Walking sticks mimic two leafy looks and split their species. (Biology).A species of walking stick walking stick or stick insect, names applied to extremely longbodied, slow-moving, herbivorous insects, forming a single family in the order Phasmatodea. Walking sticks have green, gray, or brown bodies that closely resemble twigs or grass stems. Most are wingless and have long antennae. They range from less than 1 in. to over 1 ft (2–33 cm) in length, thus including the longest insects in the world., an insect that pretends it's part of a plant, may be evolving into two species by adapting to different environments. The insect, Timena cristinae, seems to be adapting so that it can hide on either of two species of plants. By doing so, it's probably morphing Plotting the Points The prominent points of both the before and after images are marked in Gryphon's Morph software, which computes all the in-between stages. (Image courtesy of Gryphon Software Corporation.)     into two separate species, says Cristina Sandoval of the University of California, Santa Barbara. Such a process of parallel evolution fits into basic theories of natural selection but few scientists have documented real cases, Sandoval and her colleagues at Simon Fraser University Simon Fraser University, main campus at Burnaby, British Columbia, Canada; provincially supported; coeducational; chartered 1963, opened 1965. The Harbour Centre campus in downtown Vancouver opened in 1989. Simon Fraser has faculties of arts, sciences, applied sciences, business administration, education, and graduate studies. in Burnaby, Canada, say in the May 23 Nature. The stickleback stickleback, common name for members of the family Gasterosteidae, small fishes, widely distributed in both fresh- and saltwaters of the Northern Hemisphere. Sticklebacks range from 1 1-2 to 4 in. (3.7–10 cm) in length and lack true scales; they are equipped with short, strong spines in front of the dorsal and on the ventral fins, the number varying with the species. fish in North America are the other clear example, they say. The walking stick, named for Sandoval, comes in two genetically determined color patterns--with or without stripes. In California's Santa Ynez Mountains, the striped insects tend to be more common on a plant called chamise while the unstriped ones predominate on blue lilac lilac, any plant of the genus Syringa, deciduous Old World shrubs or small trees of the family Oleaceae (olive family), widely cultivated as ornamentals. Since colonial days, the common lilac has been in America one of the best loved of the flowering shrubs, meriting its favor by its cone-shaped masses of lavender or white flowers, its fragrance, and its ease of cultivation. Some cities (e.g., Rochester, N.Y.) have lilac festivals.. Lizards and birds zestily eat walking sticks of either pattern, so camouflage offers a big advantage. The researchers found that each form of the insect was more likely to blend into the foliage when on its preferred plant species. Mating tests in the lab showed that each insect type preferred mating with one of its own color pattern. "This is an example of speciation speciation /spe·ci·a·tion/ (spe?se-a´shun) the evolutionary formation of new species. spe·ci·a·tion (sp   sh in process," Sandoval says.--S.M.
|
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion