New Data View, New Opinion: Male GSI Data For Burrheads and Silverstripes

After my post last night, I sat down with the GSI data I have for the male fish in my burrhead (Notropis asperifrons) and silverstripe (N. stilbius) shiner study. My prejudice to date has been to focus on the female data, since it would seem that the reproductive condition of female fish would be primarily important; that's where eggs come from! But, treating (with ANCOVA again, for a better allometric view of gonadal growth) and graphing my data on the relative size of male testes, I come to a new realization. Female reproductive effort for both species peaked in April (see the graph in my last post), followed by a summer-long decline in the relative size of ovaries. But the male data, in the graph below, is very different (notice that the GSI values on the left scale are also much smaller than female values). N. stilbius has a major peak in April, with a very low GSI by late July. N. asperifrons has higher GSI values for most of the summer before plummeting in August. Since it takes two to tango, it would seem that N. asperifrons has a somewhat longer reproductive season, into late July, than N. stilbius. This isn't earthshaking but suggests some interesting differences between two related species living in the same Alabama creek. I could be succumbing to my tendency to overinterpret data, but.... I think it's true!