Thursday, 24 April 2014

Great Prominent map

Following on from Isabel's Cilycwm Great Prom, here's a map of where the species has been caught in Carmarthenshire. It's impressively northern, though the lack of recent records from the Teifi Valley (4 small dots indicate pre-2000 records) suggests that north-south is not the only factor at play.

9 comments:

  1. Your nickname must be `Psychic Sam`, as I was going to ask if you could kindly prepare a map - thanks!....yes, very northern.

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  2. I can't figure out this moth's distribution at all. In most of southern England it is a lowland species (I used to catch plenty of them in oak woodland in Berkshire) but in Wales it misses out Glamorgan as well as southern Gwent and Carms, but is widespread in mid Wales. There's no shortage of oak in the north Cardiff woods so why isn't it there? Odd.

    George

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  3. George. I`ve not long got out of bed, thinking about what the great prominent UK distribution map looks like. I`d expected a northern and western upland oakwood species that reaches its southern distribution boundary in N Carms. However, when I looked - just 5 mins ago- at the Atlas map, I noted that it was exactly as you said (I`ve only seen your blog now).
    With the great prominent, there are the classic `S and SE England` populations, but also the more localised western British ones. I`ve got a pet theory that many peculiar Brit Isles distributions are more logical when you consider colonisation by more than the one dominant SE/E Eng route/s ie, in this case via the west. DNA analysis is certainly showing two or more races of taxa of certain spp (eg pine marten, house spiders, certain plants etc etc) and I speculate whether something more complex happened here too. Human genetics and palynological data certainly shows a western colonisation route, and some moth peculiarities (Ashworth`s rustic, Weaver`s wave, Silurian, the grey....silky wave (and the other western limestone suite of rare taxa, moth and non-moth, including plants).....and, eg brown hairstreak, plus a lot of more obscure inverts) perhaps make more sense when a western colonisastion route is invoked. Incidentally, I don`t for one second believe any the human introduction `tosh` that is suggested for the survival of the distinctive Irish assemblage. They would have either survived the Ice Age or colonised very quickly afterwards.When people can`t explain a distribution they invoke `introduction`, but introduced species are usually `weedy` and successful and not localised, unless there particular life style limitations (eg temperature controls re stick insects). I`ll stop now, as this is too big a topic for the moth blog and I want breakfast!

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  4. I forgot to add that the UK distribution MAY be aggregated one of two genetic populations, one which entered the British Isles along the coastal seaboard and a later colonisation via the SE.

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  5. That's certainly an interesting explanation for it Ian! It did occur in Glamorgan in the past though, but could perhaps have been lost when mixed/oak woodlands were replaced with conifers?

    You'd also need to account for the isolated populations in northern England and southern Scotland - a long way from other known sites for what is probably a sedentary species.

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  6. Regarding your first point (re non-persistence of the species in vc41), I would have thought there were still (eg) upland Coalfield woods which were n`t coniferised?
    It`s often speculative to ponder why `species x` occurs somewhere, unless one of the adaptable widespread spp, as I`ll be the first to suggest. Perhaps the N Eng/S Scotland populations were also colonised from the west or surviving from wider past distributions. As I said, my speculation. However, consider `west coasts colonisations` as well as via the classic Dover Straits option, to possibly explain some peculiar distributions; also consider the possibility of more than one different genetic populations of certain species.

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  7. Regarding your first point (re non-persistence of the species in vc41), I would have thought there were still (eg) upland Coalfield woods which were n`t coniferised?
    It`s often speculative to ponder why `species x` occurs somewhere, unless one of the adaptable widespread spp, as I`ll be the first to suggest. Perhaps the N Eng/S Scotland populations were also colonised from the west or surviving from wider past distributions. As I said, my speculation. However, consider `west coasts colonisations` as well as via the classic Dover Straits option, to possibly explain some peculiar distributions; also consider the possibility of more than one different genetic populations of certain species.

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  8. Yes it's all speculation of course, but it's fun isn't it.

    You're right that there are still upland and upland fringe oak woods in Glamorgan so its absence is still a puzzle, even if there is a "western upland oakwood" genetic strain. I suppose it could still be out there in the less well recorded north of the county, especially as the more upland sites tend not to be trapped so often in the spring.

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