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- Creators: Haydn, Joseph, 1732-1809
Description
Social structure affects many aspects of ecology including mating systems, dispersal, and movements. The quality and pattern of associations among individuals can define social structure, thus detailed behavioral observations are vital to understanding species social structure and many other aspects of their ecology. In squamate reptiles (lizards and snakes), detailed observations of associations among individuals have been primarily limited to several lineages of lizards and have revealed a variety of social structures, including polygynous family group-living and monogamous pair-living. Here I describe the social structure of two communities within a population of Arizona black rattlesnakes (Crotalus cerberus) using association indices and social network analysis. I used remote timelapse cameras to semi-continuously sample rattlesnake behavior at communal basking sites during early April through mid-May in 2011 and 2012. I calculated an association index for each dyad (proportion of time they spent together) and used these indices to construct a weighted, undirected social network for each community. I found that individual C. cerberus vary in their tendency to form associations and are selective about with whom they associate. Some individuals preferred to be alone or in small groups while others preferred to be in large groups. Overall, rattlesnakes exhibited non-random association patterns, and this result was mainly driven by association selection of adults. Adults had greater association strengths and were more likely to have limited and selected associates. I identified eight subgroups within the two communities (five in one, three in the other), all of which contained adults and juveniles. My study is the first to show selected associations among individual snakes, but to my knowledge it is also the first to use association indices and social network analysis to examine association patterns among snakes. When these methods are applied to other snake species that aggregate, I anticipate the `discovery' of similar social structures.
ContributorsAmarello, Melissa (Author) / DeNardo, Dale F (Thesis advisor) / Sullivan, Brian K. (Committee member) / Schuett, Gordon W. (Committee member) / Arizona State University (Publisher)
Created2012
ContributorsHaydn, Joseph, 1732-1809 (Composer)
ContributorsHaydn, Joseph, 1732-1809 (Composer)
Description
Sexual and social signals have long been thought to play an important role in speciation and diversity; hence, investigations of intraspecific communication may lead to important insights regarding key processes of evolution. Though we have learned much about the control, function, and evolution of animal communication by studying several very common signal types, investigating rare classes of signals may provide new information about how and why animals communicate. My dissertation research focused on rapid physiological color change, a rare signal-type used by relatively few taxa. To answer longstanding questions about this rare class of signals, I employed novel methods to measure rapid color change signals of male veiled chameleons Chamaeleo calyptratus in real-time as seen by the intended conspecific receivers, as well as the associated behaviors of signalers and receivers. In the context of agonistic male-male interactions, I found that the brightness achieved by individual males and the speed of color change were the best predictors of aggression and fighting ability. Conversely, I found that rapid skin darkening serves as a signal of submission for male chameleons, reducing aggression from winners when displayed by losers. Additionally, my research revealed that the timing of maximum skin brightness and speed of brightening were the best predictors of maximum bite force and circulating testosterone levels, respectively. Together, these results indicated that different aspects of color change can communicate information about contest strategy, physiology, and performance ability. Lastly, when I experimentally manipulated the external appearance of chameleons, I found that "dishonestly" signaling individuals (i.e. those whose behavior did not match their manipulated color) received higher aggression from unpainted opponents. The increased aggression received by dishonest signalers suggests that social costs play an important role in maintaining the honesty of rapid color change signals in veiled chameleons. Though the color change abilities of chameleons have interested humans since the time of Aristotle, little was previously known about the signal content of such changes. Documenting the behavioral contexts and information content of these signals has provided an important first step in understanding the current function, underlying control mechanisms, and evolutionary origins of this rare signal type.
ContributorsLigon, Russell (Author) / McGraw, Kevin J. (Committee member) / DeNardo, Dale F (Committee member) / Karsten, Kristopher B (Committee member) / Rutowski, Ronald L (Committee member) / Deviche, Pierre (Committee member) / Arizona State University (Publisher)
Created2015
Description
Environmental changes are occurring at an unprecedented rate, and these changes will undoubtedly lead to alterations in resource availability for many organisms. To effectively predict the implications of such changes, it is critical to better understand how organisms have adapted to coping with seasonally limited resources. The vast majority of previous work has focused on energy balance as the driver of changes in organismal physiology. While energy is clearly a vital currency, other resources can also be limited and impact physiological functions. Water is essential for life as it is the main constituent of cells, tissues, and organs. Yet, water has received little consideration for its role as a currency that impacts physiological functions. Given the importance of water to most major physiological systems, I investigated how water limitations interact with immune function, metabolism, and reproductive investment, an almost entirely unexplored area. Using multiple species and life stages, I demonstrated that dehydrated animals typically have enhanced innate immunity, regardless of whether the dehydration is a result of seasonal water constraints, water deprivation in the lab, or high physiological demand for water. My work contributed greatly to the understanding of immune function dynamics and lays a foundation for the study of hydration immunology as a component of the burgeoning field of ecoimmunology. While a large portion of my dissertation focused on the interaction between water balance and immune function, there are many other physiological processes that may be impacted by water restrictions. Accordingly, I recently expanded the understanding of how reproductive females can alter metabolic substrates to reallocate internal water during times of water scarcity, an important development in our knowledge of reproductive investments. Overall, by thoroughly evaluating implications and responses to water limitations, my dissertation, when combined previous acquired knowledge on food limitation, will enable scientists to better predict the impacts of future climate change, where, in many regions, rainfall events are forecasted to be less reliable, resulting in more frequent drought.
ContributorsBrusch, George, IV (Author) / DeNardo, Dale F (Thesis advisor) / Blattman, Joseph (Committee member) / French, Susannah (Committee member) / Sabo, John (Committee member) / Taylor, Emily (Committee member) / Arizona State University (Publisher)
Created2019
Description
Though it is a widespread adaptation in humans and many other animals, parental care comes in a variety of forms and its subtle physiological costs, benefits, and tradeoffs related to offspring are often unknown. Thus, I studied the hydric, respiratory, thermal, and fitness dynamics of maternal egg-brooding behavior in Children's pythons (Antaresia childreni). I demonstrated that tight coiling detrimentally creates a hypoxic developmental environment that is alleviated by periodic postural adjustments. Alternatively, maternal postural adjustments detrimentally elevate rates of egg water loss relative to tight coiling. Despite ventilating postural adjustments, the developmental environment becomes increasingly hypoxic near the end of incubation, which reduces embryonic metabolism. I further demonstrated that brooding-induced hypoxia detrimentally affects offspring size, performance, locomotion, and behavior. Thus, parental care in A. childreni comes at a cost to offspring due to intra-offspring tradeoffs (i.e., those that reflect competing offspring needs, such as water balance and respiration). Next, I showed that, despite being unable to intrinsically produce body heat, A. childreni adjust egg-brooding behavior in response to shifts in nest temperature, which enhances egg temperature (e.g., reduced tight coiling during nest warming facilitated beneficial heat transfer to eggs). Last, I demonstrated that A. childreni adaptively adjust their egg-brooding behaviors due to an interaction between nest temperature and humidity. Specifically, females' behavioral response to nest warming was eliminated during low nest humidity. In combination with other studies, these results show that female pythons sense environmental temperature and humidity and utilize this information at multiple time points (i.e., during gravidity [egg bearing], at oviposition [egg laying], and during egg brooding) to enhance the developmental environment of their offspring. This research demonstrates that maternal behaviors that are simple and subtle, yet easily quantifiable, can balance several critical developmental variables (i.e., thermoregulation, water balance, and respiration).
ContributorsStahlschmidt, Zachary R (Author) / DeNardo, Dale F (Thesis advisor) / Harrison, Jon (Committee member) / McGraw, Kevin (Committee member) / Rutowski, Ronald (Committee member) / Walsberg, Glenn (Committee member) / Arizona State University (Publisher)
Created2011
ContributorsHaydn, Joseph, 1732-1809 (Composer)
ContributorsHaydn, Joseph, 1732-1809 (Composer)
ContributorsHaydn, Joseph, 1732-1809 (Composer)
ContributorsHaydn, Joseph, 1732-1809 (Composer)