Adaptability of trees endures through millions of years of climate shifts

Adaptability of trees endures through millions of years of climate shifts
by Robert Schreiber
Berlin, Germany (SPX) Oct 16, 2024

Seven of Europe's most common forest tree species have shown remarkable resilience in maintaining genetic diversity despite significant environmental changes over millions of years. These findings come from a new study by a European research consortium, including Uppsala University, recently published in *Nature Communications*.

"From a biodiversity perspective, this is very positive because these trees are keystone species on which many other species depend," said Pascal Milesi, Associate Professor of Plant Ecology and Evolution at Uppsala University and the study's first author.

The research focused on understanding how ice age cycles affected the genetic diversity of these tree species. Despite drastic reductions in their ranges and population numbers during the last ice age, approximately 10,000 years ago, the trees displayed high levels of genetic diversity. This unexpected finding suggests that these species have been highly resilient to drastic habitat changes.

"We believe the reason for this high genetic diversity is related to the way these tree species survived through the ice ages and the fact that tree pollen can travel thousands of kilometers, bringing together trees that grow far apart. This is a welcome sign. The evolutionary processes that were at play in the past may also be useful to cope with today's rapid climate change," Milesi explained.

The study involved collaboration with scientists from 22 European research institutes who examined seven forest tree species. They collected needles and leaves from approximately 3,500 trees representing 164 different populations across Europe. DNA analysis of these samples provided insight into the genetic resilience of these species.

"Contrary to what was long thought, the ice age cycles had little impact on the genetic diversity of these seven key species. This is mainly explained by a combination of unique characteristics, namely long generation time and the ability of their pollen to spread thousands of kilometers," added Milesi.

In Sweden, the research specifically looked at Norway spruce, Scots pine, and silver birch. These species dominate Swedish forests and are vital to local ecosystems and the economy, as they represent a significant portion of the timber used in forestry.

Milesi emphasized the study's significance in light of ongoing environmental challenges: "Due to the sixth mass extinction event and the ongoing biodiversity crisis, people can easily get the feeling that it is too late and be ready to give up. This study sends a positive signal about our forest and provides important information to help manage forest biodiversity in the face of climate change."

The species studied in the research were Fagus sylvatica (European beech), Pinus pinaster (Maritime pine), Quercus petraea (Sessile oak), Betula pendula (Silver birch), Pinus sylvestris (Scots pine), Picea abies (Norway spruce), and Populus nigra (Black poplar).

Research Report:Resilience of genetic diversity in forest trees over the Quaternary