“Micro- and macroevolutionary trade-offs in plant-feeding insects”
Daniel A. Peterson, Nate B. Hardy, and Benjamin B. Normark
Micro- and macroevolutionary trade-offs in plant-feeding insects
The huge of diversity of life on earth is often attributed to the division of resources among species – for example, plant-feeding insects may be so diverse because each is a specialist at eating one small group of plant species. This hypothesis is intuitive because “a jack of all trades is master of none”: natural selection should favor specialists when trade-offs prevent any one species from being good at everything. However, a new study from researchers at the University of Massachusetts and Auburn University suggests that evolutionary trade-offs may be less important than we thought.
Using records of insects feeding on particular host-plants gathered from online databases, the researchers reconstructed the evolutionary changes in the host-plants used by thousands of species of North American caterpillars and true bugs over hundreds of millions of years. They found that when an insect species evolved the ability to use a new host-plant type, that species's chances of evolving to also use other host-plant types increased, rather than decreased. In true bugs, they found no trade-offs in host-plant use at all; in fact, some species of mealybugs and aphids have evolved to eat all eleven host-plant types considered in the study, including diverse plant groups like pines, grasses, and oaks. Even in caterpillars, trade-offs were found only at very broad levels, for example between feeding on trees and feeding on plants without woody stems.
The authors conclude that trade-offs between different skill sets are probably not the main reason why most insects are so specialized, which may have more to do with the intricacies of each species's mating habits or predators than with any challenges inherent in being a generalist eater. Read the Article