Study systems
The heliconiian butterflies, especially the specious GenusHeliconius , have been extensively studied in relation to color patterns that both warn predators of their potent toxins and signal important identifying information to conspecifics (Merrill et al. 2015). Complex mimicry systems have evolved to exploit predator avoidance learning and subtle visual cues are used by conspecifics to identify potential mates (Bybee et al. 2012; Dell’Aglio et al. 2018; Merrill et al. 2015). The butterflies are potential prey to a diversity of predators, including insectivorous birds and lizards, many of which have vision sensitive to UV reflectance (Dell’Aglio et al. 2018). Similarly, the butterflies themselves are also able to see ultraviolet with some species having evolved two UV sensitive photoreceptors that allow for fine scale discrimination of UV wavelengths (Briscoe et al. 2010; Finkbeiner and Briscoe 2020). For example female Heliconius eratohave a functionally pentachromatic (cone peak sensitivities (λmax) of 355 nm, 390 nm, 470 nm, 555 nm, and 600 nm) visual system (McCulloch et al. 2016). The evolution of a duplicate UV-sensitive opsins is constrained to the genus Heliconius and appears to have co-evolved with the presence of specific UV-reflecting yellow pigments which are predicted to be important in directing both intra- and interspecific behaviors (Briscoe et al. 2010).
Poison frogs have similarly become a model system for understanding the interplay between aposematic and sexually selected signals (Stynoski et al. 2015). Brighter and more contrasting colors offer greater protection from predators (Dreher et al. 2015; Maan and Cummings 2012), are more intimidating to rivals (Crothers et al. 2011; Crothers and Cummings 2015; Galeano and Harms 2016), and are favored by potential mates (Dreher et al. 2017; Maan and Cummings 2008; Maan and Cummings 2009). Poison frogs, like heliconiian butterflies, are at risk from a wide range of UV-sensitive predators, including birds, snakes, and lizards (Alvarado et al. 2013; de Lanuza and Font 2014; Dreher et al. 2015; Lenger et al. 2014; Maan and Cummings 2012; Master 1998; Santos and Cannatella 2011; Saporito et al. 2007; Siddiqi et al. 2004; Willink et al. 2013). However, unlike the butterflies, poison frogs are not known to possess UV-sensitive vision. The one well described poison frog visual system being that of Oophaga pumilio , which has trichromatic vision (λmax of 466 nm, 489 nm, and 561 nm) that both lacks a UV-sensitive cone and has a lens that filters out UV wavelengths (Siddiqi et al. 2004; Yovanovich et al. 2020).