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Amanda Sparkman, Stephen Howe, Stephanie Hynes, Brooke Hobbs, Karina Handal
The spread of urban development has dramatically altered natural habitats, modifying community relationships, abiotic factors, and structural features. Animal populations living in these areas must perish, emigrate, or find ways to adjust to a suite of new selective pressures. Those that successfully inhabit the urban environment may make behavioral, physiological, and/or morphological adjustments that represent either evolutionary change and/or phenotypic plasticity. We tested for effects of urbanization on antipredator behavior and associated morphology across an urban-wild gradient in the western fence lizard (Sceloporus occidentalis) in two California counties, Santa Barbara and San Luis Obispo...
2018: PloS One
Ryan J Seddon, Diana K Hews
Hormones mediate the expression of suites of correlated traits and hence may act either to facilitate or constrain adaptive evolution. Selection on one trait within a hormone-mediated suite of traits may lead to a change in the strength of the hormone signal, causing changes in correlated traits. Growing evidence suggests that melanization, which is in part regulated by hormonal signals, is tightly linked to other traits, such as aggression and stress physiology. Here, we examine six populations of Sceloporus occidentalis lizards differing in degree of melanization (three dark higher-elevation populations and three less-melanized lower-elevation populations) to investigate potential correlations between behavior, hormones, and parasites...
October 2017: Journal of Experimental Zoology. Part A, Ecological and Integrative Physiology
Agustin Camacho Guerrero, John M VandenBrooks, Angela Riley, Rory S Telemeco, Michael J Angilletta
Zoologists rely on mechanistic niche models of behavioral thermoregulation to understand how animals respond to climate change. These models predict that species will need to disperse to higher altitudes to persist in a warmer world. However, thermal stress and thus thermoregulatory behavior may depend on atmospheric oxygen as well as environmental temperatures. Severe hypoxia causes animals to prefer lower body temperatures, which could be interpreted as evidence that oxygen supply limits heat tolerance. Such a constraint could prevent animals from successfully dispersing to high elevations during climate change...
January 9, 2018: Integrative Zoology
Dustin A S Owen, Travis R Robbins, Tracy Langkilde
Environmental changes, such as the introduction of non-native species, can impose novel selective pressures. This can result in changes in fitness-relevant traits within an individual's lifetime or across multiple generations. We investigated the effects of early life versus trans-generational exposure to a predatory invasive insect stressor, the red imported fire ant (Solenopsis invicta), on the morphology and survival of the eastern fence lizard (Sceloporus undulatus). We captured gravid lizards from high-stress populations with long histories of invasion by fire ants and from uninvaded sites...
February 2018: Oecologia
Rocco V Carsia, Patrick J McIlroy, Henry B John-Alder
Our previous work with adrenocortical cells from several Sceloporus lizard species suggests that gonadal hormones influence the steroidogenic capacity and the sensitivity to ACTH. However, there are discrepancies in these cellular response parameters suggesting that the effects of gonadal hormones on adrenocortical function vary with species, sex, age, season, and environmental/experimental conditions. To gain further insight into these complex interactions, here we report studies on Coleonyx elegans, Eublepharidae (Yucatán Banded Gecko), which is only distantly related to Sceloporus lizards via a basal common ancestor and in captivity, reproduces throughout the year...
April 1, 2018: General and Comparative Endocrinology
L D Patterson, C-A Darveau, G Blouin-Demers
The thermal coadaptation hypothesis posits that ectotherms thermoregulate behaviorally to maintain body temperatures (Tb) that maximize performance, such as net energy gain. Huey's (1982) energetics model describes how food availability and Tb interact to affect net energy gain. We tested the thermal coadaptation hypothesis and Huey's energetics model with growth rates of juvenile Yarrow's spiny lizards (Sceloporus jarrovii). We compared the preferred (selected) Tb range (Tsel) of lizards in high and low energy states to their optimal temperature (To) for growth over nine weeks, and determined whether the To for growth depended on food availability...
December 2017: Journal of Thermal Biology
Rodrigo Megía-Palma, Javier Martínez, Dhanashree Paranjpe, Verónica D'Amico, Rocío Aguilar, María Gabriela Palacios, Robert Cooper, Francisco Ferri-Yáñez, Barry Sinervo, Santiago Merino
BACKGROUND: Species of Schellackia Reichenow, 1919 have been described from the blood of reptiles distributed worldwide. Recently, Schellackia spp. detected in European and Asian lizards have been molecularly characterised. However, parasites detected in American lizard hosts remain uncharacterised. Thus, phylogenetic affinities between the Old and New World parasite species are unknown. METHODS: In the present study, we characterised morphologically and molecularly the hemococcidian parasites (sporozoites) that infect three lizard hosts from North America and two from South America...
October 10, 2017: Parasites & Vectors
Juan Carlos González-Morales, Rene Beamonte-Barrientos, Elizabeth Bastiaans, Palestina Guevara-Fiore, Erendira Quintana, Victor Fajardo
High-altitude organisms exhibit hematological adaptations to augment blood transport of oxygen. One common mechanism is through increased values of blood traits such as erythrocyte count, hematocrit, and hemoglobin concentration. However, a positive relationship between altitude and blood traits is not observed in all high-altitude systems. To understand how organisms adapt to high altitudes, it is important to document physiological patterns related to hypoxia gradients from a greater variety of species. Here, we present an extensive hematological description for three populations of Sceloporus grammicus living at 2,500, 3,400, and 4,300 m...
November 2017: Physiological and Biochemical Zoology: PBZ
Jay K Goldberg, Alisa K Wallace, Stacey L Weiss
Sex pheromones can perform a variety of functions ranging from revealing the location of suitable mates to being honest signals of mate quality, and they are used in the mate selection process by many species of reptile. In this study, we determined whether the skin lipids of female striped plateau lizards (Sceloporus virgatus) can predict the reproductive quality of females, thereby having the potential to serve as pheromones. Using gas chromatography/mass spectrometry, we identified 17 compounds present in skin lipids of female lizards...
September 14, 2017: Die Naturwissenschaften
Nicholas B Pollock, Stephanie Feigin, Marko Drazenovic, Henry B John-Alder
Sexual differences in adult body size (sexual size dimorphism; SSD) and color (sexual dichromatism) are widespread, and both male- and female-biased dimorphisms are observed even among closely related species. A growing body of evidence indicates testosterone (T) can regulate growth, thus the development of SSD, and sexual dichromatism. However, the mechanism(s) underlying these effects are conjectural, including possible conversions of T to estradiol (E2) or 5 α-dihydrotestosterone (DHT). In the present study, we hypothesized that effects of T are physiological responses mediated by androgen receptors, and we tested two specific predictions: 1) that DHT would mimic effects of T by inhibiting growth and enhancing coloration, and 2) that removal of endogenous T via surgical castration would stimulate growth...
September 14, 2017: Journal of Experimental Biology
Breanna J Putman, Jonathan P Drury, Daniel T Blumstein, Gregory B Pauly
Animals often view humans as predators, leading to alterations in their behavior. Even nuanced aspects of human activity like clothing color affect animal behavior, but we lack an understanding of when and where such effects will occur. The species confidence hypothesis posits that birds are attracted to colors found on their bodies and repelled by non-body colors. Here, we extend this hypothesis taxonomically and conceptually to test whether this pattern is applicable in a non-avian reptile and to suggest that species should respond less fearfully to their sexually-selected signaling color...
2017: PloS One
Antonio-Rubio Nivia Rocio, Villagrán-SantaCruz Maricela, Moreno-Mendoza Norma
Among vertebrates, several specific proteins are involved in the function and development of gonads. Several genes such as SOX9, FOXL2, DDX4, IFITM3, and DPPA3, are active during embryonic differentiation and maintain their expression in adult tissues, playing important roles in the function and development of the line cell, where these are produced. Among reptiles, molecular mechanisms for sex differentiation have been analyzed in turtles, crocodiles, and some lizards, while in adult stages such studies are scarce...
June 2017: Acta Histochemica
J Balaban, E Azizi
Extended periods of skeletal muscle disuse can cause a significant loss of contractile proteins, which compromises the ability to generate force, mechanical work or power, thus compromising locomotor performance. Several hibernating organisms can resist muscle atrophy despite months of inactivity. This resistance has been attributed to a reduction in body temperature and metabolic rate and activation of physiological pathways that counteract pathways of protein degradation. However, in these systems such strategies are not mutually exclusive and the effects of these mechanisms can be difficult to separate...
May 15, 2017: Journal of Experimental Biology
Stephanie M Campos, Chloe Strauss, Emília P Martins
Territorial animals lay scent marks around their territories to broadcast their presence, but these olfactory signals can both attract and repel con-specifics. Attraction or aversion can have a profound impact in terms of space use and thereby influence an individual's access to resources and mates. Here, we test the impact of chemical signals on the long-term space use and activity of receivers, comparing the response of males and females, territory holders, and temporary visitors in Sceloporus undulatus lizards in the field...
February 2017: Ethology: Formerly Zeitschrift Für Tierpsychologie
Brenda Díaz-Cárdenas, Eduardo Ruiz-Sanchez, Patricia Castro-Felix, Gamaliel Castañeda-Gaytán, Sergio Ruiz-Santana, Héctor Gadsden
Species delimitation is a major topic in systematics. Species delimitation methods based on molecular data have become more common since this approach provides insights about species identification via levels of gene flow, the degree of hybridization and phylogenetic relationships. Also, combining multilocus mitochondrial and nuclear DNA leads to more reliable conclusions about species limits. Coalescent-based species delimitation methods explicitly reveal separately evolving lineages using probabilistic approaches and testing the delimitation hypotheses for several species...
June 2017: Molecular Phylogenetics and Evolution
Sean P Graham, Nicole A Freidenfelds, Christopher J Thawley, Travis R Robbins, Tracy Langkilde
Invasive species represent a substantial threat to native species worldwide. Research on the impacts of invasive species on wild living vertebrates has focused primarily on population-level effects. The sublethal, individual-level effects of invaders may be equally important but are poorly understood. We investigated the effects of invasive fire ants (Solenopsis invicta) on the physiological stress response of a native lizard (Sceloporus undulatus) within two experimental contexts: directly exposing lizards to a fire ant attack and housing lizards with fire ants in seminatural field enclosures...
May 2017: Physiological and Biochemical Zoology: PBZ
Víctor H Jiménez-Arcos, Salomón Sanabria-Urbán, Raúl Cueva Del Castillo
Sexual size dimorphism (SSD) evolves because body size is usually related to reproductive success through different pathways in females and males. Female body size is strongly correlated with fecundity, while in males, body size is correlated with mating success. In many lizard species, males are larger than females, whereas in others, females are the larger sex, suggesting that selection on fecundity has been stronger than sexual selection on males. As placental development or egg retention requires more space within the abdominal cavity, it has been suggested that females of viviparous lizards have larger abdomens or body size than their oviparous relatives...
February 2017: Ecology and Evolution
Adam D Leaché, Jared A Grummer, Rebecca B Harris, Ian K Breckheimer
Moving hybrid zones provide compelling examples of evolution in action, yet long-term studies that test the assumptions of hybrid zone stability are rare. Using replicated transect samples collected over a 10-year interval from 2002 to 2012, we find evidence for concerted movement of genetic clines in a plateau fence lizard hybrid zone (Sceloporus tristichus) in Arizona. Cline-fitting analyses of SNP and mtDNA data both provide evidence that the hybrid zone shifted northward by approximately 2 km during the 10-year interval...
April 2017: Molecular Ecology
Saúl López-Alcaide, Miguel Nakamura, Eric N Smith, Enrique Martínez-Meyer
Sceloporus lizards depend on external heat to achieve their preferred temperature (Tsel ) for performing physiological processes. Evidence both in the field and laboratory indicates that pregnant females of this Genus select body temperatures (Tb ) lower than 34 °C as higher temperatures may be lethal to embryos. Therefore, thermoregulation is crucial for successful embryo development. Given the increase in global air temperature, it is expected that the first compensatory response of species that inhabit tropical climates will be behavioral thermoregulation...
September 2017: Integrative Zoology
Alison G Ossip-Drahos, José R Oyola Morales, Cuauhcihuatl Vital-García, J Jaime Zúñiga-Vega, Diana K Hews, Emília P Martins
Many evolutionary forces can shape the evolution of communicative signals, and the long-term impact of each force may depend on relative timing and magnitude. We use a phylogenetic analysis to infer the history of blue belly patches of Sceloporus lizards, and a detailed spectrophotometric analysis of four species to explore the specific forces shaping evolutionary change. We find that the ancestor of Sceloporus had blue patches. We then focus on four species; the first evolutionary shift (captured by comparison of S...
November 2016: Royal Society Open Science
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