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Barauna AA, Conte MI, Leporati JL, Quiroga LB, Sanabria EA, Fornés MW. Testosterone is closely related to Leydig cell activity, environmental factors, and androgen receptor distribution in adult male lizards of Liolaemus cuyanus (Reptilia: Liolaemidae) during the reproductive cycle. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:421-430. [PMID: 38369873 DOI: 10.1002/jez.2794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 12/29/2023] [Accepted: 02/05/2024] [Indexed: 02/20/2024]
Abstract
Testosterone, the primary sex hormone in male lizards, is closely linked to Leydig cell activity (the cells where steroidogenesis occurs) throughout the reproductive cycle, but testosterone action is related to androgen receptors (ARs) distribution in the seminiferous epithelium. In temperate zones, environmental factors detected through the hypothalamic-pituitary-gonadal axis, downregulate plasma testosterone, resulting in a seasonal reproductive cycle. The aim of this work is to study plasma testosterone in adult male lizards of Liolaemus cuyanus, an oviparous species, throughout its reproductive cycle and its relationship with Leydig cell histology, TotalLeydigCell/ActiveLeydigCell (TLC/ALC) ratio, environmental factors (temperature, relative humidity and solar irradiation) and ARs distribution in seminiferous epithelium. Specimens (N = 27) were captured (October to March) in a semi-arid zone (Valle de Matagusanos, San Juan, Argentina) and grouped into three relevant reproductive periods: pre-reproductive (PrR), reproductive (R), and post-reproductive (PsR). Significant differences in plasma testosterone were found among these periods, highest during R than in PsR. A significant positive correlation between plasma testosterone and TLC/ALC ratio was also observed. Plasma testosterone has a significant positive correlation only with solar irradiation, but not with the other variables. In PrR and R, ARs distribution was cytoplasmic and nuclear, shifting to only cytoplasmic in PsR. These results highlight the close correspondence between plasma testosterone, Leydig cell histology and activity, environmental factors, and ARs distribution, resulting in a synchronization that allows males of L. cuyanus to coordinate their reproductive cycle with the most favorable environmental conditions, probably for mating and birth of offspring.
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Affiliation(s)
- Andrea Anabella Barauna
- IHEM (Instituto de Histología y Embriología de Mendoza)-CONICET, Facultad de Ciencias Médicas-Universidad Nacional de Cuyo, Mendoza, Argentina
| | - María Inés Conte
- IHEM (Instituto de Histología y Embriología de Mendoza)-CONICET, Facultad de Ciencias Médicas-Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Jorge Leandro Leporati
- Universidad Nacional de San Luis, Facultad de Ingeniería y Ciencias Agropecuarias, San Luis, Argentina
| | - Lorena Beatriz Quiroga
- ICB, Universidad Nacional de San Juan, CONICET, Facultad de Filosofía Humanidades y Artes, San Juan, Argentina
| | - Eduardo Alfredo Sanabria
- ICB, Universidad Nacional de San Juan, CONICET, Facultad de Filosofía Humanidades y Artes, San Juan, Argentina
- Universidad Nacional de Cuyo, Facultad de Ciencias Exactas y Naturales, Mendoza, Argentina
| | - Miguel Walter Fornés
- IHEM (Instituto de Histología y Embriología de Mendoza)-CONICET, Facultad de Ciencias Médicas-Universidad Nacional de Cuyo, Mendoza, Argentina
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Megía-Palma R, Paranjpe D, Cooper RD, Blaimont P, Sinervo B. Natural parasites in conjunction with behavioral and color traits explain male agonistic behaviors in a lizard. Curr Zool 2024; 70:59-69. [PMID: 38476133 PMCID: PMC10926264 DOI: 10.1093/cz/zoac095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 11/19/2022] [Indexed: 03/14/2024] Open
Abstract
Male competition conforms to a cost-benefit model, because while aggression may increase reproductive prospects, it can also increase the risk of injury. We hypothesize that an additional cost in aggressive males would be an increase in parasite load associated with a high energy investment into sexual competition. Some of these infections, in turn, may downmodulate the level of host aggression via energetic trade-offs. We staged dyadic male contests in the lab to investigate the relationships of multiple parasites with the agonistic behavior of lizard hosts, Sceloporus occidentalis. We also included both color and behavioral traits from opponents in the analyses because (1) color patches of lizards may serve as intraspecific signals used by conspecifics to assess the quality of opponents, and (2) contests between male lizards fit classical models of escalated aggression, where lizards increase aggression displays in response to an opponent's behavior. The results conform to our hypothesis because male lizards displayed more pushups when they had more ticks. Moreover, some parasites may modulate the levels of aggression because lizards infected by hematic coccidians performed fewer pushups. Interestingly, lizards also displayed fewer pushups when both the chroma and size of the opponent's blue patch were greater. The results thus also supported the role of the blue patch of S. occidentalis as a sexual armament, because it contributed to the deterrence of aggression from opponent lizards. We revealed that natural parasitic infections in lizard hosts can contribute to their agonistic behavior. We encourage future studies to account for parasites in behavioral tests with lizards.
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Affiliation(s)
- Rodrigo Megía-Palma
- Department of Biomedicine and Biotechnology, Parasitology Unit, Universidad de Alcalá (UAH), E-28805, Alcalá de Henares, Spain
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, P-4485-661 Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, P-4485-661 Vairão, Portugal
| | - Dhanashree Paranjpe
- Rupa Rahul Bajaj Center for Environment and Art, Empress Botanical Gardens, Kavade Mala, Pune, India
| | - Robert D Cooper
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA
| | - Pauline Blaimont
- Department of Biology, University of Houston Downtown, 1 Main St., Houston, TX 77002, USA
| | - Barry Sinervo
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
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Robinson CD, Hale MD, Wittman TN, Cox CL, John-Alder HB, Cox RM. Species differences in hormonally mediated gene expression underlie the evolutionary loss of sexually dimorphic coloration in Sceloporus lizards. J Hered 2023; 114:637-653. [PMID: 37498153 DOI: 10.1093/jhered/esad046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/24/2023] [Indexed: 07/28/2023] Open
Abstract
Phenotypic sexual dimorphism often involves the hormonal regulation of sex-biased expression for underlying genes. However, it is generally unknown whether the evolution of hormonally mediated sexual dimorphism occurs through upstream changes in tissue sensitivity to hormone signals, downstream changes in responsiveness of target genes, or both. Here, we use comparative transcriptomics to explore these possibilities in 2 species of Sceloporus lizards exhibiting different patterns of sexual dichromatism. Sexually dimorphic S. undulatus develops blue and black ventral coloration in response to testosterone, while sexually monomorphic S. virgatus does not, despite exhibiting similar sex differences in circulating testosterone levels. We administered testosterone implants to juveniles of each species and used RNAseq to quantify gene expression in ventral skin. Transcriptome-wide responses to testosterone were stronger in S. undulatus than in S. virgatus, suggesting species differences in tissue sensitivity to this hormone signal. Species differences in the expression of genes for androgen metabolism and sex hormone-binding globulin were consistent with this idea, but expression of the androgen receptor gene was higher in S. virgatus, complicating this interpretation. Downstream of androgen signaling, we found clear species differences in hormonal responsiveness of genes related to melanin synthesis, which were upregulated by testosterone in S. undulatus, but not in S. virgatus. Collectively, our results indicate that hormonal regulation of melanin synthesis pathways contributes to the development of sexual dimorphism in S. undulatus, and that changes in the hormonal responsiveness of these genes in S. virgatus contribute to the evolutionary loss of ventral coloration.
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Affiliation(s)
| | - Matthew D Hale
- University of Virginia, Department of Biology, Charlottesville, VA, United States
- U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD, United States
- Henry M. Jackson Foundation for the Advancement of Military Medicine Inc., Bethesda, MD, United States
| | - Tyler N Wittman
- University of Virginia, Department of Biology, Charlottesville, VA, United States
| | - Christian L Cox
- Florida International University, Department of Biological Sciences and Institute of Environment, Miami, FL, United States
| | - Henry B John-Alder
- Rutgers University, Department of Ecology, Evolution, and Natural Resources, New Brunswick, NJ, United States
| | - Robert M Cox
- University of Virginia, Department of Biology, Charlottesville, VA, United States
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Robinson CD, Lance SL, Gifford ME. Reproductive success, apparent survival, and ventral blue coloration in male prairie lizards (
Sceloporus consobrinus
). J Zool (1987) 2021. [DOI: 10.1111/jzo.12890] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- C. D. Robinson
- University of Virginia Charlottesville VA USA
- University of Central Arkansas Conway AR USA
| | - S. L. Lance
- Savannah River Ecology Laboratory University of Georgia Aiken SC USA
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Assis BA, Jarrett BJM, Koscky G, Langkilde T, Avery JD. Plastic sexual ornaments: Assessing temperature effects on color metrics in a color-changing reptile. PLoS One 2020; 15:e0233221. [PMID: 32433700 PMCID: PMC7239470 DOI: 10.1371/journal.pone.0233221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 04/30/2020] [Indexed: 11/19/2022] Open
Abstract
Conspicuous coloration is an important subject in social communication and animal behavior, and it can provide valuable insight into the role of visual signals in social selection. However, animal coloration can be plastic and affected by abiotic factors such as temperature, making its quantification problematic. In such cases, careful consideration is required so that metric choices are consistent across environments and least sensitive to abiotic factors. A detailed assessment of plastic trait in response to environmental conditions could help identify more robust methods for quantifying color. Temperature affects sexual ornamentation of eastern fence lizards, Sceloporus undulatus, with ventral coloration shifting from green to blue hues as temperatures rise, making the calculation of saturation (color purity) difficult under conditions where temperatures vary. We aimed to characterize how abiotic factors influence phenotypic expression and to identify a metric for quantifying animal color that is either independent from temperature (ideally) or best conserves individual's ranks. We compared the rates of change in saturation across two temperature treatments using seven metrics: three that are based on fixed spectral ranges (with two of them designed by us specifically for this system) and three that track the expressed hue (with one of them designed by us to circumvent spurious results in unornamented individuals). We also applied a lizard visual sensitivity model to understand how temperature-induced color changes may be perceived by conspecifics. We show that the rate of change in saturation between two temperatures is inconsistent across individuals, increasing at a higher rate in individuals with higher baseline saturation at lower temperatures. In addition, the relative color rank of individuals in a population varies with the temperature standardized by the investigator, but more so for some metrics than others. While we were unable to completely eliminate the effect of temperature, current tools for quantifying color allowed us to use spectral data to estimate saturation in a variety of ways and to largely preserve saturation ranks of individuals across temperatures while avoiding erroneous color scores. We describe our approaches and suggest best-practices for quantifying and interpreting color, particularly in cases where color changes in response to environmental factors.
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Affiliation(s)
- Braulio A. Assis
- Department of Biology, Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA, United States of America
| | - Benjamin J. M. Jarrett
- Department of Entomology, Michigan State University, East Lansing, MI, United States of America
| | - Gabe Koscky
- Independent scholar, New York, NY, United States of America
| | - Tracy Langkilde
- Department of Biology, Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA, United States of America
| | - Julian D. Avery
- The Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA, United States of America
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To cool or not to cool? Intestinal coccidians disrupt the behavioral hypothermia of lizards in response to tick infestation. Ticks Tick Borne Dis 2019; 11:101275. [PMID: 31540802 DOI: 10.1016/j.ttbdis.2019.101275] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 07/16/2019] [Accepted: 08/20/2019] [Indexed: 01/27/2023]
Abstract
It is generally accepted that parasites exert negative effects on their hosts and that natural selection favors specific host responses that mitigate this impact. It is also known that some components of the host immune system often co-evolve with parasite antigens resulting in a host-parasite arms race. In addition to immunological components of the anti-parasitic response, host behavioral responses are also important in this arms race and natural selection may favor avoidance strategies that preclude contact with parasites, or shifts in the host's thermoregulatory strategy to combat active infections (e.g., behavioral fever). Ticks are widespread parasites with direct and indirect costs on their vertebrate hosts. Their saliva provokes hemolysis in the blood of their hosts and can transmit a plethora of tick-borne pathogens. We enquired whether tick infestation by Ixodes pacificus can provoke a thermoregulatory response in Sceloporus occidentalis. For this, we compared the thermoregulatory behavior of tick-infested lizards against tick-infested lizards co-infected with two different species of coccidians (Lankesterella occidentalis and Acroeimeria sceloporis). After this, lizards were kept in individual terraria with a basking spot and fed ad libitum. We found that tick-infested lizards sought cooler temperatures in proportion to their tick load, and this response was independent of the co-infection status by L. occidentalis. This was consistent in April and June (when tick loads were significantly lower) and suggests a conservative strategy to save energy which might have been selected to overcome tick infestations during phenological peaks of this parasite. However, this behavior was not observed in lizards co-infected with A. sceloporis, suggesting that co-infection with this intestinal parasite prompt lizards to be active. Cost of tick infestation was confirmed because housed lizards lost weight at a constant ratio to initial tick load, independently of other infections. The broader implications of these findings are discussed in the context of climate change.
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