Click For Photo: https://www.sciencedaily.com/images/2018/03/180308105158_1_540x360.jpg
James Umen, Ph.D., member, Enterprise Rent-a-Car Institute for Renewable Fuels and Joseph Varner Distinguished Investigator at the Donald Danforth Plant Science Center was part of a research team led by Dr. Hisayoshi Nozaki at the University of Tokyo who have been investigating the evolution of male and female sexes in a group of freshwater photosynthetic protists called volvocine green algae, a group that is well-known to scientists for capturing early stages in the evolution of sexes and multicellularity. Previous studies in animals and plants identified a general trend of expansion and differentiation between male and female sex chromosomes, often leading to large genetic differences between them; but these studies could not capture the earliest stages of evolution where distinct sperm and egg cell types first evolved from a simpler ancestral mating system with equal-sized gametes, known as isogamy.
The research team focused on two especially informative and closely-related multicellular volvocine species from the genera Yamagishiella and Eudorina which bracket the transition from isogamy to male/female sexes. While 32-celled Yamagishiella and Eudorina colonies look very similar to each other, the former is isogamous while...
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