Espece du Jour: Melanargia galathea
Sticking with the Lepidoptera for the moment, here's a question for pub quiz trivia/crapology buffs:
Which of these four British butterflies is the odd one out and why: Large White, Small White, Marbled White, and Green-veined White?
Three groups of British butterflies have got a 'colour name': the 'whites' (Pieridae), the 'blues' (Lycaenidae), and the 'browns' (Satyrinae, once a family in their own right but now apparently a subfamily of the Nymphalidae, which includes the big gaudy things like Peacock and Red Admiral). Most whites get dismissed as 'cabbage whites' (not a recognised species), and they are either Large, Small or Green-veined - all three species are common, at least as butterflies go.
The Marbled White, Melanargia galathea, is the odd one out since it is not a white at all. It is actually a brown, closely related to the Meadow Brown, Gatekeeper, Ringlet and suchlike. I photographed the one above this evening, as I strolled around some 'waste' land while my laundry was cycling, and I was amazed to get so passable a portrait of this attractive species. Butterflies are uncooperative subjects at the best of times, and this evening was not the best of times given the stiff breeze whipping the long grass about.
As with most of the browns, the larval foodplant of the Marbled White is grass. Particularly Red Fescue, apparently, which I know grows in abundance at the site where I took the picture. But the larvae will turn to other grasses, including Yorkshire Fog (also present there) and Tor Grass (which I haven't found there, not that I'd know it if I saw it). Other grasses may or may not be eaten, but the preference for Red Fescue does go to show that grass is not simply grass. There are many species of grass, each with its own place in the complex web of ecological relationships.
British butterflies are in trouble, and have been for decades. Numbers are falling, ranges contracting. And yet, with a warming climate, they ought to be doing well. I found a couple of pages online from the Centre for Ecology and Hydrology relating to butterfly distribution - and hence conservaion - in the UK. This one suggests that the potential benefits of climate change are offset by loss and fragmentation of habitat, while this one deals specifically with the Marbled White, particularly the role of deliberate translocation of populations outside of the natural range to new localities that have become suitable as the climate warms. The Marbled White is, as it happens, bucking the general trend where butterflies are concerned - its range is expanding. Once largely confined to the south of England, it has spread northwards as far as Yorkshire and can survive yet farther north, as the translocation project has demonstrated.
I also came across this PubMed abstract which touches on another theme I've harped on in the past, post-glacial range expansion and consequent speciation. Not that the Marbled White has diverged into a plethora or even a handful of species since the glaciers shrank, but a survey of populations in the Balkans suggests that genetically distinct varieties in that region are a result of glacial isolation. I think you'd need to know a bit about the geography of the region, or at least have an atlas to hand, to make sense of it. There are no firm conclusions, but it is hypothesised that the Marbled White in the Ice Age Balkans was pushed south to the Mediterranean coast, and then expanded its range northwards through three or more routes. Such canalisation is only to be expected in a mountainous region. Somewhere along the way, genetically distinct varieties emerged.
To be honest, I didn't get a lot out of the abstract, but I did at least learn a new word: refugium. I like it and want more opportunities to use it.
Which of these four British butterflies is the odd one out and why: Large White, Small White, Marbled White, and Green-veined White?
Three groups of British butterflies have got a 'colour name': the 'whites' (Pieridae), the 'blues' (Lycaenidae), and the 'browns' (Satyrinae, once a family in their own right but now apparently a subfamily of the Nymphalidae, which includes the big gaudy things like Peacock and Red Admiral). Most whites get dismissed as 'cabbage whites' (not a recognised species), and they are either Large, Small or Green-veined - all three species are common, at least as butterflies go.
The Marbled White, Melanargia galathea, is the odd one out since it is not a white at all. It is actually a brown, closely related to the Meadow Brown, Gatekeeper, Ringlet and suchlike. I photographed the one above this evening, as I strolled around some 'waste' land while my laundry was cycling, and I was amazed to get so passable a portrait of this attractive species. Butterflies are uncooperative subjects at the best of times, and this evening was not the best of times given the stiff breeze whipping the long grass about.
As with most of the browns, the larval foodplant of the Marbled White is grass. Particularly Red Fescue, apparently, which I know grows in abundance at the site where I took the picture. But the larvae will turn to other grasses, including Yorkshire Fog (also present there) and Tor Grass (which I haven't found there, not that I'd know it if I saw it). Other grasses may or may not be eaten, but the preference for Red Fescue does go to show that grass is not simply grass. There are many species of grass, each with its own place in the complex web of ecological relationships.
British butterflies are in trouble, and have been for decades. Numbers are falling, ranges contracting. And yet, with a warming climate, they ought to be doing well. I found a couple of pages online from the Centre for Ecology and Hydrology relating to butterfly distribution - and hence conservaion - in the UK. This one suggests that the potential benefits of climate change are offset by loss and fragmentation of habitat, while this one deals specifically with the Marbled White, particularly the role of deliberate translocation of populations outside of the natural range to new localities that have become suitable as the climate warms. The Marbled White is, as it happens, bucking the general trend where butterflies are concerned - its range is expanding. Once largely confined to the south of England, it has spread northwards as far as Yorkshire and can survive yet farther north, as the translocation project has demonstrated.
I also came across this PubMed abstract which touches on another theme I've harped on in the past, post-glacial range expansion and consequent speciation. Not that the Marbled White has diverged into a plethora or even a handful of species since the glaciers shrank, but a survey of populations in the Balkans suggests that genetically distinct varieties in that region are a result of glacial isolation. I think you'd need to know a bit about the geography of the region, or at least have an atlas to hand, to make sense of it. There are no firm conclusions, but it is hypothesised that the Marbled White in the Ice Age Balkans was pushed south to the Mediterranean coast, and then expanded its range northwards through three or more routes. Such canalisation is only to be expected in a mountainous region. Somewhere along the way, genetically distinct varieties emerged.
To be honest, I didn't get a lot out of the abstract, but I did at least learn a new word: refugium. I like it and want more opportunities to use it.