all Naomi Pierce stories

Forests, reefs, mountaintop illuminate tropical biology

404132862 — Tue, 16 Oct 2007 12:30:43 -0400

Morning came in the middle of the night in the hikers’ hut partway up the side of Borneo’s towering Mount Kinabalu.

At 2 a.m., after just a few hours’ sleep, the Harvard Summer School students slowly roused themselves, creating a chorus of rustling sleeping bags, zippers, and boots on the wooden floor.

They’d been on the go for weeks, traveling across the island to sample its natural wonders, and they’d be on the go for a few weeks more. But where they’d been and where they’d be didn’t matter that morning. It was time to hike. The sun was coming and the peak was still hours away.

First orchid fossil puts showy blooms at some 80 million years old

50443248 — Mon, 01 Oct 2007 16:27:21 -0400

Biologists at Harvard University have identified the ancient fossilized remains of a pollen-bearing bee as the first hint of orchids in the fossil record, a find they say suggests orchids are old enough to have coexisted with dinosaurs.

Their analysis, published this week (Aug. 29) in the journal Nature, indicates orchids arose some 76 to 84 million years ago, much longer ago than many scientists had estimated. The extinct bee they studied, preserved in amber with a mass of orchid pollen on its back, represents some of the only direct evidence of pollination in the fossil record.

Ants are surprisingly ancient, arising 140-168 million years ago

70652986 — Mon, 26 Mar 2007 06:26:16 -0400

Ants are considerably older than previously believed, having originated 140 million to 168 million years ago, according to new Harvard University research published in the journal Science. But these resilient insects, now found in terrestrial ecosystems the world over, apparently only began to diversify about 100 million years ago in concert with the flowering plants, Harvard scientists say.

Led by Corrie S. Moreau and Naomi E. Pierce, the researchers reconstructed the ant family tree using DNA sequencing of six genes from 139 representative ant genera, encompassing 19 of 20 ant subfamilies around the world.

"Ants are a dominant feature of nearly all terrestrial ecosystems, and yet we know surprisingly little about their evolutionary history: the major groupings of ants, how they are related to each other, and when and how they arose," says Moreau, a graduate student in Harvard's Department of Organismic and Evolutionary Biology. "This work provides a clear picture of how this extraordinarily dominant - in ecological terms - and successful - in evolutionary terms - group of insects originated and diversified."

Moreau, Pierce, and colleagues used a "molecular clock" calibrated with 43 fossils distributed throughout the ant family tree to date key events in the evolution of ants, providing a well- supported estimate for the age of modern lineages. Their conclusion that modern-day ants arose 140 million to 168 million years ago pushes back the origin of ants at least 40 million years earlier than had previously been believed based on estimates from the fossil record.

Wing color not just for looks

70652986 — Mon, 26 Mar 2007 05:41:13 -0400

Harvard and Russian researchers have documented natural selection's role in the creation of new species through a process called reinforcement, where butterfly wing colors differ enough to avoid confusion with other species at mating time, helping the butterflies avoid creating less-fit hybrid offspring.

Though more distantly related species tend to be more physically distinct, researchers found this was not the case with species of the blue butterfly Agrodiaetus, found in a broad swath across much of Central Asia and Europe. Researchers found instead that species that might be expected to have the most trouble telling each other apart had the greatest differences in wing color.

That meant that newly diverged species living in the same area that could still mate and have hybrid young had more distinctive wing colors than other closely-related species that had diverged at an earlier time, as well as those living in different areas from each other.

Hessel Professor of Biology Naomi Pierce said a critical factor in this research is the fact that the butterflies are still closely related enough that they can - and sometimes do - interbreed. The hybrids created by this interbreeding, however, are less fit than the parents. That makes it advantageous for parents to ensure more offspring will survive by developing distinguishing characteristics, such as male wing color, and thereby avoiding the costly mistake of mating outside their own species.

"The fact that the hybrids are less viable drives the divergence between the parent species," Pierce said. "Wing colors must be one of the first traits the butterflies use to recognize the right mate."

The research was published in the July 21, 2005 issue of the journal Nature.