Discussion 8

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Dec 6, 2023

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Box 8.2 page 275-276 Ultrasonic signals. Answer the questions in Thinking outside of the box: Where does this example fit into the communication framework we introduced earlier? (Figure 8.2) Certain moths’ species such as the Australian whistling moth can detect ultrasonic signals produced by males’ moths. The signals produced often mimic those produced by predatory bats. Researchers have argued that these unusual characteristics could have evolved from an ancestor of the species who used ultrasonic signals to detect predatory bats, overtime this mechanism could have aided females bats to allocate males better, increasing the species fitness. (Alcock, 2019) This is further supported by the Asian corn borer mating behavior. Females respond to bat ultrasounds at high intensity by diving, looping flight, or escaping in some way, but when the bats ultrasonic call is far away and at low intensity instead of fleeing, they freeze. (Alcock, 2019) Asian corn borer males mimic these low ultrasonic signals, tricking the female into thinking there is a predator far away and proceeding to freeze. In this way the female is suppressed from escaping and the male can proceed to copulate, this therefore, increases the fitness of the male moth. Why do you think bat-conspecific discrimination has not yet happened in this system? Bat-conspecific discrimination at first sight might seem counterintuitive and “maladaptive” to the females, since it leaves them exposed to predation. Nakano and colleagues concluded that “females do not distinguish between male songs and bat calls…” (Alcock, 2019) This could be due to preexisting sensory mechanism used by an ancestor to detect bats, which evolved to be used simultaneously as a communication system between male and female moths to provoke mating. (Alcock, 2019) Due to this, I think that the reason bat-conspecific discrimination has not

happened in this system, is because the benefit of mating outweighs the potential threat of being detected by a bat. Nakano and colleagues found in 2009 that males who sing tend to copulate more than males who do not sing. (Alcock, 2019) This could suggest that there is a benefit bring provided to females, and perhaps developing bat-conspecific discrimination mechanisms could lead males to reproduce less. Bat-conspecific discrimination DOES occur in another species of moth, the Japanese lichen moth. Contrast this type of communication system with that of the Asian corn borer, why has female discrimination evolved in one species and not the other? In Chapter 4, we learned that bats use ultrasonic call or echolocation to find food and navigate at night. (Alcock, 2019) Along with this idea, we also learned that moths can detect high frequency sounds produced by bats at a frequency of 20 to 80 kHz. (Alcock, 2019) The female Japanese lichen can detect these frequencies and detect which calls are coming from males of the same species and which are coming from a predatory bat. This discrimination allows the female Japanese lichen to produce defensive clicks against the bat, but not the male moths. This ability suggest that the Japanese lichen possess special auditory mechanisms, previously discussed in chapter 4, which aides them in their survival by differentiating between bat calls and calls from their own species. On the other hand, the Asian corn borer doesn’t seem to have the same discriminatory processes that the Japanese lichen has. As previously discussed in question 2, male Asian corn borer mimic the low frequency ultrasonic call from predatory bats, tricking the females into thinking she must freeze and stay in place. By doing this the male can then easily copulate with the female and pass on his genes. These behaviors may have evolved differently in different moths’ species due to the advantages it brought to them. For the Japanese lichen

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