15. Figure 1 compares two models of speciation, A and B.
Figure 1. A comparison of two speciation models
Which of the following best explains how the ecological conditions are likely to be different in the
two models?

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

what is the statement?

above statement is not a true statement about the open ocean because the open ocean has low levels of nutrients. most of the photosynthetic activity on earth occurs in the open ocean within the photic zone. organisms in the deep ocean are exposed to frigid temperatures and total darkness but it does not begin at the low-tide mark.