The Bogert Effect and environmental heterogeneity
A classic question in evolutionary biology is whether behavioral flexibility hastens or hinders evolutionary change. The latter idea, that behavior reduces the number of environmental states experienced by an organism and buffers that organism against selection, has been dubbed the “Bogert Effect” after Charles Bogert, the biologist who first popularized the phenomenon using data from lizards. The Bogert Effect is pervasive when traits like body temperature, which tend to be invariant across space in species that behaviorally thermoregulate, are considered. Nevertheless, behavioral thermoregulation decreases or stops when spatial variation in operative temperature is low. We compared environmental temperatures, thermoregulatory behavior, and a suite of physiological and morphological traits between two populations of the southern rock agama (Agama atra) in South Africa that experience different climatic regimes. Individuals from both populations thermoregulated efficiently, maintaining body temperatures within their preferred temperature range throughout most of their activity cycle. Nevertheless, they differed in the thermal sensitivity of resting metabolic rate at cooler body temperatures and in morphology. Our results support the common assertion that thermoregulatory behavior may prevent divergence in traits like field-active body temperature, which are measured during periods of high environmental heterogeneity. Nevertheless, we show that other traits may be free to diverge if they are under selection during times when environments are homogenous. We argue that the importance of the Bogert Effect is critically dependent on the nature of environmental heterogeneity and will therefore be relevant to some traits and irrelevant to others in many populations.
KeywordsAdaptation Agama Behavioral thermoregulation Metabolic rate Water loss
The authors would like to thank A. Hougaard and J. S. Terblanche for assistance in the field and lab, respectively. We would like to thank K. Keegan for help with analyses. Funding for this project was provided by a United States National Science Foundation Postdoctoral Fellowship in Biology awarded to MLL (award number DBI-1402497), and by Stellenbosch University and the Centre of Excellence for Invasion Biology to SCT.
Author contributions statement
MLL and SCT designed the study. MLL and JVB collected the data. MLL and SCT analyzed the data. MLL, SCT, and JVB wrote the paper.
Compliance ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Statement of human and animal rights
All applicable institutional and/or national guidelines for the care and use of animals were followed. All research was carried out under Stellenbosch University animal ethics protocol no. SU-ACUD14-00110 and under CapeNature permit no. 0056-AAA007-00156.
- de la Vega-Perez AHD, Jimenez-Arcos VH, Manriquez-Moran NL, Mendez-de la Cruz FR (2013) Conservatism of thermal preferences between parthenogenetic Aspidoscelis cozumela complex (Squamata: Teiidae) and their parental species. Herpetol J 23:93–104Google Scholar
- Hardy A (1965) The living stream: evolution and man. Harper & Row, New YorkGoogle Scholar
- Husak JF, Fox SF, Lovern MB, Van Den Bussche RA (2006) Faster lizards sire more offspring: sexual selection on whole-animal performance. Evolution 60:2122–2130. https://doi.org/10.1111/j.0014-3820.2006.tb01849.x CrossRefPubMedGoogle Scholar
- Logan ML (2019) Did pathogens facilitate the rise of endothermy? Ideas Ecol Evol 12:1–8Google Scholar
- Logan ML, Montgomery CE, Boback SM, Reed RN, Campbell JA (2012) Divergence in morphology, but not habitat use, despite low genetic differentiation among insular populations of the lizard Anolis lemurinus in Honduras. J Trop Ecol 28:215–222. https://doi.org/10.1017/s0266467411000745 CrossRefGoogle Scholar
- Losos JB (2009) Lizards in an evolutionary tree: ecology and adaptive radiation of anoles. University of California Press, BerkelyGoogle Scholar
- Losos JB et al (2000) Evolutionary implications of phenotypic plasticity in the hindlimb of the lizard Anolis sagrei. Evolution 54:301–305. https://doi.org/10.1111/j.0014-3820.2000.tb00032.x CrossRefPubMedPubMedCentralGoogle Scholar
- Mayr E (1959) The emergence of evolutionary novelties. University of Chicago Press, ChicagoGoogle Scholar
- Miles DB (2004) The race goes to the swift: fitness consequences of variation in sprint performance in juvenile lizards. Evol Ecol Res 6:63–75Google Scholar
- West-Eberhard MJ (1989) Phenotypic plasticity and the origins of diversity. Annu Rev Ecol Syst 20:249–278. https://doi.org/10.1146/annurev.es.20.110189.001341 CrossRefGoogle Scholar