Fungal apocalypse?

One of the most brilliant people I ever interacted with in research gave me a great idea that I just want to get down.  If I save these in a folder I will forget, so I am going to put it out here in raw format… I still have an exam to write for tomorrow

Fishing Facebook for ideas.  With just 2 hours more sleep a night I could come up with my own.

Fishing Facebook for ideas. With just 2 hours more sleep a night I could come up with my own.

His brilliant response:


I was SO not thinking that.  My attempt to summarize to a second friend:

I was aware of observations of a “spike” of fungal spores in sediments dating right after the K-T extinction event (just above the iridium layer, if you have heard of that), but the interpretation that this contributed to the demise of the dinosaurs doesn’t appear to be universally accepted.  This is way outside of my area of expertise, but I can think of two problems right away.
1.  How widespread is the layer of fungal spores? (the iridium layer, for instance is found in many different parts of the world at the same sedimentary depth)  Is this just a local event?
2.  How easy is it to tell a fossilized fungal spore (single cell) from a piece of schmutz?  I know there are experts who can identify this kind of stuff, but I also know that it must be difficult to identify.
Anyhow, ach ief proponent of the idea appears to be a guy at Albert Einstein College (PDF).  I am not sure of the evidence for when endothermy (ability to produce body heat) evolved, but it does make sense that a fungal bloom on lots of dinosaur corpses and dead plant material would give any endotherms an advantage; fungi in general do not appear to be able to stand body heat and most of the fungi that do grow on the body do so in the upper respiratory tract or the skin, both areas with lower-than-average temperatures.  That would be a powerful selection.  But when things make “too much sense” I get a little nervous – biological realities often make no “sense” and I would bet that confidence multiplies the effects of confirmation bias.
Interesting idea.  I am sure that there is plenty of literature on adaptability of fungi to temperature, or at least I hope there is.

Soil Amoebae might be important…from the Casadevall paper:

“The link between interactions with soil amoeboid predators
and mammalian virulence was strengthened by the
demonstration that in vitro passage of avirulent fungal
strains with amoeboid cells increased the virulence of
the fungi for mice (Steenbergen et al., 2003, 2004). Co-incubation of a relatively avirulent C. neoformans strain
with D. discoideum resulted in a significant increase in virulence
as measured by shorter survival time (Steenbergen
et al., 2003). Similarly, passage of an avirulent H. capsulatum
strain in A. castellani resulted in the re-acquisition of
virulence as measured by the ability of this strain to persist
in mouse lungs and to elicit an inflammatory response
(Steenbergen et al., 2004). The mechanism by which passage
in amoeba increases virulence has not been elucidated.
Nonetheless, this phenomenon provides strong
experimental support for the view that fungal interactions
with soil predators can be a mechanism for the emergence
and maintenance of characteristics necessary for animal
virulence without the necessity for regular interactions
with mammalian hosts.”

Argument that reduced sunlight and global temperature after the KT event would have favored favored fungal growth  and (selected against?) ectotherms at end of Casadevall paper –> any evidence in any ectothermic lineage of a bottleneck at this time?  Examples of insects that go extinct right at the time?


About SubOptimist

I am an Associate Professor in the Science Department at Georgia Perimeter College, Clarkston. I teach introductory biology courses at both the majors and non-majors level in addition to microbiology. Previous to that I spent 7 years as a postdoctoral researcher on different viruses. While I don't miss being on the "grant treadmill", I think better when I write and miss writing up data for papers and grants; this blog helps me with that a little. And sometimes my kids' insanely funny and cute antics need to be shared with the world. Any view expressed in this blog is that of me personally and not Georgia Perimeter College or the GPC Clarkston Science Department.
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