Recording of sustainable traits requires a large financial and logistic input and the economic advantages for the market are not as clear as for traditional selection traits.
Further, as with naturally selected traits, direct selection for preferences for condition dependent male traits balances out direct selection against female preference due to competition, allowing preference to evolve under lower strengths and higher competition.
This led to a paradigm shift in breeding programs, as selection for nutritional traits commenced, with the objectives of elevating Fe and Zn, and incorporating β-carotene into polished grains.
Tradeoffs, or compromises, are ubiquitous in evolution, as selection that favors one trait is often at the expense of another.
First, as selection is acting on phenotypic traits usually controlled by many genes (Stranger et al. 2011), we would expect it to affect multiple genes or a whole pathway rather than a single gene.
Root traits have been seldom considered as selection criteria to improve Nitrogen Use Efficiency of crops, due to the difficulty of measuring root traits under field conditions.
Selection: As selection acts on organisms, individuals with particular traits are more likely to successfully reproduce than others.
As a result of selection for traits that influence the fitness of each sex, males and females can differ dramatically, displaying sexual dimorphism in a range of physiological or behavioural characters [ 18- 20].
Behaviours can evolve by means of natural selection as adaptive traits conferring functional utilities that increases reproductive fitness.
