Temporal population genetic structure in the pollen pool for flowering time: A field experiment with <i>Brassica rapa</i> (Brassicaceae)

Ison, Jennifer L.; Weis, Arthur E.

doi:10.3732/ajb.1700210

Cited by 8 publications

(6 citation statements)

References 58 publications

(80 reference statements)

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“…However, many of these mechanisms provide unsatisfactory explanations for the observed patterns of reproduction in Echinacea and potentially other pollen-limited plants (Wagenius 2006, Ison andWagenius 2014). The changes in pollinator service that we observed across one season support the hypothesis that pollinators mediate seasonal declines in reproductive success in Echinacea (Ison and Wagenius 2014), which has strong implications for selection and temporal assortative mating Kossler 2004, Ison andWeis 2017). The overall observed bee community composition, dominant taxa, and changes over time are consistent with observations in the same study area over two years (Wagenius and Lyon 2010).…”

Section: Implications Selection On Phenological Traits and Populationmentioning

confidence: 53%

“…For example, nearby individuals or populations exchange alleles more often than distant individuals or populations, and individuals with overlapping mating periods are more likely to mate than asynchronous individuals. Mating patterns that change over a season are prevalent in insects (Rowe andLudwig 1991, Robinet et al 2008), salmon (Morbey andYdenberg 2003, Hendry et al 2004), birds (Rowe et al 1994, Kaiser et al 2017, and are particularly common in plants (Augspurger 1981, Schmitt 1983, Kitamoto et al 2006, Ison and Weis 2017. Mating between plants may be limited if timing of flowering among individuals does not overlap or if timing mismatches with pollinators (Augspurger 1981, Price and Waser 1998, Forrest 2015.…”

Section: Introductionmentioning

confidence: 99%

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Pollinator‐mediated mechanisms for increased reproductive success in early flowering plants

Ison

Prescott

Nordstrom

et al. 2018

Oikos

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Mating activities change within a season in many animal and plant populations. In plants, selection towards early flowering is commonly observed. Pollinator‐mediated selection is hypothesized to be a pervasive evolutionary force acting directionally on flowering time. However, pollinator‐mediated mechanisms have rarely been tested in realistic field conditions, especially in perennial plants visited by a diversity of generalist insect pollinators. We examined pollinator visitation in eight Echinacea angustifolia populations in western Minnesota, USA, to gauge the potential for pollinator‐mediated selection. Echinacea is a common prairie perennial that persists in isolated remnant populations. Echinacea is self‐incompatible and is pollinated by a diversity of generalist solitary bees. A previous study found that early flowering Echinacea plants have higher seed set and their reproduction is less pollen‐limited than late flowering plants. Twelve times throughout a flowering season, we quantified pollinator visitation rates and pollinator community composition. In three sites, we also estimated the quality of pollinator visits by examining the composition of pollinators’ pollen loads brought to Echinacea plants. We found that three aspects of pollination dramatically decreased over the course of the flowering season. 1) Pollinators visited early flowering plants more frequently than late flowering plants. 2) The pollinator community was also less diverse late in the flowering season and became dominated by a single species of small bee, Augochlorella aurata. 3) Pollinators visiting Echinacea late in the season carried proportionally less conspecific pollen compared to pollinators visiting Echinacea early in the flowering season. Understanding within‐season dynamics of pollination helps predict the prevalence of inbreeding, phenological assortative mating, and reproductive failure, especially in fragmented plant populations.

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Section: Implications Selection On Phenological Traits and Populationmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Pollinator‐mediated mechanisms for increased reproductive success in early flowering plants

Ison

Prescott

Nordstrom

et al. 2018

Oikos

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“…Variation in reproductive phenology is widely observed, and many studies have found a genetic component to flowering time (e.g., Best and McIntyre, 1972; Mazer, 1987; Andersson, 1996; O'Neil, 1997; Weis and Kossler, 2004; Franks et al, 2007). In a study of the annual plant species, Plectritis congesta , heritability of flowering time estimated in selfed and outcrossed natural populations ranged from 0.42 to 0.72 (Carey, 1983), while for open‐pollinated experimental plots of the annual species Brassica rapa heritability estimates ranged from 0.51 to 0.67 (Austen and Weis, 2016; Ison and Weis, 2017). Studies of inbred accessions of annual plant species have demonstrated that numerous genes influence the date of flowering onset (maize, Buckler et al, 2009; Arabidopsis thaliana , Wilczek et al, 2010).…”

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confidence: 99%

“…Over extended periods, assortative mating influences the evolution of genetic variance in populations (Godineau et al, 2022 and references therein) and can result in reproductive isolation of subpopulations by time. This isolation can create or exacerbate temporal genetic structure via limited gene transfer among subpopulations differing in reproductive phenology (Hendry and Day, 2005; Daïnou et al, 2012; Ison and Weis, 2017). The severity of isolation by time and temporal genetic structure within a population will depend heavily on the degree to which variation in parental phenotypes is heritable.…”

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confidence: 99%

Genetic variation in reproductive timing in a long‐lived herbaceous perennial

Reed

Ison

Waananen

et al. 2022

American J of Botany

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Premise: Reproductive fitness of individual plants depends on the timing of flowering, especially in mate-limited populations, such as those in fragmented habitats. When flowering time traits are associated with differential reproductive success, the narrow-sense heritability (h 2 ) of traits will determine how rapidly trait means evolve in response to selection. Heritability of flowering time is documented in many annual plants. However, estimating h 2 of flowering time in perennials presents additional methodological challenges, often including paternity assignment and trait expression over multiple years. Methods: We evaluated the h 2 of onset and duration of flowering using offspring-midparent regressions and restricted maximum likelihood methods in an experimental population of an iterocarpic, perennial, herbaceous plant, Echinacea angustifolia, growing in natural conditions. We assessed the flowering time of the parental cohort in 2005 and 2006; the offspring in 2014 through 2017. We also examined the effects of the paternity assignment from Cervus and MasterBayes on estimates of h 2 . Results: We found substantial h 2 for onset and duration of flowering. We also observed variation in estimates among years. The most reliable estimates for both traits fell in the range of 0.1-0.17. We found evidence of a genotype by year interaction for onset of flowering and strong evidence that genotypes are consistent in their duration of flowering across years. Conclusions: Substantial heritabilities in this population imply the capacity for a response to natural selection, while also suggesting the potential for differential contributions to adaptive evolution among seasons.

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“…We call this ‘isolation by phenology’ (IBP). Most populations harbour quantitative genetic variation for flowering phenology (Geber & Griffen, ), and so allele frequencies at phenology loci shift across successive mating pools: ‘early’ alleles predominate as the season starts and ‘late’ alleles as it ends (Ison & Weis, ). One consequence of phenological isolation is that uniting gametes tend to carry alleles of similar effect across the phenology loci (Weis et al .…”

Section: Introductionmentioning

confidence: 99%

Isolation by phenology synergizes isolation by distance across a continuous landscape

Peters

Weis

2019

New Phytologist

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Pollen is generally dispersed over short distances, which promotes population genetic structure across continuous two-dimensional space. Quantitative genetic variance in flowering time structures mating pools in the temporal dimension, at least with respect to the phenology loci. We asked if these two phenomena, isolation by distance (IBD) and isolation by phenology (IBP), synergistically promote genetic structure.We constructed an individual-based model that tracked genotype frequencies at flowering time and neutral loci across a uniform landscape, over multiple generations, under four mating schemes: panmixia, IBD only, IBP only, and IBP 9 IBD.IBD 9 IBP divided the population into spatial clusters of early-, mid-, and late-flowering genotypes and strongly increased its quantitative genetic variance. Flowering time did not cluster under IBP, but its genetic variance increased moderately. IBD induced mild spatial structure in a nonassortative reference trait but did not change its variance. Importantly, the spatial correlation of genotypes at neutral loci was twice as strong under IBD 9 IBP compared with IBD alone. IBD 9 IBP also drew neutral loci into gametic disequilibrium with flowering time loci, structuring them temporally.Temporal and spatial mating pool structure promotes local differentiation. This trend would facilitate adaptation on small spatial scales.

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Temporal population genetic structure in the pollen pool for flowering time: A field experiment with Brassica rapa (Brassicaceae)

Cited by 8 publications

References 58 publications

Pollinator‐mediated mechanisms for increased reproductive success in early flowering plants

Pollinator‐mediated mechanisms for increased reproductive success in early flowering plants

Genetic variation in reproductive timing in a long‐lived herbaceous perennial

Isolation by phenology synergizes isolation by distance across a continuous landscape

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