Color under pressure: how multiple factors shape defensive coloration

Elizabeth G. Postema, Mia K. Lippey, Tiernan Armstrong-Ingram


Behavioral ecologists have long studied the role of coloration as a defense against natural enemies. Recent reviews of defensive coloration have emphasized that these visual signals are rarely selected by single predatory receivers. Complex interactions between signaler, receiver, and environmental pressures produce a striking array of color strategies—many of which must serve multiple, sometimes conflicting, functions. In this review, we describe six common conflicts in selection pressures that produce multifunctional color patterns, and three key strategies of multifunctionality. Six general scenarios that produce conflicting selection pressures on defensive coloration are: (1) multiple antagonists, (2) conspecific communication, (3) hunting while being hunted, (4) variation in transmission environment, (5) ontogenetic changes, and (6) abiotic/physiological factors. Organisms resolve these apparent conflicts via (1) intermediate, (2) simultaneous, and/or (3) plastic color strategies. These strategies apply across the full spectrum of color defenses, from aposematism to crypsis, and reflect how complexity in sets of selection pressures can produce and maintain the diversity of animal color patterns we see in nature. Finally, we discuss how best to approach studies of multifunctionality in animal color, with specific examples of unresolved questions in the field.

Behavioral Ecology

Monarch Summit in Washington, D.C.

A Monarch Butterfly Summit was held June 22-23 at the Capitol in Washington D.C. to discuss western monarch conservation. The summit was organized by Senator Jeff Merkley (OR) and attended by Secretary of the Interior Deb Haaland, Senators Ron Wyden (OR) and Alex Padilla (CA), Congressperson Jimmy Panetta (CA), Assistant Secretary for Fish and Wildlife and Parks Shannon Estenoz, and U.S. Fish and Wildlife Service (FWS) Director Martha Williams. Scientific presenters included Amanda Barth (Western Monarch and Native Pollinator Working Group), Wendy Caldwell (Monarch Joint Venture), Ryan Drum (USFWS) and Wayne Thogmartin (USGS), Cat Darst (USFWS), Cheryl Schultz (Washington State University), Matt Forister (University of Nevada – Reno), Louie Yang (University of California – Davis), Sarah Hoyle (Xerces Society for Invertebrate Conservation), Francis Villablanca (Cal Poly State University), Elizabeth Crone (University of California – Davis), and Sarina Jepsen (Xerces Society for Invertebrate Conservation).

The Department of the Interior announced a $1 million dollar award to the National Fish and Wildlife Foundation’s (NFWF) Monarch Butterfly and Pollinators Conservation Fund, and the Fish and Wildlife Service announced a Pollinator Conservation Center. In addition, two bills to support the Monarch Action, Recovery, and Conservation of Habitat (MONARCH) Act and the Monarch and Pollinator Highway Act were proposed last year; if passed, these acts would support a variety of initiatives focused on monarch research and conservation.