Final answer:
One gene can compensate for another's lost function through a process known as gene duplication or paralogs, which are vital for the evolution of new functions and increasing species diversity, while alternative splicing also contributes to creating protein variants for new functions.
Step-by-step explanation:
One gene can compensate for the loss of function of another gene in cases where a duplicate gene or paralog has arisen over evolutionary time or when the function of another gene product can be increased to compensate for the missing protein product of the non-functional gene. This process can be observed in gene duplication events that allow the free modification of one gene copy by mutation, selection, or drift. The second copy continues to produce a functional protein, preserving the organism's viability while creating room for evolutionary innovation and increased species diversity. Alternative splicing can also contribute to functional diversity by creating protein variants that may adapt to new functions without the loss of the original protein. Introns and noncoding DNA play an essential role in this evolutionary process by buffering mutations and enabling exon shuffling, which increases the variety of functional proteins.