The Hidden Side of Invasions: Massive Introgression by Local Genes

  title={The Hidden Side of Invasions: Massive Introgression by Local Genes},
  author={Mathias Currat and Manuel Ruedi and R{\'e}my J. Petit and Laurent Excoffier},
  booktitle={Evolution; international journal of organic evolution},
Abstract Despite hundreds of reports involving both plants and animals, the mechanisms underlying introgression remain obscure, even if some form of selection is frequently invoked. Introgression has repeatedly been reported in species that have recently colonized a new habitat, suggesting that demographic processes should be given more attention for understanding the mechanisms of introgression. Here we show by spatially explicit simulations that massive introgression of neutral genes takes… 
The Spatial Signature of Introgression After a Biological Invasion With Hybridization
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Revisiting a classic case of introgression: hybridization and gene flow in Californian sunflowers
During invasion, colonizing species can hybridize with native species, potentially swamping out native genomes. However, theory predicts that introgression will often be biased into the invading
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It is predicted that without specific management action, A. vulgaris will further expand its range, which might lead to local extinction of A. rufus and other native slugs in the near future, and spatial differences in admixture patterns that might reflect distinct invasion histories among the regions are found.
Hybridization and introgression during density‐dependent range expansion: European wildcats as a case study
The simulations explained better the observed level of introgression at nuclear, mtDNA, and Y chromosome markers, when using solitary dispersal for wildcats instead of random or gregarious dispersal, in accordance with ecological knowledge, and use of density‐dependent dispersal models increases the predictive power of the approach.
Cryptic Biological Invasions: a General Model of Hybridization
A general model that considers concurrently: multiple loci, quantitative and qualitative gene expression, assortative mating, dominance/recessivity inheritance and density-dependent demographic effects, argues that it represents a powerful tool for the study of a wide range of biological and societal questions.
Negligible nuclear introgression despite complete mitochondrial capture between two species of chipmunks
The genomic contribution of gene flow between two hybridizing chipmunk species, Tamias ruficaudus and T. amoenus, is examined to find that most of the nuclear genome is sorted between these species and that overall genealogical patterns do not show evidence for introgression.
Birth of a hotspot of intraspecific genetic diversity: notes from the underground
The results point to the admixture between differentiated lineages as the main cause of the higher levels of diversity of refugial populations, when compared with the Pleistocene evolutionary history recently inferred for species from both the same and other geographic regions.
Home-loving boreal hare mitochondria survived several invasions in Iberia: the relative roles of recurrent hybridisation and allele surfing
It is shown that admixture across the border is quasi-absent, making it unlikely that lack of interspecific mtDNA differentiation results from ongoing gene flow, and it is also unlikely that ongoing ecology-driven movement of the contact account for mtDNA introgression.


Hybridization as an invasion of the genome.
  • J. Mallet
  • Biology
    Trends in ecology & evolution
  • 2005
Extinction and Introgression in a Community of Partially Cross‐Fertile Plant Species
It is found that hybridization can create positive frequency dependence and make extinction possible, even when hybrid individuals have no intrinsic fitness advantage.
The results argue that recombination will be important, that introgression can be very selective, and that evolutionary forces within the hybrid population to effectively “filter” gene flow between species are needed to make introgress adaptive, prevent genetic assimilation, and contribute to the stability of hybrid zones.
A direct test for the existence of local exchanges must be comparatively recent, that is, contemporaneous with or later than the last postglacial recolonization of oak species, to distinguish between ancient hybridization events and ongoing introgression.
Hybridization as a mechanism of invasion in oaks
Summary We review here our own research and related work on hybridization between two widespread and largely sympatric European oak species (Quercus petraea and Q. robur). There is a near total lack
Hybridization and the colonization of novel habitats by annual sunflowers
Evidence is presented that the colonization of sand dune, desert floor, and salt marsh habitats by three hybrid sunflower species was made possible by selection on extreme or “transgressive” phenotypes generated by hybridization.
Hybrid zones and the genetic architecture of a barrier to gene flow between two sunflower species.
The utility of hybrid zones for identifying factors contributing to isolation and the prediction of increased resolution relative to controlled crosses are demonstrated and verified.
The effect of the Neolithic expansion on European molecular diversity
It is concluded that the different patterns of molecular diversity observed for Y chromosome and mitochondrial DNA can be at least partly owing to an ascertainment bias when selecting Y chromosome SNPs for studying European populations.
The role of hybridization in evolution
Fisher’s model of stabilizing selection on multiple traits, under which reproductive isolation evolves as a side‐effect of adaptation in allopatry, confirms a priori arguments that while recombinant hybrids are less fit on average, some gene combinations may be fitter than the parents, even in the parental environment.
Contrasting effects of long distance seed dispersal on genetic diversity during range expansion
The simulations reveal a close relationship between the frequency of long distance seed dispersal events and the amount of genetic diversity preserved during colonization, up to the point that diversity is better preserved than in a pure diffusion model.