Figure 2a: Day 2 of the Gaian simulation. Most plankton have ineffective phenotypes and merely sink to the bottom. However, a few have risen to the surface to photosynthesize. Shape coding conveys the activities of each plankton cloud: (a) photosynthezing - thin spines on exterior, (b) grazing - large mouth-like opening on right side, (c) consumed by grazer(s) - small sliver removed from left side, (d) swimming - tail fin on left side. Color-coding of grid cells indicates relative oxygen concentration from high (red) to low (blue).

Figure 2b: Day 3 of the Gaian simulation. One of the surface autotrophs gains enough biomass to reproduce asexually. The newborn clouds sink to the bottom during their dormant period and then become active and rise to the surface to photosynthesize and/or graze.

Figure 2c: The afternoon of day 12 of the Gaian simulation. Most clouds now photosynthesize and/or graze on the surface. Note the diffusive spreading of oxygen as compared to Figures 2a and 2b.

Figure 2d: At dusk on day 13 of the Gaian simulation. Surface plankton tend to reproduce in waves due to their common ancestry. At vertical levels 6 through 8, a wave of newborns sinks to the bottom, while just above them at level 5, a slightly older wave of juveniles has recently emerged from dormancy and has returned halfway to the surface. A third wave photosynthesizes, grazes and/or swims on the surface.

Figure 2e: Day 80 of the Gaian simulation. Most clouds are now autotrophs or hybrids and live on the surface. Reproduction has become asynchronous, so sinking eggs and rising juveniles are more evenly distributed in time and space.

Figure 2f: The evening of Day 800 of the Gaian simulation. In a population dominated by surface hybrids, most reproduction now occurs synchronously, just before sunset. The spatial spreading of eggs is due to evolved differences in sinking velocity. Color-coding of grid cells now displays nitrate concentrations, with high values on the bottom.

Figure 2g: Dusk on Day 800 of the Gaian simulation. Many surface hybrids that could not reproduce now sink to the bottom to graze on eggs and other hybrids.