Biology subjects

Wong, M. K. L.

Publications and source records attributed to Wong, M. K. L..

5 recordsLinked to original sources

bioRxiv2024

A latitudinal gradient in the diel partitioning of species richness?

The writings of naturalists from two centuries past are brimming with accounts of the stark differences in the kinds and numbers of organisms encountered during the day and night and between the tropical and temperate zones. However, only recently have ecologists begun to systematically describe and explain the geographic variation in the diel activities of species on Earth. Examining data from 60 insect communities globally, I find that the partitioning of total species richness across three diel activity periods tracks the latitudinal gradient. In general, the proportions of diurnal and nocturnal species are highest among tropical communities and decline poleward, while cathemeral activity characterises over half of all species in communities at high latitudes. These latitudinal trends in diel partitioning at the community level broadly reflect recently documented patterns in the global distributions of vertebrate species using different activity periods. I outline six hypotheses that may account for a latitudinal gradient in the diel partitioning of species richness.

ecology↗

bioRxiv2021

The global spread and invasion capacities of alien ants

The ecological and economic impacts of biological invasions are usually highly conspicuous, but these are the outcome of a global, multistage process that is obscured from view. For most taxa, we lack a large-scale picture of the movements of alien species, the biases and barriers that promote or inhibit their spread at each stage, and blind spots in our ability to detect species during their spread. For instance, countries rely heavily on customs interceptions to prevent new species introductions, but their efficacy for detecting invaders remains unclear. To address these gaps, we synthesize and provide data at unprecedented geographic resolution on the global diversity and distribution of alien ants, a pervasive group strongly impacting humans and ecosystems. From >145,000 records spanning 602 regions, we identify 522 ant species exhibiting human-mediated spread, doubling recent estimates of their diversity. We show that movements of alien ant species across regions globally are non-random and, moreover, that these flows differ by the extents to which species invade--ranging from arrival to indoor establishment, naturalization, and harmful status. Importantly, we find that almost two-thirds of the 309 species that naturalize globally--most of which are ground- and litter-dwelling--are absent from customs interceptions, which record disproportionately high numbers of arboreal species. Our results illustrate the vast, yet uneven extent of ant invasions globally, and suggest that most alien species bypass biosecurity controls while spreading successfully worldwide. This raises doubts on the efficacy of current customs interceptions procedures and highlights a need for radically new approaches. Significance statementBiological invasions impact humans and ecosystems tremendously. Invasions are difficult to address because little is known about large-scale patterns of spread, species capacities to invade ecosystems, and the efficacy of existing biosecurity measures. This paper tackles these issues for alien ants, one of the most damaging groups of invasive animals. An unprecedented dataset reveals that 522 ant species exhibit human-mediated spread, 270 more than previously known. Species are grouped under four levels of invasion capacity corresponding to different invasion barriers. Geographic sources and sinks for the groups differ globally. Two-thirds of species with naturalization capacity have never been recorded at customs interceptions, which fail to detect many litter-dwelling species. Novel detection and control strategies for inconspicuous alien organisms are needed.

ecology↗

bioRxiv2021

Opposing effects of competitive exclusion determine invasion outcomes and structure ant assemblages

Understanding how species phenotypic differences affect competition is key to explaining community assembly and predicting biodiversity responses. Many studies overlook the variable effects that species trait differences can have on the direction of competitive exclusion, which reverses depending on the specific mechanism at play. We performed a comprehensive trait-based study of an ant invasion integrating morphological, dietary, physiological and behavioral analyses. We found that trait differences between invasive and resident species were not only associated with niche differences which promoted the coexistence of dissimilar species, but also competitive ability differences which acted in the opposite fashion. Furthermore, competition along separate trait axes led to complex and contrasting patterns in the invaded assemblages, where species were at once similar (clustered) in some traits but also dissimilar (overdispersed) in others. Our results reveal that different aspects of phenotype may distinctly modulate the effect of competition in structuring ecological communities and functional diversity.

ecology↗

bioRxiv2020

Including intraspecific trait variability to avoid distortion of functional diversity and ecological inference: lessons from natural assemblages

O_LIFunctional diversity assessments are crucial and increasingly used for understanding ecological processes and managing ecosystems. The functional diversity of a community is assessed by sampling traits at one or more scales (individuals, populations, species) and calculating a summary index of the variation in trait values. However, it remains unclear how the scale at which traits are sampled and the indices used to estimate functional diversity may alter the patterns observed and inferences about ecological processes. C_LIO_LIFor 40 plant and 61 ant communities, we assess functional diversity using six methods - encompassing various mean-based and probabilistic methods - chosen to reflect common scenarios where different levels of detail are available in trait data. We test whether including trait variability at different scales (from individuals to species) alter functional diversity values calculated using volume-based and dissimilarity-based indices, Functional Richness (FRic) and Rao, respectively. We further test whether such effects alter the functional diversity patterns observed across communities and their relationships with environmental drivers such as abiotic gradients and occurrences of invasive species. C_LIO_LIIntraspecific trait variability strongly determined FRic and Rao. Methods using only species mean trait values to calculate FRic (convex hulls) and Rao (Gower-based dissimilarity) distorted the patterns observed when intraspecific trait variability was considered. These distortions generated Type I and Type II errors for the effects of environmental factors structuring the plant and ant communities. C_LIO_LIThe high sensitivity of FRic to individuals with extreme trait values was revealed in comparisons of different probabilistic methods including among-individual and among-population trait variability in functional diversity. By contrast, values and ecological patterns in Rao were consistent among methods including different scales of intraspecific trait variability. C_LIO_LIDecisions about where traits are sampled and how trait variability is included in functional diversity can drastically change the patterns observed and conclusions about ecological processes. We recommend sampling the traits of multiple individuals per species and capturing their intraspecific trait variability using probabilistic methods. We discuss how intraspecific trait variability can be reasonably estimated and included in functional diversity in the common circumstance where only limited trait data are available. C_LI

ecology↗

bioRxiv2020

Trait-similarity and trait-hierarchy jointly determine co-occurrences of resident and invasive ant species

Interspecific competition, a dominant process structuring ecological communities, acts on species phenotypic differences. Species with similar traits should compete intensely (trait-similarity), while those with traits that confer competitive ability should outcompete others (trait-hierarchy). Either or both of these mechanisms may drive competitive exclusion within a community, but their relative importance and interacting effects are rarely studied. We show empirically that spatial associations (pairwise co-occurrences) between an invasive ant Solenopsis invicta and 28 other ant species across a relatively homogenous landscape are explained largely by an interaction of trait-similarity and trait-hierarchy in one morphological trait. We find that increasing trait-hierarchy leads to more negative associations; however these effects are counteracted when species are sufficiently dissimilar (by 37-95%) in their trait ranges. We also show that a model of species co-occurrences integrating trait-similarity and trait-hierarchy consolidates predictions of different theoretical assembly rules. This highlights the explanatory potential of the trait-based co-occurrence approach.

ecology↗