Washington: By studying two species of butterfly, University of Notre Dame researchers have found evidence of how some species respond to global warming.
Dr. Jessica Hellmann and her team have conducted a series of studies in which manipulating the temperature of the butterfly larvae''s environment revealed how the two species might respond to global warming.
The Notre Dame team studied the larvae-or caterpillar phase-of two butterfly species, the Propertius duskywing butterfly (Erynnis propertius) and the Anise swallowtail butterfly (Papilio zelicaon).
The duskywing is a small butterfly that does not easily fly great distances -keeping genetic makeup of the group limited.
The species is also characterized by the fact that its larvae consume only the new leaves of oak trees, making it highly specialized.
The Anise swallowtail, on the other hand, is a much larger butterfly, and can fly greater distances with greater ease. Its genes are more likely to be spread out over a larger range.
The team theorized that northern members of a species whose genes are more spread out, like the swallowtail’s, might be pre-adapted to rising temperatures and could perhaps even thrive as the northern climate gets warmer.
Conversely, species like the duskytail, whose genes are not as spread out, could be locally adapted to climatic conditions at the edge of the range and northern populations might reduce under climate change.
"In summer conditions, the duskywing larvae grew bigger, faster, and they survived better, which suggested that they liked it warmer, but winter was another story," said Hellmann.
"In the warmer winter, they increased metabolism and burned through energy faster. This suggests that they were adapted to the cooler winters of Vancouver," she added.
As for northern swallowtails in central conditions, "They just didn’t care," said Hellmann.
"They didn’t respond to warming at all. They didn’t do better or worse," she added.
The team has begun studying the genetic explanation for how the two species respond to warming.
"Expecting creatures to pick up and move north makes sense theoretically," said Hellmann.
"But the reality is that genetic and physiological interactions are so complicated, it’s hard to imagine how it will play out for all species everywhere," she added.
First Published: Friday, August 06, 2010, 14:05