Hybridization is a common phenomenon, yet its evolutionary outcomes remain debated. Here, we ask whether hybridization can speed adaptive evolution using resynthesized hybrids between two species of Texas sunflowers (
The origins of geographic races in wide‐ranging species are poorly understood. In Texas, the
- NSF-PAR ID:
- 10370258
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 30
- Issue:
- 23
- ISSN:
- 0962-1083
- Page Range / eLocation ID:
- p. 6229-6245
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Helianthus annuus andH. debilis ) that form a natural hybrid in the wild (H. annuus ssp.texanus ). We established separate control and hybrid populations and allowed them to evolve naturally in a field evolutionary experiment. In a final common-garden, we measured fitness and a suite of key traits for these lineages. We show that hybrid fitness evolved in just seven generations, with fitness of the hybrid lines exceeding that of the controls by 14% and 51% by the end of the experiment, though only the latter represents a significant increase. More traits evolved significantly in hybrids relative to controls, and hybrid evolution was faster for most traits. Some traits in both hybrid and control lineages evolved in an adaptive manner consistent with the direction of phenotypic selection. These findings show a causal pathway from hybridization to rapid adaptation and suggest an explanation for the frequently noted association between hybridization and adaptive radiation, range expansion, and invasion. -
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Helianthus annuus ) alters natural selection on reproductive traits of wild sunflowers (Helianthus annuus texanus ). Across two years and multiple sites, we planted replicated paired populations of wildH. a. texanus bordering sunflower crop fields versus approximately 2.5 km away. We measured fitness, floral traits, and interactions of the plants with insect pollinators and seed predators. We found limited evidence that proximity to crop sunflowers altered selection on individual traits, as total or direct selection differed by proximity for only three of eleven traits: ray length (a marginally significant effect),Isophrictis (Gelechiidae, moth) attack, andNeolasioptera (Cecidomyiidae, midge) attack. Direct (but not total) selection was significantly more heterogenous far from crop sunflowers relative to near crop sunflowers. Both mutualist pollinators and antagonist seed predators mediated differences in selection in some population‐pairs near versus far from crop sunflowers. Here, we demonstrate that agriculture can influence the evolution of wild species via altered selection arising from shared biotic interactions, complementing previously demonstrated evolutionary effects via hybridization. -
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Fundulus notatus species complex. Two of the species have undergone extensive range expansions resulting in broadly overlapping distributions, and sympatry within drainages has provided opportunities for hybridization and introgression. We assessed the timing and pattern of range expansion in the context of late Pleistocene–Holocene drainage events and evaluated the evidence for introgressive hybridization between species.Location Central and southern United States including drainages of the Gulf of Mexico Coastal Plain and portions of the Mississippi River drainage in and around the Central Highlands.
Taxon Topminnows, Genus
Fundulus , subgenusZygonectes —Fundulus notatus, Fundulus olivaceus, Fundulus euryzonus .Methods We sampled members of the
F. notatus species complex throughout their respective ranges, including numerous drainage systems where species co‐occur. We collected genome‐wide single nucleotide polymorphisms (SNP s) using the genotype‐by‐sequencing (GBS ) method and subjected data to population genetic analyses to infer the population histories of both species, including explicit tests for admixture and introgression. The methods employed includedSTRUCTURE , principal coordinates analysis, TreeMix and approximate Bayesian computation.Results Genetic data are presented for 749 individuals sampled from 14
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