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Can Males Successfully Invade Hermaphroditic Populations Of Clam Shrimp (Eulimnadia Texana)?, Stephen C. Weeks
Can Males Successfully Invade Hermaphroditic Populations Of Clam Shrimp (Eulimnadia Texana)?, Stephen C. Weeks
Stephen C. Weeks
Androdioecy (mixtures of males and hermaphrodites) is distinguished by its rarity, being found in only similar to 40 animal species. Many of these species are clam shrimp in the genus Eulimnadia. A metapopulation model for the maintenance of androdioecy is tested herein by examining male success in aquaria with a single male-producing hermaphrodite introduced into an otherwise all-hermaphrodite population. This migration experiment did allow males to persist in these populations for seven generations, although at levels below those found in other populations of these shrimp. These results suggest that the maintenance of androdioecy via 'reproductive assurance' is unlikely by way …
Inbreeding Effects On Sperm Production In Clam Shrimp (Eulimnadia Texana), Stephen C. Weeks, Sadie K. Reed, Donald W. Ott, Franca Scanabissi
Inbreeding Effects On Sperm Production In Clam Shrimp (Eulimnadia Texana), Stephen C. Weeks, Sadie K. Reed, Donald W. Ott, Franca Scanabissi
Donald W. Ott
Hypothesis: Inbreeding depression is manifest in lower sperm production. Organism: Freshwater crustaceans (clam shrimp - Eulimnadia texana), from the southwestern United States, which have high levels of inbreeding. Methods: Comparisons of semi-thin sections of the male gonad among selfed and outcrossed siblings from four families. Results: There was a twofold reduction in sperm production in inbred relative to outcrossed males. Inbreeding depression in males was higher than previous estimates from hermaphrodites. Conclusions: Inbreeding markedly reduces sperm production. The observed low levels of sperm production can explain both the low average outcrossing rates as well as the variation in these rates …