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Adaptive introgression in invasive slugs

Wolfgang Hasselmann @unsplash

Background

Questions

Implications

Team

Why are some invasive species more successful than others?

Theoretical work predicts that during a species invasion, genes from a native species often move into the genome of the invasive species, potentially facilitating its adaptation to local environmental conditions. Such asymmetric introgression has been confirmed in diverse taxa such as plants, fish, and even humans. It is yet unclear if introgression is selectively adaptive facilitating invasiveness, or if it is neutral reflecting demographic history. We provide insights into this question by studying the divergence and gene flow of Arion slugs. Within the last 100 years, likely facilitated by changes in climate and land use, the slug species Arion vulgaris expanded from southwestern France to all of Europe, and more recently to North America, becoming an important plague in agriculture. In this process, this invasive species hybridized with several native slug species, leading to their destruction across most of their range. 

We use genomic methods to understand the following questions:

 

1. How did species diverge in the past?


2. Did the demographic history of invasion lead to introgression?


3. Is there a signature of adaptive introgression in locally adaptive genes?
 

These results will help to better understand if hybridization can favor species invasiveness, and will show how natural history collections can offer unique insights into biodiversity change over time.

Ricardo Pereira, Niloofar Alaei Kakhki, Ira Richling, John Hutchinson, Heike Reise.

Fig. 1: Hybridization between species during invasion. As the invasive species Arion vulgaris expanded through central Europe over the range of the native species Arion ater, they produced F1 hybrids, backcross towards the invasive species, leading to the extinction of the native species.

Fig. 1: Hybridization between species during invasion. As the invasive species Arion vulgaris expanded through central Europe over the range of the native species Arion ater, they produced F1 hybrids, backcross towards the invasive species, leading to the extinction of the native species.

Fig. 2. Expectations for genomewide introgression during a species invasion. As an invasive species expands over a native species, asymmetric backcrossing towards the invasive species will occur as a result from a demographic imbalance. Genes under strong genetic drift and locally adapted genes are expected to remain at the initial contact zone, while most of the alleles from the invasive species move in the front wave of the expansion.

Fig. 2. Expectations for genomewide introgression during a species invasion. As an invasive species expands over a native species, asymmetric backcrossing towards the invasive species will occur as a result from a demographic imbalance. Genes under strong genetic drift and locally adapted genes are expected to remain at the initial contact zone, while most of the alleles from the invasive species move in the front wave of the expansion.

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