- News Home
27 November 2013 12:59 pm ,
Vol. 342 ,
The new head of the National Center for Science Education promises to "fight the good fight" against attacks on...
Analyses of the H7N9 strains isolated from four new cases show that the virus is evolving rapidly, heightening anxiety...
In 2009, Jack Szostak shared a Nobel Prize for his part in discovering the role of telomeres, the end bits of...
Science has exposed a thriving academic black market in China involving shady agencies, corrupt scientists, and...
Paper-selling agencies flourish in the aura of reputable businesses. For some scientists, it may be difficult to tell...
Featuring the first lunar rover in 40 years, Chang'e-3 is seen as an important milestone on China's quest to send a...
Data collected by satellites and floating probes have chronicled a 2-decade rise in the temperature and thickness of a...
Cholesterol, the artery-clogging molecule that contributes to cardiovascular disease, has another nasty trick up its...
- 27 November 2013 12:59 pm , Vol. 342 , #6162
- About Us
Speciation in Place
8 February 2006 (All day)
Kentia palms live on an island in the South Pacific, yet some of them somehow evolved--right there in the same gene pool--into the curly palm. Likewise, the Arrow cichlid fish of Nicaragua evolved as a sister species to the Midas cichlid without any physical barrier to gene flow. These unusual cases, described online 8 February in Nature, help bolster support for a controversial idea called sympatric speciation: speciation that occurs without geographic isolation.
Typically, one species splits into two new species only when some of its members wind up isolated in a different location. Many theorists have predicted that sympatric speciation is also possible, but the phenomenon has been difficult to prove. Now there are two case studies.
Axel Meyer, an evolutionary biologist at the University of Konstanz in Germany, visited an isolated 5-kilometer-wide crater lake in Nicaragua. Early in its 23,000-year history, the lake was settled by the Midas cichlid. When the team compared its mitochondrial DNA and other genes to those of an endemic fish called the Arrow cichlid, they found that the Arrow cichlid--which evolved from the Midas cichlid fewer than 10,000 years ago--was different enough to warrant its current status as a separate species. There were other signs that the fishes had gone their separate ways: One is a bottom feeder whereas the other isn't, and they can't interbreed successfully. Meyer thinks this sympatric speciation may underlie at least some of the hard-to-explain vast diversity of African cichlids.
Vincent Savolainen and William Baker of the Royal Botanic Gardens, Kew, in Richmond, U.K., went to Lord Howe Island in the Pacific Ocean--a 12-square-kilometer speck of volcanic rock, 580 kilometers east of Australia. They and colleagues built a DNA-based family tree that included the two palms. They found that the curly palm descended from the Kentia palm (a common houseplant) about 1 million to 2 million years ago. Although the two species coexist in 20% of the sites surveyed, they flower 6 weeks apart. Kentia palms thrive in basic soil, whereas curly palms stick to acidic soils. Savolainen and his colleagues suggest that as the Kentia palm spread into different soils, flowering time was delayed, possibly because the genes needed to adapt to the altered pH affected the transmission of those involved in flowering. Eventually, plants in basic soil could no longer pollinate trees in acidic soil and vice versa.
"These papers are important because they are very convincing, and they are timely," says Giacomo Bernardi, an evolutionary biologist at the University of California, Santa Cruz. Now evolutionary biologists have real data with which to evaluate theoretical models of this process. Indeed, adds Jeffrey Feder, an evolutionary biologist at the University of Notre Dame in Indiana, sympatric speciation “may not be as uncommon as some presume."