Leo Ohyama: Navigating the ecological traits of insect societies

Leo Ohyama: Navigating the ecological traits of insect societies

In this blog post, Leo Ohyama, a PhD candidate, discusses his study “Ecological traits of social insects: Colony, queen and worker size relationships reveal a nexus trait with broad ecological relevance“, which has been shortlisted for Functional Ecology’s 2023 Haldane Prize for Early Career Researchers.

About the Paper

Trait-based approaches in ecology allow researchers to associate ecological characteristics spanning phenology, morphology, and physiology to species identities. This provides an additional dimension to quantify and understand the diversity of ecological communities and assemblages. However, these approaches are underdeveloped when assessing the ecological traits of eusocial organisms that live in societies. For example, in ants, strong division of labor can result in multiple measures of body size (worker size, queen size, colony size, male size) with each trait being products of varying ecological and evolutionary processes. Given these difficulties in assessing the ecological traits of eusocial organisms, our paper sought to better quantify and disentangle this trait complexity using ants as a model organism.

More specifically, our paper assessed the trait by trait and trait by environment relationships of the ant fauna of Florida (USA). Because the ant communities of this state have been studied extensively, especially in the context of nonnative ants which make up to ~ 25% of the fauna, we were able to amass a comprehensive data set across queen, worker, and colony traits for ~80% of the fauna (211 species). Additionally, we were able to classify species to dietary classes and nesting preferences. This level of data coverage for an entire regional ant fauna is both novel and unique because colony size estimates and queen specimens are rarely recorded and hard to obtain for most ant species.

The missing link between most ecologically relevant traits across species in our study was social complexity, measured as the morphological difference between workers and queens, highlighting the importance in collected queen and colony data. We found strong support for empirical relationships between colony size and social complexity across multiple subfamilies and genera. Both these traits also exhibited patterns across space with colony size and social complexity associated with mean annual temperature and precipitation. Additionally social complexity was correlated with diets and nesting niches with omnivorous species exhibiting higher levels of social complexity.

Ultimately our work suggests two major conclusions that apply to ants but likely other eusocial taxa. First, traits that can quantify the complexity of a society is one that captures maximal variation amongst other traits, serving as a nexus trait. Second, even though obtaining detailed and comprehensive trait data across regional faunas can be difficult, it can improve our understanding of a eusocial animal systems by linking the ecological components represented by different traits under a single framework.

About the Author

I grew up in Tokyo, Japan where most of my childhood was spent navigating various subway systems within a cement and steel jungle. I’d occasionally take trips to the beach or local wildlife areas, but I didn’t really get exposed to nature until my higher education. More specifically, my introduction to ecology really started with my field-based masters work at the University of Central Florida. There I ran large-scale field experiments and surveys of ant populations which allowed me to gain an appreciation of natural history as well as a strong understanding of my study system. Moving into my PhD, I continued my work with ants but expanded the spatial scales at which I quantified and studied them. I got drawn to large-scale macroecology and developed a strong passion for quantitative ecology and statistics. I like to say that the ants pulled me into being an ecologist but the data science skills I picked up along the way kept me motivated and curious.

Right now, my main research interests are in two areas. The first involves continuing my traits-based research with social insects, especially in the context of nonnative species and how they impact the diversity and distribution of traits. I’m currently drafting a follow-up study to the current one and hope to get it submitted soon. The second area is the assessment of insect diversity at macroecological scales. I plan on finishing my PhD this spring and starting as a post-doctoral fellow at the University of Michigan working with Dr. Nate Sanders on projects relating to global ant ecology and insect declines.

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