tag:blogger.com,1999:blog-37148773.post2548835922766780885..comments2024-03-27T14:50:47.345-04:00Comments on <center>Sandwalk</center>: More Evidence of Short-term StasisLarry Moranhttp://www.blogger.com/profile/05756598746605455848noreply@blogger.comBlogger34125tag:blogger.com,1999:blog-37148773.post-26047634625891088742012-10-18T17:30:43.700-04:002012-10-18T17:30:43.700-04:00Larry, thank you. Fascinating. Ecological Successi...Larry, thank you. Fascinating. Ecological Succession reminds me of an ongoing experiment taking place in an area of Colombia called Gaviotas. They are reforesting a deforested area, gradually restoring it to rainforest like conditions, by beginning with the groundlaying plants. <br />The technique has turned out to be working more quickly there than even the scientists suspected it would. I think it's probably a fifty or sixty year old project at this point and various flora and fauna have already made their way back from the surviving rainforests in the region. andyboergerhttps://www.blogger.com/profile/11159573123843322700noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-44234424878342987422012-10-18T10:50:52.375-04:002012-10-18T10:50:52.375-04:00I think a large part of the concern about rising g...I think a large part of the concern about rising global temperatures is movement of organisms away from their usual habitat. They will become exposed to microorganisms which their immune systems are not familiar, and bring new microorganisms with which the endemic species are not familiar.Matt Ghttps://www.blogger.com/profile/07745943486966305844noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-7882328477000139042012-10-18T10:49:56.671-04:002012-10-18T10:49:56.671-04:00I'll post a quotation from Richard Dawkins tha...I'll post a quotation from Richard Dawkins that you can discuss.Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-66777381438179515332012-10-18T10:30:19.664-04:002012-10-18T10:30:19.664-04:00andybeorger asks,
Somewhat confused. Do plants al...andybeorger asks,<br /><br /><i>Somewhat confused. Do plants also have some form of habitat tracking? </i><br /><br />Yes, of course. In fact the habitat tracking of plants is the paradigm for the entire phenomenon.<br /><br />We are seeing it right now as the treeline moves north in Canada and all kinds of plants are spreading into the valleys left by former glaciers. There's an entire subsection of ecology devoted to <a href="http://en.wikipedia.org/wiki/Ecological_succession" rel="nofollow">Ecological Succession</a>.Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-45946849382177636302012-10-18T10:00:04.671-04:002012-10-18T10:00:04.671-04:00There were some 50 glacial-interglacial cycles dur...There were some 50 glacial-interglacial cycles during the Pleistocene, weren't there? Adaptation to fluctuations sounds reasonable in such circumstances.Piotr Gąsiorowskihttps://www.blogger.com/profile/06339278493073512102noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-29987657395390384072012-10-18T08:55:45.758-04:002012-10-18T08:55:45.758-04:00Pedro, thanks.
I definitely see your last point i....Pedro, thanks.<br />I definitely see your last point i.e., "The apparent conflict seems more propense (is this a word?) to happen if you are thinking in adaptationist terms.", in which case it really does seem, to me at least, to actually BE a contradiction. <br />In terms of other causes for species diversification, particularly genetic drift, I confess I am still trying to work out in my head exactly how it works. <br />So, I'm still puzzling over it, but your answer does help me quite a bit.<br />andyboergerhttps://www.blogger.com/profile/11159573123843322700noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-18054715905976622532012-10-18T08:54:35.047-04:002012-10-18T08:54:35.047-04:00You'd be surprised how many professional biolo...You'd be surprised how many professional biologists of "renown" think exactely the same, so no worries.Pedronoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-19262188728347977912012-10-18T08:48:52.281-04:002012-10-18T08:48:52.281-04:00Andy wrote:
"But then, would they also move b...Andy wrote:<br />"But then, would they also move back again when the climate change restored itself?"<br /><br />Presumably, yes. In fact, there are many indications that the Amazon forest is still undergoing ecological succession from a few loci that are richer in biodiversity and that map well to what is thought was the spots that managed to "survive" the last Ice Age. The same can be said about much of the taiga in the northern latitudes, which also seem to be moving "north" and undergoing ecological succession since the last Ice Age.<br /><br />Andy wrote:<br />"It seems like the ones that had remained would be able to repel plants that tried to return"<br /><br />That, of course, is possible, but complicated to gauge in general terms. You have to take into account all the complexities of competition theory and look in practice at specific events to see what's happening. But there will certainly be some competition.<br /><br />Andy wrote:<br />"Still trying to make this fit with 'doing quite fine in their current environment' which seems to suggest diversification of life form as an exception rather than a rule"<br /><br />That depends. You have to consider that both the separation of small populations from a bigger one and genetic drift will allow nicelly for diversification to happen without any conflict with "doing quite fine in their current environment". The apparent conflict seems more propense (is this a word?) to happen if you are thinking in adaptationist terms.<br /><br />I can be wrong, of course.<br /><br /><br /><br />Pedronoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-63189880520421344312012-10-18T08:28:03.576-04:002012-10-18T08:28:03.576-04:00sorry, the above should be 'suggest' rathe...sorry, the above should be 'suggest' rather than 'indicate' in the last sentence.andyboergerhttps://www.blogger.com/profile/11159573123843322700noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-23723354755155857382012-10-18T08:26:09.481-04:002012-10-18T08:26:09.481-04:00NE, thanks, I see that. But then, would they also ...NE, thanks, I see that. But then, would they also move back again when the climate change restored itself? I'm still trying to figure out why so many species cohabit the same plot of land. It seems like the ones that had remained would be able to repel plants that tried to return.<br /><br />Still trying to make this fit with 'doing quite fine in their current environment' which seems to indicate diversification of life form as an exception rather than a rule.andyboergerhttps://www.blogger.com/profile/11159573123843322700noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-72555742640755669042012-10-18T08:15:59.032-04:002012-10-18T08:15:59.032-04:00Plants "move" as seeds. The tracking wou...Plants "move" as seeds. The tracking would happen when a seed falls where it will grow right.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-61958191956879619002012-10-18T08:01:01.431-04:002012-10-18T08:01:01.431-04:00Not a biologist, but I would suspect that some, if...Not a biologist, but I would suspect that some, if not all, of these species were already adapted to fluctuations in seasons and thus would have changed very little over the duration.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-5250888672128648382012-10-18T07:29:40.313-04:002012-10-18T07:29:40.313-04:00I'm not convinced that 'certain traits'...I'm not convinced that 'certain traits' didn't vary. There's more to variation than what can be determined with bones. As El PaleoFreak said:<br /><br />"Who knows how those animals could have been evolving at their life history, metabolism, fur coats, behavior..." The whole truthhttps://www.blogger.com/profile/07219999357041824471noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-69020216895545010652012-10-18T07:08:07.208-04:002012-10-18T07:08:07.208-04:00LM writes
The important point is that most specie...LM writes<br /> The important point is that most species are doing quite fine in their current environment and they have enough buffering capacity to withstand fairly substantive changes in the environment. If the change is too drastic they move (habitat tracking). <br /><br />Somewhat confused. Do plants also have some form of habitat tracking? I'm trying to work out how the above statement is consistent with the vast variety and array of plant life.. It seems like plants would just go extinct, rather than adapt as prolifically as they have. Hundreds, if not thousands, of plants all inhabit the same plots of land, presumably all pretty much needing the same type of nutrients (water, sunshine, particular soil minerals), to survive. If they are all 'doing quite fine', why did they differentiate so much?andyboergerhttps://www.blogger.com/profile/11159573123843322700noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-39028731740516807402012-10-18T06:11:24.814-04:002012-10-18T06:11:24.814-04:00I've got to say that I'm a little surprise...I've got to say that I'm a little surprised, as I figured there would have been at least some variation among certain traits over that time. Then again, I'm not a biologist, so my surprise doesn't really count for much.Khttps://www.blogger.com/profile/12460075520187803334noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-67217109020797866632012-10-17T23:31:14.716-04:002012-10-17T23:31:14.716-04:00I totally agree with Rumraket that it is weird to ...I totally agree with Rumraket that it is weird to assume that populations are "infinitely sensitive and responsive" (and I am an evol. biol., fwiw). I don't think many evolutionary biologists think that adaptation is that simple.Bjørn Østmanhttps://www.blogger.com/profile/08859177313382114917noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-68948357325684361732012-10-17T15:46:49.628-04:002012-10-17T15:46:49.628-04:00Seems as if experiments in microorganisms could be...Seems as if experiments in microorganisms could be relevant here. Some favorable mutations in microorganisms take place over such short time frames that some experimenters thought it appeared to be directed. But long term experiments by Lenski, for example, show bacteria taking tens of thousands of generations to hit the "right" combination of mutations to adapt well to certain environments. Seems as if even in microorganisms some mutations and combinations thereof are much more easily achieved and propagated through a population than others. So perhaps this might be one factor, along with lack of sufficient breeding isolation, etc.Judnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-19740954003203864972012-10-17T15:28:09.500-04:002012-10-17T15:28:09.500-04:00I should add that the paper wasn't written by ...I should add that the paper wasn't written by the ID guys of course, only that they chose to highlight this paper because of the implication they see. <br /><br />I still think it's weird to write that species are assumed to be "infinitely sensitive and responsive" to their environments. I'm not an evolutionary biologist, I'm a layman nobody, but I've read around quite a lot and I've never got the impression that this was a working assumption for anyone. It's definitely overstated. Mikkel Rumraket Rasmussenhttps://www.blogger.com/profile/07670550711237457368noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-41047427171773106122012-10-17T14:40:10.287-04:002012-10-17T14:40:10.287-04:00Going extinct in the face of a slight change in th...<b>Going extinct in the face of a slight change in the environment strikes me as being quite sensitive and responsive.</b><br />Yeah but that's not what I meant, nor what I think was implied in their "paper". I took it to mean that Axe and co. thinks that evolution implies species will quickly adapt to even the most minute changes and so adaptation is infinitely minute, gradual, inevitable and smoothly follows the environment wherever it goes. It's essentially a strawman they erect, in order to point out how evolution must thereby be falsified when that doesn't happen. <br /><br /><b>Don't most biologists believe we're facing a crisis of extinction just because the average temperature of our planet will increase by a few degrees?</b><br />Yeah, because species are <b>not</b> infinitely sensitive in their adaptive ability, especially over so short timescales. <br /><br />When there's no more ice on the north-pole, noone but the ID strawman being erected is expecting polar-bears to become whales in 50 years or less. When polar bears aren't whales in 50 years, but extinct instead because they couldn't find land to stand on or food to eat(either because it migrated south or went extinct itself), the Discovery Institute will tout this as a falsification of evolution. <br /><br />Incidentially, a minor adjustment in temperature is not a complete or very adequate description of an environment to make predictions from. If the average temperature changes from -1 to +1, well, large landmasses can disappear under water. And the amount of CO2 in the atmosphere also has consequences for the acidity of the oceans etc. Mikkel Rumraket Rasmussenhttps://www.blogger.com/profile/07670550711237457368noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-40765438509881291402012-10-17T12:52:16.001-04:002012-10-17T12:52:16.001-04:00Thanks for your last two posts, they are quite elu...Thanks for your last two posts, they are quite elucidative. I didn't know about Gould's change of stance, but then again I didn't read his last book. Maybe I should.Pedronoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-56872599729363042562012-10-17T12:14:46.215-04:002012-10-17T12:14:46.215-04:00The impacts section of the IPCC says "Protect...The impacts section of the IPCC says "Protecting species that currently are vulnerable, endangered, or critically endangered (see Table 5-5) requires measures that, in general, reverse the trend toward rarity. Without management, there is high confidence that rapid climate change, in conjunction with other pressures, probably will cause many species that currently are classified as critically endangered to become extinct and several of those that are labeled endangered or vulnerable to become much rarer, and thereby closer to extinction, in the 21st century (Rabinowitz, 1981)."t_p_hamiltonnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-39590223359414730972012-10-17T10:47:09.395-04:002012-10-17T10:47:09.395-04:00I am not at all surprised by the results of this p...I am not at all surprised by the results of this paper. Even some evolutionary ecologists (e. g. Douglas Futuyma and Michael L. Rosenzweig) recognize the existence of long-term ecological stasis as well as evolutionary stasis, which this paper is an excellent demosntration of both.<br /><br />John KwokAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-31730430459269234282012-10-17T09:38:04.274-04:002012-10-17T09:38:04.274-04:00Stabilizing selection implies fine-tuning of a spe...Stabilizing selection implies fine-tuning of a species to it's environment such that any deviation from the status quo will be eliminated because it reduces fitness. It suggests that all the observable phenotypic characteristics of a species are the best possible adaptations to the current habitat. In other words, most species sit atop an adaptive peak.<br /><br />This is inconsistent with punctuated equilibria because the observation is that evolutionary change is coupled to cladogenesis where a new daughter species is formed but the parental species continues to exist in the same environment.<br /><br />This gives rise to species sorting, according to Gould and others, because these species compete in the same environment. Cladogenesis wouldn't be possible if the changes in the new species were maladaptive as implied by stabilizing selection. <br /><br />It's much more likely that most species are only part way up an adaptive peak and for many phenotpyic characteristics there may not even be an adaptive peak. The reason you don't see more phenotypic adaptation is because it doesn't confer very much fitness advantage in a species that's doing well enough. Stasis then becomes simply a consequence of huge population sizes where change takes a very long time.<br /><br />Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-90446776856613645262012-10-17T09:24:07.549-04:002012-10-17T09:24:07.549-04:00Going extinct in the face of a slight change in th...Going extinct in the face of a slight change in the environment strikes me as being quite sensitive and responsive.<br /><br />Don't most biologists believe we're facing a crisis of extinction just because the average temperature of our planet will increase by a few degrees?<br />Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-28366233795202367552012-10-17T09:20:26.931-04:002012-10-17T09:20:26.931-04:00When he died in 2002, Gould claimed that he no lon...When he died in 2002, Gould claimed that he no longer believed that "constraint" was the explanation for stasis (TSET p. 880). <br /><br />His preferred model at that time was that species with huge population sizes—that's mostly what they're looking at—are subdivided into many smaller demes. These demes might adapt slightly to local environments but the adaptations can't spread to other demes in slightly different environments. The net effect is that the species as a whole doesn't change very much even though there might be small localized changes in different parts of the range. <br /><br />You'll have to read Gould and others for a more detailed view of current thinking about stasis. The important point is that most species are doing quite fine in their current environment and they have enough buffering capacity to withstand fairly substantive changes in the environment. If the change is too drastic they move (habitat tracking). <br /><br />It's wrong to think that most species are so fine-tuned to their existing environment that any small environmental change requires adaptations in order to avoid extinction. On the other hand, it's clear that some catastrophic changes will cause mass extinctions. <br /><br /><br /> Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.com