A quantitative measure of functional redundancy in microbial ecosystems

Although functional redundancy has received increased attention in the microbial ecology literature, no quantitative functional redundancy measurement is currently available which compares multiple communities and integrates of ‘omics data rather than phenotypic traits. Here, we propose an approach for quantifying functional redundancy that use ‘omics data. This approach, termed trait contribution evenness (TCE), is based on traditional measures of community diversity. We measure functional redundancy of a trait within a community as the evenness in relative contribution of that trait among taxa within the community. This definition has several appealing properties including: TCE is an extension of established diversity theory, functional redundancy measurements from communities with different richness and relative trait contribution by taxa are easily comparable, and any quantifiable trait data (genes copies, protein abundance, transcript copies, respiration rates, etc.) is suitable for analysis. Resilience of a trait to taxa extinctions is often viewed as an ecological consequence of traits with high functional redundancy. We demonstrate that TCE functional redundancy is closely and monotonically related to the resilience of a trait to extinctions of trait-bearing taxa. Finally, to illustrate the applicability of TCE, we analyzed the functional redundancy of eight nitrogen-transforming pathways using 2,631 metagenome-assembled genomes from 47 TARA Oceans sites. We found that the NH4+ assimilation pathway was the most functionally redundant (0.6 to 0.7) while nitrification had the lowest functional redundancy (0 to 0.1). Here, TCE functional redundancy addresses shortfalls of other functional redundancy measurements by providing a generalizable, quantitative, and comparable functional redundancy measurement.ImportanceThe broad application of ‘omics technologies in microbiological studies highlights the necessity of integrating traditional ecological theory with omics data when quantifying community functional redundancy. Such an approach should allow for comparisons in functional redundancy between different samples, sites, and studies. Here, we propose measuring functional redundancy based on an expansion of already existing diversity theory. This approach measures how evenly different members in a community contribute to the overall level of a trait within a community. The utility in the approach proposed here will allow for broad evaluation of traits.

Germination characteristics and phytotoxic inhibition of germination in Artemisia adamsii, a low-palatability weed in the Mongolian steppe

Artemisia adamsii is a weed with low palatability to livestock and is thus recognized as an indicator of rangeland degradation in Mongolia. We investigated the germination characteristics of this species, phytotoxic suppression of its germination by its own residue, and the applicability of such germination behaviour to the control of this species. We also discussed the ecological consequence of these factors regarding the vegetation dynamics of the Mongolian steppe. Germination of A. adamsii was tested at different light and temperature conditions. Germination was also tested for A. adamsii and four native grassland species in the presence or absence of A. adamsii residue. Germination of A. adamsii was light-demanding and temperature-dependent. Artemisia adamsii residue showed autotoxic but sub-fatal suppression of germination, and the chemicals causing that suppression were shown to be aqueous and volatile. Phytotoxicity of A. adamsii residue on the germination of grassland species was low, except for in Artemisia frigida. The applicability of the observed sub-fatal autotoxicity for controlling this species was likely to be low, but the elucidated germination characteristics could contribute to developing a strategy for controlling this species. The autotoxicity in A. adamsii germination was suggested to have an ecological consequence that mediates species transition from A. adamsii to other species in degraded land occupied by A. adamsii. As low-palatability A. adamsii can act as a nurse plant of palatable species under grazing conditions, the invasion of A. adamsii into disturbed grasslands may facilitate the recovery of such grasslands in terms of improving pasture quality.

“Two Days to Shape the Future”

The hyper-elite events, “Cityquest KAEC Forum,” are held yearly in Saudi Arabia. Cityquest takes lessons from development initiatives in the Gulf, combining them with others, to foster optimum strategies for creating a new genre of city. Hosted by the King Abdullah Economic City (KAEC) – the first of Saudi Arabia’s four new cities – the event aims to be a new node in the circulation of urban strategies, supplanting what now appear to be almost antique forms of urban conferencing. Experiencing an over-the-top luxury environment, the author was among the technologists, planners, architects, CEOs and visionaries, exchanging views on how to master plan new cities in the world. Projects like King Abdullah Economic City have become leaders in shaping visions of world urbanism, inspiring with a mantle of utopian boldness, albeit questionable in social and ecological consequence.

The bark of eucalypt trees: habitat quality for arthropods and impact of fire.

The bark of eucalypt trees is a significant habitat attribute of forests and woodlands, with different bark types supporting varying populations of invertebrate and vertebrate fauna. Bark also contributes to fuel load in wildfires and hazard reduction burning, with a concomitant loss of habitat and modification of habitat resources. We compared the composition and abundance of tree trunk invertebrates inhabiting four eucalypt bark types and determined the impact of burning the bark on population abundance and community composition. Trees of four bark types (gum, box, stringybark, ironbark) were selected at three sites and arthropod traps placed on burnt and unburnt trees of each type. Traps were left in place for 12 days and arthropod preferences for the four bark types (burnt and unburnt) were analysed. The total number of arthropods differed between bark types, with stringybark and ironbark supporting the largest numbers of invertebrates and the most diverse communities. Burnt stringybark and gum bark had reduced arthropod abundance compared to unburnt bark. The study highlights an ecological consequence of fire on an aspect of invertebrate habitat, with flow-on effects for vertebrates, that should be considered in fire management, as greater areas of land are subject to frequent hazard reduction burning in eastern Australia.

Experimental burning changes the quality of fallen timber as habitat for vertebrate and invertebrate fauna: implications for fire management

Context Fallen timber is a key habitat feature in forests and woodlands for vertebrate and invertebrate fauna, and is either consumed or left partially burnt after the passage of fire. This impact on habitat quality assumes significance because increasing areas of land are subject to frequent hazard-reduction burning and wildfire in eastern Australia. Aims We test here whether partially burnt or charred fallen timber is employed as habitat to the same extent as unburnt fallen timber. Methods Vertebrate and invertebrate abundance beneath burnt and unburnt fence posts was monitored for 13 months in unburnt forest and forest burnt by a wildfire. Key results Both vertebrate and invertebrate fauna made significantly less use of charred refuges. In most taxa, twice as many animals occurred under unburnt as under burnt artificial timber refuges, ant nests being the exception. Fauna made greater use of experimental refuges in burnt forest. Key conclusions Partially burnt fallen-timber refuges, where the log surface is left charred, are inferior habitat for fauna. Habitat quality in burnt forest may be enhanced by introducing fallen timber. Implications The study highlights an ecological consequence of fire for habitat quality, whether through wildfire or hazard-reduction burning, which should be considered in fire management.

Size-Related Differences in the Thermoregulatory Habits of Free-Ranging Komodo Dragons

Thermoregulatory processes were compared among three-size groups of free-ranging Komodo dragons (Varanus komodoensis) comprising small (5–20 kg), medium (20–40 gm) and large (40–70 kg) lizards. While all size groups maintained a similar preferred body temperature of≈35∘C, they achieved this end point differently. Small dragons appeared to engage in sun shuttling behavior more vigorously than large dragons as represented by their greater frequency of daily ambient temperature and light intensity changes as well as a greater activity and overall exposure to the sun. Large dragons were more sedentary and sun shuttled less. Further, they appear to rely to a greater extent on microhabitat selection and employed mouth gaping evaporative cooling to maintain their preferred operational temperature and prevent overheating. A potential ecological consequence of size-specific thermoregulatory habits for dragons is separation of foraging areas. In part, differences in thermoregulation could contribute to inducing shifts in predatory strategies from active foraging in small dragons to more sedentary sit-and-wait ambush predators in adults.