Female Telescope Shiners Show Ovarian Development... Yeah, It's Important!

At least I hope it's important. I sat down with five students yesterday and we started our dissections of the telescopes we caught at the Walls of Jericho on Feb. 3 to look for evidence of gonadal development. We started with four of the largest individuals, since I had a feeling that the larger ones would be females and I'm more interested in them. Sure enough, three of the four we looked at were female and all showed some evidence of gonadal activation. We found evidence of intermediate oocyte development, cortical alveolar or early exogenous vitellogenesis. It wasn't difficult to find the ovaries in the abdominal cavity and remove them under a dissecting microscope. The three had gonadosomatic index (GSI) values of 1.2, 2.9 and 3.2 which is about as high as the burrhead and silverstripe shiner March values from Borden Creek three years ago. I'm surprised that the development was that advanced, even though they weren't nearly ready to spawn. The male we looked at wasn't tuberculated, and we couldn't find his testes, either; I assigned his sex purely because we couldn't find ovaries which were so obvious in the three females. We'll continue with this "quest for ovaries" next week. We also measured standard length for all the fish since I have my digital calipers back from Enrique. Pooling all of the length-weight data together, the correlation coefficient between length and weight was 0.9. I guess that's not surprising, the correlation will probably weaken between sexes once females fill up with eggs.

On the mtDNA front with our mummichogs (Fundulus heteroclitus), Kris has been on a roll with PCR's this week. One run produced good DNA amplification in six of six samples, and another run was five for six. So we now have 17 - 19 successful amplifications ready for purification and sequencing. These include individuals from Martha's Vineyard, Nantucket, Boston Harbor, Chincoteague, Virginia Beach, and maybe Marion, MA. If the sequences all come out clean we'd probably have enough for our final analysis of population structure and history for this species. I think we'll get greedy and run some more.....