selective
method of breeding that allows only those
breeding
individual organisms with desired characteristics
that are chosen to produce the next generation
cross
Breeding animals from different varieties to produce
breeding
a breed with traits of both parents
Directions: Read the article all the way through the first time. The second time, go
back and highlight the evidence or main facts from the articles that you can use to support
your argumentative paper for your morphed animal. Make notes in the margins that help
support your thesis for why your hybrid species should be cross breed.
Evolution Revolution: Two Species
Become One, Study Says
James Owen
for National Geographic News
July 27, 2005
A newfound insect shows that two species can combine to create a third
species, and that humans may be unknowingly encouraging evolution,
according to researchers.
Most new animal species are believed to arise when a single species splits into
two. But new animals can also be created when two species come together to
create a single new species, the researchers say.
This two-become-one evolutionary process, common among plants, has long been
considered extremely rare and unimportant among animals. The new study, based
on a fly species found in the northeastern United States, suggests otherwise.
The Lonicera fly evolved as a hybrid of two existing U.S. species, the blueberry
maggot and the snowberry maggot, according to the study. The newfound species
is named after the honeysuckle plant (scientific name: Lonicera), which the insect's
life cycle revolves around.
Humans may have indirectly "caused" the new species by introducing an Asian
honeysuckle species to North America.
The fly began as a hybrid. A hybrid is a type of animal that is created from the
mating of two other species. Mules, for example, are donkey-horse hybrids, but
they can't breed with each other. Hybrids that aren't sterile may have the
opportunity to become a full-blown new species.
For this to happen, the hybrid requires a distinct niche where it can evolve
separately from its two parent species. For the Lonicera fly, the alien honeysuckle
plant provided that niche.
As a result, the fly provides the first evidence that two different animal species can
interbreed and evolve into a new, distinct animal if their hybrid moves to a new
habitat, the study suggests.
Conducted by researchers from Pennsylvania State University's entomology
department, the study will be reported tomorrow in the journal Nature.
DNA Analysis
The team established the insect's hybrid origins through detailed DNA
"fingerprinting" techniques.
Many other animals, particularly parasitic insects whose life cycles depend on a
particular host plant, may also have arisen through hybridization, says the study's
lead author, evolutionary ecologist Dietmar Schwarz. The difficulty, he says, is in
detecting this method of evolution.
"The problem is detection, which requires extensive genetic studies," Schwarz said.
"In animals there has been so far only limited information on this mode of
speciation."
George Turner is a professor of evolutionary biology and biodiversity at the
University of Hull in England. He agrees that animal evolution through hybridization
may be much more widespread than previously believed.
As DNA analysis of different species becomes more sophisticated and extensive,
he expects other examples to emerge.
"I think this kind of speciation is most likely in animals were there are lots of similar,
fast-evolving species, such as in certain types of insects and fish," he added.
Fish Hybrids
Turner says recent evidence indicates that some fish species also evolved as
hybrids.
German researchers have studied cichlids (a type of tropical freshwater fish) living
in tiny volcano-crater lakes in Cameroon, West Africa. Their studies have shown
that at least one cichlid species started off as a hybrid.
Among cichlids this process likely takes thousands of years. The Lonicera fly's
evolution, however, has occurred only in the 250 years since its honeysuckle host
plant arrived in North America.
The introduction, via humans, of non-native species makes speciation through
hybridization more likely, says Schwarz, the Penn State ecologist.
"On the one hand, introduced organisms provide new habitats," he said. "On the
other, one could imagine that introducing a parasite that is closely related to a
native species could lead to hybridization and, as a consequence, to the formation
of new [species] that might be able to utilize a previously unused host."
"Evolution hasn't ended," George Turner added. "New species are evolving, and
humans can have a big influence on that process."
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