Final answer:
Barbara McClintock expanded on Hertig's description of meiosis by uncovering the process of crossing-over. Additionally, Marilee Ramesh and colleagues contributed to our understanding of meiosis evolution through genetic comparison in single-celled protists.
Step-by-step explanation:
Building on Hertig's description of meiosis, it was Barbara McClintock who made significant contributions by discovering how chromosomes exchange information during meiosis. McClintock's work with corn in the 1950s provided profound insights into the genetic mechanisms underlying inheritance. Particularly, she demonstrated the process of crossing-over using color traits in corn kernels, which showed how chromosomes exchange segments and contribute to genetic diversity.
Research efforts extended by Marilee Ramesh and colleagues have focused on parsing out the evolution of meiosis by comparing the meiotic genes of protists. This investigation helps in understanding when and where meiosis may have evolved, suggesting that some aspects of meiosis might be more ancient than others, highlighting the continuous evolutionary path from simpler forms of cell division to the complex process of meiosis as observed in higher organisms today.