Re: Killer Cactus?
Posted: Thu Sep 10, 2015 10:35 pm
I entirely agree with Dave's points, and, as he has pointed out, points that were being made from the outset, it's just very sad that 'survival of the fittest' caught on so well, but I suppose that 'non-survival of some of the less fit' doesn't really have the same impact.
It's also risky to make assumptions that any trait has an absolute advantage especially when there were no records kept at the time the trait was first observed and subsequently. Not only because inevitably, well, that's a bit risky in itself - so let's say 'in all likelihood' - the conditions when the trait was established were not the same as today.
As for predation, i.e. killing, as a anti-herbivore mechanism I have my doubts. It seems to be that there are several more effective ones: deterrence (i.e. sharp pointy things); bad taste (usually bitter, often alkaloids); hiding - very high often and so on. It's impossible to know how the proto-mammals behaved but whether rodents or ungulates and equids it's very likely that they had the vestiges of learned behaviour - from the mother, the family group or the herd - and in such a situation deterrence is a far more effective strategy: deter one, then another, then the offspring then the rest of the herd will avoid the plant, but killing means that the killed cannot pass on the "don't eat that plant" message.
Finally as for sheep-killing Puyas; I have to ask are there examples of the local camelids being killed ? Or the local rodents ? Or the native sheep ? Or is it just the bred for meat and wool essentially European sheep (also seemingly bred for lack of intelligence - or so some would claim) ?
graham
It's also risky to make assumptions that any trait has an absolute advantage especially when there were no records kept at the time the trait was first observed and subsequently. Not only because inevitably, well, that's a bit risky in itself - so let's say 'in all likelihood' - the conditions when the trait was established were not the same as today.
As for predation, i.e. killing, as a anti-herbivore mechanism I have my doubts. It seems to be that there are several more effective ones: deterrence (i.e. sharp pointy things); bad taste (usually bitter, often alkaloids); hiding - very high often and so on. It's impossible to know how the proto-mammals behaved but whether rodents or ungulates and equids it's very likely that they had the vestiges of learned behaviour - from the mother, the family group or the herd - and in such a situation deterrence is a far more effective strategy: deter one, then another, then the offspring then the rest of the herd will avoid the plant, but killing means that the killed cannot pass on the "don't eat that plant" message.
Finally as for sheep-killing Puyas; I have to ask are there examples of the local camelids being killed ? Or the local rodents ? Or the native sheep ? Or is it just the bred for meat and wool essentially European sheep (also seemingly bred for lack of intelligence - or so some would claim) ?
graham