Life Sciences Commons^™

The Complexity Of Female Treefrog Mate Choice: Choosiness And Preferences Are Independent Behaviors And Each Are Prone To Separate Sources Of Variation, Olivia S. Feagles

Theses and Dissertations

Mate choice is an important cause of natural and sexual selection, driving the evolution of ornaments and promoting diversification and speciation. Mate choice decisions arise from the interaction of several components, and knowledge of whether they interact, and how, is crucial for understanding their contributions to selection. There are multiple components of mate choice theoretically proposed, and here I focus specifically on preference functions (attractiveness ranking of prospective mates) and/or choosiness (willingness to invest effort in obtaining the preferred mate). Objective 1 (addressed in Chapter I) of this dissertation focuses specifically on the relationship between preferences and choosiness, testing the …

Influence Of Testosterone On Male-Male Competition In The Red-Sided Garter Snake, Thamnophis Sirtalis Parietalis, Isabella M. G. Bukovich

Senior Honors Projects, 2020-current

Female mimicry in the red-sided garter snake, Thamnophis sirtalis parietalis, is described in several well-studied evolutionary advantages, but an aspect that remains elusive is how reproductive traits are linked to the 3-fold higher circulating androgens in males with this phenotype. In this study, we implanted male garter snakes (n=15 per group) with either a blank implant (SHAM; control) or a T implant, the latter simulating the female mimic phenotype. Following simulated low-temperature dormancy, males were scored for courtship intensity over three days of behavioral trials with females housed in the same facility. Males were sacrificed, and sperm were collected …

Connecting The Dots: Exploring The Relationship Between Avian Eggshell Pigmentation And Paternal Provisioning Effort, Kara E. Hodges

Theses and Dissertations

In a number of bird species, eggs laid by females breeding in the same population can vary extensively in the extent of their eggshell pigmentation, but the adaptive significance of this intraspecific variation remains unknown. One hypothesis posits that shell pigmentation is an honest signal of female quality that reflects her level of oxidative stress, one that is used by males to inform their subsequent paternal investment. We employed a reciprocal clutch cross-fostering design to test whether provisioning by male house wrens (Troglodytes aedon) responds to the clutch pigmentation of their mates. In experimental replicates, dark clutches were swapped with …

Reproductive Character Displacement In Calopteryx Aequabilis And C. Maculata: Improving Species Recognition Through The Divergence Of Male Mating Preferences, Melissa Encinias

Masters Theses, 2010-2019

An ongoing evolutionary question is how co-occurring species maintain reproductive barriers when they are morphologically, behaviorally, and ecologically similar. Without geographic isolation, traits involved in species recognition may be under selection to enhance reproductive barriers. Exaggerated trait differences between species in sympatric populations may reflect selection to reduce misdirected mating between species, or reproductive character displacement. While this phenomenon is widely recognized as an important stage in the speciation process, there is little direct evidence of this process in nature. In two North American damselfly species, Calopteryx aequabilis and C. maculata, wing pigmentation is sexually dimorphic and also shows …

The Meaning Of Song Type: Exploring Behavioral Responses Of Field Sparrows To Three Simple Song Types, Eliza Foli

Honors Theses

The frequency, rate, and overall quality of a male’s song may indicate the singer’s physical quality, either as a threat or as a potential mate, and are used for species recognition. However, the degree to which a song must differ acoustically to communicate different information about the singer remains unclear. Analysis of male field sparrow simple song recorded in southwest Michigan revealed three structurally distinct clusters of simple song that differ in frequency characteristics. We hypothesize that songs in each cluster convey information about the singer and that receivers respond more strongly to songs more similar to their own song. …

Understanding Patterns Of Diversity And Evolution In Mainland Anolis Lizards, Levi Gray

Biology ETDs

Patterns of organismal diversity and evolution are often difficult to interpret with a high level of confidence. The number of mechanisms and processes that contribute to shaping patterns of diversity is extensive and is reflected in the many methods researchers have used to infer causation. Taxonomic groups that are well-studied can offer more precise interpretation of pattern and process due to the considerable amount of research addressing ecology, natural history, and behavior of the organisms.

In this dissertation, I explore patterns of phylogenetic and phenotypic variation in Anolis lizards (anoles) by testing hypotheses that could have led to the observed …

Plumage Ornaments Signal Male Physiological Quality In Common Yellowthroats, Amberleigh E'Vaughn Henschen

Theses and Dissertations

Elaborate ornaments are thought to honestly signal quality to potential mates. These ornaments may signal a variety of physiological processes that affect health and fitness. I examined the relationship between ornaments and physiological quality in a bird, the common yellowthroat (Geothlypis trichas). Male common yellowthroats have two plumage ornaments, a black (eumelanin-based) mask and a yellow (carotenoid-based) bib. Males with larger masks are preferred by females for both extra-pair and social mates. I found that both the mask and the bib of male common yellowthroats honestly signal their ability to resist oxidative stress. Males with larger masks and more colorful …

Primate Proteomic Composition Of Seminal Plasma And Prostate-Specific Transglutaminase Activity In Relation To Sexual Selection., Amanda M.C. Zielen

Electronic Theses and Dissertations

Humans (Homo sapiens), chimpanzees (Pan troglodytes), and gorillas (Gorilla gorilla) have diverse mating systems with varying levels of sperm competition. Several seminal plasma genes have been claimed to evolve under positive selection, while others are altered or lost. This study aims to identify biologically relevant differences among seminal plasma proteomes of primates in relation to mating systems and previous genomic studies. Seminal plasma from three individuals of each species were run in triplicate in shotgun liquid chromatography – tandem mass spectrometry (LC-MS/MS) and confirmed with Western blots. Over 7,000 peptides were identified across all …

The Importance Of The Multicomponent Display In Sexual Selection Of Black Morph Girardinus Metallicus (Pisces: Poeciliidae), Erin M. Wojan

Master's Theses

Multicomponent displays are composed of traits, such as coloration, structural ornaments, and behavior, that become integrated and signal information to conspecifics. Estimation of multicomponent displays in fishes often involves measurement of color traits. Fish color measurements are often obtained following immobilization via chemical anesthesia; however, the anesthetics may alter the resulting measurements, for example by darkening the skin. Girardinus metallicus, a poeciliid fish endemic to Cuba, has a multicomponent courtship and aggressive display. Black morph males exhibit black ventral coloration including the gonopodium (copulatory organ) and yellow in the non-black areas of their bodies. I investigated the effects of …

A Test Of The Effects Of Androgens On Immunity: No Relationship Between 11-Keto Testosterone And Immune Performance In Bluegill Sunfish (Lepomis Macrochirus), John W. Loggie

Electronic Thesis and Dissertation Repository

The posited immunosuppressive effects of androgens are a key component of the immunocompetence handicap hypothesis (ICHH). My thesis uses bluegill sunfish (Lepomis macrochirus) to test two predictions arising from this hypothesis: (1) natural concentrations of the androgen 11-keto testosterone (11-KT) will be negatively related with immunity, and (2) an immunochallenge will lower 11-KT concentration. I found no evidence for a relationship between natural 11-KT concentration and measures of immunity (leukocyte counts, respiratory burst, cytokine gene expression), and an immunochallenge with Vibrio vaccine did not affect 11-KT concentration. I performed a meta-analysis of immunochallenge studies to help interpret my …

Stress, Sexual Signaling, And Alternative Mating Tactics In Male Green Treefrogs, Hyla Cinerea, Sarah Crocker-Buta

Electronic Theses and Dissertations

This thesis examines how the endocrine stress response mediates the expression of courtship signals and alternative mating tactics in male green treefrogs, Hyla cinerea. Males of this species produce acoustic signals that stimulate production of the stress hormone corticosterone (CORT) in vocal competitors, suggesting a role of CORT in intrasexual competition. I predicted that modulation of CORT level during intraspecific contests plays a pivotal role in regulating the expression of male courtship signals and behavior. Consistent with this prediction, CORT administration to calling males, simulating CORT production during male vocal contests, decreased attractiveness by compromising energetic investment in vocalization, increasing …

Sexual Selection Dynamics In A Smoky Hills Population Of Crotaphytus Collaris, Katherine Talbott

Master's Theses

Recent studies in behavioral ecology have suggested environmental pressures might influence sexual selection dynamics to the extent that sexually-selected signals reflect local adaptation. I experimentally tested this hypothesis by manipulating a potential male ornament and observing the sexual selection dynamics in a Smoky Hills population of eastern collared lizards (Crotaphytus collaris). Sexual selection dynamics were investigated by characterizing habitat structure, describing individual lizard spatial distribution, and investigating morphological predictors of adult male territorial success. Habitat occupied by lizards had significantly different and higher percentages of rock cover, and significantly different and lower percentages of vegetation cover, than unoccupied habitat. No …

Ecology Of Mating Patterns And Sexual Selection In Dickcissels Breeding In Managed Prairie, Bridget Frances Sousa

Theses and Dissertations--Biology

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 …

The Maintenance Of Male Color Polymorphism In Poecilia Parae, Jorge L. Hurtado-Gonzales

Biology - Dissertations

Genetic color polymorphisms are common in nature, and a major challenge for evolutionary biologists has been to understand how they are maintained despite the effects of directional selection. Recent studies suggest that frequency-dependent selection may explain the persistence of intraspecific variation in color. However, it remains to be determined whether frequency-dependent selection is the most predominant (or perhaps the only) mechanism to maintain such genetically-based polymorphisms. Using a South American fish, Poecilia parae, my dissertation aims to elucidate the relative roles of natural and sexual selection in the maintenance of polymorphisms in natural populations. Poecilia parae males exhibit five distinct, …

Sex-Biased Parasitism And The Reproductive Costs Of Parasites In A Social African Ground Squirrel, Melissa Ann Hillegass

Electronic Theses and Dissertations

Vertebrate males frequently carry higher numbers of parasites than females. This bias in parasite loads could be a consequence of sexual selection. Grouping species are also assumed to be afflicted with larger numbers of parasites than solitary animals and associated costs of this parasitism could vary with group size or structure. I examined sex-biased parasitism and the influence of group size on parasite loads in Cape ground squirrels (Xerus inauris), a highly social species that occurs in the arid regions of southern Africa. Males carried three times as many ectoparasites as females, but females harbored nearly three times more endoparasites …