Sammanfattning

Although the vinegar fly Drosophila melanogaster is arguably the most studied organism on the planet, fundamental aspects of this species' natural ecology have remained enigmatic [1]. We have here investigated a wild population of D. melanogaster from a mopane forest in Zimbabwe. We find that these flies are closely associated with marula fruit (Sclerocarya birrea) and propose that this seasonally abundant and predominantly Southern African fruit is a key ancestral host of D. melanogaster. Moreover, when fruiting, marula is nearly exclusively used by D. melanogaster, suggesting that these forest-dwelling D. melanogaster are seasonal specialists, in a similar manner to, e.g., Drosophila erecta on screw pine cones [2]. We further demonstrate that the main chemicals released by marula activate odorant receptors that mediate species-specific host choice (Or22a) [3, 4] and oviposition site selection (Or19a) [5]. The Or22a-expressing neurons-ab3A-respond strongly to the marula ester ethyl isovalerate, a volatile rarely encountered in high amounts in other fruit. We also show that Or22a differs among African populations sampled from a wide range of habitats, in line with a function associated with host fruit usage. Flies from Southern Africa, most of which carry a distinct allele at the Or22a/Or22b locus, have ab3A neurons that are more sensitive to ethyl isovalerate than, e.g., European flies. Finally, we discuss the possibility that marula, which is also a culturally and nutritionally important resource to humans, may have helped the transition to commensalism in D. melanogaster.

Publicerad i

Current Biology
2018, Volym: 28, nummer: 24, sidor: 3960-3968
Utgivare: CELL PRESS

SLU författare

• Rehermann Del Rio, Guillermo

  • Institutionen för växtskyddsbiologi, Sveriges lantbruksuniversitet
    

• Becher, Paul

  • Institutionen för växtskyddsbiologi, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Ekologi


Publikationens identifierare

DOI: https://doi.org/10.1016/j.cub.2018.10.033

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/97634