By Petra Dreiser

Rowan French, who graduated with her PhD in Ecology & Evolutionary Biology (EEB) this June, has won the prestigious 2026 Ernst Mayr Award from the Society of Systematic Biologists (SSB) for a talk titled “Function and Macroevolution of Exaggerated Male Antennae in Longhorned Beetles.” Considered the SSB’s premier prize, the Ernst Mayr Award recognizes the presenter of an exceptional student lecture in the field of systematics at SSB annual meetings. 

The paper, which summarized French’s doctoral research conducted under the supervision of Luke Mahler and Locke Rowe, looks at the varied morphology (anatomy) and sexual dimorphism (differing between males and females) of a peculiar and poorly understood sensory trait in longhorned beetles (Cerambycidae). Within this group of more than 40,000 species, members of which are found across the globe, males tend to use their antennae to locate potential mates via smell and touch. Many of these males sport exceptionally long feelers (not horns, despite the common name)—up to five times their body length and often twice as long as the antennae of females in the same species. In her research, French sought to understand why and how these functionally important structures became so exaggerated and sexually dimorphic in some species. 

To that end, French set out to build molecular phylogenies—to reconstruct the evolutionary history and relationships between distinct species of longhorned beetles—and to generate and synthesize morphological and natural history data for almost 200 species. Using these data as a basis, she looked for patterns in varied modes and speeds of antenna-length development across more than 100 million years of evolution. The datasets also helped her test specific hypotheses about how antenna diversity and sexual dimorphism evolved. 

French sought to understand why and how the antennae of longhorned beetles, functionally important structures, became so exaggerated and sexually dimorphic.

French’s results suggest that species searching for mates on larger substrates (e.g., tree trunks) tend to be bigger and have longer antennae than those searching on smaller substrates like flowers, where mates can be more easily found. Additionally, antenna segments used for contact-based mate recognition—those furthest away from the head—evolved twice as rapidly as other parts of the feelers. 

Much variation within the family of Cerambycidae (which takes its scientific name from a figure in Greek mythology whose insolence got him turned into a wood-gnawing beetle as punishment), remains to be explained, but French’s findings have shed light on the evolution of an elaborate yet understudied sensory feature. In fact, the literature on sexual selection has often focused on traits that serve either as weapons (e.g., elongated mandibles) or as ornaments (e.g. bright coloration), while she examined antennae as a trait evolving in response to chemosensory demands. 

“As key sensory traits,” French notes, “longhorn antennae could teach us much about the origins, evolution, and consequences of trait exaggeration in contexts where rapid mate-finding” can determine reproductive success. 

Her award-winning work stands as the culmination of almost two decades of fascination. French first came across a longhorned beetle during a road trip in the Canadian West when she was eight years old—on top of her screaming younger sister’s head. “I had never seen a biological structure as impressive as this beetle’s massive, flailing antennae—slim rods . . . more than twice the length of its body and nearly as long as my child-sized hand,” she remembers. While the encounter “laid to waste one pigtail” and led to a life-long aversion to insects in her sibling, for French, the serendipitous observation sparked a determined research trajectory. 

In her current, NSERC-funded postdoctoral work at the Field Museum (supervised by Bruno de Medeiros) and Indiana University (supervised by Kathy Darragh), French has turned her attention to other beetles: Brazilian palm flower weevils in the family Curculionidae. But conceptually, she says, “both my PhD and my postdoc work are linked to my broader interests in beetle diversity and the evolution of their chemosensory systems across biological scales.” 

Listen to the entirety of French’s award-winning talk (starting at time stamp 44:30).