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Stick insects are not as shallow as we are; they sniff before they look.

We humans, though dependent majorly on looks for most of the times when choosing a mate, do like it when our partners smell good. Well, it is no different for Stick insects. In fact, according to a new study conducted by scientists at the University of Sheffield and Royal Holloway, University of London, fragrance of the opposite gender is a significant factor when it comes to choosing a mate. The main purpose behind conducting this study was to understand what drives new species formation in the Animal kingdom.

Evolution, in its, for now, mysterious ways, has worked out a system so that we maintain the differences that exist between species and the characteristic retained in all the newly formed species are important for survival. Though Natural Selection is one of the major factors involved in speciation, scientists think it is not the only one. Well, when it comes to insects, for some of these creepy-crawly creatures, the smells emitted by the members play an equally significant role in speciation.

“Species formation generally takes place over huge time-scales and it’s very difficult to observe directly- mainly we just get snapshots of what’s happening at a particular moment in time,” stated Dr. Patrik Nosil, from the department of Animal and Plant sciences at the University of Sheffield.

The researchers conducting the study realized that even though kept together, Stick insects belonging not only to different species but also to different populations refused to mate. It was discovered that the oily chemicals present on the insects’ bodies, made them more or less attractive for mating to their counterparts. The main purpose of these chemical compounds is to protect the insects and to prevent their bodies from drying, but now according to the study, it also helps in attracting mates.

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“We discovered that populations that differed most strongly in their chemical profiles discriminated more strongly against mating with one another, and they also differed more in their genomic sequences,” explains Dr Rudiger Riesch from the School of Biological Sciences at Royal Holloway, University of London.

To understand this phenomena better, the team perfumed some females artificially with chemicals from their own or from different species, and found out that this actually affected the level of their attractiveness to the males. This suggests that when placed into different environments, these chemicals prevent gene mixing in species, at least in Stick insects.

Though a major find, this cannot act as a total confirmation of speciation. Natural selection and mate choice can cause substantial progress towards speciation, but Stick insects might sometimes choose mates from a different population or species, irrespective of their chemical scent.