----- Original Message ----- > Do you know any wild plants who started to split their chromosoms .? I googled, using different search terms such as paleopolyploids, "ancient polyploids," "natural polyploid," polyploid + wheat, polyploid + fruit, etc. Play around with different combinations, and you'll surely find a lot to read. :-o But to answer your question as directly as I can, below are a few things I found. Theola ___________________________________ http://www.tarweed.com/pgr/PGR00-011.html "Tetraploid wheats were established by 10000-8000 BC. T. dicoccum was probably the first cultivated wheat, but may have arisen in the wild and become established as a result of the artificial selection of naturally occurring stands of wild wheat." http://fletcher.ces.state.nc.us/programs/nursery/metria/metria11/ranney/poly ploidy.htm Polyploidy can naturally arise in a number of different ways. .......... Role of polyploids in plant evolution. In contrast to the gradual evolutionary process whereby new species evolve from isolated populations, new species of plants can also arise abruptly. The most common mechanism for abrupt speciation is through the formation of natural polyploids. Once a tetraploid arises in a population, it can generally hybridize with other tetraploids. However, these tetraploids are reproductively isolated from their parental species. Tetraploids that cross with diploids of the parental species will result in triploids that are typically sterile. This phenomenon provides a "reproductive barrier" between the polyploids and the parental species - a driving force for speciation. ........ One question that frequently arises is whether or not polyploids inherently have greater stress tolerance. For example, it has often been observed that disproportionate number of polyploids are found in cold, dry regions. Some argue that this is a spurious correlation (Sanford, 1983) or possibly the result of intermixing of species and formation of allopolyploids during glacial periods (Stebbins, 1984). However, polyploids may also have certain characteristics that do provide some adaptive benefits. Molecular studies have demonstrated that allopolyploids exhibit "enzyme multiplicity" (Soltis and Soltis, 1993). Since allopolyploids represent a fusion of two distinctly different genomes, these polyploids can potentially produce all of the enzymes produced by each parent as well as new hybrid enzymes. This enzyme multiplicity may provide polyploids with greater biochemical flexibility; possibly extending the range of environments in which the plant can grow (Roose and Gottlieb, 1976). Interesting article about apples: http://peacecorps.mtu.edu/povel/Eng_the_apple.htm Like cats and people, most apple trees are diploid--that is, their genes occur on pairs of chromosomes. Typically, apples have seventeen pairs of chromosomes, for a total of thirty-four. But some varieties are haploid, with seventeen single chromosomes. Others, especially among crab apples, are polyploid, which means that their chromosomes are not paired but tripled, quadrupled, quintupled, or even wadded up into bundles of six. In fact, some apples have as many as eighty-five chromosomes. And each of the genes on each of the chromosomes can have different alleles (alternative forms). A single seed may thus contain a lot of genetic variation that has accumulated down through the ancestral lines. Orchardists have unquestionably benefited from the apple's easygoing acceptance of extra chromosomes. Many familiar varieties of apples are polyploid: Stayman, Jonagold, Baldwin, and the beloved old pie apple Rhode Island Greening. The Jonagold is a modern, contrived cross between Jonathan and Golden Delicious parents. But the Stayman sprang up all on its own, from a Winesap seedling in Kansas; the Baldwin and Rhode Island Greening, too, were spontaneous polyploids.