Adapting to a Warming Climate
Posted: Thu Mar 04, 2010 7:44 pm
Last night I attended the Royal Entomological Society annual Verrall Lectures and Supper at the Natural History Museum.
Professor Chris Thomas gave a very interesting lecture outlining how certain British butterflies are adapting (and even evolving) to deal with a changing climate far faster than could have been predicted even a little as ten years ago. It was fascinating stuff, backed up by research and studies that were hot off the press.
Of particular note was a study of the Brown Argus butterfly: This species has historically used Common Rock Rose (Helianthemum nummularium) as a larval host plant, and it was always considered that the northerly movement of this species would be limited by the distribution of larval food plant, which peters out north of the Southern counties, becoming widely distributed again further North. Conventional thinking was that the species would have (at best) extremely limited ability to bridge the gap to the northern counties because of the absence of larval host plant.
This species has historically also been recorded to have used Cranesbills (geranium) as larval food plant, but almost always choosing to lay upon H. nummularium.
It has been discovered however, that in the last decade the Brown Argus has expanded northward at a pace that could not have been predicted, as it is using Doves Foot Cranesbill (Geranium molle) (an opportunist annual plant of disturbed ground, field margins etc.) as a larval host plant.
Furthermore, experiments with both 'old' and 'new' colonies have revealed startling results: When females from old long established colonies are presented with both H. nummularium and G. molle as plants upon which to oviposit (under controlled conditions), in almost every instance the female chooses H. nummularium. However, females from 'new' colonies when presented with the same options almost always choose to oviposit upon G. molle.
Thus the butterfly has quickly (very quickly) adapted to be able to exploit the opportunity that a warming climate has presented for a northerly migration of the species from the southern counties.
Similar examples were provided with other species.
Of particular interest also was the changing habitat requirements for species whose optimum environment (particularly for oviposition) had been thought to have been set in stone. Such species (Silver Spotted Skipper being a prime example) have actually been shown to decline rapidly where land management practises are in line with conventional thinking, i.e. to provide habitat that was previously considered to be optimum for the species (closely cropped, steep south facing down land with plenty of bare ground in the case of the S. S. Skipper).
Research has shown that in these situations the species is now seeking shaded areas (even relatively dense cover) in which to lay because the open down has actually become too hot for successful larval development.
It would seem that current management practises eschewed by local wildlife trusts and other conservation bodies for several species (the Duke springs to mind) are already somewhat out of date and potentially detrimental to the species rather than being beneficial. In the case of the Duke, it is possible that the species shall continue to seek even shadier environments in which to oviposit in order to ensure that the larvae have the necessary microclimate (particularly humidity) to ensure successful development.
If only there was some way in which this information could be quickly and efficiently disseminated to those folk 'on the ground' who make the decisions regarding habitat management.
Felix
Professor Chris Thomas gave a very interesting lecture outlining how certain British butterflies are adapting (and even evolving) to deal with a changing climate far faster than could have been predicted even a little as ten years ago. It was fascinating stuff, backed up by research and studies that were hot off the press.
Of particular note was a study of the Brown Argus butterfly: This species has historically used Common Rock Rose (Helianthemum nummularium) as a larval host plant, and it was always considered that the northerly movement of this species would be limited by the distribution of larval food plant, which peters out north of the Southern counties, becoming widely distributed again further North. Conventional thinking was that the species would have (at best) extremely limited ability to bridge the gap to the northern counties because of the absence of larval host plant.
This species has historically also been recorded to have used Cranesbills (geranium) as larval food plant, but almost always choosing to lay upon H. nummularium.
It has been discovered however, that in the last decade the Brown Argus has expanded northward at a pace that could not have been predicted, as it is using Doves Foot Cranesbill (Geranium molle) (an opportunist annual plant of disturbed ground, field margins etc.) as a larval host plant.
Furthermore, experiments with both 'old' and 'new' colonies have revealed startling results: When females from old long established colonies are presented with both H. nummularium and G. molle as plants upon which to oviposit (under controlled conditions), in almost every instance the female chooses H. nummularium. However, females from 'new' colonies when presented with the same options almost always choose to oviposit upon G. molle.
Thus the butterfly has quickly (very quickly) adapted to be able to exploit the opportunity that a warming climate has presented for a northerly migration of the species from the southern counties.
Similar examples were provided with other species.
Of particular interest also was the changing habitat requirements for species whose optimum environment (particularly for oviposition) had been thought to have been set in stone. Such species (Silver Spotted Skipper being a prime example) have actually been shown to decline rapidly where land management practises are in line with conventional thinking, i.e. to provide habitat that was previously considered to be optimum for the species (closely cropped, steep south facing down land with plenty of bare ground in the case of the S. S. Skipper).
Research has shown that in these situations the species is now seeking shaded areas (even relatively dense cover) in which to lay because the open down has actually become too hot for successful larval development.
It would seem that current management practises eschewed by local wildlife trusts and other conservation bodies for several species (the Duke springs to mind) are already somewhat out of date and potentially detrimental to the species rather than being beneficial. In the case of the Duke, it is possible that the species shall continue to seek even shadier environments in which to oviposit in order to ensure that the larvae have the necessary microclimate (particularly humidity) to ensure successful development.
If only there was some way in which this information could be quickly and efficiently disseminated to those folk 'on the ground' who make the decisions regarding habitat management.
Felix