2005 Teacher of the Year Announced; Delaware state butterfly
The butterflies' wings offer clues to speciation
Given our planet's rich biodiversity, "speciation" clearly happens regularly, but scientists cannot quite pinpoint the driving forces behind it.
Now, researchers studying a family of butterflies think they have witnessed a subtle process, which could be forcing a wedge between newly formed species.
These wing colours apparently evolved as a sort of "team strip", allowing butterflies to easily identify the species of a potential mate.
| For me, this is a big discovery just because the system is very beautiful |
Dr Nikolai Kandul, Harvard University
Although scientists have speculated about this mechanism for years, it has rarely been witnessed in nature.
"The phenomenon of reinforcement is one of the very few mechanisms that has natural selection playing a role in speciation," said Harvard co-author Nikolai Kandul. "It might be very widespread but it is hard to find good evidence of it."
For speciation to occur, two branches of the same species must stop breeding with one another for long enough to grow apart genetically.
The butterflies choose mates with similar markingsThe most obvious way this can happen is through geographical isolation.
But geographical isolation is not enough to explain all speciation. Clearly, organisms do sometimes speciate even if there is no clear river or mountain separating them.
The other mechanism that can theoretically divide a species is "reproductive isolation". This occurs when organisms are not separated physically, but "choose" not to breed with each other thereby causing genetic isolation, which amounts to the same thing.
Reproductive isolation is much hazier and more difficult to pin down than geographic isolation, which is why biologists are so excited about this family of butterflies.
The Harvard team made the discovery while studying the butterfly genus Agrodiaetus , which has a wide ranging habitat in Asia.
The females are brown while the males exhibit a variety of wing colours ranging from silver and blue to brown.
Dr Kandul and his colleagues found that if closely related species of Agrodiaetus are geographically separate, they tend to look quite similar. That is to say, they do not display a distinctive "team strip".
Scientists are excited about this new research
This has the effect of discouraging inter-species mating, thus encouraging genetic isolation and species divergence.
"This butterfly study presents evidence that the differences in the male's wing colouration is stronger [when the species share a habitat] than [when they do not]," said the speciation expert Axel Meyer, from Konstanz University in Germany.
"This pattern would therefore support the interpretation that it was brought about by reinforcement, hence natural selection."
The reason evolution favours the emergence of a "team strip" in related species, or sub species, living side-by-side is that hybridisation is not usually a desirable thing.
Although many of the Agrodiaetus species are close enough genetically to breed, their hybrid offspring tend to be rather weedy and less likely to thrive.
Therefore natural selection will favour ways of distinguishing the species, which is why the clear markings exist.
"For me, this is a big discovery just because the system is very beautiful," said Dr Kandul. "As much as we can we are showing that [reinforcement] is the most likely mechanism."
This research was published in the latest edition of Nature magazine.
| BUTTERFLY SIGNS: The insect, seen here in a Washington, N.J., butterfly garden, is a good indicator of various environmental conditions.|
JOE GILL/THE EXPRESS-TIMES/AP
If it succeeds, the United States will have in place a biological gauge to measure everything from the health of prairies to changing weather patterns. It will also be following in the footsteps of Canada and Mexico, which already have butterfly databases.
"People think these are dusty old things," Dr. Miller says. "But there is a lot of information locked in these collections."
For example, many butterfly species rely on one family of plants for survival. Often, these plants are found only in a particular habitat (such as prairie or tropical rain forest), and in a certain temperature range. So by tracking the butterfly population in a certain area, scientist can tell, for example, that the tall-grass prairie is quickly disappearing from a broad swath of North America. Or that the long-term weather patterns in an area have shifted over several decades.
"My family really thought I needed to get out more, so I did an Internet search for volunteering and gardening, and I found the butterfly garden," said Chappelle, 36, who is communications coordinator for the Organization for Educational Technology and Curriculum in Wilsonville.
Chappelle works with two other volunteers, Pat Sharp and Marilyn Allen, and has been pruning, weeding and planting in the garden since February. The butterfly garden is a popular spot in the 79-acre regional park, which is owned and operated by Tigard.
The busiest time for the volunteers is spring, when they often work four hours a week to maintain the flowers and plants that attract butterflies. Volunteers spend about two hours a week in the garden during the summer, and in February, Chappelle stopped by once every two weeks to rake and prune.
Her other responsibilities include labeling plants and researching plant species that attract butterflies or repel pests such as mosquitoes.
Chappelle says the results drive her gardening efforts. "I can be a little obsessive-compulsive about it. The end result is always worth it for me, even if I have a sore back for three days. I enjoy a yard that just looks good and has nice colors. Twenty percent of my motivation is hoping that others will appreciate it visually, too." -- Skipp Thomsen
Hershey Garden's Butterfly Festival will take place from 10 a.m. to 1 p.m. on Saturday, July 23, rain or shine. The celebration will take place in and around the Children's Garden and the Butterfly House at Hershey Gardens. It is included in general admission price.
It's a unique place," John Fortino, Butterfly House coordinator, said. "When it was built, there were less than 10 houses. Today there are [almost] 30."
The original structure was a greenhouse built by Milton Hershey in 1930. It was later moved to various venues until it was repurchased by the Gardens. The glass of the house was later removed and replaced with a mesh covering.
One might confess to not being a nature lover. However, Fortino insists that there is something for everyone at the Butterfly House.
"Some guys come into the Butterfly House and look like they have been dragged along by a girlfriend or wife," he said. "But then they really enjoy it and their eyes just light up."
The entire life cycle of a butterfly can be viewed inside the structure. At the entrance, a box of chrysalises hangs on the wall and visitors can watch the insects as they emerge from their protective covering. The chrysalises are purchased and adhered to the case using, surprisingly, Elmer's glue.
"It gets annoying when people call them cocoons," Fortino said. "They're called chrysalises. Cocoons are for moths."
The average life span of a butterfly is 10 to 17 days so chrysalises are consistently being purchased to stock the house's 300-butterfly capacity.
"When people walk through, it's a new environment," Fortino said. "In nature, you're never going to encounter 300 butterflies in one place."
For educational purposes, plaques are posted throughout the house to explain the natural activities of a butterfly including the roosting stage where butterflies absorb shade in a nearby tree.
"A lot of people also go there to enjoy the quiet," Fortino explained. "Overall, there is a wide range of visitors."
For those who enjoy interactive experiences, butterflies will sometimes land on observers if the temperature is right, explaining the need for the sign and mirror near the door.
"Sometimes they'll go after body perspiration," Fortino explained. "But they're really looking for food or a mate. Sometimes they will think you are a plant, but when they realize you're not, they'll take off."
Serving as a butterfly landing spot is allowed, but deliberately handling the insects is prohibited, as grabbing hands can take a toll on the wings.
"People rub the wings and think it is dust. It isn't dust," Fortino said. "It's the scales on the wing, and if you rub the wrong way, you could damage the wings and the butterfly might not be able to fly."
To teach students, the Butterfly House is located near the Gardens' Education Center where three-part classes are given to school children detailing the life cycle and the difference between a butterfly and a moth and featuring a tour of the house.
"There's a lot to learn here," Fortino said. "I thought I knew a lot, but I'm still learning."
Aiding in the teaching process are several volunteers ranging in age from 14 to 82.
"Our volunteers are wonderful," Fortino said. "We don't choose them. They choose us."
Currently, the Butterfly House is home to 25 varieties of butterfly, including the newly- added Brazilian Heliconius Erato (Small Postman) butterfly. Last year, more than 120,000 people experienced the education that the house has to offer.
"If they don't learn anything about butterflies when they're here, I don't know where else they are going to learn about it," Fortino said.
For more information about admission prices and hours, contact the Hershey Gardens at 534-3492 or visit the Web site at www.HersheyGardens.org.
What makes the Maharashtra Nature Park truly remarkable is that it was once a municipal landfill site, buried under tons of garbage, and touching a creek reeling under effluent.
One of the nicer ways to spend a weekend this monsoon, if you like green spaces and don't mind getting a little wet, is to take a walk down a Maharashtra Nature Park trail. This park is right in the heart of the city — in fact, it stands cheek by jowl against the Dharavi slums, but the contrasts between the two worlds could not be greater.
You would have driven past it often enough, on the Sion-Dharavi Link Road that is perpetually locked in traffic snarls. A 37-acre plot with 27 acres as a functional nature park, a thick woodland with nearly 14,000 plants of about 300 varieties and 100 species of trees, including the baobab, of which there are barely 50 specimens in Mumbai.
You will also find 115 species of birds, both common ones such as cormorants, and other more elusive ones such as the Little Green Heron, which has been sighted at least twice, according to Sunjoy Monga's book Back to Nature, which was launched at the park recently.
What makes this park truly remarkable is that it was once a municipal landfill site, buried under tons of garbage, and touching a creek reeling under effluent. Then, in 1983, when the idea of the nature park first originated, the Mumbai Metropolitan Region Development Authority (MMRDA) approached World Wildlife Fund - India to oversee the rebirth of these grounds.
It was not a pleasant task, scraping through harmful garbage, and spreading soil over it; Dr Salim Ali, the well-known ornithologist, planted the first tree, and over the years, several thousand saplings were planted. The Maharashtra Nature Park was finally opened to the public on April 22, 1994 — Earth Day.
Amazingly, absolutely no artificial fertilisers or chemicals were used in the transformation. Instead, vermiculture programmes and rainwater harvesting have made all the difference.
The park has crossed another milestone this monsoon, with the launch of its rainwater harvesting project. Avinash Kubal, Deputy Director, says the project is designed to collect 22,500 kilolitres of rainwater, making it independent of the municipal water supply — an amount that would be enough for the daily needs of 250 families. The water collected from the project will be stored in an open pond, encouraging water birds and aquatic plants, and providing a backdrop for the Rain Education Centre.
Today, when an average of 150-200 people visit the park on weekends, it's hard to believe this was once a smelly, uninhabitable municipal landfill site. Instead, there are nature trails, butterfly walks, bird-watching, treasure hunts, plant shows, and many other activities.