Browsing by Subject "Mating behavior"
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Item The cognitive biology of mate choice in túngara frogs (Physalaemus pustulosus)(2010-05) Akre, Karin Lise; Ryan, Michael J. (Michael Joseph), 1953-; Cummings, Molly E.; Domjan, Michael; Fuiman, Lee A.; Mueller, Ulrich G.Sexual selection is responsible for a great diversity of elaborate male traits. A general female preference for males that have exaggerated traits drives this process, but the reasons females exhibit this preference are often unclear. Recent advances in understanding signal evolution have emerged from studies of receiver psychology that focus on how receivers perceive and process communication signals. I apply the perspective of receiver psychology to understand female preference for elaborate signals in túngara frogs (Physalaemus pustulosus). Male túngara frogs produce advertisement calls of variable complexity. Females exhibit a strong preference for complex to simple calls, but previous studies have not found consistent patterns of preference between calls of variable complexity. In my doctoral research, I investigate the function of variable complexity in túngara frogs. Specifically, I address the following questions: 1) Are calls of variable complexity especially relevant to females in certain contexts? Do males respond to female behavior by increasing their production of complex calls? 2) Does male to female proximity influence female response to call complexity? 3) Are females constrained by their perceptual biology in discriminating differences in call complexity? 4) Can females remember attractive males over silences between bouts of advertising? Is working memory for attractive males dependent upon signal complexity? And 5) Does signal memorability increase with signal complexity in a linear relationship? These studies provide several new perspectives to an understanding of female preference for elaborate signals. Phonotaxis experiments demonstrate that females use elicitation behaviors to influence male production of complex calls, that proximity influences female response to signal elaboration, that females are constrained by their perceptual biology in discriminating between complex calls, that memory can influence the evolution of signal complexity, and that memorability and signal complexity share a non-linear relationship.Item Mechanisms of Mating-Behavior Deterioration in Early Aging Male C. elegans(2014-08-06) Guo, XiaoyanAging has been a subject of interest throughout history. Scientific studies have focused on lifespan regulation, but ignored many other aspects of aging such as behavioral decline. Research using the model organism C. elegans has contributed significantly to the aging field. In this dissertation, I used C. elegans males to determine the molecular mechanisms of behavioral deterioration during aging. Through mating potency assays, I found that the mating behavior of C. elegans declines at early adulthood, as the mating potency of 3-day-old wild-type males is significantly lower than 1-day-old males. Meanwhile, using both pharmacological tests and calcium imaging, I showed that the excitability of the mating circuit increased during early adulthood. This is consistent with the observation that old males exhibit reduced control over their ability to mate. Caloric restriction is an efficient non-genetic intervention to increase lifespan. I demonstrated here that it also improves mating behavior in 3-day-old males, possibly through reducing the excitability of the mating circuitry by up-regulation of potassium channels and additional metabolic enzymes. To explore the relationship between metabolic status and behavioral deterioration, I characterized the dynamics of male mating deterioration in males containing a deletion in the metabolism-regulator sir-2.1. sir-2.1 encodes a NAD^(+) dependent histone deacetylase, which might be involved in regulating aging. I discovered that sir-2.1(0) males have a premature decline in mating potency and an accelerated increase in the excitability of the mating circuitry. Direct mating behavior observations indicated that a significant proportion of 2-day-old sir-2.1(0) males cannot transfer their sperm into their hermaphrodite mates. Through Ca^(2+) imaging, I found that the genital sex muscles are hyper-contracted during sperm transfer. This hyper-contraction blocks the vas deferens and obstructs sperm release. Furthermore, through qPCR, measurements of metabolites, and diet supplementation, I found that the potentially enhanced catabolism in 1-day-old sir-2.1(0) and 2-day-old wild-type males generates excess reactive oxygen species (ROS). ROS increases the excitability of the mating circuitry and leads to the mating potency decline in subsequent days. Meanwhile, anabolic processes such as gluconeogenesis/glyceroneogenesis are also elevated. These processes shunt pyruvate from oxidative processes to lipid synthesis, and serve as a potential compensatory mechanism to reduce energy and ROS production. In conclusion, I demonstrated that a complex behavior in C. elegans deteriorated during early aging due to the physiological state change, which is possibly caused by ROS induced by both metabolic and stress-response alteration.