Trade‐off between mating and predation risk in the marine snail, Littorina plena

Abstract

Abstract. We investigated the hypothesis that predation risk affects mating decisions in the intertidal snail Littorina plena in Bamfield Inlet, Northeast Pacific. First, we conducted a field tethering experiment to test the assumption that mating pairs of snails are more susceptible to predation than solitary individuals, and then performed a laboratory experiment to quantify the effect of predation threat on the propensity of snails to form mating pairs. Our results support the hypothesis, in that ''mating pairs'' were more frequently killed than single snails in the field, and snails were less likely to form mating pairs in the laboratory when simulated predation risk was high (chemical cues from crushed conspecifics were added to the water) than when it was low (no risk cues were added to the water). In contrast to several earlier studies, we found no effect of individual size on snail susceptibility to predation, perhaps because our two size classes were contiguous and snails within them were not dissimilar enough. The results of the behavioral experiment were consistent with this lack of individual size effect on snail vulnerability; both size classes of snails showed a significant and similar tendency to decrease mating when predation risk was high. Taken together, the results of this and recent studies indicate that predators can considerably affect the behavior of littorinid snails, including their movement patterns, feeding, and reproduction. We argue that greater consideration should be given to how marine invertebrates trade off predation risk and activities related to reproduction.Additional key words: gastropod, copulatory behavior, intertidal ecology In 1990, Lima and Dill published an influential review demonstrating that an array of animal species adaptively trade off the risk of predation with various activities. In such cases, behavioral responses to a general threat stimulus are not inflexible, but rather vary depending on the magnitude of the threat as well as the cost of the response; costs can be in terms of energy and/or lost opportunities (e.g., feeding, reproduction). For example, many animals readily compromise safety from predators to obtain food when the value of a given feeding opportunity is high (e.g., when starved) or when the risk of predation is low (e.g., when cover is close by). Lima and Dill's review also revealed two marked biases in the literature. First, of the B250 studies reviewed that focused on particular organisms, o3% involved marine invertebrates. Second, onlyB6% of organism-based studies investigated how predation risk affects reproductive behavior; most studies addressed aspects of feeding and sociality, as well as defense responses (i.e., escape, vigilance, group size, mobbing) to variable predation threat. The scarcity of studies involving reproductive behaviors and predation risk may reflect a greater difficulty of quantifying, in many systems, the impact of predation on reproduction decisions than on feeding decisions. However, because courtship and reproduct...

Effects of newt chemical cues on the distribution and foraging behavior of stream macroinvertebrates

“…It is also clear that chemical cues from predators affect foraging behavior and trophic relationships (Abrams, 1983;Juliano & Gravel, 2002;Koch et al, 2007;Camacho & Thacker, 2013;Naddafi & Rudstam, 2013;Schneider et al, 2014). The idea that defensive compounds can affect community organization, trophic webs, and biogeochemical processes has been proposed (McClintock & Baker, 2001;Pohnert et al, 2007;Hay, 2009), and in marine Fig.…”

“…Macroinvertebrates have demonstrated vast behavioral responses to predator chemical cues (Burks & Lodge, 2002;Dodson et al, 1994), whereby the indirect effects of these compounds elicit decreased browsing, foraging, and reproductive activity (Juliano & Gravel, 2002;Koch et al, 2007;Schneider et al, 2014), reduced predatory behavior (Wisenden et al, 1997), altered habitat use (Camacho & Thacker, 2013), and increased attachment strength to substrates and aggregation rate (Naddafi & Rudstam, 2013).…”

Mate Choice and Mechanical Constraint on Size‐Assortative Paring Success in a Simultaneous Hermaphroditic Pond Snail Radix lagotis (Gastropoda: Pulmonata) on the Tibetan Plateau

“…However, the paired individuals of R. lagotis may be more susceptible to predation than single individuals (Koch et al 2007). The smaller individuals, based upon personal observation, were unable to successfully inseminate either a large or a small partner due to their short copulatory organ.…”

“…Our results also indicate that the copulations were longer with small sperm donors, this suggests that physiological factors play a role in the duration of insemination in R. lagotis. However, the paired individuals of R. lagotis may be more susceptible to predation than single individuals (Koch et al 2007). Thus, larger snails acting as the sperm donors may have a lower risk of predation because the duration of copulation is shorter.…”

Female size and pre-copulatory sexual selection by males of intertidal snail (Littorina saxatilis)

“…Males of L. littorea have been shown to mate for less time with parasitized females (Saur, 1990). Other factors such as predation risk, wave exposure, etc., may affect mating duration, but were not involved in this experiment (Koch et al, 2007); Pardo & Johnson, 2006). Other factors influencing mating duration could be age and fitness.…”