Lack of support for Rensch＇s rule in an intraspecific test using red flour beetle （Tribo/ium castaneum） populations  

作　　者：Oliver Y. Martin Lukasz Michalczyk Anna L. Millard Brent C. Emerson Matthew J. G. Gage 

机构地区：[1]School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7T J, United Kingdom [2]ETH Zurich, Experimental Ecology, Institute of Integrative Biology, D-USYS, Universitatsstrasse 16, CH-8092 Zurich, Switzerland [3]Department of Entomology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland [4]Island Ecology and Evolution Research Group (IPNA-CSIC), CIAstrofisico Francisco Sanchez 3, 38206 La Laguna, Tenerife, Canary Islands, Spain

出　　处：《Insect Science》2017年第1期133-140,共8页昆虫科学（英文版）

基　　金：Acknowledgments The authors thank Richard Beeman （USDA） for generously sending us the beetles used to start our lab stocks, and Wolf Blanckenhorn for kindly providing a copy of an Excel spreadsheet designed for calculation of RMA and MA slopes. The authors further thank NERC （Standard research grant to MJGG, BCE and OYM）, Swiss National Science Foundation （postdoctoral fellowships and Ambizione grants to OYM）, the University of East Anglia and ETH Zurich for support, and the anonymous reviewers for comments on the manuscript.

摘　　要：Rensch＇s rule proposes a universal allometric scaling phenomenon across species where sexual size dimorphism （SSD） has evolved： in taxa with male-biased dimorphism, degree of SSD should increase with overall body size, and in taxa with female-biased dimorphism, degree of SSD should decrease with increasing average body size. Rensch＇s rule appears to hold widely across taxa where SSD is male-biased, but not consistently when SSD is female-biased. Furthermore, studies addressing this question within species are rare, so it remains unclear whether this rule applies at the intraspecific level. We assess body size and SSD within Tribolium castaneum （Herbst）, a species where females are larger than males, using 21 populations derived from separate locations across the world, and maintained in isolated laboratory culture for at least 20 years. Body size, and hence SSD patterns, are highly susceptible to variations in temperature, diet quality and other environmental factors. Crucially, here we nullify interference of such confounds as all populations were maintained under identical conditions （similar densities, standard diet and exposed to identical temperature, relative humidity and photoperiod）. We measured thirty beetles of each sex for all populations, and found body size variation across populations, and （as expected） female-biased SSD in all populations. We test whether Rensch＇s rule holds for our populations, but find isometry, i.e. no allometry for SSD. Our results thus show that Rensch＇s rule does not hold across populations within this species. Our intraspecific test matches previous interspecific studies showing that Rensch＇s rule fails in species with female-biased SSD.Rensch＇s rule proposes a universal allometric scaling phenomenon across species where sexual size dimorphism （SSD） has evolved： in taxa with male-biased dimorphism, degree of SSD should increase with overall body size, and in taxa with female-biased dimorphism, degree of SSD should decrease with increasing average body size. Rensch＇s rule appears to hold widely across taxa where SSD is male-biased, but not consistently when SSD is female-biased. Furthermore, studies addressing this question within species are rare, so it remains unclear whether this rule applies at the intraspecific level. We assess body size and SSD within Tribolium castaneum （Herbst）, a species where females are larger than males, using 21 populations derived from separate locations across the world, and maintained in isolated laboratory culture for at least 20 years. Body size, and hence SSD patterns, are highly susceptible to variations in temperature, diet quality and other environmental factors. Crucially, here we nullify interference of such confounds as all populations were maintained under identical conditions （similar densities, standard diet and exposed to identical temperature, relative humidity and photoperiod）. We measured thirty beetles of each sex for all populations, and found body size variation across populations, and （as expected） female-biased SSD in all populations. We test whether Rensch＇s rule holds for our populations, but find isometry, i.e. no allometry for SSD. Our results thus show that Rensch＇s rule does not hold across populations within this species. Our intraspecific test matches previous interspecific studies showing that Rensch＇s rule fails in species with female-biased SSD.

关 键 词：ALLOMETRY body size COLEOPTERA sexual selection sexual size dimorphism TENEBRIONIDAE 

分 类 号：Q987[生物学—遗传学] S661.103.5[生物学—人类学]