Experimental admixture among geographically disjunct populations of an invasive plant yields a global mosaic of reproductive incompatibility and heterosis
1. Invasive species have the ability to rapidly adapt in the new regions where they are introduced. Classic evolutionary theory predicts that the accumulation of genetic differences over time in allopatric isolation may lead to reproductive incompatibilities resulting in decreases in reproductive success and, eventually, to speciation. However, experimental evidence for this theoretical prediction in the context of invasive species is lacking. We aimed to test for the potential of allopatry to determine reproductive success of invasive plants, by experimentally admixing genotypes from six different native and non-native regions of Centaurea solstitialis, an invasive forb for which preliminary studies have detected some degree of reproductive isolation between one native and non-native region. 2. We grew plants under common garden conditions and outcrossed individuals originating from different source populations in the native and introduced range to evaluate reproductive success in terms of seed to ovule ratio produced. We also assessed geographical and genetic isolation among C. solstitialis regions as a potential driving factor of reproductive success. 3. Experimental admixture generated mixed fitness effects, including significant increases, decreases and no differences in reproductive success as compared to crosses within population (control). Centaurea solstitialis invasive populations in the Americas generated preponderantly negative fitness interactions, regardless of the pollen source, suggesting selection against immigrants and reinforcement. Other non-native populations (Australia) as well as individuals from the native range of Spain demonstrated an increase in fitness for between-region crosses, indicating inbreeding. These differences show an asymmetrical response to inter-regional gene flow, but no evidence of isolation by distance. 4. Synthesis. The speed of adaptation and the accumulation of reproductive incompatibilities among allopatric populations of invasive species might be more rapid than previously assumed. Our data show a global mosaic of reproductive outputs, showcasing an array of evolutionary processes unfolding during colonization at large biogeographical scales.
Main Authors: | , , , , , , , , , |
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Format: | Artículo de revista biblioteca |
Language: | English |
Published: |
Wiley
2021
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Subjects: | Allopatry, Biological invasions, Fecundity, Gene flow, Local adaptation, Reproductive isolation, Yellow starthistle, |
Online Access: | https://repositorio.uchile.cl/handle/2250/183726 |
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Summary: | 1. Invasive species have the ability to rapidly adapt in the new regions where they
are introduced. Classic evolutionary theory predicts that the accumulation of
genetic differences over time in allopatric isolation may lead to reproductive incompatibilities
resulting in decreases in reproductive success and, eventually, to
speciation. However, experimental evidence for this theoretical prediction in the
context of invasive species is lacking. We aimed to test for the potential of allopatry
to determine reproductive success of invasive plants, by experimentally
admixing genotypes from six different native and non-native
regions of Centaurea
solstitialis, an invasive forb for which preliminary studies have detected some degree
of reproductive isolation between one native and non-native
region.
2. We grew plants under common garden conditions and outcrossed individuals
originating from different source populations in the native and introduced range
to evaluate reproductive success in terms of seed to ovule ratio produced. We
also assessed geographical and genetic isolation among C. solstitialis regions as a
potential driving factor of reproductive success.
3. Experimental admixture generated mixed fitness effects, including significant increases,
decreases and no differences in reproductive success as compared to
crosses within population (control). Centaurea solstitialis invasive populations in
the Americas generated preponderantly negative fitness interactions, regardless of the pollen source, suggesting selection against immigrants and reinforcement.
Other non-native
populations (Australia) as well as individuals from the native
range of Spain demonstrated an increase in fitness for between-region
crosses,
indicating inbreeding. These differences show an asymmetrical response to inter-regional
gene flow, but no evidence of isolation by distance.
4. Synthesis. The speed of adaptation and the accumulation of reproductive incompatibilities
among allopatric populations of invasive species might be more rapid
than previously assumed. Our data show a global mosaic of reproductive outputs,
showcasing an array of evolutionary processes unfolding during colonization at
large biogeographical scales. |
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