Biodiversity Creates Biodiversity

Feb 5, 2009

Biodiversity creates biodiversity.

That point comes through loud and clear when you read the scientific paper on the apple maggot/parasitic wasp research led by UC Davis evolutionary ecologist Andrew Forbes.

The news embargo lifted at 11 a.m. today and the research will be published Friday, Feb. 6 in the journal Science.

When the apple maggot shifted hosts from the hawthorn to the apple, that triggered a cascading effect on the ecosystem.

A parasitic wasp (Diachasma alloeum) that attacks the apple maggot (Rhagoletis pomonella) has “formed new incipient species as a result of specializing on diversifying fly hosts, including the recently derived apple-infesting race of R. pomonella,” Forbes said.

The apple maggot, native to North America, shifted from its ancestral hawthorn host (Crataegus spp.), to introduced European apples less than 250 years ago. “The two populations,” Forbes said, “have since become partially reproductively isolated due to a number of host-related adaptations and are now distinct host races, on their way to becoming separate species.” 

A host race is a group of organisms in the process of becoming a new species due to its close association with a particular host (plant or animal).

In this new study, Forbes and his co-authors showed that the wasp D. alloeum is undergoing the same evolutionary changes.

“The research shows the process of speciation in action and might tell us more about why certain groups of organisms are more diverse than others.” said Forbes, who received his doctorate from the University of Notre Dame and is now a postdoctoral researcher in professor Jay Rosenheim’s laboratory, UC Davis Department of Entomology. “It also suggests why certain areas and/or biotic regions may have more species than others.”

The research, titled “Sequential Sympatric Speciation Across Trophic Levels,” provides insight into what Forbes calls “the tangled bank of life.”

“As new species form, they create new opportunities for others to exploit which, in turn, begets ever more new species,” he said.

“And all this is happening right before our eyes in our own backyards.”

 Forbes captured excellent images of the apple maggot fly and wasp.  His image of a wasp emerging from an apple maggot pupa is particularly amazing. 

By Kathy Keatley Garvey
Author - Communications specialist

Attached Images:

IN THE LAB--UC Davis evolutionary ecologist Andrew Forbes works in the lab. His research on the apple maggot and a parasitic wasp will be published Feb. 6 in the journal Science. (Photo by Kathy Keatley Garvey)

Andrew Forbes

This is a male Diachasma alloeum wasp on an apple. (Photo by Andrew Forbes)

Parasitic Wasp

This is a female apple maggot fly (Rhagoletis pomonella) on the surface of an apple  (Photo by Andrew Forbes)

Apple Maggot Fly

A wasp, Diachasma alloeum, emerges from the puparium of an apple maggot. (Photo by Andrew Forbes)