Polyandry Hypothesis

Polyandry is a mating system where females mate exclusively with a group of males that only mate with the one female. This is different from polygyny, which can be thought of as the opposite of polyandry as one male mates exclusively with a group of females. Promiscuity can be defined as a mating system where both males and females mate with several individuals, and there is no long-term or pair bonding. Each mating system offers certain costs and benefits to each sex, and typically arise due to different evolutionary circumstances. For females, polyandry is thought to be beneficial as it insures a higher rate of fertilization, can secure more resources, and even a higher level of parental care from males. In polygynous systems where males
The good-genes and sexy-sons hypotheses focus on direct benefits associated with female choice. The good-genes hypothesis proposes that a female will choose to mate with males that they believe will produce better offspring. Typically this decision is based off a phenotypic trait that is an sign of higher genetic fitness, however sometimes these traits are not good indicators. The sexy-sons hypothesis is similar however it posits that females will choose the most attractive males to mate with so that those same genes are passed on to her son. The sexy-sperm and good-sperm hypotheses are similar, but focus on how female choice can influence sperm competition in males. The sexy-sperm hypothesis says that females who mate with multiple males will produce offspring sired by the males with the most competitive sperm. The good-sperm hypothesis proposes the same theory as the sexy-sperm hypothesis, but also predicts that superiorly competitive sperm will produce offspring with a higher level of fitness. It is also important to note that both the sexy-sperm and good-sperm hypotheses assume that traits relating to sperm-competitive ness are heritable. These two hypotheses confer a selective advantage to polyandrous females over monandrous females. Both agree that the more males a female mates with, the higher the chance that one of those males will
The offspring of these copulations were then raised to maturity and further test. For both hypotheses it was predicted that the sons of polyandrous mothers would have higher sperm viability. This was tested by using a Live:Dead Sperm Viability Kit on spermatophores removed from males directly. For the good-sperm model, it was also hypothesized that the offspring of polyandrous mothers would have higher immune function, and be able to fight off infection better. To test this, hemolymph was removed from offspring and tested for phenoloxidase and lytic activity
Results found that sons of polyandrous mothers had higher sperm viability than those of monandrous mothers. This supports the sexy-sperm hypothesis, and the first postulate of the good-sperm hypothesis. However, results of the immunocompetence testing did not find any significant difference between the offspring of the polyandrous and monandrous mothers, which does support the second postulate of the good-sperm model. This provides evidence that good-sperm model did not influence the evolution of polyandry within the species, but there is a strong possibility that the sexy-sperm model