Vertical stratification of ithomiine butterfly (Nymphalidae: Ithomiinae) mimicry complexes: the relationship between adult flight height and larval host-plant height

Abstract

Data are presented which confirm previous findings that syrnpatric mimicry complexes dominated by unpalatable Neotropical ithomiine butterflies (Nymphalidae: Ithomiinae) are vertically stratified by height of flight. Flight height of ithomiine species is positively correlated with the height of their larval host-plants. Thus members of a mimicry complex utilize hostplants of similar heights. Non-mimetic British woodland butterflies also show a positive relationship between flight height and host-plant height, which suggests that the relationship is independent of mimicry. I propose that female butterflies fly at heights which maximize the probability of encountering their larval host-plants, and that males fly at similar heights to females in order to maximize the probability of encountering potential mates. Female butterflies probably encounter plants of similar heights to their larval hosts more frequently than they encounter plants of other heights. I suggest that butterlly species may therefore be more likely to make host shifts to plant species of a similar height to their current hostplants. Finally, I discuss how the relationship between flight height and height of larval hostplants, coupled with microhabitat-dependent selection on colour pattern, could lead to the evolution in sympatry of vertically stratiied mimicry complexes. 0 1997 The Iinnean Socirty of London ADDITIONAL KEY WORDS-behaviourecologyevolutionhost shifts -Lepidoptera

Forest use and vertical stratification in fruit-feeding butterflies of Sulawesi, Indonesia: impacts for conservation

“…The nymphalid community baited during this study showed a clear vertical structure similar to previous findings in DeVries (1988); Beccaloni (1997);DeVries et al (1997DeVries et al ( , 1999; DeVries and Walla (2001); Schulze et al (2001);Fermon (2002); Fermon et al (2003). The community was characterised by a significant decrease in both abundance and diversity with forest stratum height.…”

“…This might mainly reflect the availability of rotting fruits falling on the ground (see Schulze et al 2001). In addition to the distribution of adult resources, vertical stratification in butterflies might equally be maintained by the height location of oviposition habitats (Beccaloni 1997), by differences in microclimate (wind, temperature, and especially light intensity, see e.g., DeVries 1988;DeVries et al 1997DeVries et al , 1999, and=or by variations in vegetation structure and predation pressure (Hill et al 2001;Schulze et al 2001).…”

“…and the Apaturinae species Rohana macar, are known as relatively fast and manoeuvrable flyers, frequently trapped at higher strata or in forest gaps with sparse vegetation (DeVries and Walla 2001;Hill et al 2001;Schulze et al 2001). Rohana species feed on Celtis trees (Ulmaceae; Robinson et al 2001), Charaxes larvae are know to feed on leaves of tree species in many families (mainly Fabaceae; Larsen 1999), illustrating the relation between butterfly stratification and host plant height (Beccaloni 1997). Similarly, most butterfly species of the subfamilies Morphinae and Satyrinae, characteristic of lower forest strata, exclusively use monocotyledon food plants mainly growing in the understorey.…”

Ecology of tropical butterflies in rainforest gaps

“…However, some canopy species were not recorded in ground-level traps indicating that some species may feed on fruit rotting in situ, or trapped in the upper branches. Vertical stratification of butterflies may also be maintained by the location of larval host plants (Beccaloni 1997); for example, many of the Satyrinae feed as larvae on species of Poaceae which are confined to ground level (Corbet and Pendlebury 1992;Fiedler 1998).…”

Habitat segregation among mimetic ithomiine butterflies (Nymphalidae)

“…Strong selection for mimetic similarity reduces the local diversity of mimetic forms rather than maintaining it. One way diversity could be maintained is by habitat segregation among mimicry complexes (Mallet and Gilbert 1995;Beccaloni 1997b;Joron and Mallet 1998;DeVries et al 1999a;Mallet and Joron 1999;Joron 2005). Habitat-specific predation could lead to convergence among warningly colored species coexisting in the same habitat type as suggested by Beccaloni (1997b) and DeVries et al (1999a).…”