Chemical data of Hawaiian Tetragnatha spiders

Studies of adaptive radiations have played a central role in our
understanding of reproductive isolation. Yet the focus has been on
human-biased visual and auditory signals, leaving gaps in our knowledge of
other modalities. To date, studies on chemical signals in adaptive
radiations have focused on systems with multimodal signaling, making it
difficult to isolate the role chemicals play in reproductive isolation. In
this study we examine the use of chemical signals in the species
recognition and adaptive radiation of Hawaiian Tetragnatha spiders by
focusing on entire communities of co-occurring species, and conducting
behavioral assays in conjunction with chemical analysis of their silks
using gas chromatography-mass spectrometry. Male spiders significantly
preferred the silk extracts of conspecific mates over those of sympatric
heterospecifics. The compounds found in the silk extracts, long chain
alkyl methyl ethers, were remarkably species-specific in the combination
and quantity. The differences in the profile were greatest between
co-occurring species and between closely related sibling species. Lastly,
there were significant differences in the chemical profile between two
populations of a particular species. These findings provide key insights
into the role chemical signals play in the attainment and maintenance of
reproductive barriers between closely related co-occurring species.