Camper, B. | Search bioRxiv

bioRxiv2025

Host and Microbe Scale Processes Shape Spatial Variation in Aphaenogaster (Hymenoptera: Formicidae) Genetics and Their Microbiota

Like all ecological communities, host-associated (HA) microbiota are shaped by environmental selection and dispersal limitation. However, unlike communities of free-living organisms, communities of HA microbes experience selection and dispersal at two separate scales - the scale of the microbes and the scale of their hosts. Thus, HA microbes must tolerate not only the environment created by their host (microbe-scale environment), but also, the environment in which their host resides (host-scale environment). Likewise, HA microbes can disperse between hosts through either horizontal or vertical transmission (microbe-scale dispersal) but can also disperse between locations through host movement (host-scale dispersal). In this paper, we examine how multiscale environmental selection and dispersal limitation shape the genetics and HA microbiota of ants in the Aphaenogaster fulva-rudis-texana (Hymenoptera: Formicidae) complex. We begin by showing how spatial variation in Aphaenogaster genetics is shaped by host-scale environmental selection and dispersal limitation. We then show how this allows both host- and microbe-scale environmental selection to govern spatial variation in Aphaenogaster microbiota. Finally, we discuss the possibility that microbe-scale dispersal limitation also impacts spatial variation in Aphaenogaster microbiota and that this, in turn, may contribute to spatial variation in Aphaenogaster genetics. Ultimately, our results help to shed light on the myriad of interacting factors governing spatial variation in HA microbiota, including the potential for complex, bidirectional interactions between host- and microbe-scale processes.

ecology↗

bioRxiv2023

A Conceptual Framework for Host-Associated Microbiomes of Hybrid Organisms

Hybridization between organisms from evolutionarily distinct lineages can have profound consequences on organism ecology, with cascading effects on fitness and evolution. Most studies of hybrid organisms have focused on organismal traits, for example various aspects of morphology and physiology. However, with the recent emergence of holobiont theory, there has been growing interest in understanding how hybridization impacts and is impacted by host-associated microbiomes. Better understanding of the interplay between host hybridization and host-associated microbiomes has the potential to provide insight into both the roles of host-associated microbiomes as dictators of host performance as well as the fundamental rules governing host-associated microbiome assembly. Unfortunately, there is a current lack of frameworks for understanding the structure of host-associated microbiomes of hybrid organisms. In this paper, we develop four conceptual models describing possible relationships between the host-associated microbiomes of hybrids and their progenitor or parent taxa. We then integrate these models into a quantitative 4H index and present a new R package for calculation, visualization, and analysis of this index. Finally, we demonstrate how the 4H index can be used to compare hybrid microbiomes across disparate plant and animal systems.

ecology↗