michaelm@bcsaic.UUCP (03/07/87)
There is a fruit tree around here (Seattle) that has just put out beautiful pink-purple flowers. (Sorry, I don't know what the name is.) What surprised me is that all of the trees within the local area (several miles, at least) seemed to flower within a day or so. I can see what an advantage this would be for cross-pollenization, but how do they synchronize their flowering? I suspect that it was a sudden warm day we just had after a cold spell. If so, I would imagine that there is enough variability in the threshold of individual trees that some years they're "fooled." That is, there is a day which is enough warmer than previous days that some--but not all--trees of this species flower. Has this been studied? Also, assuming the flowers are pollinated by insects (the flowers are both showy and odiferous), what guarantee is there that the appropriate flying insects will be active on a given warm day? I also understand that synchronized flowering is common among tropical trees. There, it's even harder to understand what environmental clues would lead to this synchronization, at least in those tropical forests where the climate is relatively steady (as opposed to those with a sudden onset of the monsoon seasons). Or am I overestimating the steadiness of tropical climates? (I've lived in the Amazon basin, but not over an entire year.) -- Mike Maxwell Boeing Advanced Technology Center arpa: michaelm@boeing.com uucp: uw-beaver!uw-june!bcsaic!michaelm
evs@duke.UUCP (03/12/87)
In article <534@bcsaic.UUCP> michaelm@bcsaic.UUCP (Michael Maxwell) writes: >There is a fruit tree around here (Seattle) that has just put out beautiful >pink-purple flowers. What surprised >me is that all of the trees within the local area (several miles, at least) >seemed to flower within a day or so. I can see what an advantage this would >be for cross-pollenization, but how do they synchronize their flowering? >I suspect that it was a sudden warm day we just had after a cold spell. If >so, I would imagine that there is enough variability in the threshold of >individual trees that some years they're "fooled." That is, there >is a day which is enough warmer than previous days that some--but not >all--trees of this species flower. Has this been studied? If the Seattle population of trees was "ideal", then all trees in Seattle would always bloom at the same time. If, however, some of them then some tress will bloom and others won't. If they are using temperature as a cue then it is not hard to imagine that each tree has some internal temperature threshold that is genetically controlled. Then assuming that proximal trees are closely related, we would expect trees to bloom in pockets (local areas, as Michael observed). What this effectively does is to create locally isolated popluations, thus increasing the inbreeding in the Seattle metapopulation. This inbreeding would tend to make proximal trees in future generations even more closely related, thus possibly accentuating the pocket blooming effect the next time we get an isolated warm day. So in years when we get short warm periods that "fool" only some of the population, inbreeding should increase. But then some years we may not get a warm day until spring has come for real. Then all trees would bloom more or less at the same time and inbreeding should decrease. Thus it may be that the inbreeding coefficient (measure of inbreeding for a population) for the Seattle population is fluctuating over time. However if false springs and true springs alternate years or something close to that, the inbreeding coefficient may just be an average of these yearly fluctuations. L.L. Cavalli-Sforza has looked at inbreeding and genetic drift in isolated human populations in the Parma River valley in Italy. He used blood groups in his study. See: Cavalli-Sforza, L.L., and W.F. Bodmer. 1971. "The Genetics of Human Populations." San Francisco: Freeman. -- UUCP: {decvax, seismo}!mcnc!duke!evs ARPA: evs@cs.duke.edu CSNET: evs@duke Ed Simpson, P.O.Box 3140, Duke Univ. Medical Center, Durham, NC, USA 27710
geoffs@gssc.UUCP (Geoff Shapiro) (03/16/87)
I've been out of the field of biology for some 10 years now, but can occasionally keep up on current news items. It seems to me that I recently read an article which describes current research that might help explain the synchronized flowering of the trees in Seattle. This article explains that recent research has discovered that some members of a plant population may induce other members of a population to some desired (or advantageous) goal via chemical communication. What this means for the Seattle tree population is that when environmental cues cause some members of the population to start flowering, chemicals released into the air or the soil (I don't know which, the researchers may not know either) induce other members which have not yet started their flowering sequence to do so. The genetic advantage of this should be quite apparent. Hope this helps explain some stuff... Geoff Shapiro Graphic Software Systems
michaelm@bcsaic.UUCP (Michael Maxwell) (03/19/87)
In article <351@gssc.UUCP> geoffs@gssc.UUCP (Geoff Shapiro) writes: >[about] the synchronized flowering of the trees in Seattle... > > ...some members >of a plant population may induce other members of a population to some desired >(or advantageous) goal via chemical communication. What this means for the >Seattle tree population is that when environmental cues cause some members of >the population to start flowering, chemicals released into the air or the soil >(I don't know which, the researchers may not know either) induce other members >which have not yet started their flowering sequence to do so. >advantage of this should be quite apparent. Fascinating idea: pheromones of the plant world. And the flowers in question are indeed quite odiferous. But everyone *knows*, this is just to attract insects. What if everyone is wrong? -- Mike Maxwell Boeing Advanced Technology Center arpa: michaelm@boeing.com uucp: uw-beaver!uw-june!bcsaic!michaelm
greg@mind.UUCP (03/20/87)
In article <630@bcsaic.UUCP>, michaelm@bcsaic.UUCP (Michael Maxwell) writes: > > Fascinating idea: pheromones of the plant world. And the flowers in question > are indeed quite odiferous. But everyone *knows*, this is just to attract > insects. What if everyone is wrong? > -- > Mike Maxwell Here's what I'm curious about: If one plant truly triggers another to blossom by chemicals released by the *flowers*, then plant 1 must be in full blossom in order to send the signal, and plant 2 is presumably still waiting for spring -- it may have buds, but at an early enough stage that it can hold off. Seems to me (rough guess, of course) that by the time plant 2 is ready for plant 1, plant 2 is over the hill ... So, either the chemical message is sent in some other way ("let's all start blossoming!" rather than "I'm blossoming, so you should, too!") or I'm completely confused ... (somebody please tell me one way or the other ...) Greg