No description available.

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

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Animal, 2011. / Submitted by Albânia Cézar de Melo (albania@bce.unb.br) on 2011-10-04T14:59:54Z No. of bitstreams: 1 2011_LaisBatistaAlvarengaVeludo.pdf: 1010704 bytes, checksum: 321be5e0f4d761b53864b901106dcc4b (MD5) / Approved for entry into archive by Jaqueline Ferreira de Souza(jaquefs.braz@gmail.com) on 2011-10-13T12:31:52Z (GMT) No. of bitstreams: 1 2011_LaisBatistaAlvarengaVeludo.pdf: 1010704 bytes, checksum: 321be5e0f4d761b53864b901106dcc4b (MD5) / Made available in DSpace on 2011-10-13T12:31:52Z (GMT). No. of bitstreams: 1 2011_LaisBatistaAlvarengaVeludo.pdf: 1010704 bytes, checksum: 321be5e0f4d761b53864b901106dcc4b (MD5) / Anolis meridionalis é uma lagarto de hábito diurno, que utiliza principalmente poleiros baixos ou o chão. É uma espécie endêmica do Cerrado, sendo A. annectens, A. chrysolepis, A.auratus, A. onca e A. lineatopus as espécies filogeneticamente mais próximas. O objetivo desse trabalho é invesdtigar os padrões e processos determinantes do dimorfismo sexual, dieta e reprodução de A. meridionalis. Todos os indivíduos analisados são oriundos da Coleção Herpetológica da Universidade de Brasília (CHUNB). Não existe dimorfismo sexual no tamanho de A. meridionalis, mas machos possuem cauda, mão e dedo IV mais alongados que fêmeas; essas, por sua vez, possuem o corpo mais alongado que machos. A sobreposição de nicho alimentar foi alta tanto entre machos e fêmeas adultos, entre machos e fêmeas jovens e entre adultos e jovens. A reprodução dessa espécie ocorre o ano todo com maior atividade reprodutiva a partir de agosto, relacionada à temperatura máxima absoluta. A ausência de competição por recursos alimentares e as baixas densidades populacionais podem ser a principal explicação para a ausência de dimorfismo no tamanho. Por outro lado, o alongamento das fêmeas pode estar relacionado ao aumento do sucesso reprodutivo, enquanto que o alongamento da mão, dedo IV e cauda nos machos pode estar relacionado à seleção sexual. Anolis meridionalis é uma lagarto de hábito diurno, que utiliza principalmente poleiros baixos ou o chão. É uma espécie endêmica do Cerrado, sendo A. annectens, A. chrysolepis, A.auratus, A. onca e A. lineatopus as espécies filogeneticamente mais próximas. O objetivo desse trabalho é invesdtigar os padrões e processos determinantes do dimorfismo sexual, dieta e reprodução de A. meridionalis. Todos os indivíduos analisados são oriundos da Coleção Herpetológica da Universidade de Brasília (CHUNB). Não existe dimorfismo sexual no tamanho de A. meridionalis, mas machos possuem cauda, mão e dedo IV mais alongados que fêmeas; essas, por sua vez, possuem o corpo mais alongado que machos. A sobreposição de nicho alimentar foi alta tanto entre machos e fêmeas adultos, entre machos e fêmeas jovens e entre adultos e jovens. A reprodução dessa espécie ocorre o ano todo com maior atividade reprodutiva a partir de agosto, relacionada à temperatura máxima absoluta. A ausência de competição por recursos alimentares e as baixas densidades populacionais podem ser a principal explicação para a ausência de dimorfismo no tamanho. Por outro lado, o alongamento das fêmeas pode estar relacionado ao aumento do sucesso reprodutivo, enquanto que o alongamento da mão, dedo IV e cauda nos machos pode estar relacionado à seleçãoAnolis meridionalis é uma lagarto de hábito diurno, que utiliza principalmente poleiros baixos ou o chão. É uma espécie endêmica do Cerrado, sendo A. annectens, A. chrysolepis, A.auratus, A. onca e A. lineatopus as espécies filogeneticamente mais próximas. O objetivo desse trabalho é invesdtigar os padrões e processos determinantes do dimorfismo sexual, dieta e reprodução de A. meridionalis. Todos os indivíduos analisados são oriundos da Coleção Herpetológica da Universidade de Brasília (CHUNB). Não existe dimorfismo sexual no tamanho de A. meridionalis, mas machos possuem cauda, mão e dedo IV mais alongados que fêmeas; essas, por sua vez, possuem o corpo mais alongado que machos. A sobreposição de nicho alimentar foi alta tanto entre machos e fêmeas adultos, entre machos e fêmeas jovens e entre adultos e jovens. A reprodução dessa espécie ocorre o ano todo com maior atividade reprodutiva a partir de agosto, relacionada à temperatura máxima absoluta. A ausência de competição por recursos alimentares e as baixas densidades populacionais podem ser a principal explicação para a ausência de dimorfismo no tamanho. Por outro lado, o alongamento das fêmeas pode estar relacionado ao aumento do sucesso reprodutivo, enquanto que o alongamento da mão, dedo IV e cauda nos machos pode estar relacionado à seleção. ______________________________________________________________________________ ABSTRACT Anolis meridionalis is a diurnal lizard that uses mainly low perches or the ground. It is an endemic specie from Cerrado with A. annectens, A. chrysolepis, A.auratus, A. onca and A. lineatopus the most phylogenically related species. The aim of this work is to investigate the patterns and determinant process of the sexual dimorphism, diet and reproduction. All of the individuals analyzed were from Coleção Herpetológica da Universidade de Brasilia (CHUNB). There is no sexual size dimorphism in Anolis meridionalis, but the tail, hand and IV finger are larger in males than in females, and females are more elongated than males. Niche overlap was high between adult males and females, juvenile males and females, and finally between adults and juveniles. This species reproduces throughout the year with an increase in reproductive activities from August on, mainly related to maximum absolute temperature. The lack of competition for food resources and low population density are seemingly the main explanation for the lack of sexual size dimorphism. On the other hand, female body elongation could be related to increased reproductive success, while hand, IV finger and tail elongation could be related to sexual selection.

This work focuses on the optical communication of the Green Anole lizard. Experiment group consisted of eleven specimen, six males and five females, each being kept separately. The animals were being kept at constant temperature and humidity levels. Seven predetermined behavior patterns were examined, occuring during a contact of two specimen, wheter two males or a male and a female. For each behavior pattern, three time data were measured duration, frequency and latency. When examining two males, size difference and territorial status of territory owner/intruder were taken into account. Each interaction was documented, in total sixty videos were made, each fifteen minutes long. The territory status positively influenced the duration and latency of Headbob C, size difference positively influenced the duration and latency of Nuchal crest and the latency of Extended throat. Sex of the animal positively influenced the duration of Dewlap. Territorial status, size differnce or sex had no influence on the rest of the behavior patterns.

Displays are ubiquitous throughout the animal kingdom. While many have been thoroughly documented, the factors affecting the expression of such displays are still not fully understood. We tested the hypotheses that display production would be affected by ecological context (i.e. the identity of the receiver) and intrinsic qualities of the signaler (i.e. heavyweight and lightweight size class) in the green anole lizard, Anolis carolinensis. Our results supported these predictions and show that a) ecological context, specifically displaying to conspecifics, has the greatest impact on display production; b) size class influenced display rate with heavyweight males displaying more to green females and lightweight males displaying more to green males in similar frequency between the two size classes to their respective target stimuli. Furthermore, our results provide empirical support for differential use of the three major display types (A, B and C displays), and uncover unexpected complexity in green anole display production.

The neotropical lizard genus Anolis is an important model system for studies of the ecology and evolution of animal diversity. One of the most striking elements of Anolis diversity is found in the morphology of the dewlap, an extensible flap of colored skin on the throat that anoles use to communicate during social interactions. The evolutionary forces that have promoted the evolution of dewlap diversity are poorly understood. A study of reproductive success in A. carolinensis showed for the first time that dewlap color is currently under selection in an anole (Chapter 1). However, this is unlikely to be a result of intrasexual competition because neither dewlap morphology nor reproductive success are related to male territory size or quality. Instead the dewlap may be under intersexual selection from female mate choice. In addition to sexual selection, the dewlap may evolve in response to a variety of other processes such as species recognition, predation, sensory drive, or a combination of these. A study of variation among populations of a single species, A. sagrei, revealed that the dewlap may be undergoing rapid adaptive diversification driven by several of these processes simultaneously (Chapter 2), while a study of variation among species in dewlap size showed that similar processes are likely shaping the evolution of the dewlap in female anoles (Chapter 3). In a case study of male-female pair formation in the Costa Rican anole A. limifrons, dewlap size or color were not good predictors of which males would form pairs and which would not, though males and females that were similar in size were found to form pairs more often than animals that were dissimilar in size (Chapter 4). Finally, a study of the correlated evolution of traits related to locomotion in anoles found that morphology, behavior, and habitat use evolve in tandem among 31 species of anoles from the Greater Antilles (Chapter 5). Together, these studies suggest that the evolutionary ecology of anoles is more complex than previously thought, and that future studies of the dewlap may provide more general insight into the evolution of diversity of animal ornaments.

<p>The evolution of animal signals is driven largely by characteristics of the signaling environment and properties of receiver sensory systems. Selection favors signal traits that increase the probability that a signal will stimulate the sensory systems of intended receivers, but not potential predators, under average environmental conditions. However, environmental conditions often fluctuate, which means that a given signal property may not be equally effective at all times. One potential mechanism that an organism might employ to overcome this challenge is to modulate its signal properties as environmental conditions change in order to maintain stimulation of the receiver sensory system. In this dissertation, I explore the possible role of signal modulation using the motion detection and communication systems of tropical Anolis lizards. </p><p>In order to assess the possible role of signal modulation in the communication behavior of anoles, it was necessary to determine the properties of their motion detection systems. In Chapter 2, I tested whether motion detection properties are conserved across species of anole. I adapted a behavioral assay to quantify the spatial parameters of the motion detectors of three species of Puerto Rican Anolis lizards, with each preferring a distinct structural habitat type. I then compared the results to data previously collected for anoles from Cuba, Puerto Rico, and Central America. Results indicated that all species share a minimum amplitude threshold for detecting moving objects and exhibit multiple peaks in relative response to various motion amplitudes. Fine-scale interspecific differences in the number and values of response peaks were not correlated with structural niche. Overall, the study suggests that the motion detection systems of Anolis lizards are relatively conserved, which may help explain shared features of movement-based signals in anoles.</p><p>For mobile organisms, the spatial relationships of signaling individuals and intended receivers can be fluid. Such fluctuation in the distance between signalers and receivers can greatly impact signal efficacy, but it is unclear exactly how animals cope with this problem. In Chapter 3, I investigated whether signal modulation can serve as an effective strategy to cope with variation in the spacing of receivers in the environment by tuning a signal to maintain stimulation of the receiver sensory system. I evaluated this hypothesis by testing the use of modulation in the tropical lizard Anolis gundlachi in Puerto Rico. I first characterized the motion detection properties of the sensory system of A. gundlachi in the laboratory. I then measured the physical properties of movement-based headbob displays given during staged social encounters under natural conditions. I found a significant positive association between the maximum amplitude of headbob displays and the physical distance to intended receivers. Modulation occurred in response to small-scale changes in signaler-receiver distance, and signalers gave displays that fell within a range of amplitudes predicted to optimally stimulate the visual system of A. gundlachi. These findings strongly suggest that modulation of the physical properties of motion-based signals can be an effective mechanism to tune signals to both characteristics of receiver sensory systems and receiver distance, and can serve as a behavioral strategy to cope with relatively frequent changes in the spacing of individuals. </p><p>Although signaling individuals must effectively capture and hold the attention of intended conspecific receivers, they must also limit eavesdropping by potential parasites or predators. However, predation pressure can vary over the course of an individual's lifetime, or over the course of a day, thereby altering signal efficacy. In Chapter 4, I tested the hypothesis that prey can modulate the physical properties of their signals or their display behavior in order to decrease conspicuousness and potentially limit predation risk. To do so, I conducted a manipulative experiment in nature to determine the effect of predation pressure on the properties of movement-based signals and the display rate of the semiarboreal lizard Anolis sagrei. I found that male anoles reduced the maximum amplitude of headbob displays but not the proportion of time spent signaling on islands onto which predators were introduced, in comparison to males from control islands lacking the predator. Characteristics of the motion detection system and social behavior of A. sagrei show that this reduction in amplitude also decreases signal active space, which might alter the reproductive success of signaling individuals. I suggest that future studies of predator-prey interactions consider the risk effects generated by changes in signals or signaling behavior to fully determine the influence of predation pressure on the dynamics of prey populations.</p> / Dissertation

<p>Human activity has resulted in significant increases in air temperature over the last century, and air temperatures are expected to continue rising at an accelerating rate over the next 100 years (IPCC 2007). The warming that has already occurred has had significant impacts on the worlds biota: species ranges are shifting north (or upslope), seasonal phenological events are occurring earlier, disease dynamics are changing, and populations are going extinct (Walther et al. 2002; Parmesan & Yohe 2003; Parmesan 2006; Walther 2010; Pau et al. 2011). Understanding the temperature-dependent biological mechanisms that lead to such changes is a major priority: only with such understanding can we hope to make a concerted effort to mitigate the effects of continuing climatic change. </p><p> There are three general biological mechanisms by which organisms can respond to, and potentially buffer themselves from, the direct effects of climate change: 1) physiological plasticity, 2) behavior, and 3) evolution. Here, I refer to physiological plasticity as changes in thermal reaction norms, which include sensitivity to thermal change and tolerance for thermal extremes (Huey & Stevenson 1979). These plastic responses can be reversible (acclimation) or be fixed by developmental or cross-generational non-genetic processes (West-Eberhard 2003; Ghalambor et al. 2007; Angilletta 2009). There appear to be global patterns of plasticity in thermal physiology, as temperate ectotherms tend to be more plastic than tropical ectotherms (Feder 1978; Tsuji 1988; Ghalambor et al. 2006). This difference is hypothesized to result from differences in seasonality: temperate ectotherms can experience a much wider range of thermal conditions than tropical ectotherms, and thus temperate environment might select for plasticity to track changing conditions. If physiological plasticity can buffer organisms from warming (Stillman 2003; Somero 2010), then tropical ectotherms may be at a disadvantage in the face of climate change (Huey et al. 2009). </p><p> In general, behavioral responses to thermal challenges can be thought of as occurring on either local or regional scales. At the local scale ectotherms can engage in behavioral thermoregulation, seeking out thermally suitable microhabitats within their home ranges (Bogert 1949; Huey et al. 2003; Kearney et al. 2009). At the regional scale, organisms may shift their ranges by migrating along elevation or latitudinal thermal gradients (usually up or north, respectively) to escape warming (Buckley et al. 2013). The degree to which local- and regional-scale behavioral responses can buffer populations from warming depends on numerous factors. For example, behavioral thermoregulation requires fine-scale thermal variation within the environment. However, habitats such as heavily shaded tropical forests have little thermal heterogeneity, precluding behavioral thermoregulation as an effective buffering mechanism (Huey et al. 2009). On the other hand, range shifts can be hindered by factors such as inherent mobility and natural and man-made barriers (Forero&#8208;Medina et al. 2011). Both behavioral thermoregulation and migration can be hindered by the presence of competitors or antagonistic species such as predators or parasites in thermally favorable locations (Araújo & Luoto 2007). </p><p> Most work on the evolution of thermal physiology focuses on the evolution of thermal tolerance limits (i.e., the lower and upper lethal temperature thresholds) (Stillman & Somero 2000; Angilletta et al. 2007; Barrett et al. 2011). Broad-scale comparative analyses have demonstrated that upper thermal limits vary less than lower thermal limits, suggesting that upper thermal limits may be evolutionarily constrained (Kellermann et al. 2012; Araújo et al. 2013; Grigg & Buckley 2013). This pattern is particularly strong looking over terrestrial latitudinal gradients; cold tolerance increases with latitude, but heat tolerance does not change appreciably (Sunday et al. 2012). Artificial selection experiments have demonstrated that the upper thermal tolerances of animals can evolve, but there may be limits to how much they can change (Huey et al. 1991; Loeschcke & Krebs 1996).</p><p> Physiology, behavior, and evolution are of course not mutually exclusive mechanisms. As noted above, physiological traits such as tolerance to extreme temperature can evolve, as can behavioral mechanisms. In addition, behavior may promote or inhibit the evolution of physiology. For example, behavioral thermoregulation can potentially inhibit the evolution of thermal physiology because it allows organisms to buffer themselves from thermal change (Huey et al. 2003). Furthermore, the physiological state of an organism can dictate how it behaviorally responds to a given stimulus (Atkins-Regan 2005). For example, lizards that are dehydrated seek out cooler microclimates (Crowley 1987). </p><p> My dissertation focuses on the physiological, behavioral, and evolutionary axes of organismal response to climatic challenges, and their interactions, using the arboreal Caribbean lizard Anolis cristatellus as a model system. The general approach that I take throughout each chapter is to consider climatic data and organismal responses to climate at a fine-scale. A recent review and meta-analysis of climate change studies found that, on average, researchers consider climatic data at a scale 10,000X larger then the animals they study (Potter et al. 2013). In other words, we frequently consider the climatic environment very coarsely relative to our focal organisms. Such an approach can yield broad patterns of warming vulnerability over large geographic scales. Nonetheless, much of the climatic variation important to organisms occurs at the scale of meters rather than kilometers (Helmuth et al. 2010). Similarly, broad-scale studies must typically make assumptions about how organisms respond to climatic variation, rather than actually measuring responses. Throughout, I highlight the benefits of working at the scale of the organism. </p><p> Chapter 1 is the only chapter that does not deal directly with thermal biology. In it, I investigate whether or not A. cristatellus from mesic and xeric habitats differ in their water loss rates, and ask whether the differences that I observe can be explained by plasticity (Gunderson et al. 2011). In the second chapter, I explore the vulnerability of A. cristatellus to climate warming by integrating behavior and physiology with fine-scale measurements of the thermal environment (Gunderson & Leal 2012). In the third chapter, I investigate the ability of thermal tolerance limits to evolve rapidly in response to climatic change using the recent introduction of A. cristatellus to Miami from Puerto Rico (Leal & Gunderson 2012). In the final chapter, I focus solely on behavior and use A. cristatellus to ask how well current models of thermal constraint on activity predict observed patterns at a fine scale in the field (Gunderson and Leal, in review).</p> / Dissertation

Recent advances in high-throughput, genomic sequencing allow unprecedented insight into the evolution of biodiversity. Chapter 1 of this thesis is a phylogenetic study of 1,145 sequenced loci, isolated using a novel high-throughput sequence capture methodology to address the phylogenetic position of turtles within tetrapods. The results reported here unambiguously place turtles as sister to archosaurs and resolve this long-standing question. Chapter 2 investigates the genetic basis of colorful pigmentation in the Green anole (Anolis carolinensis) by sequencing complete transcriptomes from the green dorsal, white ventral and pink dewlap skin. Anoles comprise an adaptive radiation of more than 400 species and color plays a central role in their ecology and evolution, but little is known about the genetic basis of colorful pigmentation in any vertebrate. This study identified 1,719 differentially expressed genes among the three differently colored tissues. Twenty-three of these genes are involved in melanin, pteridine, and carotenoid pigmentation pathways that contribute to the coloration of anole skin. Identifying candidate genes for colorful pigmentation is a significant advance that opens the field for comparative analysis in other taxa. To determine if the genes identified in Chapter 2 are involved in population divergence and speciation, Chapter 3 investigates the complete genomes of twenty individuals from two closely related subspecies of Anolis marmoratus. While the two subspecies differ markedly in pigmentation, this study found few genetic differences between populations except in five regions of the genome, which together contained 447 genes. Of these genes, only two, melanophilin (mlph) and 'cluster of differentiation 36' (cd36), are associated with pigmentation. The intersection of the genes identified in Chapter 2 and Chapter 3 includes both cd36 and mlph, suggesting that both are involved in divergence of coloration. Cd36 is of particular interest because it regulates the uptake of carotenoid pigments and is an important candidate gene contributing to carotenoid pigmentation. Together, this research demonstrates the power of genomic approaches to address fundamental questions in systematics, micro-evolution, and speciation. The findings bolster the emerging field of phylogenomics and broadly impact future research into the genetic basis of coloration in vertebrates.

abstract: Postnatal skeletal muscle repair is dependent on the tight regulation of an adult stem cell population known as satellite cells. In response to injury, these quiescent cells are activated, proliferate and express skeletal muscle-specific genes. The majority of satellite cells will fuse to damaged fibers or form new muscle fibers, while a subset will return to a quiescent state, where they are available for future rounds of repair. Robust muscle repair is dependent on the signals that regulate the mutually exclusive decisions of differentiation and self-renewal. A likely candidate for regulating this process is NUMB, an inhibitor of Notch signaling pathway that has been shown to asymmetrically localize in daughter cells undergoing cell fate decisions. In order to study the role of this protein in muscle repair, an inducible knockout of Numb was made in mice. Numb deficient muscle had a defective repair response to acute induced damage as characterized by smaller myofibers, increased collagen deposition and infiltration of fibrotic cells. Satellite cells isolated from Numb-deficient mice show decreased proliferation rates. Subsequent analyses of gene expression demonstrated that these cells had an aberrantly up-regulated Myostatin (Mstn), an inhibitor of myoblast proliferation. Further, this defect could be rescued with Mstn specific siRNAs. These data indicate that NUMB is necessary for postnatal muscle repair and early proliferative expansion of satellite cells. We used an evolutionary compatible to examine processes controlling satellite cell fate decisions, primary satellite cell lines were generated from Anolis carolinensis. This green anole lizard is evolutionarily the closet animal to mammals that forms de novo muscle tissue while undergoing tail regeneration. The mechanism of regeneration in anoles and the sources of stem cells for skeletal muscle, cartilage and nerves are poorly understood. Thus, satellite cells were isolated from A. carolinensis and analyzed for their plasticity. Anole satellite cells show increased plasticity as compared to mouse as determined by expression of key markers specific for bone and cartilage without administration of exogenous morphogens. These novel data suggest that satellite cells might contribute to more than muscle in tail regeneration of A. carolinensis. / Dissertation/Thesis / Ph.D. Molecular and Cellular Biology 2012