No abstract

In nature, many multicellular and unicellular organisms use constitutive defenses such as armor, spines, and noxious chemicals to keep predators at bay. These defenses render the prey difficult and/or dangerous to subdue and handle, which confers a strong deterrent for predators. The distinct benefit of this mode of defense is that prey can defend in place and continue activities such as foraging even under imminent threat of predation. The same qualitative types of armor-like, spine-like, and noxious defenses have evolved independently and repeatedly in nature, and we present evidence that cancer is no exception. Cancer cells exist in environments inundated with predator-like immune cells, so the ability of cancer cells to defend in place while foraging and proliferating would clearly be advantageous. We argue that these defenses repeatedly evolve in cancers and may be among the most advanced and important adaptations of cancers. By drawing parallels between several taxa exhibiting armor-like, spine-like, and noxious defenses, we present an overview of different ways these defenses can appear and emphasize how phenotypes that appear vastly different can nevertheless have the same essential functions. This cross-taxa comparison reveals how cancer phenotypes can be interpreted as anti-predator defenses, which can facilitate therapy approaches which aim to give the predators (the immune system) the upper hand. This cross-taxa comparison is also informative for evolutionary ecology. Cancer provides an opportunity to observe how prey evolve in the context of a unique predatory threat (the immune system) and varied environments.

The endangered black‐footed ferret (ferret; Mustela nigripes) is a North American carnivore that is actively managed to reestablish self‐sustaining wild populations. Behavioral abnormalities have been reported in the breeding program and may be a limiting factor for the species' success. Our goal was to design and test an assay that examines the ferret's exploratory response to odor cues in the form of soiled bedding from opposite‐sex conspecifics. Across two breeding seasons, males and females were tested using a T‐maze that connected their home nest box to two novel nest boxes containing two different conspecific's soiled bedding. For a control, we provided two clean bedding samples. We ran linear mixed models to determine the effect of sex, type of odor cue (soiled, clean), and order of trial (first, second) on time exploring and proportion of that time spent in each behavior. Ferrets spent the majority of time in the novel nest boxes sniffing (44%), standing alert (27%) and scratching (14%). Males explored for longer than females; however, both displayed similar behaviors. Type of cue influenced behavior, with ferrets sniffing more among soiled cues than clean cues. Habituation to the assay was also observed, with less exploration and more standing alert during the second trial of the day. This study is the first step in characterizing the ferret's exploratory response and provides information regarding vital investigatory and vigilance behaviors. The continual development of this assay to further evaluate reproductive and mate choice behaviors will facilitate more successful breeding of the species.

To monitor adrenocortical activity in zoo-housed species, we propose using physiological and behavioral indicators that are non-invasive and practical to implement. We explore this model in the southern three-banded armadillo (Tolypeutes matacus; armadillo), which is a near-threatened species commonly found in zoos. We aimed to (1) deploy food patches to quantify foraging behavior (via giving-up densities, GUDs); (2) determine the effects of food patch and environmental modifications on individuals’ GUDs and adrenocortical activity (via fecal glucocorticoid metabolites, FGMs); and (3) examine the relationship between GUDs and FGMs. Three males and four females received food patches under varying experimental conditions at the Lincoln Park Zoo (Chicago, IL, USA). Fecal samples were collected before, during, and after foraging experiments to examine FGMs. Armadillos did not respond to patch modifications but did forage more when given increased cover. Individual mean FGMs and GUDs were highly variable, and individuals had consistent FGM and GUD ranks across experiments. FGMs and GUDs did not vary across the experiments nor did they relate to each other. Armadillos and species with a limited behavioral repertoire (i.e., constant movement) can benefit from this multi-trait model to determine the effect of environmental modifications on individuals and provide meaningful information about adrenocortical activity.