Revista Chilena de Historia Natural 76 (4): 717-724, 2003
REVIEW ARTICLE
Genome dynamics, genetic complexity and macroevolution
Genome data analysis indicates that the major evolutionary transitions have been driven
by substantial increases in genomic complexity. These increases, accounting for novelty in evolution, have proceeded mainly by gene
duplication. This idea, advanced by Ohno (1968), remains current in the study of several organisms whose genomes have been
sequenced. Maize, yeast, and humans contain more paralogons than would be expected to occur by chance, and this supports the
contention that gene families were not formed de novo, but by large-scale DNA duplications. Lineage hybridization emerges as an
efficient and widespread mechanism to create evolutionary novelty by recruiting redundant genes to new roles. Lateral gene transfer
indicates a chimeric composition of prokaryote genomes. This peculiar manner of inheritance blurs the edges of phylogenetic lineages
and suggests that the anastomosing and dichotomization of branches play key roles in determining the shape of the tree of life.
Adaptive mutations have also enlarged the genetic framework of evolutionary thought by incorporating a new mechanism of gene
formation. Moreover, developmental biology has provided solid grounds for understanding organisms as consisting of onto- and
epigenetically organized modules. Rapid and drastic changes brought about by the study of developmental genes have discredited the
notions that adaptation is achieved exclusively by stepwise allele replacement within populations, and that macroevolutionary change is
extrapolated microevolution. Apparently, a broadening, if not a remodeling of the genetic framework in which we understand phylogeny
and the evolution of morphological complexity, is emerging through the study of comparative genomics.
Key words:
gene duplication,
genome, genetics, evolution, macroevolution, evolutionary theory
