D1- Polymorphism in warning signals

Polymorphism- several morphs, alternative phenotypes, 4 types (genetic, morphological, behavioural, ecological)

Colour polymorphism- camouflage, warning, mate choice, non-signals

Aposematism- develop noticeable signals to indicate they are toxic, unpalatable or have other defences- mimicry, predation learning

Geographic mosaic of selection by avian predators on hindwing warning colour in a polymorphic aposematic moth, Katja Ronka, 2020

Warning signals are predicted to develop signal monomorphism (one signal) via positive frequency-dependent selection (the fitness of a phenotype or genotype increases as it becomes more common) but many aposematic systems exhibit signal polymorphism- is a mismatch
method-> conducted a large-scale predation experiment in four countries, among which the frequencies of hindwing warning coloration of the aposematic moth, Arctia plantaginis, differ.
results-> +FDS to be the strongest in monomorphic Scotland and lowest in polymorphic Finland, where the attack risk of moth morphs depended on the local avian community. +FDS was also found where the predator community was the least diverse (Georgia), whereas in the most diverse avian community (Estonia), hardly any models were attacked. Show that selection by avian predators on warning colour is predicted by local morph frequency and predator community composition.
conclusion-> support the idea that spatial variation in predator communities alters the strength or direction of selection on warning signals, thus facilitating a geographic mosaic of selection.

Geographic mosaic of signals, across 4 countries

Scotland monomorphic, georgia mostly red with some yellow, estonia polymorphic, finland polymorphism with all colours

How does the genetic variation impact the selection of different warning colour morphs

+FDS drives monomorphism at local scales, not global

The evolution of polymorphism in the warning coloration of the Amazonian poison frog Adelphobates galactonotus, Diana Rojas et al., 2020

There is intraspecific variation in aposematic (warning) signals, they can be selected for by different predatory responses, but their evolution is also contingent on other processes shaping genetic variation.
aim -> evaluate the relative contributions of selection, geographic isolation, and random genetic drift to the evolution of aposematic color polymorphism in the poison frog Adelphobates galactonotus, distributed throughout eastern Brazilian Amazonia.
method-> dorsal coloration was measured for 111 individuals and genetic data were obtained from 220 individuals at two mitochondrial genes (mtDNA) and 7963 Single Nucleotide Polymorphisms (SNPs). Four color categories were described (brown, blue, yellow, orange).
results->
- no genetic evidence for color being under divergent selection (the accumulation of differences between closely related populations within a species, can lead to speciation).
- A time-calibrated mtDNA tree suggests that the present distribution of dorsal coloration resulted from processes occurring during the Pleistocene.
- Separate phylogenies based on SNPs and mtDNA resolved the same well supported clades, each containing different colored populations. Ancestral character state analysis provided some evidence for evolutionary transitions in color type.
- Genetic structure was more strongly associated with geographic features than color category, suggesting that the distribution of color is explained by localized processes.
- Evidence for geographic isolation together with estimates of low effective population size implicates drift as playing a key role in color diversification.
conclusion-> highlight the relevance of considering the neutral processes involved with the evolution of traits with important fitness consequences.