Browsing by Author "Meffert, Lisa M."

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    Does more choice equal a better choice? Courtship behavior, mating propensity and female fitness in relation to the number and density of potential partners
    (2007) Carrillo, Juli Ann; Meffert, Lisa M.
    The good genes hypothesis predicts that females discriminate among potential mates on the basis of their genetic quality. We measured the indirect benefits received by females with different levels of choice---from no choice to choosing among 5 males---in the housefly, Musca domestica , at high and low density. Secondly, we tested how the degree of choice affected the courtship behavior of both sexes and whether this behavior was correlated to female reproductive success. Opportunity for choice did not affect mating propensity or offspring survivorship, but did affect male courtship rate and the number of eggs females laid in their first clutch. Females at low density were more likely to mate, laid more eggs in their first clutches, and had greater egg-to-adult viability than females mated at high density. Overall, the degree of choice affected some aspects of mating behavior and fitness, but the effects were primarily density dependent.
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    Experience-dependent courtship modification in the housefly, Musca domestica
    (2005) Hagenbuch, Kara Leigh; Meffert, Lisa M.
    The genetics of mating behavior may be complicated by factors such as an association with fitness, social interactions, and genotype-by-environment interactions. In order to evaluate the potential consequences of these factors, I analyzed courtship behavior in the housefly, Musca domestica L. by specifically examining (1) mating success, (2) experience-dependent courtship modification (learning), and (3) heritability. Males (N = 120) were paired with six virgin females over the course of three days and videotaped for a maximum of 30 minutes, or until copulation occurred. Courtships were analyzed for six behaviors within and among females. Successful courtships, in comparison to unsuccessful attempts, were characterized by a shorter Duration of Courtship, less intense Lunge and Wingout, and more intense Buzz, Hold, and Lift. Among courtship attempts within females, males decreased Buzz and increased Lunge. The females also adjusted their behavior by modifying Wingout, which demonstrates a male-female interaction component of mating success. Among courtship attempts across serially mated females, males decreased the Duration of Courtship and Lunge. Analyses were also completed using both within and across female data, and there was a general trend for a decrease in the behavior traits, except for Buzz, which did not change. Also, males decreased the number of courtship attempts with successively mated females, indicating the ability to learn through improved courtship technique. Weibull functions showed that the males had significant learning curve functions for individual behavior traits, although the tests for the repeatability and heritability of such functions were not significant. Finally, repeatabilities and heritabilities (estimated by a broad-sense family effect) were calculated for the courtship traits. Pooled analyses on successful and unsuccessful courtship attempts revealed significant repeatabilities (0.05-0.67) and heritabilities (0.07-0.50) for almost all of the courtship traits, although analyses on just the successful courtships failed to replicate the significant effects, except for the male display, Hold (0.29). These results demonstrate that male courtship behavior is multifaceted in that it consists of not only a learning component, but a genetic component, too. Although previous housefly experiments have shown indirect support, this is the first direct evidence for male learning within courtship behavior.
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    The effects of population density on courtship behavior in the housefly, Musca domestica
    (2004) Hicks, Sara Kolb; Meffert, Lisa M.
    The housefly, Musca domestica, was used to test the short-term and long-term environmental effects of high population density. The first phase addresses the issue that there are two main selection forces that drive mating behavior, inter- and intrasexual selection. In intersexual selection the females are actively discriminating when choosing a mate and, thus, these male-female interactions are what predominantly define that population. However, in intrasexual selection, males potentially compete against each other over the pool of receptive females. I tested the hypothesis that a less complex courtship would be optimal in a high-density environment, short-term (i.e., one generation). Specifically, I videotaped the mating behavior of individuals subjected to one of two treatments: high-density or low-density (i.e., 200 virgin male-female pairs in a 2 L or 114 L cage, respectively). In both treatments, the flies were allowed to mate for 30 minutes while being videotaped. The proportion of time spent in three male courtship behaviors (HOLD, FORWARD, BUZZ) and one female courtship behavior (WINGOUT) were determined. I found that the mating propensity (percent of mated pairs) was significantly greater in the high-density environment. The courtships in the high-density environment were also significantly less complex (i.e., less FORWARD, less HOLD). My findings suggest that high-density environments stimulated competition among males causing the intrasexual selection processes to outweigh the intersexual processes. The second phase tests the prediction that long-term (i.e., eight generations), high population density will drive the evolution of courtship repertoire towards decreased complexity. I applied the previously outlined methods. Additionally, only those pairs that mated within the allotted time were allowed to contribute to the following generation. The courtship behavior assays suggest that the synergistic effects of high density on the males and inbreeding depression drove the evolution of increased courtship complexity and exaggerated inbreeding depression, therefore, not supporting the prediction or the results of first phase. In the low-density treatment, courtship became less complex and mating propensity increased. These results are applicable to populations with unnaturally high densities and potential for inbreeding such as those in laboratory agricultural pest control, and conservation projects.