Rise of the Grasshoppers: New analysis redraws evolutionary tree for major insect family

(Photo credit: Maria Marta Cigliano)

Grasshoppers are one of the most ubiquitous groups of insects in the world, found everywhere from grasslands to tropical rainforests to isolated mountain ranges to sandy deserts.

And now, thanks to a decade-long analysis of grasshoppers’ genetic relationships, scientists have the clearest picture yet of the evolutionary pathways grasshoppers have followed to attain such diversity–and the findings put the birthplace of the broadest lineage of grasshoppers in South America, not Africa, as previously thought. These findings were published in the latest issue of Insect Systematics and Diversity.

Led by associate professor Dr. Hojun Song, researchers at Texas A&M and the Museo de La Plata in Argentina gathered grasshopper specimens from 22 countries and extracted DNA samples. During the study, the researchers analyzed nucleotide sequences of both nuclear and mitochondrial genomes from 142 grasshopper species to learn how they are related to each other.

“We used the differences in nucleotides among different species to infer the relationships,” Song said. “For example, closely related species will share similar stretches of nucleotides because they share a common ancestor, but distantly related species will have more different nucleotides between them.”

The resulting phylogeny of the family Acrididae, which is the largest taxonomic family of grasshoppers, gives science a new, more nuanced understanding of how grasshoppers have evolved. It shows that grasshoppers within Acrididae descended and diversified from one common ancestor, but many of the currently recognized subfamilies are deemed “paraphyletic,” meaning they couldn’t be narrowed down to their own single common ancestor on the Acrididae family tree.

The taxonomy has been very difficult to understand due to convergent evolution, but Song and his group said that their genetic analysis offers a new lens through which taxonomists may look to revisit grasshopper classification.

Read more at Department of Entomology