Natural Selection: experimental evidence

Do Tephritid flies mimic jumping spiders?

Zonosemata

Coevolution

• Two or more species.• Change in one species serves as a selector for

change in the other species.• Interplay of changing gene frequencies.• Parallel evolutionary paths.

Models of coevolution

Phylogenies of coevolving species1. Perfect congruence between mutualistic species

tryptophan

2. Partial congruence between hosts and parasites

A famous Müllerian mimicrycomplex.

Each species withsubspecies defined bycolor pattern and geography.

What happens at subspecificboundaries?

Micrurus eryxanthus: Western coral snakeAposematic colorationProblem: how established?

A mimetic system

Batesian and MüllerianMimicry

Aposematic coloration

Parallel geographic variation

Micrurus 6 species. Highly venomousFixed front fangsNeotropicalElapidae

Pliocercus 1 or 2 species.Mildly venomousFixed rear fangsColubridae

Does aposematic coloration work?Plasticine models

Forest floor: on white paper and on forest floor

Experiment carried outin natural habitat

Resemblance does nothave to be perfect to confer protection

Significantdifferences

• Is avoidance of aposematic coloration innate?

• Naïve motmots (Neotropical birds)

• Caged birds presented with:

– 1. coral snake models

– 2. models of natural prey species.