Why are there so many more species of insects? Because insects have been here longer

April 3, 2007

J. B. S. Haldane once famously quipped that "God is inordinately fond of beetles." Results of a study by Mark A. McPeek of Dartmouth College and Jonathan M. Brown of Grinnell College suggest that this fondness was expressed not by making so many, but rather by allowing them to persist for so long.

In a study appearing in the April issue of the American Naturalist, McPeek and Brown show that many insect groups like beetles and butterflies have fantastic numbers of species because these groups are so old. In contrast, less diverse groups, like mammals and birds, are evolutionarily younger.

This is a surprisingly simple answer to a fundamental biological puzzle. They accumulated data from molecular phylogenies (which date the evolutionary relationships among species using genetic information) and from the fossil record to ask whether groups with more species today had accumulated species at faster rates. Animals as diverse as mollusks, insects, spiders, fish, amphibians, reptiles, birds, and mammals appear to have accumulated new species at surprisingly similar rates over evolutionary time.

Groups with more species were simply those that had survived longer. Their analyses thus identify time as a primary determinant of species diversity patterns across animals. Given the unprecedented extinction rates that the Earth's biota are currently experiencing, these findings are also quite sobering. We are rapidly losing what it has taken nature hundreds of millions of years to construct, and only time can repair it.

Citation: Mark A. McPeek and Jonathan M. Brown, "Clade Age and Not Diversification Rate Explains Species Richness among Animal Taxa" The American Naturalist, volume 169 (2007), pages E97–E106 DOI: 10.1086/512135

Source: University of Chicago

Explore further: Professor seeks to increase awareness, monitoring of declining bat populations in Maine

Related Stories

Sight set on tracking threatened species

October 13, 2015

Ever wanted to track a rock wallaby in the rugged Australian bush or watch an orangutan swing past you in the wild jungles of Borneo but without the dangers of being there?

Mercury contamination threatens Antarctic birds

April 11, 2014

Mercury contamination in the Antarctic and Subantarctic affects bird populations, reveal researchers from the Centre d'Etudes Biologiques de Chizé and from the 'Littoral, Environnement et Sociétés' Laboratory (CNRS / Université ...

Recommended for you

Amazon deforestation leaps 16 percent in 2015

November 28, 2015

Illegal logging and clearing of Brazil's Amazon rainforest increased 16 percent in the last year, the government said, in a setback to the aim of stopping destruction of the world's greatest forest by 2030.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.