The Elements of Evolution (38-5) A New Trait

A New Trait

The parallel genetic changes underlying similar phenotypes in independently evolved lineages provide empirical evidence of adaptive diversification as a predictable evolutionary process. ~ American evolutionary biologist Matthew Herron & Canadian evolutionary biologist Michael Doebeli

A trait is an organic expression. The routes to realizing a new trait are multifarious. One path begins with genetic copies (alleles) being made that have the genesis of the emergent trait. The ancestor of these alleles has the rudimentary potential for the new trait which is, at best, undeveloped.

Amplification of alleles proceeds with different variants emerging. Through progressive selection, alleles with trait improvement continue to evolve and are further amplified, while less functional copies become inactive or even eliminated. The process continues until there remains the conserved ancestral gene with the parent activity and an allele that encodes the new trait in functional form. The divergence between the gene that scripted the old trait and the allele for the new trait signifies evolution.

This process is necessarily adaptive in aiming at a needed functionality. Otherwise there would be no criterion upon which progressive selection could proceed.

Researchers experimentally observed such evolution in Salmonella bacteria. Surgically deprived of its primary means for producing the amino acid tryptophan, the bacteria re-evolved the needed capability within 3,000 generations through the described process.

There is more to inheritance than genes. ~ English evolutionary biologist Kevin Laland et al

The material mechanics of evolution happen at the molecular level. Mutations of genes are the coarsest means, and by far the least common way that organisms evolve.

Tweaking the genomic database through epigenetic changes which regulate gene expression occurs throughout life. It is basis for development in many complex organisms.

Epigenetic alterations are inheritable. While prolific manipulators of their genomes, plants often carry their legacy epigenetically.

Changing alleles may seem more profound, but its import is the same as altering DNA sequences. Selection of epigenetic alleles underlie many complex traits in eukaryotes.

In bursts of creative problem-solving, new alleles are often created which are not immediately used. Instead, the reserved variations provide a ready database of possibilities if adaptive need arises.

Evolution retains many mysteries at the empirical level. Animal population sex ratios is exemplary.