The composition of the large-bodied animal community in Sahul (Australia and New Guinea) has changed dramatically since the Late Pleistocene. Despite the essential ecological roles large animals play, we lack an overarching quantification of how the composition of this community has changed across time and taxa — a perspective needed to evaluate the causes and consequences of these changes. Indeed, most studies have focused on a single period, taxonomic class, or trophic group. We (i) quantified shifts in Sahul’s large-bodied (> 10 kg) animal community, (ii) tested for associations between taxonomic class and trophic group, and (iii) assessed whether any class or trophic group was over- or under-represented among extinct or newly arrived species. We examined changes over two periods: 100,000 years ago to 1788 (i.e., prior to European invasion), and 1788 to the present. Large-bodied species richness fluctuated through time (between 103 and 37 species), with mammals and herbivores most affected. Most herbivores and invertivores were mammals (> 95% and 100%, respectively), most carnivores were reptiles (≥ 79%), and most omnivores were birds (> 62%). Prior to European invasion, extinction risk differed among trophic guilds and taxonomic classes — mammals and herbivores were over-represented among extinct large-bodied species. Although mammals remain the most vulnerable among large-bodied animals, post-1788 patterns do not show large differences among taxonomic or trophic groups. Community composition also changed due to the arrival of new species: two large species arrived before European invasion, and 21 have been introduced since, nearly all of which were mammals. Overall, extinctions and introductions have predominantly involved mammals and herbivores. Understanding why mammals are especially vulnerable compared to other amniotes could assist in their conservation and address the ecological impacts of past faunal change in Sahul.

Parasites are among the most abundant and diverse organisms on Earth, yet they remain persistently underrepresented in biodiversity research. This neglect has serious consequences, as it can lead to skewed ecological interpretations and missed opportunities for understanding ecosystem function. In this presentation, I argue that excluding parasites from biodiversity assessments provides an incomplete and potentially misleading picture of ecological complexity. Drawing on compelling case studies from aquatic and terrestrial systems, I demonstrate how parasites influence host population dynamics, food web structure, and even conservation outcomes. These examples illustrate the profound role parasites play in shaping community interactions and maintaining ecological balance. I advocate for a more inclusive approach to biodiversity research, one that fully integrates parasite ecology, highlighting the need for cross-disciplinary collaboration and renewed appreciation of these often-overlooked organisms. Ignoring parasites not only limits our understanding of biodiversity but undermines our capacity to make informed conservation and management decisions.

Australian alpine microclimates are highly heterogeneous due to strong variability in thermal conditions created by topographic variation. Microclimates are microcosms of broader ecosystems, so understanding how species interactions are affected by temperature variation at this scale can provide key insights into how larger systems might be affected by climate change. Currently, the relationship between microclimatic variation, flowering phenology and plant-pollinator interactions is poorly understood. We aimed to determine the extent to which microclimatic variation affects floral characteristics of alpine plant species, and how this variation affects plant-visitor interaction networks. The study was conducted at Kosciuszko National Park, at two locations (ridgeline and frost-hollow) and two aspects (NW and SE) at each location. At these four microclimates, plants in flower were identified, with floral trait measurements recorded. Visitors to flowers were identified to the closest taxonomic level possible in situ, and plant-visitor network level metrics were compared across microclimates. There was an aspect-driven difference in the abundance of plants in flower and a location-driven effect on flowering level, showing that microclimate played a key role in the floral output of plants. Network analyses revealed higher connectance and greater network asymmetry at higher-elevated ridgeline microclimates, which infers higher network stability at these sites. Additionally, flower-visitor networks at NW aspects had higher network level specialisation, indicating that these relatively more exposed sites encouraged unique visitors that were more tolerant of these conditions. There was also a higher network modularity at lower-elevated valley microclimates, suggesting more distinct specialist subsets of species. The high variability observed in floral characteristics and plant-pollinator networks across distinct microclimates suggests that networks are extremely sensitive to changes in this alpine environment. These findings indicate that climatic shifts in alpine systems could alter pollination network structure and the function of key ecosystem processes.

Mistletoes occur worldwide, with most relying on birds to disperse their sticky seeds to suitable host trees. There has been considerable ecological research on these interactions, emphasizing those birds dependent on mistletoe fruit as their principal food source, but the origins and evolutionary trajectories of these dietary specialists have rarely been considered. Of the ten lineages of mistletoe fruit specialists, five are from the Tyrannida infraorder of South American songbirds comprising mannakins, cotingas, tyrant flycatchers and allies. Integrating current understanding of early songbird evolution with dietary information, two sets of findings emerged. First; dependence on mistletoe fruit is conserved over time, with strong evidence that the 137 mistletoe-dependent species in ten groups scattered among Neotropical suboscines arose from a rapid radiation in the late Oligocene and early Miocene. Although interpreted as a single origin of mistletoe fruit dependency, the degree of dependence was dynamic, mistletoe fruit specialists evolving from more generalised mistletoe-dependent lineages on five separate occasions as they radiated into the Americas from Gondwanan connections. Second, variation in diversity of modern mistletoe specialist frugivores can be explained by lineage age. Considering both representatives from the neotropical groups evaluated here and the other five families across modern birds, mistletoe fruit specialists initially spread rapidly, colonising new areas and speciating, then eventually becoming restricted to single regions represented by relictual lineages with divergent morphologies. After exploring the historic basis, evolutionary implications and ecological relevance of these findings, I consider alternative explanations and articulate testable predictions to corroborate or refute these inferences and guide future work.

Herbivory imposes a loss of aboveground biomass, prompting plants to respond through combinations of avoidance, resistance (survival), and tolerance (regrowth) traits. While resistance is a prerequisite for tolerance, the degree of resistance can influence the level of tolerance needed for recovery. To assess the capacity of native grasses to withstand repeated defoliation, and to identify predictors of this response, we evaluated 21 native tussock grass species (comprising sixteen C3 species and five C4 species, across 12 genera and nine tribes) under a simulated grazing regime. Plants were subjected to five defoliation events at approximately monthly intervals, clipped either close to the crown (5 mm) or well above it (50 mm). We measured plant survival and tiller regrowth as indicators of plant fitness. Most species exhibited strong resistance, even under frequent defoliation; however, tolerance varied significantly by photosynthetic pathway and taxonomic tribe. These findings offer valuable insights for the conservation, management and restoration of Australia’s grassy ecosystems, particularly in the context of degradation from overgrazing.