Feature theory and the two-step hypothesis of Müllerian mimicry evolution.

The two-step hypothesis of Müllerian mimicry evolution states that mimicry starts with a major mutational leap between adaptive peaks, followed by gradual fine-tuning. The hypothesis was suggested to solve the problem of apostatic selection producing a valley between adaptive peaks, and appears reasonable for a one-dimensional phenotype. Extending the hypothesis to the realistic scenario of multidimensional phenotypes controlled by multiple genetic loci can be problematic, because it is unlikely that major mutational leaps occur simultaneously in several traits.

EVOLUTION OF GREGARIOUSNESS IN APOSEMATIC BUTTERFLY LARVAE: A PHYLOGENETIC ANALYSIS.

Gregariousness ought to be disadvantageous for palatable organisms that live exposed and are relatively immobile and small in comparison to potential predators. Therefore, the idea that unpalatability generally evolves before egg clustering/larval gregariousness in butterflies was tested. Aposematic coloration in the larva was used as the criterion of unpalatability (it is argued that Batesian mimicry is rare in butterfly larvae), and the relative order of evolution of aposematism and gregariousness was inferred through phylogenetic analysis.

The role of variable weather for the dynamics of a seed-seed predator system.

A simple model is presented describing the interaction between weather conditions, seed production of a longlived herb, Vincetoxicum hirundinaria (Asclepiadaceae), and abundance of a predispersal seed predator, Euphranta connexa (Diptera, Tephritidae). The model is used to investigate the role of weather-induced fluctuations in seed set on the interaction between plant and seed predator and the resulting longterm production of seeds escaping predispersal seed predation.As weather variability increases Euphranta populations become less effective in tracking their food resources, leading to increased longterm production of dispersing seeds.

Higher survival of an aposematic than of a cryptic form of a distasteful bug.

An experiment was performed to assess the relative survival of two forms of 5th instar larvae of Lygaeus equestris (Heteroptera, Lygaeidae) - the normal red form, called aposematic, and a mutant grey form, called cryptic - when given to hand-raised great tits (Parus major).Sixteen birds were presented with aposematic larvae and 16 were presented with cryptic larvae in 10 consecutive trials. One attack per trial was allowed.