The evolution of the Ascomycota new insights from Mesozoic and Cenozoic amber fossils

by Christina Beimforde
Doctoral thesis
Date of Examination:2013-05-16
Date of issue:2013-08-14
Advisor:PD Dr. Alexander R. Schmidt
Referee:PD Dr. Alexander R. Schmidt
Referee:Prof. Dr. Joachim Reitner
Referee:Prof. Dr. Daphne Lee
Persistent Address: http://dx.doi.org/10.53846/goediss-3988

 

 

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Abstract

English

This thesis contributes to the knowledge of the evolutionary history and palaeoecology of the Ascomycota (sac fungi). The six included papers are based on the investigation of Cretaceous and Palaeogene amber inclusions and deal with systematics, taphonomy and palaeoecology of newly discovered ascomycetes. Two new fossil ascomycetes of the resinicolous genus Chaenothecopsis (Mycocaliciales, Eurotiomycetes) are described from Eocene Baltic and Oligocene Bitterfeld ambers and are compared to a new modern representative, described as Chaenothecopsis proliferatus. Besides, the anamorphic fungal genus Monotosporella (Ascomycota, Sordariomycetes) has been recovered from a piece of Early Eocene Indian amber, as well as from the surface of extant resin flows in New Caledonia. The newly described fossil Monotosporella doerfeltii represents the second fossil record of Sordariomycetes, as well as the first fossil of its particular order (either Savoryellales or Chaetosphaeriales). Furthermore, an overview about the fossil record of capnodialean sooty moulds fungi is provided. This traces the fossil record of this group of fungi from the Early Miocene back to the Early Cretaceous. Another study presents the first known fossil ectomycorrhizae from an angiosperm forest. The fossil ascomycete mycobiont is associated to an angiosperm of the family Dipterocarpaceae and is described as Eomelanomyces cenococcoides. Apart from previously described fossil ascomycetes, the new described fossils were used to constrain a molecular clock in order to estimate the origin and divergence of Ascomycota lineages with a Bayesian approach (BEAST). This is the first study to combine molecular and fossil data solely from within the Ascomycota in order to produce a chronogram with multiple calibration points throughout the Phanerozoic. According to our results the diversification of the ascomycetes started in the Cambrian, followed by a continuous diversification throughout the Phanerozoic that was likely unaffected by mass extinctions. This suggests that the ecological diversity within each lineages ensured that at least some taxa of each group were able to survive global crises and rapidly recovered. 3
Keywords: fungi; Ascomycota; molecular dating; evolution; taphonomy; systematic; amber; resin
 
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