It's probably obvious that I'm no great shakes at biology. Still, I've got a very good friend who's an entomologist, and to whom I go with biological questions (which makes for some rather long waits occasionally, as he's frequently travelling, to conferences or to give lectures)
So I went to him for an example of observed speciation (one population developing characteristics which classify it as a different species from its parent group) Considering time intervals involved, I was expecting this to be among micro-organisms that can get through many, many generations in a year. The one I received was from his speciality, insects.
Chris has, for the last thirty years or so, been specialised in bugs ((not a generic term for creepy-crawlies, Hemitera, with beetle-like characteristics and sucking mouthparts.) The Triatominae are biggish (cockroach size) bloodsuckers, and they are widely distributed in Latin America, and in the southernmost regions of the USA (they don't like cold weather) In addition, there are seven species in south east Asia, particularly Indonesia.
Convergent evolution? After all, bloodsucking is a popular means of feeding. But genetic analysis, when people got round to it, showed the widely separated Asian species to be closely related to each other (odd, but could have occurred due to extinctions between the groups) and, odder yet, to a species in the south-eastern United States.
Similarity of form could be explained away by function; genetic clues, with more difficulty.
Now we leave scientific data, and move onto hypothesis; and the most likely means of transport for these bugs is aboard ships trading with the (then) Dutch east Indies; and for ships going direct, this had to have happened less than three hundred years ago. And yet we have not one, but seven new species. The argument given is that Darwinian natural selection is not the only possible mechanism for evolution. The population leaving the ship at any port of call was probably quite small, possibly only one gravid female, so the potential gene pool was much reduced. Inbreeding, and fixing of characteristics with no particular survival factor, is not merely probable, but inevitable; you either bred with a close relative, or not at all. The original "no predators, abundant resources" explosion would give way to sibling competition, and all siblings would be genetically very similar, with little to choose between them, and neutral factors could cause drift, separating them biologically from the parent population just as they'd been separated geographically.
Now, this is theory. It's possible that seven species of bug went extinct in Florida, and only the isolated colonies survived (occasionally infectious diseases can play tricks like that) It's even possible that continental drift models are wrong, and Indonesia was once attached to Cuba. But the way to bet is that, in less than three hundred years (that's only equivalent to recorded history for mankind, considerably less time than homo-sapiens has been around) these insects have developed seven, mutually infertile. visually distinct species. Maybe not "recorded" at the time, but very much observable now.
Chris has promised to give me references for papers describing the process (it might be a little while, I think his next conference is in Guatemala) but, if you think I'm difficult to understand, wait till you read these guys.
So I went to him for an example of observed speciation (one population developing characteristics which classify it as a different species from its parent group) Considering time intervals involved, I was expecting this to be among micro-organisms that can get through many, many generations in a year. The one I received was from his speciality, insects.
Chris has, for the last thirty years or so, been specialised in bugs ((not a generic term for creepy-crawlies, Hemitera, with beetle-like characteristics and sucking mouthparts.) The Triatominae are biggish (cockroach size) bloodsuckers, and they are widely distributed in Latin America, and in the southernmost regions of the USA (they don't like cold weather) In addition, there are seven species in south east Asia, particularly Indonesia.
Convergent evolution? After all, bloodsucking is a popular means of feeding. But genetic analysis, when people got round to it, showed the widely separated Asian species to be closely related to each other (odd, but could have occurred due to extinctions between the groups) and, odder yet, to a species in the south-eastern United States.
Similarity of form could be explained away by function; genetic clues, with more difficulty.
Now we leave scientific data, and move onto hypothesis; and the most likely means of transport for these bugs is aboard ships trading with the (then) Dutch east Indies; and for ships going direct, this had to have happened less than three hundred years ago. And yet we have not one, but seven new species. The argument given is that Darwinian natural selection is not the only possible mechanism for evolution. The population leaving the ship at any port of call was probably quite small, possibly only one gravid female, so the potential gene pool was much reduced. Inbreeding, and fixing of characteristics with no particular survival factor, is not merely probable, but inevitable; you either bred with a close relative, or not at all. The original "no predators, abundant resources" explosion would give way to sibling competition, and all siblings would be genetically very similar, with little to choose between them, and neutral factors could cause drift, separating them biologically from the parent population just as they'd been separated geographically.
Now, this is theory. It's possible that seven species of bug went extinct in Florida, and only the isolated colonies survived (occasionally infectious diseases can play tricks like that) It's even possible that continental drift models are wrong, and Indonesia was once attached to Cuba. But the way to bet is that, in less than three hundred years (that's only equivalent to recorded history for mankind, considerably less time than homo-sapiens has been around) these insects have developed seven, mutually infertile. visually distinct species. Maybe not "recorded" at the time, but very much observable now.
Chris has promised to give me references for papers describing the process (it might be a little while, I think his next conference is in Guatemala) but, if you think I'm difficult to understand, wait till you read these guys.
