Urbanisation generates multiple trait syndromes for terrestrial animal taxa worldwide

Cities can host significant biological diversity. Yet, urbanisation leads to the loss of habitats, species, and functional groups. Understanding how multiple taxa respond to urbanisation globally is essential to promote and conserve biodiversity in cities. Using a dataset encompassing six terrestrial faunal taxa (amphibians, bats, bees, birds, carabid beetles and reptiles) across 379 cities on 6 continents, we show that urbanisation produces taxon-specific changes in trait composition, with traits related to reproductive strategy showing the strongest response. Our findings suggest that urbanisation results in four trait syndromes (mobile generalists, site specialists, central place foragers, and mobile specialists), with resources associated with reproduction and diet likely driving patterns in traits associated with mobility and body size. Functional diversity measures showed varied responses, leading to shifts in trait space likely driven by critical resource distribution and abundance, and taxon-specific trait syndromes. Maximising opportunities to support taxa with different urban trait syndromes should be pivotal in conservation and management programmes within and among cities. This will reduce the likelihood of biotic homogenisation and helps ensure that urban environments have the capacity to respond to future challenges. These actions are critical to reframe the role of cities in global biodiversity loss.info:eu-repo/semantics/publishedVersio

Pioneer behaviour in mountain pine beetles (dendroctonus ponderosae)

Bibliography: p. 108-12

Bee-friendly community gardens : impact of environmental variables on the richness and abundance of exotic and native bees

With their abundant floral resources, urban community gardens have the potential to play an important role in pollinator conservation. At the same time, the gardens themselves are dependent upon the pollination services provided by insects. Thus, understanding the variables that can increase bee richness or abundance in community gardens can contribute to both urban agriculture and pollinator conservation. Here we examine the impact of several environmental variables on bee abundance and diversity in urban community gardens in Sydney, Australia. We used hand netting and trap nests to sample bees in 27 community gardens ranging from inner city gardens with limited surrounding green space, to suburban gardens located next to national parks. We did not find strong support for an impact of any of our variables on bee species richness, abundance or diversity.We found high abundance of a recently introduced non-native bee: the African carder bee, Afranthidium repetitum (Schulz 1906). The abundance of African carder bees was negatively correlated with the amount of surrounding green space and positively correlated with native bee abundance/ species richness. Our results highlight the seemingly rapid increase in African carder bee populations in inner city Sydney, and we call for more research into this bee’s potential environmental impacts. Our results also suggest that hard-to-change environmental factors such as garden size and distance to remnant forests may not have a strong influence on native bee diversity and abundance in highly urbanized area

Harem size and oviposition behaviour in a polygynous bark beetle

1. Harem polygyny can have fitness benefits and costs on females. In bark beetles of the genus Ips the latter may include within-harem competition between larvae. However, earlier competition between females for male care and mating opportunities may also influence oviposition behaviour. There has been relatively little investigation into the relationship between harem size and initial egg output. The present study investigated this relationship in the bark beetle Ips grandicollis.2. The measure of egg output used was the number of eggs in the gallery with the most eggs in each harem. Mean ( &plusmn; SE) harem size of 242 observed harems was 3.25 &plusmn; 0.10. A curvilinear relationship was found between egg output and harem size, with females in smaller harems (one to four females) laying more eggs with increased harem size. However, females in larger harems (five to seven females) laid fewer eggs as harem size increased. The optimal harem size (in terms of number of eggs laid) was close to four females.3. We found no evidence from a behavioural assay that females could preferentially choose unmated males over mated males with harems of two females. Additionally, the distribution of harem sizes suggests that females distribute themselves among males randomly.4. The results suggest that harem size has effects on female reproduction that extend beyond larval competition and influence patterns of oviposition. The mechanism that determines why egg laying is greatest at intermediate levels is unknown. There is no evidence that smaller harems belong to lower quality males, but females may adjust egglaying behaviour in large harems as a result of reduced male attendance or anticipated larval competition.<br /

Argentine ants (Linepithema humile) use adaptable transportation networks to track changes in resource quality

Transportation networks play a crucial role in human and animal societies. For a transportation network to be efficient, it must have adequate capacity to meet traffic demand. Network design becomes increasingly difficult in situations where traffic demand can change unexpectedly. In humans, network design is often constrained by path dependency because it is difficult to move a road once it is built. A similar issue theoretically faces pheromone-trail-laying social insects; once a trail has been laid, positive feedback makes rerouting difficult because new trails cannot compete with continually reinforced pre-existing trails. In the present study, we examined the response of Argentine ant colonies and their trail networks to variable environments where resources differ in quality and change unexpectedly. We found that Argentine ant colonies effectively tracked changes in food quality such that colonies allocated the highest proportion of foragers to the most rewarding feeder. Ant colonies maximised access to high concentration feeders by building additional trails and routes connecting the nest to the feeder. Trail networks appeared to form via a pruning process in which lower traffic trails were gradually removed from the network. At the same time, we observed several instances where new trails appear to have been built to accommodate a surge in demand. The combination of trail building when traffic demand is high and trail pruning when traffic demand is low results in a demand-driven network formation system that allows ants to monopolise multiple dynamic resources

Route selection but not trail clearing are influenced by detour length in the Australian meat ants

Animals travelling through the environment often face trade-offs between environmental parameters such as risk, travel speed and ease of movement when selecting their routes. Route selection is of particular importance for central place foragers like ants, which collectively and repeatedly use trails to exploit stable sources of food. We investigated how colonies of meat ants (Iridomyrmex purpureus) select and clear trail routes when faced with semi-permeable obstructions (strips of grass turf) that substantially slow their travel speed. Meat ant colonies usually re-routed their trails to avoid obstructions when short strips of turf were laid across existing trails, but always travelled directly across the turf when avoiding the turf would have significantly increased travel time. No significant difference in trail clearing activity was found between the short and long obstruction treatments. On binary mazes, meat ants were equally likely to choose paths obstructed with turf and equal length smooth paths, despite much higher time costs associated with the obstructed route. Colonies always chose the shorter, turf-covered path on mazes where the length of the smooth path was increased by 50%, suggesting that meat ants prioritise the minimisation of travel distance when selecting new trail routes. Meat ant route selection and clearing behaviour may reflect a long-term foraging optimisation strategy whereby colonies pay high short-term costs to minimise long-term travelling costs by selecting relatively direct, short distance trail routes which can be cleared of obstructions over time

Artificial flowers as a tool for investigating multimodal flower choice in wild insects

Abstract Flowers come in a variety of colours, shapes, sizes and odours. Flowers also differ in the quality and quantity of nutritional reward they provide to entice potential pollinators to visit. Given this diversity, generalist flower‐visiting insects face the considerable challenge of deciding which flowers to feed on and which to ignore. Working with real flowers poses logistical challenges due to correlations between flower traits, maintenance costs and uncontrolled variables. Here, we overcome this challenge by designing multimodal artificial flowers that varied in visual, olfactory and reward attributes. We used artificial flowers to investigate the impact of seven floral attributes (three visual cues, two olfactory cues and two rewarding attributes) on flower visitation and species richness. We investigated how flower attributes influenced two phases of the decision‐making process: the decision to land on a flower, and the decision to feed on a flower. Artificial flowers attracted 890 individual insects representing 15 morphospecies spanning seven arthropod orders. Honeybees were the most common visitors accounting for 46% of visitors. Higher visitation rates were driven by the presence of nectar, the presence of linalool, flower shape and flower colour and was negatively impacted by the presence of citral. Species richness was driven by the presence of nectar, the presence of linalool and flower colour. For hymenopterans, the probability of landing on the artificial flowers was influenced by the presence of nectar or pollen, shape and the presence of citral and/or linalool. The probability of feeding increased when flowers contained nectar. For dipterans, the probability of landing on artificial flowers increased when the flower was yellow and contained linalool. The probability of feeding increased when flowers contained pollen, nectar and linalool. Our results demonstrate the multi‐attribute nature of flower preferences and highlight the usefulness of artificial flowers as tools for studying flower visitation in wild insects

Limited understanding of bushfire impacts on Australian invertebrates

1. Understanding how increasing risk of frequent and severe fires affects biodiversity and ecosystem function is important for effective conservation and recovery, but large knowledge gaps exist for many taxa in many parts of the world, especially invertebrates. 2. After Australia’s 2019–2020 catastrophic bushfire disaster, estimates of biodiversity loss and government priorities for post-fire conservation activities were focused on vertebrates and plants because of lack of knowledge about invertebrates. 3. Our synthesis of published evidence reveals a fragmented and ambiguous body of literature on invertebrate responses to fire in Australian ecosystems, limiting the capacity of evidence to inform effective conservation policy in response to extreme fire events. Peer-reviewed studies are available for only six of the more than 30 invertebrate phyla and 88% were on arthropods, predominantly ants. 4. Nearly all studies (94%) were conducted in terrestrial habitats, with only four studies measuring impacts in freshwater habitats and no studies of impacts on marine invertebrates. The high variation in study designs and treatment categories, as well as the absence of key methodological details in many older observational studies, means that there is substantial opportunity to improve our approach to collating meaningful estimates of general fire effects. 5. To understand the full ecological effects of catastrophic fire events, and design effective policies that support recovery of ecosystems now and in future, it is critical that we improve understanding of how fire regimes affect invertebrates. We list key priorities for research and policy to support invertebrate conservation and ecosystem recovery in the face of increasing fire risk

Reproductive consequences of male arrival order in the Bark beetle, Ips grandicollis

The ability of birds to perceive, assess and appropriately respond to the presence of relatively novel threats is important to their survival. We hypothesized that the cognitive capacity of birds will influence their ability for accurate response to novelty. We used brain volume as a surrogate for cognitive capacity and postulated that larger brained birds would moderate their responses when presented with a benign, frequently occurring stimulus, such as a person, because they would habituate more readily. We conducted phylogenetic generalized least square regression to investigate the relationship between brain volume and flight initiation distance (FID; the distance to which a bird can be approached before initiating escape behaviour), while controlling for confounding factors including body size (body mass and wing length) and migration status. We compared seven different models using combinations of these parameters using Akaike\u27s information criterion to determine the best approximating model(s) explaining FID. The two best-supported models included only wing length and only body mass with Akaike weights of 0.396 and 0.311 respectively. No model including brain volume had an Akaike weight greater than 0.083 and brain volume was poorly correlated with FID in models after controlling for body mass. Thus, brain volume does not appear to strongly relate to bravery among these shorebirds