Color plates
Plate 1.1 An “oceanographic section” of oxygen concentration from cruises by
research ships along the line shown in the inset: along 150°W in the Pacific Ocean
from Antarctica to the Aleutian Islands. Water was collected with closing samplers at
each depth indicated by a dot and dissolved oxygen concentration (μmole kg−1) was
estimated on board the ships. The most intense oxygen minimum (violet shading) is in
the subarctic and northern subtropical gyre, beneath the intermediate water subducted
from the subarctic. Low-oxygen water outcrops near the equator. The minimum rides
above the influx of water from the deep global thermohaline circulation. Maximum
concentrations (red) are in Antarctic intermediate water. Data are from WOCE (World
Ocean Circulation Experiment) profile p16.
Plate 2.1 Schematic depiction of endosymbiotic events establishing plastids as
organelles, and the consequences for the genomes of the symbionts. In primary
symbiosis, a cyanobacterium was engulfed by (or invaded) a heterotrophic eukaryote.
The cyanobacterial genome was reduced over time, but, in all known photosynthetic
eukaryotes, at least a few genes are still retained as a plastid genome. In secondary
endosymbiosis, a heterotrophic eukaryote acquires a photosynthetic eukaryote. The
nucleus of the endosymbiont (N1) is severely reduced to a nucleomorph (Nm) or lost
altogether in the following transfer of many genes to the host nucleus.
“Stramenopiles” is an alternative name for the Heterokontophyta, including the
diatoms. Tertiary endosymbiosis followed when dinoflagellate host cells engulfed
stramenopiles, haptophytes, or cyptophytes.
(After Parker et al. 2008.)