Investigating how movement affects prey camouflage using an insect predator
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Umeton, Diana
Canonaco, Marcello
Brandmayr, Pietro
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Dottorato di Ricerca in Scienze della Vita. Ciclo XXIX; Patterns that help prey camouflage themselves whilst stationary prove to be
ineffective once prey move. Given that motion breaks camouflage, can a moving
prey ever be effectively concealed? Recent studies have found that certain patterns
might help prey deceive their predators whilst moving, as in the case of ‘motion
dazzle’. However, research with moving prey has been conducted using only
humans or birds as predator models, and consequently, it is now known how other
predator species might behave. In addition, it is important to know not just how
motion affects camouflage, but also how the speed of motion can affect the efficacy
of different defensive patterns.
This thesis aims to address these current gaps in the field. First, I explore the
visual acuity in a group of insect predators, the praying mantids, to explore if different
species vary in their visual acuity, which could impact on what they can perceive and
which selective pressure they could exert on prey defensive patterns. Second, using
praying mantids tracking computer-generated stimuli, I empirically investigate how
cryptic and conspicuous patterns might enhance the survival of moving prey. In
particular, I specifically investigate if high contrast striped prey could reduce
predation risk through the visual phenomenon known as “flicker fusion effect”. I
found that when prey were slow moving, all patterns were equally detectable by the
mantids. However, once prey moved at faster speed, a cryptic pattern was more
likely to be tracked than a more conspicuous black-and-white striped pattern
suggesting that the latter was successful in inducing flicker fusion effect in praying
mantids’ eyes.
This thesis starts to disentangle how pattern and speed could combine to help camouflage an animal when moving through its environment. The outcome of the
study are discussed in the wider context of how animals coloration and behaviour
evolved together to confer them survival advantages.; Università della Calabria.Soggetto
Camouflage; Praying mantis
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BIO/05;