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Full-Text Articles in Social and Behavioral Sciences
Monotremes Provide A Key To Understanding The Evolutionary Significance Of Epididymal Sperm Maturation, Brett Nixon, Russell Jones, Jean-Louis Dacheux, Heath Ecroyd
Monotremes Provide A Key To Understanding The Evolutionary Significance Of Epididymal Sperm Maturation, Brett Nixon, Russell Jones, Jean-Louis Dacheux, Heath Ecroyd
Heath Ecroyd
"It has been widely accepted that mammalian spermatozoa are infertile when they leave the testes and require a period of maturation in both the epididymis and the female reproductive tract before acquiring the ability to fertilize an oocyte. However, the necessity for such a complex process of posttesticular sperm maturation appears to be unique to mammals because it is well established that these processes do not directly influence the fertilizing ability of the spermatozoa of birds, reptiles, and other lower vertebrates. Because of their key evolutionary position and form of reproduction, we contend that monotremes (platypus and echidna) provide a …
A Key To The Eggs And Nests Of Iowa Turtles, James L. Christiansen, Jeffrey R. Parmelee
A Key To The Eggs And Nests Of Iowa Turtles, James L. Christiansen, Jeffrey R. Parmelee
Journal of the Iowa Academy of Science: JIAS
Biologists often need to identify destroyed turtle nests where a predator has excavated and eaten the eggs. We present a dichotomous key to the eggs and nests of Iowa's turtles based on egg or nest morphology and known range of the species. Egg and nest morphology clearly separated most nests of the families Chelydridae and Kinosternidae and many of the Emydidae. However, egg morphology must be combined with known range to distinguish wood turtles (Glyptemys insculpta) from other emydids. These factors will also separate most false map turtles (Graptemys pseudogeographica) from other species. Similarities among egg morphologies, nest morphologies, and …