When a bad mimic is good
Nature is full of mimicscreatures that have evolved to look or act like other more dangerous animals. However, some mimics imitate their models more convincingly than others, and new research helps explain why it sometimes pays to be a bad mimic. The research looked at three species of spider, all of which mimic, with varying degrees of accuracy, aggressive and bad-tasting ants. All of the mimics were good at avoiding being eaten by predators that target spiders, the research found. But the less accurate mimics also had a spider-like ability to evade predators that eat the model ants. "So by not looking like a spider, but also not quite looking like an ant, these inaccurate mimics have the best of both worlds, escaping both spider and ant predators," said Stano Pekr, a biologist at Masaryk University in the Czech Republic and one of the study's authors. The results show that the accuracy of mimics depends on the environment and the array of predators in the area.
Stano Pekr, Martin Jarab, Lutz Fromhage, and Marie E. Herberstein, "Is the Evolution of Inaccurate Mimicry a Result of Selection by a Suite of predators? A Case Study Using Myrmecomorphic Spiders."
You're not speaking my language: Sparrows don't respond to foreign dialects
Similar to regional dialects in human languages, bird songs often differ slightly between populations of the same species. A study led by Julie Danner of Virginia Tech shows that female rufous-collared sparrows have strong preferences for mating songs sung in a local dialect, and rarely respond sexually to foreign dialects. "The research indicates that picky females may inhibit breeding between close populations," Danner said. Such reproductive isolation could ultimately cause populations to diverge into different species. For their study, Danner and her team played recordings of several mating songs for captive females. One recording was a s
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