In other words, a reaction swap can be decomposed into a succession of biologically meaningful genotypic changes; the connectivity of genotype networks found in our swap approach thus holds also for single additions and deletions of reactions.
Furthermore, genotypes of identical phenotype are such that small genotypic changes (a reaction deletion, addition, or exchange) connect these genotypes into a vast graph; we refer to this graph as a genotype network.
Although gene expression is a phenotype and not a genotype, it probably reflects more directly genotypic changes than morphological or physiological phenotypes.
Specifically, it is possible to reach any genotype in such a connected set from any other genotype by a series of small genotypic changes, such as changes in individual amino acid sequences.
In this case, most viable genotypes can be reached from each other through a series of small genotypic changes that affect only single reactions each and that leave the phenotype constant.
Over time, the latter is expected to be associated with genotypic changes in the study organisms.
A longstanding question is whether such phenotypic repeatability entails similar (parallelism) or different genotypic changes (convergence).
Both techniques have shown that biofilms have distinct gene-expression patterns in comparison to planktonic cells, but much work is still needed to identify all physiological and genotypic changes that occur during the biofilm development.
Selective removal of specific species and age groups in preference to others may contribute to changes in the species and size composition of fish communities, alter trophic interactions, and may lead to phenotypic or genotypic changes in harvested stocks.
Though these data are derived from nine S0 space-stored seeds in a single exposure experiment, the results demonstrate the preservation of barley seeds in outer space for 13 months without phenotypic or genotypic changes and with healthy and vigorous growth in space.
In this way, both evolution and development might be said to leave vestigial remains not only in the phenotype we see, but also in the genotypic basis that helps to determine phenotypic expression (provided the genotypic changes are to the germ line, and thus heritable).
