Dr. Florian Altermatt, an ecologist from the University of California at Davis reported his findings in the article “Climatic warming increases voltinism in European butterflies and moths” online on December 22, 2009, in the journal Proceedings of the Royal Society B.
Dr. Altermatt and three colleagues were collecting data for a research book when he came across this interesting bit of information.
In all, the four researchers found over 180,000 records from the year 1818 to the present (in museum records and publications) that described over 1,100 species of butterflies and moths around Basel, Switzerland.
Altermatt continued his separate study to make this startling discovery.
And, Altermatt analyzed the warming trend in the area from a weather station in Basel. He found that the mean annual temperature increased about 1.5 degrees since the 1980s--a small but significant temperature increase.
The abstract to Altermatt’s paper states, “Climate change is altering geographical ranges, population dynamics and phenologies of many organisms. For ectotherms, increased ambient temperatures frequently have direct consequences for metabolic rates, activity patterns and developmental rates. Consequently, in many insect species both an earlier beginning and prolongation of seasonal duration occurred in parallel with recent global warming. However, from an ecological and evolutionary perspective, the number of generations (voltinism) and investment into each generation may be even more important than seasonality, since an additional generation per unit time may accelerate population growth or adaptation.”
What is especially interesting is the fact that some of these species have never before (as long as records have been kept) produced an extra generation of offspring at locations in Central Europe.
Page two summarizes Dr. Altermatt's statistics on butterflies and moths in Central Europe.
In fact, 44 species (just over 16% of the 263 species) had added an extra generation during the summers (over the past three decades) for the first time on record.
Approximately one-third of all the species that Dr. Altermatt studied showed the capacity to breed more than once a year.
He states in his abstract, “A significant proportion of 263 multi-voltine species showed augmented frequency of second and subsequent generations relative to the first generation in a warm period since 1980, and 44 species even increased the number of generations after 1980.”
Altermatt, a professor at UC-Davis’ Department of Environmental Science and Policy, believes that the extra long warmth of summer is allowing the insects to start their breeding season earlier and to increase the ability of the offspring to develop quicker.
Both reasons, Altermatt speculates, allows at least one extra generation to be produced.
In the 12.24.2009 Science News article “Warming Has Already Boosted Insect Breeding,” it paraphrases Altermatt by saying “When creatures manage an extra generation in a year, evolutionary processes happen faster,”
However, he adds, “I can’t say if the generations were successful.” [Science News]
And, such enhanced breeding skills give the insects (possibly) better chances to adapt to a changing climate.
Page three concludes.
However, Altermatt does not predict that bettering of their adaption skills will be enough to overcome habitat loss or climate change that is coming more prevalent around the world.
Dr. Altermatt concludes in the abstract to his paper: “Expected ecological consequences are diverse. Since multi-voltinism has been linked to insect outbreaks they include an increase in the abundance of herbivorous pests of agriculture and forestry."
"However, disruption of the developmental synchrony associated with multi-voltinism and host plant phenology may also reduce fitness, potentially having unexpected consequences for species of conservation concern."
"The ability of species to adapt evolutionarily to a changing environment may be facilitated by increased voltinism" (that is, the ability to increase the number of generations of offspring produced each year).
The Science News article “Warming Has Already Boosted Insect Breeding” is also re-produced in the U.S. News and World Report website.