Talk:Utricularia gibba

A news item involving Utricularia gibba was featured on Wikipedia's Main Page in the In the news section on 15 May 2013.

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Smallest?[edit]

This sentence confuses me "some species of Genlisea, also Lentibulariaceae, have genomes as large as 1.5 gigabases (and some as small as 60 megabases)". The genome of U. gibba is 80 Mb, which is apparently not that special if other plants have 60 Mb genomes. What's with that? Aaadddaaammm (talk) 11:21, 16 May 2013 (UTC)[reply]

Perhaps because the species with the smaller genome has not been fully sequenced yet.96.54.42.226 (talk) 17:52, 16 May 2013 (UTC)[reply]

Misuse of "Genetic Code"[edit]

The term genetic code has a defined meaning in science, the relationship between base triplets in codons and the amino acids encoded. Although the popular press commonly uses genetic code in the sense of genetic content, an authoritative scientific article should avoid doing so.96.54.42.226 (talk) 17:55, 16 May 2013 (UTC)[reply]

Fixed. Abductive (reasoning) 23:02, 19 May 2013 (UTC)[reply]

Selection pressure[edit]

For those of you who care, it has been hypothesized for at least 15 years that plants in low-nutrient environments are under selection to reduce the size of their genomes to conserve nitrogen and/or phosphorus. Such plants are often also carnivorous. Now, prior to DNA sequencing, scientists could easily estimate the size of genomes and have long published on this topic. See this Google Scholar search. Some species have gone further down this road than others. Sadly, this story was put forward in the popular press as a new discovery, a typical example of "junk science reporting". Abductive (reasoning) 17:21, 18 May 2013 (UTC)[reply]

I don't think that's an accurate assessment of the hypothesis at all. Many plants, including carnivorous plants, live in low-nutrient environments. Indeed among the Lentibulariaceae only some Utricularia and Genlisea species have been shown to have had drastic genome reductions. Why only some? And why have none of the related Pinguicula species that have had their genome size estimated done the same?

The google scholar search turns up a few excellent papers that I've already read but none of them support any such assertion made by the professor of plant genetics quoted in the Ed Yong piece (paraphrased as "He notes that bladderworts live in environments that are poor in the essential element phosphorus. That’s why it eats meat—to harvest phosphorus from the bodies of animals. And since DNA’s backbone is loaded with phosphorus, it’s reasonable to think that the plant would have evolved to have less DNA, so it can make do with less of this element." - Did you notice the next paragraph immediately rebuts that point by noting the original team thinks recombination and not selection was at work?)

Greilhuber et al. 2006 (abstract): "The possible selective factors and the corresponding mechanisms for this extreme genome downsizing are still elusive, the more so as the contrasting examples in Genlisea, such as G. margaretae and G. lobata, inhabit similar environments, which are notably very nutrient-poor and extreme (Fischer et al., 2000). In Genlisea, a possible relationship of genome size with certain clades or ecological adaptations of species requires further analyses with increased taxon sampling. Detailed analyses of a possible correlation between genome sizes and mutational rates, as well as of the evolution of genome sizes in Lentibulariaceae and the Lamiales, are underway and will be published elsewhere."

For a while there the research was suggesting that a mutation in the mitochondrial cytochrome c oxidase produced more reactive oxygen species, damaging DNA, implying this might be a driving force behind genome rearrangement or reduction. While phosphorus is one of the primary targets of prey digestion, it has not been shown anywhere that the plants are under any selection pressure for phosphorus because of the amount of DNA they have to maintain or replicate. The plants also produce a good amount of phosphatases, too. Point is - what was presented by that professor is a decent hypothesis that, to my knowledge, hasn't been explored at all so we shouldn't present it as fact. Anyway, all of this is too general for this article on the species and should be included on the genus's article. Rkitko ^(talk) 20:45, 18 May 2013 (UTC)[reply]

Well, as long as no musings on what selection pressure(s) are responsible are in the article I suppose it doesn't matter. Abductive (reasoning) 23:00, 19 May 2013 (UTC)[reply]