tag:blogger.com,1999:blog-8161161431451849208.post4900567581845215903..comments2024-03-28T02:45:03.204-07:00Comments on Antediluvian Salad: Biochemically Weaponized Cycads: Strangeria and Strangeria....Duane Nashhttp://www.blogger.com/profile/14467779935085970909noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-8161161431451849208.post-53805258979793530812013-09-22T22:50:25.644-07:002013-09-22T22:50:25.644-07:00Thanks for insightful comments Heteromeles they ad...Thanks for insightful comments Heteromeles they add much texture to the weird saga of cycads. Do you have a reference to where that amanitoxin origin in the Mesozoic is from? thats interesting... I tend to believe that foliage browsing of cycads was not common in the past among verts just as it is almost nil today- both for the structural and chemical defenses mentioned. I wonder if the softer freshly emerged cycad "fiddlheads" are more palatable? But as the several links I gave in the post suggest, perhaps cycads "fruits" are the product of a long diffuse coevolutionary saga between cycads and various animals, including dinos, throughout time. In essence a bit of a compromise, "Don't you dare nibble my fronds, but come on by once a year and you can eat these fruits and spread the seeds for me- fair enough?" And that even these fruits contain some of the toxins and that some animals can store them is interesting. On an extremely speculative note maybe some dinos that routinely munched the fruits were essentially poisonous?Duane Nashhttps://www.blogger.com/profile/14467779935085970909noreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-61866757737001820682013-09-21T10:48:39.095-07:002013-09-21T10:48:39.095-07:00Reminds me of the comment that Amanitoxins first s...Reminds me of the comment that Amanitoxins first showed up in the Mesozoic as well, based on the inferred molecular evolution tree. Whether they evolved for keeping maggots out of the gills or dinosaurs of the mushrooms is an open question.<br /><br />The question about cycad evolution is not how old most species are, but whether they're from a single lineage, or from older lineages. If they're from older lineages, then the toxins are older too.<br /><br />Personally, I doubt whether the toxins are slowing plant growth down. AFAIK, there's a good, inverse correlation between leaf toughness (as cell wall thickness) and growth rates: fast growing plants are flimsy. Toxins skew this picture, because a lightly built plant (like, say hemlock) can be extremely toxic. Cycads do use a nitrogen-based toxin, which might slow growth, but they also associate with nitrogen-fixing cyanobacteria, which makes up for that deficit. My suggestion is that they're investing in structural protection, and that's why they grow so slowly. The toxins are a secondary defense.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-68695697133189022182013-09-15T09:19:32.339-07:002013-09-15T09:19:32.339-07:00Thanks for comments
@Dean089, good point but given...Thanks for comments<br />@Dean089, good point but given the ubiquity of toxins in all extant cycad species it is very suggestive of an early innoculation of toxic chemicals in the history of this family. The link I provided Coevolution of Dinosaurs and Cycads goes into greater detail of course.<br />@Tom Hopp, thanks. I tend to think cycads were more clump/thicket forming than actually forming monotypic 'grassland' type habitats. One thing I notice from my Cycas revoluta is that it is exceptionally slow growing, a trait generally shared by all cycads. I don't know if this slow growth is due to some type of evo-devo constraints or the investment in toxins the plant makes or both.Duane Nashhttps://www.blogger.com/profile/14467779935085970909noreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-90420530988506871642013-09-15T09:02:15.224-07:002013-09-15T09:02:15.224-07:00Thanks for the great insights. I'll definitely...Thanks for the great insights. I'll definitely write some cycads into my future dinosaur stories. You have to wonder if there wasn't a form in the Mesozoic that closely matched the modern grasses. Trample-able. And not just something that resists fires, but uses fire to expand its territory!Tom Hopphttps://www.blogger.com/profile/17683044597782252722noreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-19821182238805907022013-09-15T05:41:36.411-07:002013-09-15T05:41:36.411-07:00Since most modern cycad species have only been aro...Since most modern cycad species have only been around 12 million years or so, I'm wondering if perhaps the toxins are also relatively recent. One wouldn't know from looking at a fossil all the different chemicals that a plant contained. We can make assumptions based on extant species, but those are assumptions only.Dean089https://www.blogger.com/profile/12747044433170296170noreply@blogger.com