International Aroid Society

It may be that bullate leaves have different functions in different taxa. But Jonathan may have hit upon something: a mutation that provides no disadvantage may persist, even if it also provides no advantage. Natural selection works solely by differential reproductive success. If a mutant form has the same reproductive success as a "normal" form, there may be no selective pressure for or against it. Founder effects can then come into play: a few mutants among a large population of "normals" may be genetically swamped and disappear; but if the mutant form appears in a new site, away from "normals," then it can become the "normal" for that location. Evolution is not random, but much of it is stochastic.

Jason Hernandez

Date: Fri, 24 Jun 2016 23:26:31 +0000
From: "Ertelt, Jonathan B" <jonathan.ertelt@Vanderbilt.Edu>
Subject: Re: [Aroid-l] Fiction of bullate leaves
To: Discussion of aroids <aroid-l@www.gizmoworks.com>
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<73255943A0E58248872276ECE91F9664E3583C93@ITS-HCWNEM108.ds.vanderbilt.edu>

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Corey,

I think that part of the frustration you're experiencing may be due to the plant's nature not to be mobile - this may initially sound quite absurd, and have little to nothing to do with bullate leaves, but I think that part of the much more sedentary nature of plants is that some evolutionary quirks have come and gone, while others have developed and stayed, even though a specific functionality is not always present, or in some cases is no longer present. When speed and various types of movement are particularly significant to survival, there's more often the case of gradual elimination of traits not crucial. Of course it could be argued the other way - that since there's no movement then the elimination of traits no longer needed in a microhabitat that is drier or higher light would happen more quickly - but of course the randomness of the genetic shift has to come into play as well. I'm really just playing with an idea here, but the idea that bullate leaves might be a response to one thing but then there are exceptions and what would it mean then would be at least partially calmed by the lack an additional evolutionary shift. Just musing on a Friday afternoon.