Escalating Threat of Wheat Rusts
Science Mag editorial
“Last month [6/10], nearly 600 scientists from more than 80 countries convened… to discuss the world’s most widely planted crop… [and] the rapidly spreading fungal diseases known as wheat rusts… causing epidemics that require urgent action.
In the 1940s… new plant varieties [were bred] to resist the causative pathogens… But in 1999, a virulent fungal strain (Ug99) was detected… new virulent and aggressive strains of yellow rust fungus (also known as stripe rust) now pose a severe threat to the world’s wheat supply… This epidemic trend may continue because the aggressive strains, which can tolerate higher temperatures, are still evolving [emphasis mine].”
Activity: Present this as a problem, and have students come up with solutions.
Activity: Analyze each others’ solutions for evolutionary explanations. For example, why are fungicides a short-term solution? What are the implications of some solutions for genetic diversity? For example, of replacing wheat with certain varieties. How can humans speed up evolution? Identify the postulate of natural selection we modify to speed up evolution, and explain why other species in nature can’t do this.
Preparation: What guidance and foundational knowledge do they need for this?
Carl Zimmer discusses the future of biological evolution, especially in humans. He says it’ll keep going on. I have bells ringing from Shin Han’s seminar that human evolution is still debatable. For example, since populations are exploding after bottlenecks, selection (at least K-selection?) may be weak. R selection could be rockin’ our opportunistic species, though.
What do I think of Zimmer’s article?
Science 23 July 2010:
Vol. 329. no. 5990, pp. 402 – 403
It takes a while to recognize differences among individual organisms of the same species. We all intuit them about humans, but our picture books teach us as kids that a fish is a fish is a fish. Add the fact that these differences fall into three classes, and it’s a lot to take in.
Once this appreciation sinks in, it becomes difficult to see even how twins can be truly identical. Among all those base pairs in the genome, some unruly A has to have swapped out to C. And the thing I love about Natural Selection is that it’s a beautiful syllogism: once you grasp three premises, the proposition is just there.
More than anything else in our paved paradises we encounter differences among automobiles, observing very small sample sizes of living organisms. It always jolts me out of my assumptions when I see students have ah-ha moments with the first postulate of individual variation. For a teacher struggling to grasp why students struggle to grasp selection, smacking into the gap between what students are assumed to know and what they don’t know is humbling but refreshing. I am increasingly finding that nature, not technology, is instrumental in biology classrooms. It is ridiculous to rely solely on students transferring their knowledge of mutation to individual variation. How easily do I transfer the abstract and microscopic to the warm and soft?
So, here’s a nice study of the individual differences in pigeon behavior, measured–essentially–with “critter cams”. I’ve linked below to a 3 minute news radio report summarizing the rationale and findings.
It’s not trivial that Darwin and Wallace arrived at their famous syllogism during years of sleeping under the stars, trying to avoid sleeping with the fishes. Naturalists (and profiteers) in England were great collectors, and inherent to collecting is individual variation. As James Audobon said, “When the bird and the book disagree, always believe the bird.”
NPR: Backpacked Birds Reveal Who’s The Boss