Data from: Expression of sexual ornaments in a polymorphic species: phenotypic variation in response to environmental risk

Secondary sexual traits may evolve under the antagonistic context of
sexual and natural selection. In some polymorphic species, these traits
are only expressed during the breeding period and are differently
expressed in alternative phenotypes. However, it is unknown whether such
phenotypes exhibit phenotypic plasticity of seasonal ornamentations in
response to environmental pressures such as in the presence of fish
(predation risk). This is an important question to understand the
evolution of polyphenisms. We used facultative paedomorphosis in newts as
a model system because it involves the coexistence of paedomorphs that
retain gills in the adult stage with metamorphs that have undergone
metamorphosis, but also because newts exhibit seasonal sexual traits. Our
aim was therefore to determine the influence of fish on the development of
seasonal ornamentation in the two phenotypes of the palmate newt
(Lissotriton helveticus). During the entire newt breeding period, we
assessed the importance of phenotype and fish presence with an
information-theoretic approach. Our results showed that paedomorphs
presented much less developed ornamentation than metamorphs and those
ornamentations varied over time. Fish inhibited the development of sexual
traits but differently between phenotypes: in contrast to metamorphs,
paedomorphs lack the phenotypic plasticity of sexual traits to
environmental risk. This study points out that internal and external
parameters act in complex ways in the expression of seasonal sexual
ornamentations and that similar environmental pressure can induce a
contrasted evolution in alternative phenotypes.