by Naturalis Biodiversity Center
Why do some plants grow into large woody shrubs or colossal trees, while others remain small and never produce wood in their stems? It's an evolutionary puzzle that baffled Charles Darwin more than 160 year ago. Now, scientists from the Netherlands and Germany present the first global overview of woodiness evolution on islands, which will finally help solve the puzzle.
"The first woody trees evolved on Earth some 400 million years ago, but still we know so little about why they developed wood in the first place," Frederic Lens tells, researcher at Naturalis Biodiversity Center and Leiden University. All these early woody trees are now extinct and originated in unknown climatic conditions, so it is impossible to understand the evolution of woodiness based on their fossils, but islands may offer the solution.
The evolution of woodiness is still happening today, particularly in areas that are known as natural laboratories of evolution: islands. One of the striking aspects of insular floras is that they are proportionally more woody than those of adjacent continents. Charles Darwin described this phenomenon as insular woodiness. It occurs when a non-woody continental colonizer reaches an island, and subsequently evolves into a woody shrub or even tree on the same island after tens or hundreds of thousands of years.