Speaking of moths and butterflies

[Taxon 0]

Speaking of moths and butterflies, it seems curious that there appears to be no taxonomic distinction between the two. In other words, one would expect there to be one suborder for moths, and another for butterflies, particularly when there seems to be statistics concerning the number of species that are of one or the other. Hoping that you can shed some light on this puzzlement for me, Ethan.

[down2earthlv 0]

Now I'm no bug-ologist, but I always thought there was a defining line between the two.... But now that I think about it, I dont know what that might be.....I'm intrested to lean more also....

[Ethan Bright 0]

These are EXCELLENT questions.

 

The study of systematics, and the use of various forms of cladistics in which to make and test hypotheses regarding phylogenetic (evolutionary) relationships, has often challenged (and confused) the notions of many people who grew up with certain names for organisms.

 

Check this web site: http://tolweb.org/Lepidoptera. It shows how specialists posit the evolutionary relationships of Lepidoptera. Basal clads represent organisms that have more pleisomorphic ("primitive") characters, and represent those ancesters that also gave rise to more recent clads (groups of organisms) that are recognized by having more apomorphic ("advanced") characters. In other words, the type of characters (morphological, genetic, etc., all that is inherited) give evidence to how organisms came to be over time. This is the "Decent with modification" part of the Theory of Evolution. Subsequent analyses by scientists test the subsequent parts of current evolutionary theory, such as "due to natural selection, drift, genetic mutation, etc." (BTW, there is a fantastic body of thought, both scientific and philosphical, regarding the ramifications of these endeavors to understand the history of life).

 

OK, regarding Lepidoptera, what "defines" this group. In other words, what characters are shared by all "moths and butterflies" that differentiate it from it's hypothesized (and almost universally accepted) nearest sister taxa, the Trichoptera (caddisflies)? Surprisingly, it isn't the proboscis, which almost all of them use to feed. (The most ancent group of moths have mandibulate mouthparts). Rather, it appears to be 1) Wings with dense covering of scales on veins and membrane; 2) Wings with M veins having 3 branches; 3) Foretibia with one apical spur, or none; 4) Median ocellus lost; 5) Tergum one extensively desclerotized; 6) Cerci lost; and 7) Foretibia with articulated epiphysis on inner surface. (From Grimaldi and Engels. 2005. Evolution of Insects).

 

This is now the place to talk about "paraphyly," which describes how the evolutionary history of organisms is grouped in a way that does not include other organism that are also part of its lineage. In other words, what most people call "moths" often does not include those "moths" that don't have the retractible proboscis, or those "moths" that are more recently derived from ancestors than the "butterflies." Although this is a big problem in phylogenetic systematics, it also gives rise to problems that ordinary people have with how to call an organism. Hence, "what's the difference between a moth and a butterfly?" If one is interested in how this group evolved, the common characters that people use to place leps into either group does NOT reflect their evolutionary history, and can lead to further problems when one comes across organisms that apparently are intermediate to both groups.

 

You're probably now saying, "Cut the crap, I don't have time for this. Just tell me the f***ing difference between a moth and a butterfly!" Well, if looked at some pictures of geometrid moths, you might be confused. It's definitely a moth, but many people looking at it (like probably all my relatives) would say it's a butterfly. To them, that's fine, and makes their world happy. However, if you're interesting in deeper things, well then, ask more questions and be more skeptical at "universalisms" and "classifications." Deeper things would include Roger's excellent question regarding why there are so many moths than butterflies. That's often why it's great to look at the evolutionary history - there's been much more time for moths to speciate than butterflies. (Although this statement can be very problematic, especially if a group has greatly radiated to exploit new ecological niches, or if older groups experienced considerable extinction of species).

 

And to finish up, another reason why people should have a rudimentary understanding of why scientists use phylogenetic systematics and evolutionary theory is, as Theodosius Dobzhansky put it, "Nothing in biology makes sense except in the light of evolution." Understanding relationships is how scientists are learning about infectious diseases, to find new medicines and treatments in human health, to develop programs in conservation, among many other things.

 

Time to stop, and go back to work!

Cheers, Ethan

[Ethan Bright 0]

Oh yes, just a follow-up... Two great books on insects and related invertebrates have been published, and are highly recommended:

 

Grimaldi D, Engel MS. 2005. Evolution of the Insects. Cambridge University Press.

Resh VH, Carde RT. 2003. Encyclopedia of Insects. Academic Press.

 

Cheers, Ethan

[Taxon 0]

Ethan-

 

All great information, and I was even able to follow most of it. What I conclude in regard to the question I posed is that, the reason there is no taxonomic distinction between moths and butterflies is that they are (essentially) artificial categories, and are simply based on observation of certain evolved characteristics.

[uffepuffe 0]

I read and learn, great question Roger and interesting answers Ethan.

 

Ulf

[Ethan Bright 0]

Roger writes..."I conclude in regard to the question I posed is that, the reason there is no taxonomic distinction between moths and butterflies is that they are (essentially) artificial categories, and are simply based on observation of certain evolved characteristics."

 

That is essentially correct, except the last part. I'd rephrase so that "the taxonomic distinction between moths and butterflies is that, as currently recognized, is an artificial grouping that do not reflect the evidence supporting current phylogenetic hypotheses." It's a fancy way of saying Lepidoptera contains moths and butterflies, and many more moths than butterflies, and that some of what we used to differentiate groups doesn't work for all of them. But most of them. :sleep: I'm getting tired! zzzzzzzz

 

Take care Roger - keep the great questions coming, and keep on grabbing those critters!

Cheers, Ethan