Tiger beetles’ ancestry reveals ancient continental connections
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Grey Gustafson, a researcher at Northern Arizona University, and colleagues used DNA sequencing to trace the evolutionary history of tiger beetles in North America.
The team focused on two groups of tiger beetles found in the western United States, the giant tiger beetles and the night-stalking tiger beetles, to understand how flightless beetles ended up on different continents. Previous theories suggested these beetles belonged to a tribe also found in Africa and South America, raising questions about their transatlantic dispersal.
Gustafson’s research showed that the ancestors of today’s tiger beetles lived on the supercontinent Gondwana, which included South America and Africa, before those continents separated. The DNA analysis created a family tree revealing that North American giant tiger beetles are most closely related to those in South America, and both groups share a common ancestor with tiger beetles in southern Africa.
This suggests the beetles didn’t cross the ocean but were already present when the continents drifted apart, a process called vicariance. The findings support the idea that the distribution of some species across separated landmasses can be explained by their origins on ancient supercontinents. Like other large, flightless animals such as rheas and ostriches, these tiger beetles provide evidence of Gondwanan vicariance, demonstrating how species can be carried to new continents as landmasses separate.
The research adds to the growing understanding of tiger beetle evolution, an area previously lacking in detailed genetic study.
