|MadSci Network: General Biology|
Dear Hughes, I don't think that is an answerable question. First of all, how would one figure out the "ideal conditions" for an organism that ordinarily has a long life span? Ideal conditions mean unnatural conditions. For example, animals kept in highly artificial conditions in zoos generally live longer than their wild counterparts. Those conditions were determined mostly by trial and error and not to extend the animals' life span, but primarily to maintain them healthy. To figure out the most suitable artificial conditions to extend the lifespan of a tree species that under natural conditions lives hundreds of years anyway, one would have to do experiments lasting hundreds of years! Any organism that reproduces asexually (for example, by division or budding) may be considered immortal provided that its genome never changes. For example, a bacterium divides into two and then those two bacteria each divide into two, and so on. So it seems that the original bacterium never really dies. Actually, that is not quite true. The bacterial genomes tend to change quickly as a result of mutations or horizontal gene transfer. So, after a large number of divisions (which don't take very long), the descendents of one bacterium may be quite different genetically than their common ancestor. Therefore, none of those descendents would be the original bacterium anymore. Similar processes that raise similar issues take place in many multicellular organisms. The cattail plants that commonly grow in ponds produce rhizomes, which are roots from which new plants can grow. As a result, a cattail plant that has grown from one seed in a newly formed pond may eventually end up filling up the pond with cattails connected to each other by their roots and that could be considered one giant plant. Will that plant still be there if the pond is not disturbed for, say, 1000 years? We would have to wait 1000 years to answer that question. If the plant is still there 1000 years from now, will it genetically be the same plant that is in the pond now? We would have to wait 1000 years to answer that question too, because there is no way to predict if a population of a species or a clone of an asexual organism will undergo genetic changes during a 1000-year period. Aydin Orstan
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