The Pangea continent concentrated the entire land mass during the geological era known as Mesozoic. However, 150 million years ago, the huge earth formation began to split. The fragments separated to form the continental arrangement that we have today.
The progressive breakdown of such a large land mass, involved the separation of certain groups of plants and animals. The genetic consequence of this separation is reflected in the number of divergent genealogical lines that have emerged to this day.
The biologist and director of the Munich Botanical Garden, Susanne Renner explains that fossils show that the cypress family it is "a very old group of plants”. This makes them suspect that it may be possible to continue "evolutionary history back to the period before the breakup of Pangea, as long as the various episodes of climatic changes and associated extinctions have not obscured it too much”. Renner and his research team try rebuild the family tree of cypress trees, based on the comparison of specific genetic sequences of 122 species belonging to 32 families of plants distributed throughout the world.
In order to be able to exactly date the different groups, a simple principle was applied. When two genealogical lines descended from a common ancestor are divergent, each accumulates genetic substitutions independent of the other. The number of unique substitutions provides a measure of the time that has passed since one species diverged from the other. Comparing the spectra of genetic changes found in different genealogical lines and calibrating the amount of changes that appear in the fossils, it is possible to reconstruct the history of a particular group of plants.
Renner explains that for the past 15 years, these molecular methods applied in combination with new fossil finds, have revolutionized the study of biogeography, a section of biology that is concerned with understanding the distribution patterns of animal and plant species. The discoveries of this scientific branch have revolutionized what people thought about some groups, since they have corrected existing erroneous dates that people took as valid.
According to the new study, cypresses belong to a very old genealogical group. His origins can be followed to Pangea and they show that the evolutionary divergence of the northern and southern subfamilies is the consequence of the separation of the continent 153 million years ago.
As fragmentation progressed and ancestral genealogical lines were separating from each other, new genetic branches were created that would have separate evolutionary trajectories. The "Cupressaceae”Are the first group of plants that offers us a detailed picture of the fragmentation of the enormous continent that existed on our planet millions of years ago.
Source: Ludwig-Maximilians-Universität München
Passionate about History, he has a degree in Journalism and Audiovisual Communication. Since he was a child he loved history and ended up exploring the 18th, 19th and 20th centuries above all.