Quantifying the effects of species traits on predation risk in nature: A comparative study of butterfly wing damage

Abstract

Evading predators is a fundamental aspect of the ecology and evolution of all prey animals. In studying the influence of prey traits on predation risk, previous researchers have shown that crypsis reduces attack rates on resting prey, predation risk increases with increased prey activity, and rapid locomotion reduces attack rates and increases chances of surviving predator attacks. However, evidence for these conclusions is nearly always based on observations of selected species under artificial conditions. In nature, it remains unclear how defensive traits such as crypsis, activity levels and speed influence realized predation risk across species in a community. Whereas direct observations of predator–prey interactions in nature are rare, insight can be gained by quantifying bodily damage caused by failed predator attacks. We quantified how butterfly species traits affect predation risk in nature by determining how defensive traits correlate with wing damage caused by failed predation attempts, thereby providing the first robust multi‐species comparative analysis of predator‐induced bodily damage in wild animals. For 34 species of fruit‐feeding butterflies in an African forest, we recorded wing damage and quantified crypsis, activity levels and flight speed. We then tested for correlations between damage parameters and species traits using comparative methods that account for measurement error. We detected considerable differences in the extent, location and symmetry of wing surface loss among species, with smaller differences between sexes. We found that males (but not females) of species that flew faster had substantially less wing surface loss. However, we found no correlation between cryptic coloration and symmetrical wing surface loss across species. In species in which males appeared to be more active than females, males had a lower proportion of symmetrical wing surface loss than females. Our results provide evidence that activity greatly influences the probability of attacks and that flying rapidly is effective for escaping pursuing predators in the wild, but we did not find evidence that cryptic species are less likely to be attacked while at rest.

Predation favours Bicyclus anynana butterflies with fewer forewing eyespots

“…B 288: 20202840 detrimental to survival (e.g. [38]); many species in the wild exhibit more hindwing damage [39]; and Pieris rapae and Morpho butterflies without hindwings remain able to evade predators (although at reduced height, speed and acceleration) [40,41]. Forewings, however, are critical for all stages of flight, from general flight to evasive manoeuvring [40][41][42][43].…”

Fruit‐feeding butterflies depend on adult food for reproduction: Evidence from longitudinal body mass and abundance data

“…We focused on three large‐bodied fruit‐feeding nymphalid butterfly species that are common in Kibale forest; Charaxes fulvescens (average female wing length 4.95 cm, male 4.50 cm), Euphaedra alacris (4.71, 3.81 cm) and E. medon (4.23, 3.37 cm; Valtonen et al, 2013; Molleman et al, 2020). Dietary restriction studies with wild‐caught individuals have shown that females of all three species can use amino acids from income for egg production (Molleman et al, 2008a; Molleman, Ding, Wang, & Carey, 2009), and that males (but not females) live longer when provided with amino acids in their diet (Molleman, Ding, Boggs, et al, 2009).…”

“…While the fruit‐feeding butterfly community as a whole responds to rainfall (Valtonen et al, 2013), out of the three study species, a population response to rainfall was only detected in E. alacris and E. medon (Appendix S1). All three species are understory specialists (Molleman et al, 2006) that can fly rapidly (Molleman et al, 2020), have small spermatophores (Molleman, Grunsven, et al, 2005), are long‐lived (longevity records: C. fulvescens 230 days, E. alacris 253 days, E. medon 293 days; Molleman et al, 2007) and occur throughout the year with non‐seasonal abundance fluctuations (Valtonen et al, 2013; Appendix S1). They have been observed feeding on a variety of fruits, but may also feed on other substances such as sap oozing from trees (Molleman, van Alphen, et al, 2005).…”

Evidence of attack deflection suggests adaptive evolution of wing tails in butterflies

“…The loss of wing margins and especially HW margins has a low impact on butterflies flying abilities [17] and may therefore have a limited impact on survival. Butterflies are indeed commonly observed flying in the wild with such wing damage [18]. The escape from predators after an attack might also be facilitated by enhanced fragility of the attacked parts of the wings.…”