Science Drinks – 25.2.14
Attendees: Luc Bussiere, Elizabeth Herridge, Toby Hector, Claudia Santori, Gregor Hogg
To start with, Luc discussed ongoing struggles he is having in presenting some statistical concepts to first year students. It turns out that lecturers often have just as much trouble writing lecture material as we do understanding it! We debated the issue of making the material engaging enough to keep everyone interested in a difficult subject, and considered the contrasting pressure of getting all the information across when the lecture is a pivotal point in the course. Luc will report back on how his lectures went later on….
Next onto science as Toby presented a paper that has found a novel method of looking at depth perception using jumping spiders (Depth perception from image defocus in a jumping spider, 2012). The authors report evidence for the first known example of an animal (the jumping spider) that uses defocused images as a primary mechanism for depth perception.
Claudia then shared an interesting paper on the convergent evolution between Cane Toads and the Madagascan plant Mother of Millions (Interacting Impacts of Invasive Plants and Invasive Toads on Native Lizards, 2012). In a case study on the blue tongue lizard (Tiliqua scinoides) it was observed that while these omnivorous lizards are threatened by the invasion of toads in north western Australia, conspecifics from other areas of Australia are less affected by the poison of the toads, including where the toads have yet to invade. Researchers noticed that this pattern was consistent with the geographic occurrence of an ornamental plant from Madagascar – Mother of Millions (Bryophyllum spp.), introduced in the continent around the same time as the cane toads.
This seems to be a remarkable case of convergent evolution, where the toxins produced by the Mother of Millions are chemically extremely similar to the bufotoxins produced by the toads. The lizards that were found to have evolved resistance to the plant toxins also turned out to be tolerant to the poison of the cane toad. Different individuals from various geographical areas were collected and injected with a sublethal dose of toxin, and changes in their locomotor performance were then observed. Lizards located in areas where neither Mother of Millions nor Cane Toads were present were found to have to lowest tolerance to the toxins. This supports the idea that both the Mother of Millions and the Cane Toads impose selection on bufadienolide resistance.
Finally Lilly discussed some of her ongoing work on sexual selection in dance flies!