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Cruz-Cano NB, Sánchez-Rivera UÁ, Álvarez-Rodríguez C, Dávila-Govantes R, Cárdenas-León M, Martínez-Torres M. Sex steroids are correlated with environmental factors and body condition during the reproductive cycle in females of the lizard Sceloporus torquatus. Gen Comp Endocrinol 2021; 314:113921. [PMID: 34606744 DOI: 10.1016/j.ygcen.2021.113921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 09/25/2021] [Accepted: 09/29/2021] [Indexed: 12/06/2022]
Abstract
Reproduction is regulated by multiple factors that influence physiology and behavior to ensure the continuity of species. However, more work is needed to examine the complex relationships between environmental factors and endocrine transducers that modulate reproductive cycles, particularly in lizards. Here, we aimed to characterize the variation in plasma sex steroid levels in different stages of the reproductive cycle in the lizard Sceloporus torquatus and assess whether sex steroid levels were related to environmental factors (temperature, photoperiod, precipitation, and relative humidity) and body condition. Plasma concentrations of estradiol (E2) and progesterone (P4) from blood samples were quantified by enzyme-linked immunosorbent assay (ELISA) and radioimmunoanalysis (RIA), respectively. Our results indicate that sex steroid concentrations were positively related to follicular development but negatively related to temperature and precipitation. E2 increased as the follicles grew, and its concentrations were highest in the preovulatory phase. P4 showed a similar pattern and persisted during pregnancy. Changes in body condition were non-significant and mainly unrelated to the reproductive stage and plasma sex steroids. Our findings indicate that sex steroids change depending on the season and reproductive stage. We observed high concentrations of E2 and P4 in the late vitellogenic and preovulatory stages, probably because of their role in promoting vitellogenesis and ovulation. Additionally, we observed that follicular development is correlated with temperature and photoperiod. To better understand the mechanisms underlying reproduction, future studies of captive populations where environmental factors can be manipulated are needed.
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Affiliation(s)
- Norma Berenice Cruz-Cano
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Edificio D, 1° Piso, Circuito de Posgrados, Ciudad Universitaria, Coyoacán, Ciudad de México, México; Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México.
| | - Uriel Ángel Sánchez-Rivera
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México
| | - Carmen Álvarez-Rodríguez
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México
| | - Rodrigo Dávila-Govantes
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México
| | - Mario Cárdenas-León
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México; Laboratorio de Hormonas Proteicas, Departamento de Biología de la Reproducción, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, C.P. 14080, Ciudad de México, México
| | - Martín Martínez-Torres
- Laboratorio de Biología de la Reproducción, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios s/n, Los Reyes Iztacala, Tlalnepantla, Estado de México, C.P. 54110, México.
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Currylow AF, Collier MAM, Hanslowe EB, Falk BG, Cade BS, Moy SE, Grajal‐Puche A, Ridgley FN, Reed RN, Yackel Adams AA. Thermal stability of an adaptable, invasive ectotherm: Argentine giant tegus in the Greater Everglades ecosystem, USA. Ecosphere 2021. [DOI: 10.1002/ecs2.3579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Andrea F. Currylow
- U.S. Geological Survey South Florida Field Station Fort Collins Science Center 40001 SR 9336 Homestead Florida 33034 USA
| | - Michelle A. M. Collier
- U.S. Geological Survey South Florida Field Station Fort Collins Science Center 40001 SR 9336 Homestead Florida 33034 USA
| | - Emma B. Hanslowe
- U.S. Geological Survey South Florida Field Station Fort Collins Science Center 40001 SR 9336 Homestead Florida 33034 USA
| | - Bryan G. Falk
- U.S. Geological Survey South Florida Field Station Fort Collins Science Center 40001 SR 9336 Homestead Florida 33034 USA
| | - Brian S. Cade
- U.S. Geological Survey Fort Collins Science Center 2150 Centre Avenue Building C Fort Collins Colorado 80526 USA
| | - Sarah E. Moy
- U.S. Geological Survey South Florida Field Station Fort Collins Science Center 40001 SR 9336 Homestead Florida 33034 USA
| | - Alejandro Grajal‐Puche
- U.S. Geological Survey South Florida Field Station Fort Collins Science Center 40001 SR 9336 Homestead Florida 33034 USA
| | - Frank N. Ridgley
- Conservation and Research Department Zoo Miami 12400 SW 152nd Street Miami Florida 33177 USA
| | - Robert N. Reed
- U.S. Geological Survey Fort Collins Science Center 2150 Centre Avenue Building C Fort Collins Colorado 80526 USA
| | - Amy A. Yackel Adams
- U.S. Geological Survey Fort Collins Science Center 2150 Centre Avenue Building C Fort Collins Colorado 80526 USA
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Małek DK, Czarnoleski M. Thermal Preferences of Cowpea Seed Beetles ( Callosobruchus maculatus): Effects of Sex and Nuptial Gift Transfers. INSECTS 2021; 12:insects12040310. [PMID: 33915679 PMCID: PMC8066898 DOI: 10.3390/insects12040310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/24/2021] [Accepted: 03/29/2021] [Indexed: 12/03/2022]
Abstract
Simple Summary The thermal environment is crucial for organismal functioning, and many cold-blooded organisms, including insects, behaviorally regulate their body temperature. Why do insects inhabit given thermal conditions? We propose that access to water affects thermal preference and that insects with poor access to water inhabit colder environments, which reduces evaporation and preserves water. We studied the seed beetle Callosobruchus maculatus, which, as adults, do not drink or eat; however, males provide their mates with sperm, as well as nuptial gifts, including nutrients and water sources. We compared preferred temperatures between males and females that had access to mates or remained unmated and measured the sizes of the transferred gifts. We found that females preferred higher temperatures than males, but these preferences did not change due to mating or the transfer of larger or smaller gifts. It appears that males and females receive and lose certain amounts of water during mating, but they do not alter their thermal preferences according to the amount of water they receive or lose. Abstract The thermal environment influences insect performance, but the factors affecting insect thermal preferences are rarely studied. We studied Callosobruchus maculatus seed beetles and hypothesized that thermal preferences are influenced by water balance, with individuals with limited water reserves preferring cooler habitats to reduce evaporative water loss. Adult C. maculatus, in their flightless morph, do not consume food or water, but a copulating male provides a female with a nuptial gift of ejaculate containing nutrients and water. We hypothesized that gift recipients would prefer warmer habitats than gift donors and that both sexes would plastically adjust their thermal preferences according to the size of the transferred gift. We measured the thermal preference in each sex in individuals that were mated once or were unmated. In the mated group, we measured the sizes of the nuptial gifts and calculated proportional body mass changes in each mate during copulation. Supporting the role of water balance in thermal preference, females preferred warmer habitats than males. Nevertheless, thermal preferences in either sex were not affected by mating status or gift size. It is likely that high rates of mating and gift transfers in C. maculatus living under natural conditions promoted the evolution of constitutive sex-dependent thermal preferences.
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Goetz SM, Steen DA, Miller MA, Guyer C, Kottwitz J, Roberts JF, Blankenship E, Pearson PR, Warner DA, Reed RN. Argentine Black and White Tegu (Salvator merianae) can survive the winter under semi-natural conditions well beyond their current invasive range. PLoS One 2021; 16:e0245877. [PMID: 33690637 PMCID: PMC7946314 DOI: 10.1371/journal.pone.0245877] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 01/09/2021] [Indexed: 11/19/2022] Open
Abstract
The Argentine Black and White Tegu (Salvator merianae, formerly Tupinambis merianae) is a large lizard from South America. Now established and invasive in southern Florida, and it poses threats to populations of many native species. Models suggest much of the southern United States may contain suitable temperature regimes for this species, yet there is considerable uncertainty regarding either the potential for range expansion northward out of tropical and subtropical zones or the potential for the species establishing elsewhere following additional independent introductions. We evaluated survival, body temperature, duration and timing of winter dormancy, and health of wild-caught tegus from southern Florida held in semi-natural enclosures for over a year in Auburn, Alabama (> 900 km northwest of capture location). Nine of twelve lizards emerged from winter dormancy and seven survived the greater-than-one-year duration of the study. Average length of dormancy (176 d) was greater than that reported in the native range or for invasive populations in southern Florida and females remained dormant longer than males. Tegus grew rapidly throughout the study and the presence of sperm in the testes of males and previtellogenic or early vitellogenic follicles in female ovaries at the end of our study suggest the animals would have been capable of reproduction the following spring. The survival and overall health of the majority of adult tegus in our study suggests weather and climate patterns are unlikely to prevent survival following introduction in many areas of the United States far from their current invasive range.
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Affiliation(s)
- Scott M. Goetz
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, United States of America
- * E-mail:
| | - David A. Steen
- Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, Gainesville, Florida, United States of America
| | - Melissa A. Miller
- Department of Wildlife Ecology and Conservation, Fort Lauderdale Research and Education Center, University of Florida, Davie, Florida, United States of America
| | - Craig Guyer
- Department of Biological Sciences, College of Sciences and Mathematics, Auburn University, Auburn, Alabama, United States of America
| | - Jack Kottwitz
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, United States of America
| | - John F. Roberts
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Emmett Blankenship
- All Pets Emergency and Referral Center, Alpharetta, Georgia, United States of America
| | - Phillip R. Pearson
- Centre for Conservation, Ecology, and Genetics, Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital City, Australia
| | - Daniel A. Warner
- Department of Biological Sciences, College of Sciences and Mathematics, Auburn University, Auburn, Alabama, United States of America
| | - Robert N. Reed
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, United States of America
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Logan ML, Neel LK, Nicholson DJ, Stokes AJ, Miller CL, Chung AK, Curlis JD, Keegan KM, Rosso AA, Maayan I, Folfas E, Williams CE, Casement B, Gallegos Koyner MA, Padilla Perez DJ, Falvey CH, Alexander SM, Charles KL, Graham ZA, McMillan WO, Losos JB, Cox CL. Sex-specific microhabitat use is associated with sex-biased thermal physiology in Anolis lizards. J Exp Biol 2021; 224:jeb235697. [PMID: 33328289 DOI: 10.1242/jeb.235697] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/07/2020] [Indexed: 08/25/2023]
Abstract
If fitness optima for a given trait differ between males and females in a population, sexual dimorphism may evolve. Sex-biased trait variation may affect patterns of habitat use, and if the microhabitats used by each sex have dissimilar microclimates, this can drive sex-specific selection on thermal physiology. Nevertheless, tests of differences between the sexes in thermal physiology are uncommon, and studies linking these differences to microhabitat use or behavior are even rarer. We examined microhabitat use and thermal physiology in two ectothermic congeners that are ecologically similar but differ in their degree of sexual size dimorphism. Brown anoles (Anolis sagrei) exhibit male-biased sexual size dimorphism and live in thermally heterogeneous habitats, whereas slender anoles (Anolis apletophallus) are sexually monomorphic in body size and live in thermally homogeneous habitats. We hypothesized that differences in habitat use between the sexes would drive sexual divergence in thermal physiology in brown anoles, but not slender anoles, because male and female brown anoles may be exposed to divergent microclimates. We found that male and female brown anoles, but not slender anoles, used perches with different thermal characteristics and were sexually dimorphic in thermal tolerance traits. However, field-active body temperatures and behavior in a laboratory thermal arena did not differ between females and males in either species. Our results suggest that sexual dimorphism in thermal physiology can arise from phenotypic plasticity or sex-specific selection on traits that are linked to thermal tolerance, rather than from direct effects of thermal environments experienced by males and females.
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Affiliation(s)
- Michael L Logan
- Department of Biology, University of Nevada, Reno, NV 89557, USA
- Smithsonian Tropical Research Institute, Panamá City, Panamá
| | - Lauren K Neel
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Daniel J Nicholson
- School of Biological and Chemical Sciences, Queen Mary University, London, E1 4NS, UK
- Zoological Society of London, London, NW1 4RY, UK
| | - Andrew J Stokes
- Department of Environmental Studies, University of Illinois Springfield, Springfield, IL 62703, USA
| | - Christina L Miller
- Department of Biological Sciences, University of Queensland, Queensland, Australia
| | - Albert K Chung
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA
- Department of Biology, Georgia Southern University, Statesboro, GA 30460, USA
| | - John David Curlis
- Department of Biology, Georgia Southern University, Statesboro, GA 30460, USA
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kaitlin M Keegan
- Department of Geological Sciences and Engineering, University of Nevada, Reno, NV 89557, USA
| | - Adam A Rosso
- Department of Biology, Georgia Southern University, Statesboro, GA 30460, USA
| | - Inbar Maayan
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Edite Folfas
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada, M5S 3B2
| | - Claire E Williams
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Brianna Casement
- Department of Biology and Environmental Science, Heidelberg University, Tiffin, OH 44883, USA
| | - Maria A Gallegos Koyner
- Department of Forest Sciences, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | | | - Cleo H Falvey
- Department of Biology, University of Massachusetts, Boston, MA 02125, USA
| | - Sean M Alexander
- Departement of Biology, Rutgers University, Camden, NJ 08901, USA
| | | | - Zackary A Graham
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - W Owen McMillan
- Smithsonian Tropical Research Institute, Panamá City, Panamá
| | - Jonathan B Losos
- Department of Biology, Washington University, Saint Louis, MO 63130, USA
| | - Christian L Cox
- Department of Biological Sciences and Institute for the Environment, Florida International University, FL 33199, USA
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6
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Filogonio R, Orsolini KF, Oda GM, Malte H, Leite CAC. Baroreflex gain and time of pressure decay at different body temperatures in the tegu lizard, Salvator merianae. PLoS One 2020; 15:e0242346. [PMID: 33227002 PMCID: PMC7682859 DOI: 10.1371/journal.pone.0242346] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/01/2020] [Indexed: 12/20/2022] Open
Abstract
Ectotherms may experience large body temperature (Tb) variations. Higher Tb have been reported to increase baroreflex sensitivity in ectotherm tetrapods. At lower Tb, pulse interval (PI) increases and diastolic pressure decays for longer, possibly resulting in lower end-diastolic pressures and mean arterial pressures (Pm). Additionally, compensatory baroreflex-related heart rate modulation (i.e. the cardiac branch of the baroreflex response) is delayed due to increased PI. Thus, low Tb is potentially detrimental, leading to cardiovascular malfunctioning. This raises the question on how Pm is regulated in such an adverse condition. We investigated the baroreflex compensations that enables tegu lizards, Salvator merianae, to maintain blood pressure homeostasis in a wide Tb range. Lizards had their femoral artery cannulated and pressure signals recorded at 15°C, 25°C and 35°C. We used the sequence method to analyse the heart rate baroreflex-related corrections to spontaneous pressure fluctuations at each temperature. Vascular adjustments (i.e. the peripheral branch) were assessed by calculating the time constant for arterial pressure decay (τ)—resultant from the action of both vascular resistance and compliance—by fitting the diastolic pressure descent to the two-element Windkessel equation. We observed that at lower Tb, lizards increased baroreflex gain at the operating point (Gop) and τ, indicating that the diastolic pressure decays at a slower rate. Gop normalized to Pm and PI, as well as the ratio τ/PI, did not change, indicating that both baroreflex gain and rate of pressure decay are adjusted according to PI lengthening. Consequently, pressure parameters and the oscillatory power fraction (an index of wasted cardiac energy) were unaltered by Tb, indicating that both Gop and τ modulation are crucial for cardiovascular homeostasis.
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Affiliation(s)
- Renato Filogonio
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
- * E-mail:
| | - Karina F. Orsolini
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - Gustavo M. Oda
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
| | - Hans Malte
- Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus C, Denmark
| | - Cléo A. C. Leite
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, São Paulo, Brazil
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Naretto S, Chiaraviglio M. Factors driving sexual dimorphism and colour variability in the Achala Copper Lizard (Pristidactylus achalensis), an endemic species to the highland mountains in central Argentina. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2019-0293] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intensity of mating competition varies according to the temporal and spatial distribution of individuals. Measuring sexual dimorphism over time and interpreting the association between individuals is therefore important if we aim to understand how sexual traits are influenced. We examined sex differences in the Achala Copper Lizard (Pristidactylus achalensis (Gallardo, 1964)), an endemic species from the highest part of mountains of central Argentina. Over 4 years, we explored sex-specific variation in body size, head size, interlimb length, and body colouration. Furthermore, we evaluated how these traits varied temporally, and we also explored whether the spatial distribution of individuals is explained by variation in these traits. We found that P. achalensis is a species with sexual dimorphism in multiple characters, including body size, head size, and colouration. Interestingly, some traits related to mating, such as head width, show a temporal variability in both sexes, whereas other traits, such as colouration, varies seasonally only in males. Our results underline the intriguing possibility of seasonal morphological changes related to mating, and more broadly that sex differences are influenced by sexual selection pressures mediated by temporal variation in mate competition.
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Affiliation(s)
- S. Naretto
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
| | - M. Chiaraviglio
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
- Laboratorio de Biología del Comportamiento, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Vélez Sársfield 299, CP X5000JJC, Córdoba, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Diversidad y Ecología Animal (IDEA), Córdoba, Argentina
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8
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López Juri G, Chiaraviglio M, Cardozo G. Do female reproductive stage and phenotype influence thermal requirements in an oviparous lizard? J Therm Biol 2018; 71:202-208. [DOI: 10.1016/j.jtherbio.2017.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 11/13/2017] [Accepted: 11/19/2017] [Indexed: 10/18/2022]
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Amaral-Silva LD, Scarpellini CDS, Toro-Velasquez PA, Fernandes MH, Gargaglioni LH, Bícego KC. Hypoxia during embryonic development increases energy metabolism in normoxic juvenile chicks. Comp Biochem Physiol A Mol Integr Physiol 2017; 207:93-99. [DOI: 10.1016/j.cbpa.2017.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 03/01/2017] [Accepted: 03/05/2017] [Indexed: 01/11/2023]
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10
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Ortega Z, Mencía A, Pérez-Mellado V. Sexual differences in behavioral thermoregulation of the lizard Scelarcis perspicillata. J Therm Biol 2016; 61:44-49. [PMID: 27712659 DOI: 10.1016/j.jtherbio.2016.08.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 08/05/2016] [Accepted: 08/22/2016] [Indexed: 11/18/2022]
Abstract
Temperature determines all aspects of the biology of ectotherms. Although sexual differences in thermal ecology are not the rule in lizards, some species exhibit such differences. We studied the effect of sex and reproductive condition on the thermoregulation of an introduced population of Scelarcis perspicillata during the summer in Menorca (Balearic Islands, Spain). These lizards live in the wall surfaces of a limestone quarry, where the sun is scarce because of the narrowness of the quarry walls. The population is sexually dimorphic, with larger males than females. We measured body temperature (Tb) of adult males and females in the field, and air (Ta) and substrate temperature (Ts) at the capture sites, and recorded exposure to sunlight, height of the perch, and type of substrate. We also recorded operative temperatures (Te) as a null hypothesis of thermoregulation. Finally, we studied the thermal preferences of adult males and females in a laboratory thermal gradient. Thermal preferences were similar for pregnant and non-pregnant females, and sex did not affect the thermal preferences of lizards, even after controlling for the effect of body size. However, in the field, females achieved higher Tb than males, and occupied microhabitats with higher Ta and Ts and lower perch heights than males. Furthermore, females selected perches in full sun at a higher frequency than males. As a consequence, females achieved a higher accuracy and effectiveness of thermoregulation (0.89) than males (0.84). Thus, all else being equal, females would achieve a higher performance than males. The observed results are attributable to sexual differences in behaviour, probably in relation with the reproductive season.
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Affiliation(s)
- Zaida Ortega
- Department of Animal Biology, University of Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
| | - Abraham Mencía
- Department of Animal Biology, University of Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Valentín Pérez-Mellado
- Department of Animal Biology, University of Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
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11
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de Barros FC, de Carvalho JE, Abe AS, Kohlsdorf T. Beyond body size: muscle biochemistry and body shape explain ontogenetic variation of anti-predatory behaviour in the lizard Salvator merianae. ACTA ACUST UNITED AC 2016; 219:1649-58. [PMID: 26994181 DOI: 10.1242/jeb.130740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 03/08/2016] [Indexed: 11/20/2022]
Abstract
Anti-predatory behaviour evolves under the strong action of natural selection because the success of individuals avoiding predation essentially defines their fitness. Choice of anti-predatory strategies is defined by prey characteristics as well as environmental temperature. An additional dimension often relegated in this multilevel equation is the ontogenetic component. In the tegu Salvator merianae, adults run away from predators at high temperatures but prefer fighting when it is cold, whereas juveniles exhibit the same flight strategy within a wide thermal range. Here, we integrate physiology and morphology to understand ontogenetic variation in the temperature-dependent shift of anti-predatory behaviour in these lizards. We compiled data for body shape and size, and quantified enzyme activity in hindlimb and head muscles, testing the hypothesis that morphophysiological models explain ontogenetic variation in behavioural associations. Our prediction is that juveniles exhibit body shape and muscle biochemistry that enhance flight strategies. We identified biochemical differences between muscles mainly in the LDH:CS ratio, whereby hindlimb muscles were more glycolytic than the jaw musculature. Juveniles, which often use evasive strategies to avoid predation, have more glycolytic hindlimb muscles and are much smaller when compared with adults 1-2 years old. Ontogenetic differences in body shape were identified but marginally contributed to behavioural variation between juvenile and adult tegus, and variation in anti-predatory behaviour in these lizards resides mainly in associations between body size and muscle biochemistry. Our results are discussed in the ecological context of predator avoidance by individuals differing in body size living at temperature-variable environments, where restrictions imposed by the cold could be compensated by specific phenotypes.
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Affiliation(s)
- Fábio Cury de Barros
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brazil
| | - José Eduardo de Carvalho
- Departamento de Ciências Biológicas, Universidade Federal de São Paulo - campus Diadema, Diadema, SP 09972-270, Brazil
| | - Augusto Shinya Abe
- Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista - campus Rio Claro, Rio Claro, SP 13506-900, Brazil
| | - Tiana Kohlsdorf
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brazil
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