The Queen Butterfly, Danaus Chrysippus (L.) (Lepidoptera: Nymphalidae) at Khartoum, Sudan.

Abstract

Within the region of East and Central Africa, the aposematic butterfly D. chrysippus is characterized by unusual ecology, due to the co-occurrence of polymorphism, mimicry and sex ratio distortion. In this paper, we describe a survey conducted for D. chrysippus at Khartoum, based upon morphological and molecular investigations. The goal of the study was to determine whether Sudan is a part of the presumed hybrid zone of D. chrysippus in Africa, where the butterfly shows the unusual ecology. D. chrysippus was found to display considerable colour pattern polymorphism. Only one mimetic form, the batesian mimic, female Hypolimnas misippus was recorded. The population sex ratio of D. chrysippus did not show significant deviation from the 1:1 ratio. Molecular tests for the male-killing bacteria Spiroplasma yielded negative results. The study concluded that central Sudan belongs to the hybrid zone but lacks its characteristic ecology.

Hologenomic speciation: synergy between a male-killing bacterium and sex-linkage creates a ‘magic trait’ in a butterfly hybrid zone

“…() examined D. chrysippus material from Ghana and Madagascar, which are both areas far outside the hybrid zone, and Spiroplasma was entirely absent from both areas. The sample from Khartoum, Sudan, noted above (Idris & Hassan, ), was also negative. In addition, it is clear that cc females in Nairobi are both heavily infected and suffer the male‐killing effect.…”

“…(2) The AA and aa homozygotes may mate assortatively, thus producing few heterozygous progenies. This possibility is endorsed by our analysis of data from hybridizing populations of D. c. chrysippus ( AA cc ) and D. c. alcippus ( aa cc ) that are 100% Σ– ( n = 48), collected beside the Blue Nile at Khartoum, Sudan (Idris & Hassan, ). After correction for penetrance, there is a massive shortfall of heterozygotes compared to HWE expectation and strong assortative mating must be suspected.…”

“…As is apparent from Table , male killing appears to be restricted to the hybrid zone and the available evidence suggests that this is equally true of the W‐ BC linkage. The association breaks down only in the Sudan (Idris & Hassan, ), where Spiroplasma is absent and polymorphism is largely restricted to the alcippus and chrysippus semispecies ( dorippus and albinus together making up only 1.3% of the population). The confinement of male killing to the hybrid zone may therefore turn out to be stricter than previously envisaged, with Spiroplasma infection only found where dorippus and chrysippus (and possibly orientis ) occur together in significant numbers.…”

“…Samples from outside this zone that have been screened for Spiroplasma (seven locations and 95 butterflies) are 100% negative; moreover, there is no instance of all‐female brooding (the visible sign of Spiroplasma infection) outside the hybrid zone (Table ). In only one recorded case (Khartoum, Sudan: Idris & Hassan, ) is Spiroplasma absent within the hybrid zone. In this population, 98.7% are D. c. chrysippus and Danaus chrysippus alcippus , whereas Danaus chrysippus dorippus is very rare, prompting the hypothesis that the association of Spiroplasma and hybridization only exists where D. c. dorippus and one of the other semispecies come together in significant numbers.…”

Euploea dorippus Klug, 1845: species, semispecies, subspecies, junior subjective synonym of Danaus chrysippus chrysippus (Linnaeus), and/or form – what does Klug’s dorippus represent? (Lepidoptera: Nymphalidae, Danainae)

“…2a), Khartoum lies within the range of D. c. chrysippus, beyond that of D. c. dorippus. However, Idris & Hassan (2012) report that the same morphs noted by Longstaff (2012) co-occur at Khartoum today (with 'albinus' and 'dorippus' still relatively rare) -and they conclude, in contrast to Smith et al (1998), that Khartoum lies within the hybrid zone.…”