Distribution and reproductive effects of Wolbachia i n stalk-eyed flies
... Wolbachia have been associated with female-biased sex ratio distortion, we used a PCR assay
to examine 17 species of stalk-eyed flies (Diptera: Diopsidae), two of which exhibit femalebiased sex ratios, for the presence of these microbes. Type A Wolbachia was detected in four
diopsid species, three f ...
... • The effects that androgens have on
the human body --virilization, masculinization, anabolism,
etc. --- are not brought about by
androgens themselves, but rather are
the result of androgens bound
to androgen receptors
Chapter 16 Evolution of Sex
... Ultimately, asexual reproduction should take over.
However, in nature this is not the case.
Most organisms reproduce sexually and both sexual
Animal responses to biotic environment
... individual survival. Parents invest lots of
food and effort into them from egg stage to
after birth, health of current generation
risked for the next generation
Structure of mating systems
... We can assume that the primary sex ratio in humans is 1:1. But
we’d be wrong. The primary sex ratio is somewhere between
1.079 (1948 Carnagie Institute data) and 1.2-1.6:1. Why? One
favorite explanation: Y-bearing sperm are lighter (Y is smaller
than X) and more motile.
The secondary sex ratio is 1. ...
Sex allocation is the allocation of resources to male versus female reproduction in sexual species. In dioecious species, where individuals are male or female for their entire lifetimes, the allocation decision lies between producing male or female offspring. In sequential hermaphrodites, where individuals function as one sex early in life and then switch to the other, the allocation decisions lie in what sex to be first and when to change sex. Animals may be dioecious or sequential hermaphrodites. Sex allocation theory has also been applied to plants, which can be dioecious, simultaneous hermaphrodites, have unisexual plants and hermaphroditic plants in the same population, or have unisexual flowers and hermaphroditic flowers on the same plant.