Amata variation analysis for Eco-geographic hypotheses do not explain variation in warning signals in diurnal Amata nigriceps wasp moths

Aposematic prey use conspicuous warning signals to advertise a secondary
defense. To be effective, warning signals should be reliable throughout a
prey population. However, warning signals vary considerably across and
within populations, often for unknown causes. Here, the Australian diurnal
moth Amata nigriceps, which has orange wing spots on a black background,
was used to explore four ecogeographic hypotheses explaining warning
signal variability: the thermal melanism, the photo-protection, the
desiccation resistance, and the predator-loss hypotheses. We collected
live moths from 29 populations across 746 km of coastal New South Wales,
Australia, and sampled relevant museum collections from 1896 to 1982. We
quantified the proportion of orange wing spots (warning signal size)
relative to site-specific abiotic (temperature, precipitation, solar
radiation) and biotic factors (diversity of bird predators). In museum
specimens, warning signal size varied within the decade of collection,
without a discernible temporal trend. Recent collections also varied in
signal size, but we found no support for the four hypotheses. Our results
are in contrast with studies that have found significant relationships
between warning colours and eco-geographic factors. Local phenotypic
responses in Amata nigriceps together with relaxed predator selection and
genetic effects may explain the persistence of warning signal variation.