Visual Ecology: Evolution, Behavior, and Conservation

Overall, my research interests lie at how light affects animals. In most cases, I research the visual perception of light by animals but have studied how light can affect thermoregulatory behaviors as well. Currently I have two main interests within the realm of sensory ecology: 1) Anthropogenic light and visual ecology; 2) Behavioral and visual ecology of animals. 

Anthropogenic Light and Visual Ecology

As a postdoctoral fellow with the National Park Service Night Skies Division, I have focused my research on how the overwhelming light produced by humans affects visual systems and ecology of animals. Currently, I have several research topics ranging from the effects of light from oil and gas developments on predator and prey use to the perception of light domes by myriad taxa. I will update this page as I begin to submit work from this research. Stay tuned.

Behavioral and Visual Ecology of Animals

An organism's environment can be as dynamic as its behavior. Thus animal behavior and the environment can be tightly linked. One underdeveloped topic in behavioral ecology is how the environment has sculpted animal communication. For visual signals, such as warning colors of toxic butterflies or bright ornaments of male birds, the environment can drastically affect the perception of visual signals by an intended receiver. This can happen through different backgrounds (i.e. sand vs. blue sky), different lighting environments (i.e. shady forest vs. open fields), or different perceptual abilities of receivers (dichromatic vs trichromatic color vision). Due to environmental effects, animals should behave in ways to optimize both production and reception of signals. My research focuses on how the environment has driven and affects visual systems, visual signals, and behavior, mostly in arthropods.

Environmental factors affecting signal efficacy

Visual signals can drastically be affected by available light and the background, and although this has been well known for decades, very little research into the effects of light environment on signal efficacy exists. Fortunately, we now have inexpensive techniques that enable accurate quantification of light environment that can be utilized with studying the ecology and behavior of signal-receiver interactions to shed light onto environmental effects on animal communication. Ongoing research in this sub-discipline includes how perceived conspicuousness of different mimicry rings of Heliconius butterflies is affected by the different available light environments in the tropical rainforest. We also have an ongoing project examining how the sunrise affects conspicuousness of a multicomponent warning signal in the pipeline swallowtail. This project further investigates how animals have evolved and behave to increase signal efficacy.

Physiological ecology of vision

Just as visual signals are dependent upon the environment, visual systems of animals have evolved under certain selection pressures in different environments. Sensory drive predicts that individuals will evolve sensory systems that are able to extract as much information from cues (e.g. mate condition, prey toxicity, etc) as possible. My current research investigates how and why insect visual systems differ as a result of light environment and conspecific interactions. We are currently investigating how different tropical light environments (i.e. nocturnal, forest understory, open fields) has selected for different eye morphology and visual sensitivity. 

Evolution and maintenance of mimetic populations

Over one hundred and fifty years ago, Henry Bates discovered “a most powerful proof of the theory of natural selection” by revealing the fascinating adaptation of an edible animal resembling a conspicuous, inedible animal to reduce risk of predation, termed Batesian mimicry. Then 16 years after Bates’ discovery, Fritz Müller devised one of the first mathematical models supporting natural selection. Müller demonstrated that two conspicuous and unpalatable individuals can both gain protection from predation if they converge on the same warning signal (e.g. yellow and black stripes of wasps), this phenomenon was fittingly dubbed Müllerian mimicry. Therefore, although Batesian and Müllerian mimicry both confuse predators, Batesian mimicry is a parasitic relationship between the edible mimic and the inedible model, while Müllerian mimics mutually benefit from the mimetic relationship. Although mimics can be striking lookalikes of their model, paradoxically, many resemble their model imprecisely. Furthermore, the degree of mimicry precision and accuracy varies within the same species, which begs the question: if natural selection is so powerful, then why are so many mimics imprecise? First, what determines if the mimetic resemblance is precise or imprecise? For visual mimicry (i.e. color and pattern) we now have the ability to mathematically model if two color patches or patterns are noticeably different at the level of the photoreceptors in a perceiver’s eye. These models compare the photon catch of each of the different photoreceptors of the perceiver and then calculates if the differences between the patch reflectance spectra are perceivable when neural noise is added. These visual models allow for an objective definition of imprecise mimicry: the ecologically relevant predator is able to discriminate between the coloration of the model and mimic. We are currently investigating different hypotheses explaining imprecise mimicry in many species of butterflies. 

Examples of imprecise mimicry in butterflies. A) An Ecuadorian mimicry ring that includes species in the family Nymphalidae and Papilionidae. B) Just a few examples of the extensive 'tiger pattern' mimicry of the Amazon. C) The common Monarch, Queen, Viceroy mimicry system of North and Central America. D) A blue mimicry ring of southern United States, focused on the toxic Pipevine Swallowtail. 

Examples of imprecise mimicry in butterflies. A) An Ecuadorian mimicry ring that includes species in the family Nymphalidae and Papilionidae. B) Just a few examples of the extensive 'tiger pattern' mimicry of the Amazon. C) The common Monarch, Queen, Viceroy mimicry system of North and Central America. D) A blue mimicry ring of southern United States, focused on the toxic Pipevine Swallowtail. 

Adaptive coloration

I have always been fascinated with animal coloration and I actively investigate colorful phenotypes in a range of animals. Through this fascination, I am able to ask questions into sexual selection, thermoregulation, and my favorite: predator-prey interactions. Animal coloration is a matter of life and death. Why do some butterflies have bright iridescent coloration while others are drab and inconspicuous or patterned with bands and stripes? Current research includes how bands of butterflies are effective in disruptive camouflage and thermoregulation, how spider web coloration is mediated by different environmental conditions, and colleagues and I are currently investigating gila monster developmental color change. 

Copyright of Wikimedia. A) The web of the filmy dome spider, eriene radiata. B) The bowl and doily web of Frontinella communis. These webs occupy different niches in the same geographic regions and we have shown that the web of the Neriene radiata is very conspicuous in its forest environment, while the web of Frontinella communis is cryptic in its field environment. We are currently investigating the ecological and evolutionary pressures that have led to these two different conspicuous strategies. 

Copyright of Wikimedia. A) The web of the filmy dome spider, eriene radiata. B) The bowl and doily web of Frontinella communis. These webs occupy different niches in the same geographic regions and we have shown that the web of the Neriene radiata is very conspicuous in its forest environment, while the web of Frontinella communis is cryptic in its field environment. We are currently investigating the ecological and evolutionary pressures that have led to these two different conspicuous strategies.