimated soil corrosivity in these arid soils, with only 12% of sites correctly classified as corrosive or non-corrosive. A modified index was subsequently developed using soil chemical data, which was able to correctly classify 70% of sites. Further research is needed to accurately assess the performance of this newly developed, preliminary risk index as a reliable soil corrosivity classification method in arid environments.

Wild zebra finches are attracted towards acoustic cues from conspecific social groups

Abstract Social information gathered by observing others often supplements personal information collected from direct interactions with the physical environment during decision-making. Social information use may be particularly beneficial in harsh environments or if resources are distributed patchily, ephemeral, and unpredictable, and hence difficult to locate. We experimentally tested the use of acoustic cues in wild zebra finches (Taeniopygia guttata) as they flew around their arid habitat as a way of locating conspecifics on the ground, and potentially accessing useful social information. Joining a conspecific group may reduce the predation risk, and if they are foraging may also improve foraging efficiency, as the distribution of zebra finch food (grass seed) is scattered and unpredictable in their natural habitat, the Australian arid zone. We conducted playback experiments along vegetated creek lines radiating out from an artificial dam where all birds in the population were coming for drinking water. We broadcast recordings of vocalizations from foraging conspecific groups to birds using these creek lines to move to or from the water into the wider habitat. Zebra finches were more likely to land near the loudspeaker when conspecific vocalizations were broadcast compared to white noise. Birds flying low and close to the loudspeaker were most likely to land. Our results indicate that zebra finches use acoustic cues of conspecifics as a source of social information for grouping decisions. Use of such information may also enhance foraging efficiency in environments with unpredictable and scarce foraging locations, and reduce predation risk for calling and responding individuals.

Assessing Soil Corrosivity Along Feral-Proof Fencing in the Australian Arid Zone and the Development of a New Soil Corrosivity Index

Assessing Soil Corrosivity Along Feral-Proof Fencing in the Australian Arid Zone and the Development of a New Soil Corrosivity Index

Evidence that predator satiation drives reproductive synchrony in the desert masting grass, soft spinifex (Triodia pungens)

AbstractThe predator satiation (PS) hypothesis of masting holds that seeding periodicity among plant populations enhances seed survival by starving granivores during low‐output periods and satiating reduced consumer populations during mast (high‐output) years. Although well‐studied in the northern hemisphere and in New Zealand, the PS hypothesis has received scant research attention in Australia. This is despite vegetation communities across nearly half the continent being dominated by masting species subject to high levels of seed predation (e.g. mulga [Acacia aneura] shrublands and spinifex [Triodia spp.] grasslands). Here, phenological monitoring and experimental testing of the PS hypothesis in the desert masting grass Triodia pungens (soft spinifex) occurred over 10 years at Deep Well station, central Australia. Field evidence supported the hypothesis that masting enhances seed escape from predators, as mean proportion seed survival at experimental bait stations was significantly greater during mast years (0.38 in 2012 and 0.33 in 2017) than during inter‐mast years (0.01 in 2016 and 2018). The possibility that seed decay as opposed to consumption affected results was controlled for by a deterioration experiment that indicated no significant loss of seed viability after 6‐months burial. The results support the hypothesis that masting in T. pungens is an adaptive trait related to the satiation of seed predators. However, whether masting enhances seed escape because predators are satiated at higher seed densities (i.e. masting causes a predator functional response) and/or because frequent low‐output periods reduce predator populations and make satiation more likely (i.e. a numerical predator masting response), remains unresolved. Aside from T. pungens, there are numerous other plants of the Australian arid zone that experience high levels of granivory and display masting. Seed predation may be a more important selective force acting on arid Australian plant reproduction than previously thought.

Biocrust cyanobacteria inoculants biomineralize gypsum and preserve indigenous bacterial communities in dryland topsoil

Biocrust cyanobacteria are ubiquitous organisms in dryland environments that can enhance soil stability and improve nutrient conditions in reconstructed or disturbed soils. Despite the demonstrated benefits of cyanobacterial inoculation for promoting soil fertility, there is limited knowledge about the impacts of introducing cultured cyanobacteria on the indigenous microbial communities. Here, we conducted a microcosm experiment under controlled conditions using indigenous biocrust cyanobacteria and locally sourced topsoil substrate commonly used in dryland restoration in the Australian arid zone. We inoculated the topsoil with a consortium composed of Leptolyngbya sp. and Scytonema sp. cyanobacteria, to assess the effects of the inoculated cyanobacteria on (i) the soil chemical properties, i.e., pH, electrical conductivity (EC), total organic carbon (TOC), and nitrogen (TN) of the inoculated topsoil, (ii) the early formation of an artificial soil biocrust and iii) the composition and diversity of the resident bacterial community. Our results showed that the inoculated cyanobacterial consortia decreased the EC, but changes in the TOC and TN were not significant after 80 days. A higher content of chlorophyll a in the inoculated samples compared to the control, confirmed the survival of the cyanobacterial inoculants after 80 days. The inoculated cyanobacteria promoted gypsum formation on the soil surface indicating that they are actively modifying the upper layers of the soil profile and improving habitability. Although immediately after inoculation cyanobacteria dominated the abundance of bacterial phylotypes, these were replaced by other phyla such as Actinobacteria, after 80 days. The Shannon diversity and Simpson diversity indexes between control and inoculated soils differed at the time of inoculation but were similar at the end of the experiment. These results suggest that, in the short term, the introduced cyanobacteria do not significantly affect the native resident bacterial communities and are capable of colonizing the topsoil without affecting the natural community.

Where nothing stands still: quantifying nomadism in Australian arid-zone birds

ContextNomadism is a movement strategy in response to non-seasonal environmental variability. Knowledge of nomadic species movements is poor but is necessary to understand life histories and develop appropriate conservation strategies.ObjectivesWe provide a first quantification of nomadism among Australia’s arid bird community, which is presumed to be highly nomadic, by measuring variation in species’ occurrence and abundance among years to determine whether there are clear nomadic and non-nomadic strategists.MethodsWe surveyed birds annually from 2012 to 2016. We measured how many years each species was present at a site and estimated inter-annual variability in species abundance, using both measures to infer species movement patterns. We used results to inform existing movement classifications.ResultsMost arid species showed low site persistence, with species detected at the same site, on average, 1.8 out of the five survey years. Movement varied along a continuum rather than grouping into distinct nomadic and non-nomadic groups. Species classified as nomadic showed higher variation in abundance and lower site persistence than species classified as resident. Our method of quantifying nomadism closely replicated existing expert-derived movement classifications of arid zone bird species.ConclusionsRather than a fixed attribute, movements of many species in our study can be heavily environment-dependent, and individuals of a single species can display a continuum of movements in different times and places. This complicates the conservation of species, but the growing recognition of the complexity of species movements offers opportunities for a more nuanced understanding of the relationship between species and environment.

Reintroduction of Bilbies (Macrotis lagotis) to Matuwa, an Indigenous Protected Area in Western Australia

The greater bilby (Macrotis lagotis) once occupied much of Australia's mainland. Bilbies are now listed as vulnerable and only occur in 20% of their former range. Operation Rangeland Restoration aims to to restore an ex−pastoral lease; reintroduce several species of locally extirpated fauna, including the bilby; and maintain the area in perpetuity for the conservation of Australian arid zone species. Bilbies were reintroduced to the Matuwa Indigenous Protected Area between 2007 and 2010 and, with ongoing landscape-scale control of feral predators, herbivores, and fire, have thrived. Here, we present a detailed account of the methods used during the reintroduction, showing that between 2007 and 2019 there has been an 88% increase in the area of occupancy by bilbies at Matuwa. The results of 2-ha track plot surveys conducted by the traditional owners of Matuwa suggest that the reintroduced bilbies are emigrating out of Matuwa. In addition, in 2018 and 2019 we used 120 camera-traps over 18 mo and occupancy analysis to confirm the widespread presence of bilbies across Matuwa and define significant habitat correlates. Bilbies were more likely to be detected on sandplains with Eucalyptus species as overstorey vegetation and Triodia as understorey vegetation. Bilbies were not detected in habitats with ≥ 75% bare ground. We attribute the success of the bilby reintroduction at Matuwa to the consistent implementation of landscape-scale control of feral predators.

Global change impacts on arid zone ecosystems: Seedling establishment processes are threatened by temperature and water stress.

Recruitment for many arid‐zone plant species is expected to be impacted by the projected increase in soil temperature and prolonged droughts associated with global climate change. As seed dormancy is considered a strategy to avoid unfavorable conditions, understanding the mechanisms underpinning vulnerability to these factors is critical for plant recruitment in intact communities, as well as for restoration efforts in arid ecosystems. This study determined the effects of temperature and water stress on recruitment processes in six grass species in the genus Triodia R.Br. from the Australian arid zone. Experiments in controlled environments were conducted on dormant and less‐dormant seeds at constant temperatures of 25°C, 30°C, 35°C, and 40°C, under well‐watered (Ψsoil = −0.15 MPa) and water‐limited (Ψsoil = −0.35 MPa) conditions. Success at three key recruitment stages—seed germination, emergence, and survival—and final seed viability of ungerminated seeds was assessed. For all species, less‐dormant seeds germinated to higher proportions under all conditions; however, subsequent seedling emergence and survival were higher in the more dormant seed treatment. An increase in temperature (35–40°C) under water‐limited conditions caused 95%–100% recruitment failure, regardless of the dormancy state. Ungerminated seeds maintained viability in dry soil; however, when exposed to warm (30–40°C) and well‐watered conditions, loss of viability was greater from the less‐dormant seeds across all species. This work demonstrates that the transition from seed to established seedling is highly vulnerable to microclimatic constraints and represents a critical filter for plant recruitment in the arid zone. As we demonstrate temperature and water stress‐driven mortality between seeds and established seedlings, understanding how these factors influence recruitment in other arid‐zone species should be a high priority consideration for management actions to mitigate the impacts of global change on ecosystem resilience. The knowledge gained from these outcomes must be actively incorporated into restoration initiatives.

Molecular phylogeny of tribe Myoporeae (Scrophulariaceae) using nuclear ribosomal DNA: Generic relationships and evidence for major clades

AbstractEremophila is a significant component of the Australian arid zone flora, but its generic limits and relationships to the other six genera of tribe Myoporeae remain largely untested. In this study, we assembled a dataset of the nuclear ribosomal cistron (ca. 6000 bases including ITS1+2, ETS regions, non‐transcribed spacer and associated genes) for all genera in tribe Myoporeae with a particular focus on Eremophila (205 of total 233 formally described species of Eremophila, and 28 species of related genera sampled). Phylogenetic analyses were performed using maximum likelihood and Bayesian inference methods. These resolved four major clades that were well supported. Eremophila was paraphyletic, with all other genera of tribe Myoporeae nested in it. We discuss two taxonomic options for addressing the paraphyly of Eremophila. As an immediate step, we propose that the small genera, Calamphoreus and Diocirea, should be placed in synonymy under Eremophila, and herein make the necessary new nomenclatural combinations. Additional phylogenetic data are needed, ideally in the form of multiple independent nuclear loci, to clarify the positions of Bontia, Glycocystis and Myoporum relative to Eremophila before further taxonomic changes are proposed.

Diversification of the mygalomorph spider genus Aname (Araneae: Anamidae) across the Australian arid zone: Tracing the evolution and biogeography of a continent-wide radiation

The assembly of the Australian arid zone biota has long fascinated biogeographers. Covering over two-thirds of the continent, Australia’s vast arid zone biome is home to a distinctive fauna and flora, including numerous lineages which have diversified since the Eocene. Tracing the origins and speciation history of these arid zone taxa has been an ongoing endeavour since the advent of molecular phylogenetics, and an increasing number of studies on invertebrate animals are beginning to complement a rich history of research on vertebrate and plant taxa. In this study, we apply continent-wide genetic sampling and one of the largest phylogenetic data matrices yet assembled for a genus of Australian spiders, to reconstruct the phylogeny and biogeographic history of the open-holed trapdoor spider genus Aname L. Koch, 1873. This highly diverse lineage of Australian mygalomorph spiders has a distribution covering the majority of Australia west of the Great Dividing Range, but apparently excluding the high rainfall zones of eastern Australia and Tasmania. Original and legacy sequences were obtained for three mtDNA and four nuDNA markers from 174 taxa in seven genera, including 150 Aname specimen terminals belonging to 102 species-level operational taxonomic units, sampled from 32 bioregions across Australia. Reconstruction of the phylogeny and biogeographic history of Aname revealed three radiations (Tropical, Temperate-Eastern and Continental), which could be further broken into eight major inclusive clades. Ancestral area reconstruction revealed the Pilbara, Monsoon Tropics and Mid-West to be important ancestral areas for the genus Aname and its closest relatives, with the origin of Aname itself inferred in the Pilbara bioregion. From these origins in the arid north-west of Australia, our study found evidence for a series of subsequent biome transitions in separate lineages, with at least eight tertiary incursions back into the arid zone from more mesic tropical, temperate or eastern biomes, and only two major clades which experienced widespread (primary) in situ diversification within the arid zone. Based on our phylogenetic results, and results from independent legacy divergence dating studies, we further reveal the importance of climate-driven biotic change in the Miocene and Pliocene in shaping the distribution and composition of the Australian arid zone biota, and the value of continent-wide studies in revealing potentially complex patterns of arid zone diversification in dispersal-limited invertebrate taxa.