A phylogenetic framework for wing pattern evolution in the mimetic Mocker Swallowtail Papilio dardanus

Abstract

The Batesian mimetic swallowtail butterfly Papilio dardanus exhibits numerous distinct wing colour morphs whose evolutionary origins require large phenotypic shifts. A phylogenetic framework to study the history of these morphs was established by DNA sequencing of representative subspecies from sub-Saharan Africa and Indian Ocean islands. Two mitochondrial genes and the nuclear internal transcribed spacer marker revealed deeply separated eastern and western African mainland lineages, plus one lineage each on Madagascar and Grande Comore. These markers showed very little polymorphism within lineages. In contrast, markers genetically linked to the mimicry locus H, including the transcription factor invected and two adjacent amplified fragment length polymorphisms-derived sequences, showed high nucleotide diversity but were not geographically structured. Variation in the unlinked wingless gene showed a similar pattern, rejecting the hypothesis that high level of variation in the H region is due to balancing selection exerted by the phenotypes. The separation from a common ancestor with Papilio phorcas estimated at 2.9 Ma coincides with the origin of a mimicry model, Danaus chrysippus. However, the model reached Africa only at the time of the internal splits of P. dardanus mtDNA groups, here estimated at 0.55-0.94 Ma. The nuclear genome shows less geographic structure and may not track recent population differentiation, suggesting that widespread mimicry morphs have arisen early in the evolution of the P. dardanus lineage, although after the male-female dimorphism which is ancestral. The current wide distribution of P. dardanus and population subdivision evident from mtDNA may have been achieved only with the spread of the models across Africa.

Characterising the Phenotypic Diversity of Papilio dardanus Wing Patterns Using an Extensive Museum Collection

“…This hypothesis is supported by our results, which show that the P. dardanus meseres and P. dardanus polytrophus populations, which are found in-between the diverged eastern and western mainland lineages [47], have very variable wing patterns (Figure 2, Figure 7). Almost all deviating phenotypes were collected from this region and the boundaries between subspecies are here indistinct, overlapping with P. dardanus dardanus (for P. dardanus meseres ) or P. dardanus tibullus (for P. dardanus polytrophus ).…”

“…This division was later confirmed using genetic analyses [47] and is easily recognisable from the NHM collections material as shown by the males depicted in Figure 5. The museum collection also corroborates that the male patterns of the eastern “races” P. dardanus tibullus and P. dardanus cenea are very similar.…”

“…The f. hippocoon group is separated into forms related to f. hippocoon , f. hippocoonides and the intermediate form f. meseres . Membership of the Eastern, Western or Indian Ocean clade is given based on Clark & Vogler's analysis of cytochrome b [47].…”

Independent evolution of sexual dimorphism and female‐limited mimicry in swallowtail butterflies (Papilio dardanus and Papilio phorcas)

“…; Clark et al . ; Clark & Vogler ). This group includes two sexually dimorphic species, P. dardanus and Papilio phorcas .…”

“…; Clark et al . ; Clark & Vogler ). If both species are found to be sister species, an evolutionary route involving an initial switch to sexual dimorphism would be supported, followed by the subsequent acquisition of mimetic phenotypes in the females (Clarke et al .…”