Deforestation in New Zealand is 'causing insects to evolve rapidly', study finds
Insects in New Zealand are evolving rapidly in response to deforestation, a study has shown.
Researchers at the University of Otago found that previously winged insects were evolving to become flightless.
Surprisingly, the changes are taking place over hundreds of years – rather than millennia.
The researchers believe that the insects are evolving to lose their wings, due to increased exposure to wind after the loss of shelter from the trees.
The research compared insect populations around the alpine ‘treeline’ in both forested and cleared sites, and found that recent loss of forest has increased the distribution of flightless insects that were formerly limited to alpine grassland ecosystems.
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PhD student Brodie Foster said: "Over a short period of just a few hundred years the study has found that many previously winged populations have evolved to become flightless."
The Otago team focused on the endemic Zelandoperla stonefly species that frequently have flightless populations in mountainous regions, but typically have flighted populations in lower forested regions.
The researchers also found wingless populations occurring at much lower elevations in recently deforested areas.
Genetic analysis revealed little difference between winged and flightless populations in these deforested areas, confirming that loss of flight has evolved very rapidly.
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Study co-author Dr Graham McCulloch, who led the genetic analysis, said that due to the loss of forest cover, native insect species were increasingly vulnerable to exposure and had evolved flight-loss as a strategy to cope with these windy conditions.
Human expansion has drastically shifted the balance of many ecosystems across the globe.
How wild populations will continue to adapt and evolve to sudden changes such as deforestation remains largely unknown.
Traditionally, evolutionary biologists think about change occurring over many millennia, whereas this study has found significant change taking place over a timescale of centuries.
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However, Dr McCulloch points out that while the study has shown the ability of these populations to adapt rapidly to environmental changes, it has also highlighted the increased vulnerability of these insects to local extinction as they become more isolated.
Dr McCulloch said: "While most of our flying insect species seem relatively secure, isolated flightless populations are potentially more vulnerable, as is also the case for our native birds."
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