About this Research Topic
Chemical cues were probably the first cues ever used by organisms to assess their environment, and to communicate among them. It does not astonish then, that across the currently living organisms, chemical elements are almost universally used to communicate and to receive information from their environment including other organisms. Their importance has been extensively studied for a great number of taxa, including unicellular organisms and plants. Among the most exciting interspecific relationships mediated by chemical cues we find multi-trophic interactions involving plants, herbivorous organisms and their predators: arthropods herbivory induces the release of organic volatile compounds (VOCs) by attacked plants, and these VOCs are used by predators of herbivorous arthropods to find their prey. The most known example is that of parasitoids finding their invertebrate prey by following plants’ released VOCs, but similarly, at sea, zooplanktivorous fish and petrel seabirds are attracted by chemical compounds (respectively dimethylsulfoniopropionate and its volatile breakdown, dimethyl sulfide) released by phytoplankton when grazed by zooplankton.
Chemical cues may also help organisms, to avoid or at least decrease the deleterious effects of predation. Uninfected plants close to herbivorous-infested plants detect VOCs released by the latter to develop a defense response. The detection of predators’ chemical cues produced for intraspecific communication is also an important antipredatory behavior as it allows an early assessment of predation risk without encountering the predator. The importance of chemical cues for predator recognition has been documented in a number of animal taxa including birds.
At the intra-specific level, semiochemicals (self-produced chemical compounds) may play a key role in species recognition allowing reproductive isolation (e.g. house mouse) or attracting the right mate (e.g. moths). Sometimes, semiochemicals are shared among organisms: the Asian elephant (Elephas maximus), and 140 species of moths share the same female sex pheromone. However, semiochemicals may differ among population of the same species and among individuals, allowing individual recognition (e.g. partner recognition, kin recognition, etc.). The composition of animal scents may be related to diet, hormonal levels, age, sex, reproductive status, body condition, health state and levels of parasitemia. Therefore, odors may be used to assess the dominance status of rivals and/or to select potential partners on their qualities. Some compounds of the individual scent may be genetically determined (eg. by major histocompatibility complex or major urinary proteins genes), providing cues for genetic compatibility when seeking for a mate. Chemical signals not only influence the behavior of receivers but can also alter the endocrine state of them. For example, male mice scent may induce estrus (or even abortion if the male is an intruder), accelerate the onset of puberty, and synchronize estrous cycles in females. In contrast, female scent produces a delay in the onset of puberty and suppression of estrus in other females.
In this Research Topic, we aim to draw together new advances in the knowledge of the role of olfaction in all contexts of an organism life: from interactions between organisms and their environment, such as prey and predator detection, to social contexts, ranging from social competition, sexual selection, and parent-offspring communication. Finally, we aim to include studies focused on the importance of chemical communication in applied frameworks, such as pest management. Our objective is to include articles ranging from single-species studies to comparative analyses, comments and reviews to have the broadest understanding of this topic.
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