Many species use color during courtship displays, with the more colorful individuals often selected as potential mates. Female blue crabs, Callinectes sapidus, display prominent red markings on their chelipeds, which is absent in males. I tested the hypothesis that females use this sexual dimorphism as an effective signal to potential mates. Body size was positively correlated with size of the colorful pattern on the crusher dactyl. Digital imaging techniques were used to examine and quantify a pattern of coloration in the female blue crab. Morphometric measurements were made using digital images of the carapace and chelae of crabs collected along the Gulf of Mexico coast in Galveston, Texas. Color complexity was examined on digital images of the chelae using Adobe? Photoshop? and Image J. Specific wavelengths were selected and their presence within the attribute quantified and evaluated. To determine whether male blue crabs prefer more colorful females, males were given a choice between females of different female coloration. Males displayed more often and directed more courtship displays towards the more colorful females. I hypothesize that male blue crabs use cheliped coloration as a visual cue for mate selection.

Over the past forty years a tremendous number of women have entered the labor market, removing stay-home motherhood as the most dominant female occupation. The linkage between the change in the labor market and change in family structure has drawn a lot of attention from social scientists, and it is on this linkage that this analysis is focused. An essential dimension of this changing behavior is the sharp rise in out-ofwedlock childbearing. The central issue of non-married motherhood is more related to the diminishing willingness to marry than a changing attitude toward fertility. In a setting where individuals choose marriage because of the gains from joint production of child quality as well as the division of labor, the declining gains from specialization for men influence potential spouse selection. Men and women with fewer labor market prospects become less desirable, and consequently a marriage market with more positive assortative mating will be observed. The increase in female labor market participation is larger for highly-educated women but the decrease in marriage rates is more characteristic of less-educated women over this period. What drives these changes can be explained by using a simple economic theory, the fundamental concept of which is that couples with lower labor market prospects also face lower gains from marriage because of the increases in femalemale relative wages in the less-educated and black groups. A narrowing of the gap between male and female wages would reduce the gains from division of labor and lower the incentive to marry. In addition, when the marriage market becomes more positively assorted, low educated men and women are less likely to marry each other. Our empirical results indicate an increase in the homogeneity of wages between spouses over this period regardless of whether we control for education. In particular, black couples are more positively assorted than white couples although the trend converges by the end of the century. We also show that the marriage market is tilted towards better-educated men and women over the period. These findings are consistent with the theory which explains why single motherhood is more concentrated among lesseducated women.

Darwin identified sexual selection as an important evolutionary process resulting from differences among males in their ability to secure mates. In the latter half of the 20th century, it became apparent that females often mate with multiple partners within the same reproductive cycle, leading to the overlap of ejaculates from multiple males and sperm competition for the fertilization of the eggs. Here, I examine how sperm competition has influenced the evolution of Xiphophorus nigrensis, an internally fertilized, livebearing fish with alternative male mating tactics that are dependent upon male size. I find that variation in male tactic is correlated with variation in traits relevant to sperm competition: small males that sneak copulations produce ejaculates with a greater proportion of fertilization-capable sperm (sperm viability) and sperm that is longer-lived following activation compared to large males that court females. Sperm morphology is also divergent between tactics and correlated with sperm performance: smaller males have larger midpieces and midpiece size is positively correlated with sperm velocity and longevity. Social environment also affects ejaculate quality, with sperm velocity rapidly increasing when a small male is exposed to another small male compared to when he is exposed to a large male. Large male ejaculates were invariant across social environments. Next, I demonstrate experimentally that the observed variation in sperm quality has important consequences for the outcome of sperm competition. Males with superior sperm viability sire more offspring, while sperm velocity is negatively associated with sperm competitive ability when sperm are stored within the female prior to fertilization. Finally, I show that sperm competition is likely to have important effects on male reproductive success in the wild by characterizing the genetic mating system of X. nigrensis. I find that 61% of females collected from the Nacimiento Río Choy produce offspring sired by 2-4 males. Paternity is strongly skewed among sires, with an average of 70% of offspring sired by one of the males represented in the brood. These studies illustrate sperm competition can have potent effects on the evolution of animals. / text

Reproductive traits are often thought of as fixed, genetically determined properties. However, such traits are often dynamic, exhibiting different expression patterns depending on context. Both internal state and external environment can have a strong effect on how traits are expressed. Variation in these factors across the lifetime of an individual should select for flexibility in trait expression, rather than fixation.My dissertation work examines how mating behavior and testes size respond to several previously unexplored contextual factors, using Rhagoletis juglandis, the walnut fly, as a model system. For mating behavior, I predicted that differences in female reproductive state (egg load) and experience with host resource would impact mating decisions. For testes size, I predicted that social environment (sex ratio) and changes in resource environment would determine testes size.Behavioral observations of flies showed that a large egg load increased the likelihood of copulation, while prior experience with host fruit decreased copulation time. These results are the first to distinguish effects of experience on physiological state from other effects of experience in the context of mating behavior.Manipulation of the sex ratio revealed that males develop larger testes when reared in an environment with many potential competitors. This is the first study to show that that allocation to a male reproductive organ can change depending on the sex ratio. My studies showed that resource environment is also important in determining testes investment patterns. When adult males are deprived of protein, they develop smaller testes. A stable isotope analysis of testes further confirms that resource environment is important for testes development. Males rely more on nitrogen derived at the larval stage than at the adult stage, but adult carbon sources are a large component of testes mass.In sum, this dissertation demonstrates the importance of context in the expression of reproductive traits. Recent research has shown that such traits can respond more dynamically to context than previously thought, but this area of research is young. My results help provide a greater understanding of the processes shaping the evolution of reproductive traits.

Problem of inquiry: There are no named sow‘s impregnation influence for Lithuanian swine-breeding farms. When sows are non-impregnate fall all manufacture efficiency, getting less gaining’s and enlarge the prime cost for products. Goals of inquiry: Identify sow‘s impregnation efficiency influence reasons, rate their influence for swine-breeding economics indexes. Inquiry tasks: • Identify leading reasons for saw‘s impregnation. • Rate with sow connected actions influence for impregnation indexes. • Rate with boar connected actions influence for impregnation indexes. • Rate with farm factors connected actions influence for impregnation indexes. • Rate sow‘s non-impregnation influence for swine-breeding farm‘s economic process. Conclusions: In this prospecting work were analyzing sow‘s impregnation influence for Lithuanian swine-breeding farm‘s economic process. Clear, that for impregnation has influence genetic indexes and feature of the farm. Sows impregnation directly has influence for farms practices profitability. If enlarge sows non-impregnation percentage, then profitability is lowing and enlarge price for shoats.

Pre-copulatory sexual cannibalism (pre-SC), or predation of a potential mate before sperm transfer, provides an ideal model system for behavioral ecology's current focus on inter-sexual conflict. Studying the North American fishing spider (Dolomedes triton), I tested three female-benefit hypotheses for pre-SC: indirect benefits, direct benefits, and aggressive spillover. First, pre-SC may reflect a mating bias providing females with 'good-genes' benefits. By manipulating each female's options with regard to the most cited phenotypic advantage in male spiders, body size, I show that while females exhibit no bias in their attack tendency on males of different body sizes, large males mate significantly more often than small males. Second, pre-SC may be explained by direct benefits if females use it as an adaptive foraging/mating trade-off. My work provides mixed support for this idea: (i) females vary attacks according to the availability of mates, (ii) females do not vary attacks according to the availability of food, and (iii) females derive discrete fecundity benefits from consuming a male. Finally, I tested the aggressive-spillover hypothesis, which posits that pre-SC is a by-product of selection for high levels of aggression towards prey in traditional foraging contexts. Path analysis indicated intra-individual, positive correlations between aggression in foraging contexts and the mating context, thus supporting the hypothesis. I conclude by stressing that pre-SC in a given species may rarely be explained by one hypothesis, and that studies accounting for multiple benefits that fluctuate as behavioral-ecological contexts shift should give a more realistic glimpse of behavioral ecology and evolution.

Males of many species have elaborate phenotypes that are absent in females and that are thought to be the result of sexual selection. Sexual selection requires: (i) variance in male mating success, (ii) variation in male phenotype, and (iii) covariation between male mating success and male phenotype. Environmental conditions influence these factors, and management practices that alter environmental conditions have the potential to shape mating patterns and sexual selection. I investigated the hypothesis that the frequency of fire, used to manage tallgrass prairie, affects the mating patterns and process of sexual selection in the organisms breeding in managed prairies. I studied dickcissels (Spiza americana), a small songbird resident in tallgrass prairie. I first examined mating patterns and sexual selection in dickcissels independent of burning regime. I found variation among males in the number of mates attracted, in the number of offspring sired with each mate, and the offspring sired with the mates of other males. I found a positive association between social mates and siring success, but no evidence for an effect of breeding density or synchronous nesting on mating success. Male dimorphic traits, size, song, and plumage, showed between-individual variation but selection gradients were weak and often fluctuated between the years of study. I next examined patterns of mating success in plots burned on a variable schedule. I found little evidence that burning influenced either the mean or the variance in social mating success, paternity, or male phenotype. Burning regime also had no influence on sexual selection gradients with the single exception of selection on tarsus length. Temporal variation was more important for patterns of mating success and sexual selection gradients on male traits than was burning regime. The demography of dickcissels in the breeding season suggests, however, that habitat management on a larger scale may be more influential. My findings extend our understanding of sexual selection in birds and the effects of management on the factors required for sexual selection and the magnitude of selection.

By performing a comparative analysis and using phylogenetic relationships of the Cervidaefamily this study aimed to address whether or not sexual selection may play a role in the extinctionof species by making species more vulnerable to extinction. The role of sexual selection in makingspecies more vulnerable to extinction is largely unexplored, and several factors such as ecologicaland life history traits may increase the risk of extinction.In all species of the family Cervidae (Gilbert et al. 2006, Geist 1998,Groves and Grubb2011,Meijaardand Groves2004,Price et al. 2005, Goss 1983) sexually selected characters plays amain role in determining species status and thus potentially their probability of extinction. In thisstudy the intensity of sexual selection (measured as sexual size dimorphism, antler size and matingsystem) and the rate of extinction (IUCN classification and anthropogenic effect) were counted asfactors to determine the role of sexual selection intensity in both species-rich and species-poorclades.By using the programme MESQUITE and phylogenetic trees, the results show an associationbetween species with larger body size and dimorphism, living in open habitats and having largerantler size expanded to more than three tines; such species are mostly non-territorial and formharems during the rutting season. The small species are territorial, live in closed habitats, aremonomorphic and have small antler size limited to two tines or less. Moreover species that aremore subjected to habitat degradation and anthropogenic effects tend to become smaller in size.Extinction risk for the species-rich clades with small sized, territorial and small antler sizedspecies is lower than for those consisting of species with larger antler size, larger body size, livingin open habitats and using harems as mating system.To sum up, the intensity of sexual selection in larger species in deer family put them in risk ofextinction; but on the other site, small species are more adapted to the environment by choosingdifferent strategy in mating system, and reducing antler and body size thus diminishing theextinction risk.

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Drug resistance is a major obstacle to management and control of malaria and currently progressing at a rapid rate across Africa. This thesis has examined factors influencing evolution of resistant P. falciparum at two sites in Africa, including parasite migration, cross mating and fitness cost of resistance. In Asar village, eastern Sudan, the frequencies of drug sensitive and resistant parasites were monitored throughout the dry season in the absence of anti-malarial drug usage to examine whether persistence of resistant parasites is reduced in the absence of drug pressure. Two cohorts of P. falciparum infected patients were treated with chloroquine in the transmission season (Oct-Dec), and followed monthly in the dry season into the next transmission season. A large proportion of the cohort maintained sub-patent asymptomatic P. falciparum infections throughout the entire study period. Alleles of the chloroquine resistance transporter (Pfcrt) and multi-drug resistance protein (Pfmdr1) were examined. Mutant alleles of Pfcrt reached fixation following CQ treatment and remained high in the transmission season. However, at the start of the dry season, wild type alleles of both genes started to emerge and increased significantly in frequency as the season progressed. The mutant Pfcrt haplotype was invariably CVIET, indicating migration of CQ resistant parasites into an area; otherwise the CVMNK haplotype is normal. In addition, microsatellite haplotypes of dihydrofolate reductase (dhfr) gene and dihydropteroate synthase (dhps) genes, which control the parasite response to pyrimethamine and sulfadoxine respectively, were characterized. One major dhfr haplotype with double dhfr mutations and two major mutant dhps haplotypes were seen in eastern Sudan. These haplotypes are distinct from those prevailing in other African countries, suggesting the likely local origin of dhfr and dhps haplotypes conferring drug resistance. Transmission capacities of different P. falciparum clones within a single infection in The Gambia have a high ability to produce gametocytes and infect Anopheles mosquitoes even when they exist at levels not detectable by microscopy and PCR. These findings emphasize the crucial role of gametocyte complexity and infectivity in generating the remarkable diversity of P. falciparum genotypes seen in infected people. Parasites with different resistant dihydrofolate reductase (dhfr) haplotypes have the ability to infect Anopheles mosquitoes following drug treatment, and cross-mating between parasites with different dhfr haplotypes was detected. Our results showed that the major dhfr haplotype in the Gambia is similar to the common one seen in other African countries, suggesting that parasite migration plays a major role in spread of resistance. Indeed, the dominant resistant haplotype seen in infected patients was readily transmitted to infect mosquitoes.