butterfly-plant coevolution

Patrick Foley patfoley at csus.edu
Thu Jan 10 12:43:03 EST 2002


My thoughts on this are still forming, but here are some of them.

1) Fabaceae (the legumes) are an extremely widespread and available set of hosts offering
great rewards (high protein and some nasty chemicals) to colonists. The only other families
that come close in ubiquity and biomass are Poaceae (the grasses) and Asteraceae (the
composites). We would expect a lot of convergent evolution onto these families, with a few
caveats. Grasses have only become common since the Miocene. Grasses rarely offer protective
chemicals for butterflies, so that their butterflies might tend to be cryptic: eg skippers and
satyrinae. Composites are also relatively late successes, spreading widely only since the
Miocene.

2) Papilionids tend to eat Magnoliid complex (Lauraceae, Annonaceae, Hernandiaceae,
Canellaceae, Monimiaceae) and Paleoherbs (Aristolochiaceae, Piperaceae). It may be a more
natural switch to go from these to Rutaceae (citrus) than from Legumes to Rutaceae. Although
there are some legumes with oil glands (Psoraleae) in the leaves, a trait shared by many
Rutaceae, woody Magnoliids and paleoherbs.

3) I have no big quarrel with the phylogenetic approach taken by Janz and Nylin 1998 (which is
some improvement over Mitter and Brooks 1983), but I suspect that a step by step
reconstruction of the host switching will eventually be needed, and that will require a
reconstruction of the chemical character-states in the angiosperm phylogeny. Together with a
better ability to predict the conditions of host switching.

Patrick
patfoley at csus.edu

Niklas Wahlberg wrote:

> At 14:05 09.01.2002 -0800, Patrick Foley wrote:
> >Dear list,
> >
> >For those of us who can handle Evolution, (in this case Janz, N. and S.
> >Nylin 1998. Butterflies and plants: a phylogenetic study. Evolution
> >52:486-502), what do you think about this update of the Ehrlich and
> >Raven 1964 problem?
>
> Great stuff, but then I may have a biased view.
>
> >In particular:
> >
> >1) Janz and Nylin piece together a phylogeny of the butterflies, often
> >to the genus level. Any specific problems?
>
> Certainly, when Janz and Nylin started out on that study, there were very
> few phylogenetic studies published on butterflies. What they did was to use
> the best classifications at the time to put together a possible
> phylogenetic tree. Now we know that some of those classifications got it
> wrong and there are some surprising, unexpected relationships out there. We
> are working on figuring out exactly what those relationships are at the
> moment. I bet that once we have strong phylogenetic hypotheses available
> for the butterflies, the conclusions in Janz and Nylin will be strengthened.
>
> >2) Janz and Nylin reconstruct the ancestral host plant as perhaps
> >Fabaceae or at least a Rosid. (This point was made by Scott 1986 also).
> >What about all those primitive Papilionids that eat primitive
> >Angiosperms?
>
> If you are referring to the parnassines and troidines feeding on
> Aristolochia, that appears to be a derived condition. Remember that
> Aristolochia is just packed with poisonous chemicals, and that one needs
> specialized physiological adaptations to deal with them. By the way, the
> most "primitive" papilionid (Baronia) feeds on Fabaceae, which is why that
> family came out as the most likely ancestral host plant family in Janz's
> and Nylin's study.
>
> >3) Why isn't there a Butterfly book like Mabberly's The Plant Book,
> >listing Butterfly genera and their distribution world wide. Or some kind
> >of world-wide catalog of species? Is someone working on this?
>
> Try Markku Savela's absolutely amazing site
> http://www.funet.fi/pub/sci/bio/life/insecta/lepidoptera/ditrysia/papilionoidea/index.html
> You should find all butterfly names there and their general distribution,
> if not, tell Markku! Otherwise I am not aware of anybody compiling a
> world-wide catalog. Smart's 1975 book  The Illustrated Encyclopedia of the
> Butterfly World has a checklist of all genera and most species in its
> appendix, but the classification of butterflies has changed much since then.
>
> Cheers,
> Niklas
>
> Niklas Wahlberg
> Department of Zoology
> Stockholm University
> S-106 91 Stockholm
> SWEDEN
>
> Phone: +46 8 164047
> Fax:   +46 8 167715
>
> http://www.zoologi.su.se/research/wahlberg/
>
>
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