Austral Ecology最新文献

Defaunation is an increasingly pervasive process, reaching ever larger spatial scales worldwide. We integrated data on thousands of putative local mammal assemblages across the Neotropics into 518 metacommunities to predict the phylogenetic trait-based effects of regional defaunation—here defined as meta-extirpation (i.e. extinction at the metacommunity level)—on dozens of putative ecosystem services (ESs). Further, based on 1029 real-world mammal assemblages coalesced into 236 metacommunities, we assessed the spatial extent of meta-extirpations across the Neotropics, while empirically quantifying losses in ESs in comparison with putative scenarios. Using observed data, we also sought to understand changes in the mean body size of metacommunities for different dietary guilds. We examined patterns of mammal diversity, evaluated the erosion of ESs based on ecological networks and measured the relationships between diversity metrics and ESs via dissimilarity arrangements and generalized linear models. Meta-extirpation regimes lead to a mean loss of 49.6% of the ESs provided by Neotropical mammals within metacommunities, whereas real-world meta-extirpations derived 47.2% of ES loss. We show that simulated meta-extirpations penalizing large-bodied species, induced the most severe losses in ESs. Regional-scale meta-extirpations lead to changes in the metabolic allometry and trophic structure of consumers, inducing significant metacommunity downsizing. We conclude that once-thriving mammal-mediated roles in natural ecosystems are fading, with significant consequences for human livelihoods. Many mammal populations have succumbed in several Neotropical ecoregions; so it is critical to protect representative fractions of Neotropical landscapes and regional species pools. Finally, we reinforce the appeal for effective conservation action, given that meta-extirpations are already a global reality.

Brushtail possums (Trichosurus vulpecula) are becoming increasingly recognized as key members of local scavenger guilds in Australia. Yet, our understanding of the spatiotemporal scavenging dynamics of this mainly herbivorous marsupial species remains limited. We investigated abiotic and biotic factors influencing possum carcass use across an alpine and temperate bioregion in Australia. Using camera traps set on experimentally placed kangaroo carcasses, we first examined the influence of both open and closed canopy habitats and warm and cool seasons on possum scavenging behaviour across both bioregions. While scavenging was minimal in open habitats across both bioregions—likely a reflection of possums being an arboreal species—seasonality did significantly influence possum activity. Possums scavenged on carcasses in temperate regions entirely during cooler months. Scavenging was recorded year-round in the alpine region, but with total possum feeding time on carcasses 5.9 times higher in cooler months. A more detailed 12-month study in the alpine region confirmed this strong seasonal influence on possum scavenging, with possums up to 5.4 times more likely to discover carcasses in winter and spend up to 6.7 times longer feeding on carcasses during this season. The variability in possum scavenging behaviour between bioregions and seasons highlights the spatiotemporal complexity of possum scavenging behaviour and the importance of considering abiotic and biotic factors to understand the behaviours of scavengers more broadly. Recognizing primarily herbivorous animals as important yet often overlooked members of local scavenger guilds can help advance our understanding of complex scavenging networks and the intricate pathways through which energy flows in ecosystems, both in Australia and in other systems. Improving our understanding of the spatiotemporal scavenging dynamics of typically herbivorous species may also help to inform more nuanced and effective wildlife management strategies, where supplementary foraging on atypical food resources poses conservation concerns.

The incidence of wildlife roadkill significantly threatens the persistence of wildlife populations and disrupts the ecological functionality of ecosystems. This study investigates the impact of roadkills on wildlife in the Paraguayan Chaco, focusing on a 250-km segment of Route 9 ‘Dr. Carlos Antonio López’ between Villa Hayes and Pozo Colorado. We conducted a road survey for 15 months and recorded 2338 carcasses, identifying 87 species, with mammals (41.3%), reptiles (32.3%) and birds (19.8%) being the most observed groups. The species most frequently killed included Cerdocyon thous, Caracara plancus, Thamnodynastes hypoconia and Procyon cancrivorus. We also recorded species with conservation concern. Additionally, we estimated mortality rates by accounting for sampling errors such as carcass removal and searcher efficiency, revealing annual roadkill rates of 5183 mammals, 19 402 birds and 5020 reptiles on the 250 km per year. Spatial analysis using Ripley's K statistic and HotSpot Identification highlighted significant variation in roadkill distribution across different taxonomic groups and seasons, with 51 km of road identified as hotspots when analysing all groups together. Notably, there was minimal overlap in hotspot locations between seasons and taxonomic groups, emphasizing the need for targeted mitigation strategies. Our findings challenge previous macroecological assessments suggesting low roadkill rates in Paraguay, underscoring the importance of local studies in accurately assessing ecological impacts. This study provides critical baseline data for conservation efforts and calls for further research to develop and implement effective roadkill mitigation strategies in Latin America, especially in Chaco region.

Males of the endangered northern quoll (Dasyurus hallucatus) are facultatively semelparous, often dying following their first breeding season. This is often driven by high breeding costs: males travel and mate extensively in breeding season, resulting in reduced body condition. Annual post-breeding survival rates for male northern quolls have been recorded between 0% and 12.5% across their range in northern Australia. We highlight an observed 50% survival rate of male northern quolls (3 of 6) living into their second year in a Pilbara mining landscape. High male survival here may be attributed to above average rainfall in the landscape and reduced breeding opportunities, due to low female abundance—likely driven by large amounts of unfavourable mining land. This likely led to lower hormonal stress associated with breeding for males, as well as increased resource availability. Given northern quoll population persistence is highly dependent on breeding success, high survival of male northern quolls may inadvertently stabilize populations if they can breed again in a second year, though this is yet to be observed in the Pilbara region. Nevertheless, semelparity of male northern quolls likely varies with environmental and demographic factors, demonstrating that northern quoll populations may be resilient to disturbance in an unpredictable semi-arid environment.

In the forest-steppe transition of Patagonia from Argentina, the intense physical variability promotes the occurrence of contrasting vegetation units, among which is the saxicolous meadow developed on rock outcrops. In temperate and tropical regions, these geoforms of highly variable climate and topography, and poor soil development play an ecological and evolutionary role disproportionate to their reduced area. In Aguas Frías (38°46′S, 70°54′W), the range, diversity, density and adaptation of vascular plant species growing in the saxicolous meadow were compared to those of the surrounding steppe, forest and hygrophilous meadow. We hypothesize that rock outcrops exhibit a compositionally and functionally divergent, cold-adapted flora of a previously more widespread distribution, allowing them to be categorized as refugia for species whose range retreated during the current interglacial. In comparison to the other units, the saxicolous meadow exhibited a small area, low plant cover, high total, native and rare species richness, high density and diversity of species, high richness of unique families and species and an exclusive presence of (rock) ferns. It also presented a high richness of endemic species with more extreme latitudinal and altitudinal distribution, particularly >46° S and >3000 m a.s.l. The similarity of species between the saxicolous meadow and the other units was low. Chamaephytes and nanophanerophytes were dominants, hemicryptophytes and geophytes were infrequent and mesophanerophytes and therophytes were absent. Equivalent results in terms of area of rock outcrops, and origin, strategy, composition, diversity and range of species were found in different regions. The biological and physical attributes would allow these outcrops to be characterized as reduced habitats of high diversity which could be acting as refugia for cold-adapted plants. Conservation actions must prevent and mitigate the effects of fire, biological invasion and cattle grazing that represent the current threats to this ecosystem.

High Andean lizards in the Andes face numerous challenges in high-altitude environments characterized by significant temperature, spatial and temporal variations. These factors greatly influence their thermal characteristics and adaptive strategies for coping with temperature fluctuations. This study aims were to investigate the thermal biology of high mountain lizards (>2000 m) inhabiting the Andes Mountain range, using information from existing literature, and to identify the potential impacts of the original climate change scenarios developed in this study. Within the Andes, high-altitude species are primarily found in families like Liolaemidae, Gymnophthalmidae, Tropiduridae, Anolidae and Leiourisauridae. Notably, we found in the literature that the higher body temperatures and maximum critical temperatures in southern species compared to those closer to the tropics. Typically, diurnal and seasonal temperature variations have a significant impact on the body temperature of these high-altitude lizards, but their adaptive behaviours and physiological mechanisms enhance their resistance to extreme temperatures. Populations situated below the equator often exhibit higher body temperatures and maximum critical temperatures, largely due to their exposure to higher ambient temperatures during summer. With all global warming scenarios indicating temperature increases in latitudinal regions, tropical high-altitude lizards, historically less thermally adaptable, may be particularly susceptible to these temperature rises. It is crucial to consider that additional factors, such as species activity patterns, thermal resource availability and diminishing suitable thermal habitats, will also play a pivotal role in shaping the future of these lizard species, making the situation even more complex and challenging.

We analysed nearly 31 years (1991–2022) of tree population dynamics in 108 permanent plots each 0.04 ha of the Lilyvlei Nature Reserve, a section of the Knysna Forest in South Africa which has not historically been disturbed by harvesting. The Knysna Forest is the only large piece of forest in South Africa and is marginal for tall forest, having low mean annual rainfall of only about 1000 mm and occurs on nutrient poor soils. In contrast to many studies of other forests globally, we found almost no change in overall biomass. Even at the scale of our small plots and on 10–30 year time scales, there has been little change. The forest has very low recruitment and mortality rates and thus low growth rates. Climatic changes too were minimal over this 30-year period. The proportion of stems that died per size class was concentrated in the larger size-classes per species, even for shorter species. This suggests that senescence rather than external disturbances determines the low mortality and thus the low dynamism and the high biomass (approx. 600 Mg ha⁻¹AGB or 41 m² ha⁻¹ basal area) of the forest. Mortality of some species exceeded conspecific recruitment, a trend accompanied by non-significant declines in biomass. However, these trends are not significant. In conclusion, neither composition nor biomass has changed significantly in these forests over a period of 30 years. This suggests that not all Southern Hemisphere forests are in a state of decline.

Fruit and seed morphometry was studied across 1070 plant species belonging to 140 families from 27 contrasting plant communities. The main objectives were to identify allometric relationships and describe the frequency distributions of the weights and sizes of fruits and seeds across plant species, regardless of any qualitative attribute or community type. The frequency distributions of 12 morphometric variables were then determined. Pearson correlations were used to describe associations between quantitative attributes and estimate the slopes of the lines (allometric coefficients) obtained. In general, small fruits and seeds (<1 cm) prevailed in the sample examined. The frequency distributions of the weight and size parameters of the fruits and seeds were bell-shaped, with the exception of the number of seeds per fruit, which was skewed to the right. The highest allometric coefficients were found between the dry weights and sizes of the fruits and seeds, suggesting that these traits are mutually supporting. The cost of seed packaging per fruit, or the pericarp/seed ratio, tended to decrease with increasing investment in progeny, and the number of seeds per fruit decreased with an increase in seed weight. The significant associations between the fruit shape indexes and the morphometric attributes show that the shape of fruits is related to their size and weight. The highest allometric coefficients were found between the dry weights and sizes of the fruits and seeds. Fruit and seed size can predict their biomass and vice versa. There is a close relationship between fruit biomass values and their components (seeds and pericarp). Most species invest more biomass in pericarp (protection and dispersal) compared with the investment in progeny (seed per fruit). The sample examined could be influenced taxonomically along with selective pressures that favour the reproductive economy of the species and suggest that morphometric traits have evolved in coordination.

Understanding what drives the evolution of nectar-robbing strategies is key for gaining insight into the functioning of pollination networks. However, nectar robbing is often an anecdotal behaviour, difficult to quantify and record through field observations, especially in hummingbirds, limiting our understanding of how ecological networks change across communities. Here, we report new records of nectar robbing by Peru's endemic Black Metaltail (Metallura phoebe) in a high-elevation forest at ca. 4000 m a.s.l. and how this species uses either legitimate pollination feeding or nectar robbing in relation to corolla lengths. Furthermore, by analysing 452 citizen science records of photographic observations, we found that 36% of the photographs depicting a foraging event in this species were actually nectar-robbing events. After identifying the plant species in all photographs involving foraging events, we describe how nectar robbing conducted by this hummingbird species is strongly associated with flowers that have longer corollas. We propose that the hummingbird-flower interactions in harsh high-altitude environments, where resources and competition vary markedly across seasons, can offer insight into the ecological drivers of nectar-robbing behaviour in hummingbirds.

Coeli Gomes de Lucena Costa, A. & Campos Gomides, S. (2024) Disentangling drivers of vertebrate roadkill in a protected area in the Amazon rainforest. Austral Ecology, 49, e13571. Available from: https://doi.org/10.1111/aec.13571

In the ‘Data Analysis’ section, the sentence ‘on the railroad, as monitoring took place fortnightly, the number of inspections was equal to 48.’ has been corrected to ‘on the railroad, as monitoring took place fortnightly, the number of inspections was equal to 144.’

We apologize for this error.