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Still MB, Lea AM, Hofmann HA, Ryan MJ. Multimodal stimuli regulate reproductive behavior and physiology in male túngara frogs. Horm Behav 2019; 115:104546. [PMID: 31233717 DOI: 10.1016/j.yhbeh.2019.06.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 06/14/2019] [Accepted: 06/19/2019] [Indexed: 11/23/2022]
Abstract
Unlike in terrestrial animals, the boundary between internal (e.g., hormones) and external (e.g., social) stimulation can be blurred for aquatic and amphibious species. When chemicals such as hormones and glandular secretions leach into the water, they can further interact with other signaling systems, creating multimodal stimuli. It is unclear, however, whether water-borne chemical secretions from courting male frogs affect the physiology and behavior of their rivals. In order to address this question we first established non-invasive, continuous sampling methods for simultaneously measuring both hormones and behavior in amphibious species. Then, we examined whether interactions between water-borne chemical secretions and conspecific calls affect reproductive behavior and physiology (testosterone and corticosterone) of courting male túngara frogs. Our results demonstrate that conspecific acoustic stimulation alone increases locomotor activity, decreases latency to call, and increases calling behavior but does not alter the amount of hormones excreted. In response to water containing chemical secretions from rivals, but in the absence of calls from other males, males excrete more testosterone. Interestingly, the combined acoustic and chemical stimulus causes a multiplicative increase in both calling behavior and hormonal excretion. Taken together, our results suggest that a multimodal chemical-acoustic stimulus physiologically primes males for aggressive behavior.
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Affiliation(s)
- Meghan B Still
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
| | - Amanda M Lea
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Hans A Hofmann
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Neuroscience, University of Texas at Austin, Austin, TX 78712, USA
| | - Michael J Ryan
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA; Smithsonian Tropical Research Institute, Balboa Ancon, Panama
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Rusch TW, Sears MW, Angilletta MJ. Lizards perceived abiotic and biotic stressors independently when competing for shade in terrestrial mesocosms. Horm Behav 2018; 106:44-51. [PMID: 30218647 DOI: 10.1016/j.yhbeh.2018.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 09/03/2018] [Accepted: 09/10/2018] [Indexed: 11/21/2022]
Abstract
Hormones such as glucocorticoids and androgens enable animals to respond adaptively to environmental stressors. For this reason, circulating glucocorticoids became a popular biomarker for estimating the quality of an environment, and circulating androgens are frequently used to indicate social dominance. Here, we show that access to thermal resources influence the hormones and behavior of male lizards (Sceloporus jarrovi). We exposed isolated and paired males to different thermal landscapes, ranging from one large patch of shade to sixteen smaller patches. Both the presence of a competitor and the patchiness of the thermal environment influenced hormone concentrations and movement patterns. When shade was concentrated in space, paired lizards competed more aggressively and circulated more corticosterone. Even without competitors, lizards circulated more corticosterone in landscapes with fewer patches of shade. Conversely, shifts in circulating testosterone depended only on the relative body size of a lizard; when paired, large males and small males circulated more and less testosterone, respectively. Furthermore, isolated males moved the farthest and covered the most area when shade was concentrated in a single patch, but paired males did the opposite. Because the total area of shade in each landscape was the same, these hormonal and behavioral responses of lizards reflect the ability to access shade. Thus, circulating glucocorticoids should reflect the thermal quality of an environment when researchers have controlled for other factors. Moreover, a theory of stress during thermoregulation would help ecologists anticipate physiological and behavioral responses to changing climates.
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Affiliation(s)
- Travis W Rusch
- Arizona State University, School of Life Sciences, Tempe, AZ, USA.
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Rusch TW, Angilletta MJ. Competition during thermoregulation altered the body temperatures and hormone levels of lizards. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12869] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Travis W. Rusch
- School of Life Sciences Arizona State University Tempe AZ85287 USA
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Camacho A, Rusch TW. Methods and pitfalls of measuring thermal preference and tolerance in lizards. J Therm Biol 2017; 68:63-72. [PMID: 28689723 DOI: 10.1016/j.jtherbio.2017.03.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 03/16/2017] [Accepted: 03/19/2017] [Indexed: 11/28/2022]
Abstract
Understanding methodological and biological sources of bias during the measurement of thermal parameters is essential for the advancement of thermal biology. For more than a century, studies on lizards have deepened our understanding of thermal ecophysiology, employing multiple methods to measure thermal preferences and tolerances. We reviewed 129 articles concerned with measuring preferred body temperature (PBT), voluntary thermal tolerance, and critical temperatures of lizards to offer: a) an overview of the methods used to measure and report these parameters, b) a summary of the methodological and biological factors affecting thermal preference and tolerance, c) recommendations to avoid identified pitfalls, and d) directions for continued progress in our application and understanding of these thermal parameters. We emphasize the need for more methodological and comparative studies. Lastly, we urge researchers to provide more detailed methodological descriptions and suggest ways to make their raw data more informative to increase the utility of thermal biology studies.
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Affiliation(s)
- Agustín Camacho
- Laboratório de Herpetologia, Instituto de Biociências, Universidade de São Paulo, Brazil.
| | - Travis W Rusch
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
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Dos Remedios N, Székely T, Küpper C, Lee PLM, Kosztolányi A. Ontogenic differences in sexual size dimorphism across four plover populations. THE IBIS 2015; 157:590-600. [PMID: 27499551 PMCID: PMC4957268 DOI: 10.1111/ibi.12263] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 03/22/2015] [Indexed: 06/06/2023]
Abstract
Sexual size dimorphism (SSD) among adults is commonly observed in animals and is considered to be adaptive. However, the ontogenic emergence of SSD, i.e. the timing of divergence in body size between males and females, has only recently received attention. It is widely acknowledged that the ontogeny of SSD may differ between species, but it remains unclear how variable the ontogeny of SSD is within species. Kentish Plovers Charadrius alexandrinus and Snowy Plovers C. nivosus are closely related wader species that exhibit similar, moderate (c. 4%), male-biased adult SSD. To assess when SSD emerges we recorded tarsus length variation among 759 offspring in four populations of these species. Tarsus length of chicks was measured on the day of hatching and up to three times on recapture before fledging. In one population (Mexico, Snowy Plovers), males and females differed in size from the day of hatching, whereas growth rates differed between the sexes in two populations (Turkey and United Arab Emirates, both Kentish Plovers). In contrast, a fourth population (Cape Verde, Kentish Plovers) showed no significant SSD in juveniles. Our results suggest that adult SSD can emerge at different stages of development (prenatal, postnatal and post-juvenile) in different populations of the same species. We discuss the proximate mechanisms that may underlie these developmental differences.
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Affiliation(s)
- Natalie Dos Remedios
- Department of Biology and Biochemistry University of Bath Claverton Down Bath BA2 7AY UK; NERC-Biomolecular Analysis Facility Department of Animal and Plant Sciences University of Sheffield Western Bank Sheffield S10 2TN UK
| | - Tamás Székely
- Department of Biology and Biochemistry University of Bath Claverton Down Bath BA2 7AY UK
| | - Clemens Küpper
- NERC-Biomolecular Analysis Facility Department of Animal and Plant Sciences University of Sheffield Western Bank Sheffield S10 2TN UK
| | - Patricia L M Lee
- Centre for Integrative Ecology School of Life and Environmental Sciences Deakin University Warrnambool Victoria 3280 Australia; Department of Biosciences College of Science Swansea University Singleton Park Swansea SA2 8PP UK
| | - András Kosztolányi
- MTA-DE 'Lendület' Behavioural Ecology Research Group Department of Evolutionary Zoology University of Debrecen Egyetem tér 1. H-4032 Debrecen Hungary
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Williams SC, McBrayer LD. Attack-based indices, not movement patterns, reveal intraspecific variation in foraging behavior. Behav Ecol 2011. [DOI: 10.1093/beheco/arr082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Castañeda G, Gadsden H, Contreras-Balderas AJ, GarcÍa-De la Peña C. VARIATION IN HOME RANGE OF THE SIDE-BLOTCHED LIZARD, UTA STEJNEGERI, IN COAHUILA, MEXICO. SOUTHWEST NAT 2007. [DOI: 10.1894/0038-4909(2007)52[461:vihrot]2.0.co;2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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COX ROBERTM, JOHN-ALDER HENRYB. Increased mite parasitism as a cost of testosterone in male striped plateau lizards Sceloporus virgatus. Funct Ecol 2007. [DOI: 10.1111/j.1365-2435.2007.01251.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Goodman RM. Activity Patterns and Foraging Behavior of the Endangered Grand Cayman Blue Iguana,Cyclura lewisi. CARIBB J SCI 2007. [DOI: 10.18475/cjos.v43i1.a7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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COX RM, ZILBERMAN V, JOHN-ALDER HB. Environmental sensitivity of sexual size dimorphism: laboratory common garden removes effects of sex and castration on lizard growth. Funct Ecol 2006. [DOI: 10.1111/j.1365-2435.2006.01177.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cox RM, John-Alder HB. Testosterone has opposite effects on male growth in lizards(Sceloporus spp.) with opposite patterns of sexual size dimorphism. J Exp Biol 2005; 208:4679-87. [PMID: 16326949 DOI: 10.1242/jeb.01948] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Sexual size dimorphism (SSD) has received considerable attention from evolutionary biologists, but relatively little is known about the physiological mechanisms underlying sex differences in growth that lead to SSD. Testosterone (T) stimulates growth in many male-larger vertebrates, but inhibits growth in the female-larger lizard Sceloporus undulatus. Thus, opposite patterns of SSD may develop in part because of underlying differences in the hormonal regulation of male growth. In the present study,we examined the effects of T on male growth in two sympatric congeners with opposite patterns of SSD (S. virgatus: female-larger; S. jarrovii: male-larger). During the mating season, yearling males of both species have higher plasma T levels than females, but whereas yearling males of S. virgatus grow only half as fast as females, yearling males of S. jarrovii grow more quickly than females. Thus, we hypothesized that T inhibits growth in yearling S. virgatus males, but promotes growth in yearling S. jarrovii males. In support of this hypothesis,we found that castrated (CAST) males of S. virgatus grew faster than castrated males given T implants (TEST). In contrast, TEST males of S. jarrovii grew faster than CAST males. Our results provide the first direct evidence for opposite effects of T on male growth in closely related species with opposite patterns of SSD. We speculate that growth inhibition by T reflects an energetic trade-off between growth and reproductive investment,and propose that such `costs' of male reproduction may help explain the evolution of female-larger SSD in Sceloporus.
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Affiliation(s)
- Robert M Cox
- Graduate Program in Ecology and Evolution, Department of Animal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
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Cox RM, Skelly SL, Leo A, John-Alder HB. Testosterone Regulates Sexually Dimorphic Coloration in the Eastern Fence Lizard, Sceloporus undulatus. COPEIA 2005. [DOI: 10.1643/cp-04-313r] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Cox RM, Skelly SL, John-Alder HB. Testosterone Inhibits Growth in Juvenile Male Eastern Fence Lizards (Sceloporus undulatus): Implications for Energy Allocation and Sexual Size Dimorphism. Physiol Biochem Zool 2005; 78:531-45. [PMID: 15957108 DOI: 10.1086/430226] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2004] [Indexed: 11/04/2022]
Abstract
In the eastern fence lizard, Sceloporus undulatus, female-larger sexual size dimorphism develops because yearling females grow faster than males before first reproduction. This sexual growth divergence coincides with maturational increases in male aggression, movement, and ventral coloration, all of which are influenced by the sex steroid testosterone (T). These observations suggest that male growth may be constrained by energetic costs of activity and implicate T as a physiological regulator of this potential trade-off. To test this hypothesis, we used surgical castration and subsequent administration of exogenous T to alter the physiological and behavioral phenotypes of field-active males during the period of sexual growth divergence. As predicted, T inhibited male growth, while castration promoted long-term growth. Males treated with T also exhibited increased daily activity period, movement, and home range area. Food consumption did not differ among male treatments or sexes, suggesting that the inhibitory effects of T on growth are mediated by patterns of energy allocation rather than acquisition. On the basis of estimates derived from published data, we conclude that the energetic cost of increased daily activity period following T manipulation is sufficient to explain most (79%) of the associated reduction in growth. Further, growth may have been constrained by additional energetic costs of increased ectoparasite load following T manipulation. Similar studies of the proximate behavioral, ecological, and physiological mechanisms involved in growth regulation should greatly improve our understanding of sexual size dimorphism.
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Affiliation(s)
- Robert M Cox
- Graduate Program in Ecology and Evolution, Rutgers University, New Brunswick, NJ 08901, USA
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