Evolution and biodiversity
It is evident that biodiversity is currently under serious pressure, drawing significant attention to related questions. How much biodiversity do we actually have, and how do we know this? Just how dynamic is biodiversity? And what does biodiversity have to do with evolution? We ask Edwin Pos, evolutionary ecologist and Scientific Director of the Utrecht University Botanic Gardens, where the new Evolution garden is set to officially open this June.
“Evolution is the foundation of biology; it helps in understanding how biodiversity originates, goes extinct and changes over time. The diversity in just the plant world has increased greatly over the past 900 million years. This is also reflected in the design of our new Evolution garden. Close to the starting point of the walking route, for instance, you will only find chlorophytes (perhaps more familiar to most as green algae), while at the end of the walking route you find a large variety of mostly flowering plants. This way, the Evolution garden is a very beautiful display of the relationships within the plant kingdom, based on the latest scientific insights.”
Evolution is the foundation of biology; it helps in understanding how biodiversity originates, goes extinct and changes over time.
Increase and decrease of species
“Throughout geological history, we see a constant alternation between the increase and decrease of species, also called speciation (or origination) and extinction. We differentiate between background extinction by continuous processes such as competition and chance, and mass extinction caused by events like meteorite impacts or large-scale volcanic eruptions. Interestingly, after a mass extinction, we often also see a strong increase of species diversity again. In this process of speciation and extinction, the history of life is described, in which we also see the emergence of new characteristics, innovations and adaptations to circumstances.”
Innovations and change
“A number of important innovations in plant evolution are marked as key moments in our Evolution garden, such as the transition of plants from water to land or the coming about of vascular systems. These innovations do not just pop up de novo, but evolve in many small and gradual steps. We also see changes in diversity itself: during evolution, for instance, groups disappear or become less diverse than they once were and some become more diverse. This also means that currently groups exist of which only a few or even just one representative member is left. A good example of that is Ginkgo biloba, the last remaining species in the sole remaining genus of the Ginkgoaceae family.”
Flower world
“The key moment where flowers make their appearance had a big influence on the total diversity of the plant kingdom. Once flowering plants emerged, there has been a huge diversification. This increase in species is partly driven by the relationships with pollinators, which can sometimes be very specific. Just as flowers vary greatly, so do their pollinators. All kinds of functional characteristics affect the flower-pollinator relationship. For instance, just think of a hanging flower versus a standing flower or a flower with a closed or open structure. Some flowers are even pollinated by a single, specific pollinator! Variation in one can thus lead to change in the other. This constant interaction, termed co-evolution, is partially responsible for the changes we see throughout time. Evolution never stops!”
Future
“It is impossible to predict exactly how plants will continue to evolve. In the short term, we can focus on changes we might expect, such as by looking at genetic diversity of certain groups and how this is expressed in relation to climate change. Bigger patterns of evolution can only be looked back on after a very long time. And who knows, maybe a new innovation will result in the rise of a completely new group of plants!”