Figure 1. Phylogenetic aspects of coevolution. (a) Evolutionary events influencing the extent of phylogenetic congruence between host lineages and their ecological associates. Host lineages are represented by branching tubes and associates by branching lines to illustrate cospeciation, duplication, extinction, ‘missing the boat’, and host switching. (b) Phylogenetic evidence can also support hypotheses of coadaptation, as illustrated by phylogenies for a host and its associate with dotted lines showing current ecological associations. Ancestral reconstructions for a pair of interacting traits, each with two states, red and blue, show coincident changes even though the phylogenies are not perfectly congruent. Reciprocal selection can produce such correlated trait changes in coevolutionary arms races.

Figure 2. Examples of plant–insect coevolution. (a) The edible fig, Ficus carica, showing the unique inflorescence which is home to the pollination mutualism with fig wasps. Scale 10 mm. Reproduced from Ehret GD (1750) Plantae Selectae. (b) Setora caterpillars (Limacodidae, Lepidoptera) feeding on latex-bearing leaves of Ficus nodosa in Papua New Guinea. Scale 10 mm. (c) Scanning electron micrograph of a male fig wasp, Kradibia ohuensis, the obligate pollinator of Ficus trachypison in Papua New Guinea. Scale 0.1 mm. (d) The female head and mandibular appendage of Wiebesia brusi are apparently coadapted with the inflorescence bracts of Ficus baeuerlenii from Papua New Guinea. Scale 0.1 mm. Photographs from GD Weiblen.

Figure 3. The evolution of associations between selected fig species, their pollinating mutualists, and their parasites. (a) Molecular phylogenies for Sycomorus figs and their species-specific Ceratosolen pollinators suggest a history of cospeciation (Weiblen and Bush, 2002). (b) Phylogeny of Apocryptophagus parasites attacking the same figs suggests that fewer cospeciation events have occurred than for pollinators, and several parasite lineages may have switched hosts. Unpublished data from S Silveus and GD Weiblen.