Acoustic and olfactory signals as drivers of genetic differentiation in North Atlantic seabirds

Communication of species identity, genetic relatedness, individual quality and identity is critical for mate choice and, therefore, a key behavioural process driving speciation. In birds, the role of visual and acoustic signals has been well established but olfactory signals have received much less attention. Procellariid seabirds e.g. storm-petrels are known to use smell for social functions, as well as for foraging. Storm-petrels attend their underground breeding sites at night, where they are highly vocal, so chemical and acoustic signals may be acutely important for social behaviours where visual signalling is limited. Current conservation monitoring methods use these signals (scent for locating active burrows and acoustic playback to assess nest occupancy) yet their meaning and utility remains poorly understood.

This study aims to assess the role of acoustic and chemical communication in facilitating or preventing genetic divergence and ultimately reproductive isolation, using Atlantic storm-petrels as a model system. “Band-rumped” storm-petrels Hydrobates spp. breeding sympatrically on the Azores comprise two recently diverged (~200,000 years BP), sympatric but temporally segregated species; Madeiran petrels (H. castro) breed in winter and Monteiro’s petrels (H. monteiroi) breed in summer in the same nest burrows. This is one of the very few known examples of sympatric speciation by allochrony among tetrapods. In contrast, European storm-petrels (H. pelagicus) breeding in Atlantic waters (subspecies H. p. pelagicus) show little genetic divergence, even between populations breeding >1,000km apart, but are genetically and vocally distinct from the Mediterranean-breeding subspecies (H. p. melitensis).

We will use olfactory choice and acoustic playback experiments, combined with acoustic and chemical analysis, supported by population genetics, a) to test the mechanisms by which chemical and acoustic signals are used in (i) mate selection (choosing same taxon, opposite sex, appropriate degree of relatedness) and (ii) in individual recognition; b) to identify the population genetic consequences (facilitating or inhibiting population differentiation and ultimately speciation) arising from the resulting mate choices.

Acoustic, chemical, biometric and DNA samples will be collected in breeding colonies, and analysed using state-of-the-art equipment and methods (e.g. thermal desorption in combination with GC-time-of-flight mass spectrometry, next-generation sequencing) and advanced bioinformatic methods for processing and evaluating chemical, acoustic and genetic data (e.g. voice-recognition, multivariate descriptive and predictive models).

We anticipate that the findings will reveal the behavioural processes and mechanisms driving the population genetic structure in storm-petrels, and that the methods developed will provide novel, non-invasive tools for population monitoring of these vulnerable and hard-to-monitor seabirds.