The comparative examination of eye anatomy of spring-dwelling and cave-dwelling populations of the amphipod Gammarus minus
In this project, the eye morphologies of four spring-dwelling and four cave-dwelling populations of the amphipod Gammarus minus were examined under light microscopy. Four conclusions were obtained from the examination. The first conclusion is that the eye morphologies are similar among the four spring-dwelling populations, and also are identical to the eye structure of Gammarus pulex. The second conclusion is that the eye morphologies of the four cave-dwelling populations are greatly degenerated compared to the four spring-dwelling populations. The third conclusion is that the eye morphologies are different between the four cave-dwelling populations. The fourth conclusion is that the optic elements are orderly lacking in all four cave-dwelling populations. A pattern was built based on the four conclusions, and shows that the eye degeneration is a result of accumulation of selectively neutral mutations. Also, it indicates that the accumulation of mutations may favor the optic elements which are co-formed by a large number of loci.