CHAPTER FIVE Sexual selection and social context: Web-building spiders as emerging models for adaptive plasticity Maydianne C.B. Andrade* Departments of Biological Sciences and Ecology and Evolutionary Biology, University of Toronto Scarborough, Toronto, ON, Canada *Corresponding author: e-mail address: maydianne.andrade@utoronto.ca Contents 1. Introduction 178 1.1 Adaptive phenotypic plasticity 178 1.2 Why spiders? Leveraging extreme mating for studies of plasticity 181 1.3 Tests of adaptive plasticity: Empirical challenges 185 2. Variable sexual selection linked to social context 188 2.1 Demography, social context, and sexual selection 189 2.2 Sliding, overlapping scales of variation in social context 191 3. Sexual selection and social context in (some) web-building spiders 196 3.1 Spatial distribution, phenology, and development of focal spider taxa 196 3.2 Extreme mating systems and sexual selection 204 4. Tests of adaptive plasticity in Nephila, Argiope, and Latrodectus spiders 218 4.1 Direction and intensity of sexual selection fluctuates with social context 219 4.2 Phenotypic distributions correlate with social context in nature 221 4.3 Divergent critical periods for developmental and activational plasticity 222 4.4 Developmental acceleration: Monogyny is not sufficient 226 4.5 Mate searching, developmental plasticity, and the integrated phenotype 227 5. Adaptive plasticity: Where are we now? 231 5.1 Summing it up for cannibalistic, mate-limited spiders 231 5.2 Needed: Detailed empiricism welded to an evolutionary framework 232 Acknowledgments 233 References 234 Advances in the Study of Behavior, Volume 51 # 2019 Elsevier Inc. ISSN 0065-3454 All rights reserved. https://doi.org/10.1016/bs.asb.2019.02.002 177