A2.1.7—Evidence for last universal common ancestor (LUCA) question 1
D1. Populations of threespine sticklebacks (Gasterosteus sp.), a fish living in small freshwater lakes in British Columbia, Canada, are derived from the marine threespine stickleback (Gasterosteus aculeatus). In order to investigate the process of speciation in these populations, three small lakes were studied. Each lake contained two varieties of stickleback: a large, bottom-dwelling variety that fed on invertebrates near the shore and a small, plankton-eating variety that lived in the open water. The probability of breeding between pairs of individuals was measured under laboratory conditions in the following breeding combinations:
I different varieties (small × large) from the same lake
II different varieties from different lakes
III same variety (small × small) and (large × large) from different lakes
IV same variety from the same lake.
The data are summarized below.
From H. D. Rundle et al. (2000) Science, 287, pp. 306-308. Reprinted with permission from AAAS.
Identify the highest and lowest probabilities of breeding for individuals of the same variety from different lakes.
Highest probability:
Lowest probability: