In this study I present a new mechanism for the evolution of male display as a consequence of female choice. I use a population genetic model to show that if female preferences for better males are based on a cue that is an integral part of male adaptation, a display may evolve if it amplifies the variance in this cue, and hence increases female resolution power with respect to male quality. This evolutionary mechanism is used as a core of a theory that explains the evolution of male display and adaptive female choice (i.e. female preferences that evolve because of their association with high quality genes). I argue that because an amplifying display (termed "amplifier") decreases mating success of males of poor quality, modifiers are likely to evolve that decrease the expression of the amplifier when associated with the poor quality males. As a result, the amplifier's expression becomes an indicator of male quality, and provides sufficient conditions for the evolution of a new type of female choice that is based on the amplifier's expression. This process may lead, in turn, to further changes in both female choice and male display, emphasizing either the amplifying effect of displays or their indicating effect. I show that the direction of these changes may depend on the cost that the amplifier confers on male viability, and on the degree of polygyny of the mating system in concern. I also outline explicit predictions for empirical tests.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 59-63). Also available via the Internet.

Displays of 36 Sceloporus undulatus hyacinthinus from 8 clutches were recorded on video tape from the day of hatching to adult size during 1978, 1979, and 1980. Nine hundred forty-one displays were analyzed frame by frame, and durations of display units were calculated to the nearest 0.01 s. From the day of hatching, males and females performed both of the display types found in adults, and little significant ontogenic change was found in display patterns or in unit durations; only 7% and 6% of total variance in A and B Displays, respectively, was due to ontogeny. Stereotypy of unit durations both within and among lizards was unchanged across time. Consequently, the display patterns are viewed as being purely innate. Some ontogenic changes were observed in the ways in which the lizards utilized the displays patterns. As compared with hatchlings, older lizards tended to display more frequently, to use display modifiers more often, and to perform displays in aggressive and courtship contexts as well as in assertion. Older females had a significantly higher A: B ratio than males or younger females. These changes in display behavior are viewed as being due to the influences of hormones and social experiences. Slightly more than half of the variance in unit durations for A and B Displays was attributed to inter-individual differences. Of this, approximately half was due to differences among clutches and half to differences among lizards within clutches. For B Displays there were some inter-individual differences (e. g., deleted bobs or dips preceding certain bobs) in the form of the displays as well as in unit durations. Individuals were not consistent in the inclusion of these characteristics in their B Displays. Mean heritability estimates for durations of units 1-12 were 0.60 and 0.38 for A and B Displays, respectively. / M. S.

The display repertoires of three sibling species of Anolis lizards, were quantitatively analyzed and described. These species are distributed along Haiti's western coast with no major geographic barriers separating their populations. Anolis websteri is the northernmost species, Anolis caudalis is centrally located, and Anolis brevirostris is the southernmost species. Except for contrasting dewlap color at the species contact zones, they are identical in physical appearance. Behavioral mechanisms have been implicated in the reproductive isolation of the species. Because the head bob displays consistently incorporate the dewlap and are important in anoline communication, they may be the focal point of this isolation. This study documents a species-unique display repertoire for each of the siblings and thereby supports this hypothesis. Analysis of 736 head bob displays revealed that each species possesses one stereotyped Type A display and one to three stereotyped B displays (A. caudalis, one; A. brevirostris, two; A. websteri, three). Each species' A display resembled that of its siblings, however, discriminant analysis procedure clearly discriminated between the three species' A displays. This procedure also demonstrated differences between the Type B displays. The six kinds of Type B displays in the combined repertoires were considered derived from one B display pattern. An interpretation of the evolutionary sequence of these patterns is provided in a cladogram in which the A. caudalis display was considered the outgroup. The cladogram shows the three displays of A. websteri are the most apomorphic and the two displays of A. brevirostris the most plesiomorphic. / Master of Science

Long-tailed Manakins Chiroxiphia linearis are frugivorous birds with a lek mating system and male-male cooperation in courtship display. I studied male-male networks and correlates of male mating success in a color-banded population in Monteverde, Costa Rica, from 1981 to 1986. Males were organized in teams at scattered perch-zones (75 to 300 m apart) that were usually in aural but not visual contact. Each team consisted of 3 to 15 males (x=7.1±3.4), in an apparent linear dominance hierarchy, with an alpha and beta male who did most of the courtship display. In a study population with 50 to 60 active males per season, only 6 to 8 males were alphas. Only betas inherited alpha status (n=3). Males appear to be 8 or more years of age before attaining beta status. Alpha tenure can last 4 years. Alpha males were rarely or never seen in zones other than their 'home' zone. Lower-ranking males maintained simultaneous affiliations with males at as many as 6 different zones. Each zone, therefore, was a sort of hub at which males with different affiliations around the rim came into contact. Each of the 6 major perch-zones shared at least one constituent with each of the other zones. The mean number of males shared by zones was 3.9 ± 2.7 (range=1 to 9). Marked changes occurred in male traits with increasing age and status. These included (1) Significant declines in weight throughout the lifespan, (2) a 4-year delay in plumage maturation with well-defined stages, (3) reduction in the number of zones with which males maintained affiliations, and (4) increasing probability of copulatory success (restricted to a small subset of the oldest males, ≥ 10 years of age). Variance in copulatory success was the highest yet described for birds. Of 85 males monitored between 1983 and 1986, copulations (n=121) were distributed among only 8 males. Four of these males accounted for over 90% of the copulations, with 63% accruing to one male. The beta male of this alpha copulated twice in the absence of his partner; all the other copulaters were alphas. I examined correlates of male mating success. Female visitation correlated with the number of unison 'toledo' calls given. If a female visited, copulatory success correlated both with a residual effect of the 'toledo' output and with the duration of the 'butterfly' component of the dual-male dance performance. My correlational results suggest that females do choose, on the basis of performance cues, among the small subset of males that are well-established alpha and beta partners. Development of alliances, as much as male combat, may determine attainment of high-performance partner status. Thus, sequential male-male interactions and female choice appear to produce nested subsets of successful males leading to an extreme in variance in male mating success. Males unsuccessful in male-male interactions are not 'eligible' for female choice. By requiring partnered display, females may be implicitly narrowing the subset of potentially successful males. In other lek systems the union, rather than the intersection, of the subsets produced by intra- and intersexual selection may include successful males. In that case, intrasexual selection via disruption of copulations may enlarge the pool of potentially successful males under intersexual selection and produce lower variances in male mating success. Students of sexual selection may need to consider the extent to which intra- and intersexual selection interact as union or intersecting sets to produce variance in male mating success.

Thesis (Ph.D.)--Ohio University, March, 2009. / Title from PDF t.p. Includes bibliographical references.

Invasive species can have a variety of effects on the behavior and ecology of native species. Currently in New Orleans, Louisiana, both A. sagrei and A. carolinensis lizards are relatively abundant, but the A. sagrei population is expanding rapidly. I used a combination of laboratory and field studies to investigate factors that might be influencing local dominance of invasive A. sagrei over native A. carolinensis populations, including habitat use, display behavior, interspecific aggressive interactions, and plasticity. When comparing display behavior and habitat use in anole populations across three field sites in southern Louisiana, I found differences in male display behavior of both species, and also that A. carolinensis perched higher when A. sagrei was present. In staged interspecific interactions, I discovered that A. sagrei females achieved consistently higher aggressive scores than A. carolinensis females, suggesting that female interspecific behavior is probably more important than male behavior in driving changes in habitat use. Lastly, I studied plasticity in several morphological and whole-organism performance variables by rearing males and females of each species on two different perch diameters. I found that sprinting performance in A. sagrei was significantly different between treatment groups, although the morphological differences between perch treatments were subtler than those reported in previous studies. I also found that A. carolinensis females exhibited significant differences in both sprinting and clinging performance, despite no significant differences in male or female morphology between perch size treatments, highlighting the potential for both species-specific and sex-specific plasticity.

Anolis bahorucoensis males were found to possess three species-specific stereotypic displays in their repertoire, referred to as types A, B, and C, and one nonstereotypic headbob movement, the step-bob. Female A. bahorucoensis were found to use one stereotypic display pattern, analogous to the males' type A display. Anolis bahorucoensis also performed eight display modifiers, many of which were typical of the Anolis genus, including: mouth gape/tongue protrusion, gular expansion/dewlap extension, dorsal and nuchal crests, lateral compression, lateral presentation and bow. Two modifiers performed by males were unique to A. bahorucoensis: labeled as "hip-kick" and “head-swing". Use of displays and modifiers was examined for four contexts: malealone, male-male, male-resident-female, and male-strange-female. Anolis bahorucoensis type A, B, and C displays demonstrated extreme minimalization in structure (i.e. low head amplitude, high frequency twitch-nods) and signal use (i.e. low display rates, performed at short inter-lizard separation distances) which are in direct opposition to the display behavior of other anoles. Other atypical anoline characteristics of A. bahorucoensis include reduced dewlap size and infrequent dewlap extension. / Master of Science

Particularly lacking in the current body of sexual selection literature are studies based on reptile species and intrasexually selected mating systems. Because the life history traits and ecology of reptiles are dramatically different from other animal taxa, current models of sexual selection are insufficient for predicting how sexual selection should influence the behavior and mating systems of lizards. Similarly, intersexually selected mating systems (i.e., based on female choice) are inappropriate predictive models for examining species with intrasexually selected mating systems (i.e., based on consexual contests). I investigated three aspects of Anolis carolinensis behavior and mating system (communication signals, male mate preference, and reproductive energetics) to contribute to a theoretical model for sexual selection based on a lizard with an intrasexually selected, polygynous mating system. In my first study, I quantified the structure and use of signals exchanged by both sexes, compared signal structure and use during heterosexual interactions to that of other social contexts (e.g., male-alone, male-male, female-female), then related signal structure and use to the species mating system. During heterosexual interactions, both sexes performed three kinds of stereotypic headbob displays with equal precision that were essentially identical to those previously documented for other social contexts. Thus, there is no courtship-specific headbob display for A. carolinensis. However, male and female signal use was extremely dimorphic. For the purpose of indicating sexual identity, the sexually dimorphic patterns of signal use were excessively redundant, yet equivocal. Although the male pattern of signal use reliably conveys sexual identity, the female pattern of signal use conveys ambiguous sexual identity. Based on circumstantial evidence from other studies, I propose the hypothesis that the female pattern of signal use may permit female-sized, nonterritorial males to mimic female signals. Small males may be selected to use female mimicry to gain access to the territories of larger males and mating opportunities with resident females, while females may be indirectly selected to use a signaling pattern that provides them with an alternative mating option. From field and laboratory data on A. carolinensis signal behavior during other social contexts and the species' female-defense mating system, I evaluate proposed functions for heterosexual signaling from a perspective of intrasexual selection. In my second study, I tested the prediction that males should include a preference for mating with novel females (PNF) as part of their mating strategy. This prediction was supported by both laboratory and field manipulations. Compared to their encounters with resident females, males during laboratory encounters with novel females significantly increased their display rate, volley frequency, volley length, and significantly decreased the distance and number of movements traveled away from the female. My laboratory data also suggest that males discriminated novel females from resident females independently of female behavioral or chemical cues. Similarly, compared to their interactions with resident females, free-ranging males responded to introduced novel females by significantly increasing the proportion of time spent in female-directed activities and the proportion of displays directed toward novel females, and significantly decreasing the proportion of time spent in territorial activities and the proportion of displays used in territorial activities. Data from both experiments indicate that males appear to distinguish among individual females, and use this ability to increase reproductive success by identifying and preferentially pursuing novel females over previously inseminated resident females. I suggest that males are able to cognitively identify individual resident females, and use this ability to control mating decisions within their territories. In my third study, I examined the energy expenditure of males and females during breeding and postbreeding seasons. I used laboratory respirometry to determine resting metabolic rates, and the doubly-labeled water technique to determine field metabolic rates in free-ranging lizards. Resting metabolic rates were significantly influenced by body mass and season, but not sex. Field metabolic rates were significantly influenced by body mass, but not sex or season. I attributed the ~40% seasonal increase in resting metabolic rates to a seasonal increase in feeding rates and the effect of specific dynamic action. Resting and field metabolic rates were used to calculate energy budgets for each sex during breeding and postbreeding seasons, and to calculate the energy expended by each sex for reproduction. Despite having 40% smaller body mass, females expended 46% more energy for reproduction than males, and a similar amount of total maintenance energy as males. The total maintenance energy of males was similar during both seasons, however that of females decreased 44% from breeding to postbreeding season. I found both seasonal and sexual differences in the amount of energy lizards allocated to resting and activity. Anolis carolinensis had field metabolic rates that were similar to tropical and temperate species of lizards, and higher than lizards from arid/semiarid environments. Anolis carolinensis also expended more energy on eggs, and more total energy during the breeding season, than lizards from arid/semiarid habitats. / Ph. D.