Abstracts |
Analyses of diverse eukaryotes reveal that genomes are dynamic, sometimes
dramatically so. In numerous lineages across the eukaryotic tree of life, DNA content varies
within individuals throughout life cycles and among individuals within species. Discovery of
examples of genome dynamism is accelerating as genome sequences are completed from diverse
eukaryotes. Though much is known about genomes in animals, fungi, and plants, these lineages
represent only 3 of the 60-200 lineages of eukaryotes. Here, we discuss diverse genomic
strategies in exemplar eukaryotic lineages, including numerous microbial eukaryotes, to reveal
dramatic variation that challenges established views of genome evolution. For example, in the
life cycle of some members of the ''radiolaria,'' ploidy increases from haploid (N) to
approximately 1,000N, whereas intrapopulation variability of the enteric parasite Entamoeba
ranges from 4N to 40N. Variation has also been found within our own species, with substantial
differences in both gene content and chromosome lengths between individuals. Data on the dynamic
nature of genomes shift the perception of the genome from being fixed and characteristic of a
species (typological) to plastic due to variation within and between species. |