impact of spores on evolution

fawolf at cc.usu.edu fawolf at cc.usu.edu
Sun Oct 15 06:35:43 EST 1995

In article <s2156974-1510951432380001 at>, s2156974 at cse.unsw.edu.au (Ruby Estrella) writes:
> Hi,
> I'm a 2nd year uni student studying microbiology 1 and I was wondering if
> anyone here is familiar with the article "Revival and Identification of
> Bacterial Spores in 25- to 40- MIllion Year-Old Dominican Amber" found in
> Science, May 1995? Well, this article describes the the discovery of
> ancient Bacillus spores in the gut of a bee in amber by scientists Cano
> and Borucki.  After analysis, they found this species to be closely
> related to a present day species, B.sphaericus. I was wondering how this
> is possible if the spores have been  dormant (and therefore not subjected
> to evolution) for millions of years and still share characteristics with
> B.sphaericus today?  Some would argue contamination, yet it was clear in
> the article that the scientists took special precautions to prevent that. 
> I would also appreciate if anyone could guide me to related information
> leading to references  on bacterial spores, evolution/taxonomy and 
> phylogeny. 
> thanks very much
> Ruby Estrella
> s2156974 at cse.unsw.edu.au

It depends what you (they) mean by "closely related". If B. spaericus is a
descendent of the amber spores then they might be more closely related,
interms of overall divergence than two extant species in the same genus.
If I remember correctly the paper used molecular differences (or perhaps 
not?) - but anyway, divergence between extant taxa is a function of 2 X
 the time since divergence (each taxon has a branch), whereas ancestor-
descendent differences are separated on only one branch at 1 x divergence
time.  Incorporating fossil data into phylogenetic analysis is likely
to become an exciting and challenging area.

Hope this answers the question, at least partly.

Paul Wolf
Utah State University, Logan
UT 84322, USA.
Email: wolf at cc.usu.edu

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