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Coffee!! Bats more dangerous than mothballs?


A reader kindly shares this BBC story with me, “Bat and moth arms race revealed” (19 August 2010 ) by Jason Palmer.

In a strategy that may be a moth-hunting adaptation, some bats are known to use clicks that are at a frequency, or pitch, either above or below moths’ hearing ranges.

High-pitched clicks have a larger range, while lower-pitched clicks are absorbed less by the atmosphere It remains unclear whether these pitch-shifting techniques adapted specifically to bypass moth defences or simply to cope in certain environments or situations.

Dr ter Hofstede and her colleagues were able to listen in on the Barbastella bat as it hunted, demonstrating that it had a completely different approach – its clicks were much reduced in volume, becoming even quieter as it closed in on prey.

“It seems like the majority of bats… call very loudly because they need as much information as possible from their surroundings,” Dr ter Hofstede told BBC News.

“We’re saying that this [low-volume tactic] is an adaptation to get around the moths’ defence – it doesn’t have any other useful purpose.”

While the lower volume of clicks reduces the range over which the bats can successfully hunt, the team showed that the approach leads to Barbastella bats eating significantly higher numbers of the nutrient-rich moths than other, louder species.

The information race between bats and a favoured prey, moths, is described as an arms race (it is actually a race to interpret clicks. Neither party is armed, and certainly not the moth.)

As is characteristic of legacy mainstream media, the story must all be interpreted dogmatically through Darwinist theory. But what’s missing from this very interesting account is how – exactly – the information race could evolve. “Natural selection” is increasingly evoked as a mere incantation, in the face of ever-growing awareness of complexity that are beyond its powers. That is, natural selection must be the cause because we “know” it is true.

Interestingly, Richard Dawkins (and J. R. Krebs) originated the idea of an evolutionary arms race. "Arms" was strictly metaphorical, and wasn't intended to suggest that the adaptations selecting for one another were necessarily analogous to weapons. See: Dawkins, R. & Krebs, J. R. (1979). Arms races between and within species. Proceedings of the Royal Society, London Biological Society. 205(1161), 489-511. The abstract:
Abstract An adaptation in one lineage (e.g. predators) may change the selection pressure on another lineage (e.g. prey), giving rise to a counter-adaptation. If this occurs reciprocally, an unstable runaway escalation or 'arms race' may result. We discuss various factors which might give one side an advantage in an arms race. For example, a lineage under strong selection may out-evolve a weakly selected one ('the life-dinner principle'). We then classify arms races in two independent ways. They may be symmetric or asymmetric, and they may be interspecific or intraspecific. Our example of an asymmetric interspecific arms race is that between brood parasites and their hosts. The arms race concept may help to reduce the mystery of why cuckoo hosts are so good at detecting cuckoo eggs, but so bad at detecting cuckoo nestlings. The evolutionary contest between queen and worker ants over relative parental investment is a good example of an intraspecific asymmetric arms race. Such cases raise special problems because the participants share the same gene pool. Interspecific symmetric arms races are unlikely to be important, because competitors tend to diverge rather than escalate competitive adaptations. Intraspecific symmetric arms races, exemplified by adaptations for male-male competition, may underlie Cope's Rule and even the extinction of lineages. Finally we consider ways in which arms races can end. One lineage may drive the other to extinction; one may reach an optimum, thereby preventing the other from doing so; a particularly interesting possibility, exemplified by flower-bee coevolution, is that both sides may reach a mutual local optimum; lastly, arms races may have no stable end but may cycle continuously. We do not wish necessarily to suggest that all, or even most, evolutionary change results from arms races, but we do suggest that the arms race concept may help to resolve three long-standing questions in evolutionary theory. 'Wonderful and admirable as most instincts are, yet they cannot be considered as absolutely perfect: there is a constant struggle going on throughout nature between the instinct of the one to escape its enemy and of the other to secure its prey' (Charles Darwin, in Romanes I883).
Chunga Broca
August 28, 2010
06:38 AM

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