Mittwoch, 6. August 2014

Angiosperm plants and mammal dung – food for evolution

     The sequential evolution of angiosperm plants and their mammal herbivores was tracked by the evolution of beetles, shows a newly published study from the Zoological Research Museum Alexander Koenig – Leibniz Institute for Animal Biodiversity in Bonn and the Natural History Museum London in Proceedings of the Royal Society B. using DNA sequences. Dr. Dirk Ahrens, Dr. Julia Schwarzer and their colleague Prof. Alfried Vogler reconstructed a phylogeny of scarab beetles, which include stag beetles, dung beetles and chafers. The researches dated the different lineages using fossils and a molecular clock.
The researchers showed that plant-feeding chafers, which are among the most diverse beetle groups in the world, arose almost immediately after the origin of the angiosperms in the Middle Cretaceous. The same lineage also gave rise to dung beetles, but they originated much later, and only after the mammals, including the even-toed ungulates (Artiodactyla) as the most important herbivores, had themselves started to use the angiosperms as their food source. The late origin of dung feeding rejects the widely held hypothesis that early dung beetles fed initially on dinosaur dung, which already were extinct by that time. Instead, the evolution of angiosperm plants provided a new resource that first enabled the origins of herbivory in mammals and beetles, and secondary dung feeding among the scarab beetles.
However, the researchers still try to unravel the mystery of why there are so many species of chafers. In contrast to other plant feeding insects, chafers are not specialised on certain plant species. It might thus be possible that the copious leaf litter produced by the angiosperms created highly suitable conditions for these beetles and their soil-dwelling larvae.
Ahrens D, Schwarzer J, Vogler AP. 2014 The evolution of scarab beetles tracks the sequential rise of angiosperms and mammals. Proc. R. Soc. B 20141470.
http://dx.doi.org/10.1098/rspb.2014.1470
Sabine Heine Presse- und ÖffentlichkeitsarbeitStiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere


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