Aggression and courtship differences found in Drosophila melanogaster from two different microclimates at Evolution Canyon, Israel

Xiaoying Song,Kexin Li,Caroline B Palavicino-Maggio,Séverine Trannoy,Kristina M Holton,Eviatar Nevo

doi:10.1038/s41598-019-40701-8

Abstract

Aggression and courtship behavior were examined of wild Drosophila melanogaster flies isolated from two contrasting microclimates found at Evolution Canyon in Mt. Carmel, Israel: an African-like dry tropical Slope (AS) and a European-like humid temperate Slope (ES), separated by 250 meters. Studies were carried out to ask whether behavioral differences existed between the two populations obtained from opposite slopes with divergent microclimates in Israel. First, we measured and compared intraslope aggression between same sex fly pairings collected from the same slope. Both male and female flies displayed similar fighting abilities from both slopes. ES males, however, from the humid biome, showed a tendency to lunge more per aggressive encounter, compared with AS males from the dry biome. Next, we tested interslope aggression by pairing flies from opposite slopes. ES males displayed higher numbers of lunges, and won more fights against their AS opponents. We also observed enhanced courtship performances in ES compared to AS males. The fighting and courtship superiority seen in ES males could reinforce fitness and pre-mating reproductive isolation mechanisms that underlie incipient sympatric speciation. This may support an evolutionary advantage of adaptively divergent fruit fly aggression phenotypes from different environments.

Highlights

Aggression in Drosophila species has been known for over 100 years[1,2,3], but only recently have fruit flies gained ground as a popular model for the study of aggression[4]
To ask whether the microclimates at the two abutting population sites (#2 and #6, Fig. 1) in Evolution Canyon may have an effect on the levels of aggression, we measured intraslope aggression of same sex pairings of flies obtained from the same European Slope (ES) or African-like dry tropical Slope (AS) populations (ES versus ES or AS versus AS)
In 38 ES male fly pairings, 32 pairs engaged in aggressive interactions (84%), and in 27 ES female pairings, 24 pairs engaged in aggressive interactions (89%)

Summary

Introduction

Aggression in Drosophila species has been known for over 100 years[1,2,3], but only recently have fruit flies gained ground as a popular model for the study of aggression[4]. Higher solar radiation on AS causes high temperature and drought, yielding a climate and ecology resembling a dry tropical African savanna This is in contrast to the abutting North-Facing Slope (NFS), known as the European Slope (ES), which is temperate, forested, and has 1–7% higher humidity[12] (Fig. 1). Ac.il), with many studies suggesting that at this particular microsite of opposing canyon slopes, species ranging from viruses and bacteria to mammals across phylogeny appear to be undergoing incipient sympatric ecological speciation[8,13,14,15,16,17,18,19,20] Amongst these distinct species extensively studied at EC I are Drosophila, showing differences in their behavior likely due to the difference in the microclimate regimes[21,22,23]. The evidence for genetic, phenotypic and behavioral divergences presented above suggest that these flies are undergoing incipient sympatric speciation potentially due to their adaptation to two distinct extreme microclimates, tropical versus temperate

Objectives

Methods

Results

Conclusion