Flower specialization of butterflies and impacts of non-native flower use in a transformed tropical landscape Anuj Jain a, ⁎, Krushnamegh Kunte b , Edward L. Webb a, ⁎ a Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore b National Center for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India abstract article info Article history: Received 4 March 2016 Received in revised form 4 June 2016 Accepted 30 June 2016 Available online xxxx Flower-feeding ecology of tropical butterflies remains poorly studied, particularly in transformed landscapes, de- spite that flower availability and quality affect important life-history traits and are critical to butterfly abundance. We recorded 190 butterfly species feeding on 149 flowering plant species across forests and urban parks in Sin- gapore. Butterflies were classified as flower generalists, intermediates or specialists by fitting a power function between the number of flower species utilized and the flower visits observed for that butterfly species. General- ized least squares models were constructed between the degree of flower specialization and traits of butterfly species. Our analysis showed that more species were flower generalists than flower specialists in both habitat types. Forty-three percent of feeding observations in forested sites were on non-native flowers. Yet, flower spe- cialists used significantly higher proportions of native flower species in their diet than flower generalists and tended to be forest dependent. Some forest butterflies were critically dependent (N 70%) on single native flower species. Out of 19 butterfly species examined for response across habitats, five expanded their diet but six contracted their diet with urbanization. The regression models revealed that adult conspicuousness, habitat breadth, proboscis length, and wingspan were most strongly associated with flower specialization when ac- counting for phylogenetic relatedness. Our results suggest that while landscape transformation in the tropics could benefit some flower-generalist butterflies by providing extra resources, flower-specialist butterflies could further increase dependence on few native flower sources. Such butterflies may require intervention in terms of landscape management of their preferred flower resources. © 2016 Elsevier Ltd. All rights reserved. Keywords: Diet breadth Habitat management Insect foraging Invasive species Nectar-feeding Pollination 1. Introduction Flower-feeding ecology is a critical component of butterfly life-histo- ry that affects important traits such as fecundity and longevity (Boggs and Gilbert, 1979; Schultz and Dlugosch, 1999). The distribution of nec- tar resources influences patterns of butterfly oviposition (Janz, 2005), dispersal, emigration and immigration rates in local populations and are partially responsible for shaping butterfly meta-population struc- tures (Schneider et al., 2003). Furthermore, an understanding of flower use and flower preferences is required to manage habitats for butterflies (Hardy et al., 2007). Butterfly species exhibit varying levels of flower preferences and flower specialization, defined as the utilization of fewer flower species than the average of all butterfly species scaled by the number of obser- vations made of each butterfly species (Tudor et al., 2004). Butterflies in temperate regions are believed to be flower generalists, but some tem- perate butterflies have been shown to exhibit flower specialization (e.g., Stefanescu and Traveset, 2009; Tudor et al., 2004). During the flowering season when nectar resources are abundant, butterflies can be flower specific and choose to feed only from a limited number of plant species in a habitat (Wiklund and Ahrberg, 1978; Rodriguez et al., 1994) and can sometimes be nearly absent from sites where the preferred flower resource is lacking (Severns et al., 2006). Further, preferred flowering plants can differ between time periods within sites and between sites (Wiklund and Ahrberg, 1978). Between sexes, females may visit a larger number of flowering plant species than males, presumably as a result of their higher dietary requirements (Wiklund and Ahrberg, 1978). Butter- flies also have innate preferences towards certain flower characteristics - e.g., color preferences for yellow and red flowers (Weiss, 1997, Pohl et al., 2011); species with high wing loading prefer clustered or nectar-rich flowers (Corbet, 2000; Kunte, 2007). Behavioral modifications and de- rived proboscis morphology are also often associated with specialized feeding preferences (Bauder et al., 2013; Krenn, 2010). It is thus evident, that flower specialization of butterflies is a complex phenomenon and one that interacts with species abundance, habitat matrix, environmen- tal conditions and species traits. In tropical systems, some butterflies have been shown to be flower generalists (Kunte, 2007) and flower specialists (Bauder et al., 2015b) but research efforts have been minimal and largely focused only on treatments of single species or particular groups of species. An under- standing of flower specialization across many butterfly species is Biological Conservation 201 (2016) 184–191 ⁎ Corresponding authors. E-mail addresses: anuj@u.nus.edu (A. Jain), ted.webb@nus.edu.sg (E.L. Webb). http://dx.doi.org/10.1016/j.biocon.2016.06.034 0006-3207/© 2016 Elsevier Ltd. All rights reserved. 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