Image of rock and sea.
Martin Eriksson has created mathematical models for how species ranges develop. The image shows how heather, juniper bushes, and cinder lichen have a range limit towards the sea, and how black cyanobacteria have a range limit towards land.
Photo: Kerstin Johannesson

Mathematical models provide answers to why not all species are found everywhere


Martin Eriksson has created mathematical models to be able to predict species’ possibilities for range expansion and adaptation. It’s an important question, because changes in the environment, such as climate change, drive species to either adapt, or to migrate to new areas. The models can help in preservation of biological diversity, and they work equally well for animals and plants in the sea as on land.

In his research, Martin Eriksson has taken an interest in why animals and plants have limited ranges, despite their ability to adapt to new environments via evolution. To answer this, Martin Eriksson created mathematical models for how geographic ranges develop, where he has, among other things, considered species’ various genetic characteristics.
“It’s important to understand why animals and plants have limited ranges, but also how they adapt to new environments. In theory, my models can explain why populations fail to adapt locally,” says Martin Eriksson, PhD student at the Department of Marine Sciences, University of Gothenburg.

Self-fertilisation can be favourable

Although Martin Eriksson's models are general, they are often related to empirical data from species in the Baltic Sea, a young area by geological standards, and which therefore has populations that have recently undergone an expansion of their ranges, such as bladder wrack or eelgrass.
In his models, Martin Eriksson has, among other things, been able to show that self-fertilisation can be favourable in certain environments, even though it usually results in poorer adaptability and makes the species vulnerable to environmental changes. He has also been able to show that it can be favourable for several genes to be inherited in so-called “supergenes”, to preserve local adaptation in extreme environments at range margins.  
“The advantage is that locally adapted combinations of genes are partially protected from mixing with less adapted genes. It can therefore lead to range expansions, at least if the environment stays the same,” says Martin Eriksson.

Create bridges between mathematics and biology

With his research, Martin Eriksson wants to create bridges between mathematics and biology. Mathematical modelling is a helpful alternative, since it can be difficult to study the expansion of species’ ranges using experiments or field studies.
Martin Eriksson's mathematical models can be used by researchers in, for example, evolutionary biology, or ecology, both to understand why species have the ranges they have today, but also to understand how limits in species’ ranges could look like in the future.
“I would very much like my models to be used for preservation of biological diversity, for example to improve our understanding of how global climate change affects species' ranges and genetic adaptation,” says Martin Eriksson.

Link to doctoral thesis:

Modelling the Evolution of Species’ Ranges


Martin Eriksson
PhD student at the Department of Marine Sciences