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Soularue JP, Firmat C, Caignard T, Thöni A, Arnoux L, Delzon S, Ronce O, Kremer A. Antagonistic Effects of Assortative Mating on the Evolution of Phenotypic Plasticity along Environmental Gradients. Am Nat 2023; 202:18-39. [PMID: 37384769 PMCID: PMC7614710 DOI: 10.1086/724579] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2023]
Abstract
AbstractPrevious theory has shown that assortative mating for plastic traits can maintain genetic divergence across environmental gradients despite high gene flow. Yet these models did not examine how assortative mating affects the evolution of plasticity. We here describe patterns of genetic variation across elevation for plasticity in a trait under assortative mating, using multiple-year observations of budburst date in a common garden of sessile oaks. Despite high gene flow, we found significant spatial genetic divergence for the intercept, but not for the slope, of reaction norms to temperature. We then used individual-based simulations, where both the slope and the intercept of the reaction norm evolve, to examine how assortative mating affects the evolution of plasticity, varying the intensity and distance of gene flow. Our model predicts the evolution of either suboptimal plasticity (reaction norms with a slope shallower than optimal) or hyperplasticity (slopes steeper than optimal) in the presence of assortative mating when optimal plasticity would evolve under random mating. Furthermore, a cogradient pattern of genetic divergence for the intercept of the reaction norm (where plastic and genetic effects are in the same direction) always evolves in simulations with assortative mating, consistent with our observations in the studied oak populations.
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Crain J, Larson S, Dorn K, Hagedorn T, DeHaan L, Poland J. Sequenced-based paternity analysis to improve breeding and identify self-incompatibility loci in intermediate wheatgrass (Thinopyrum intermedium). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2020; 133:3217-3233. [PMID: 32785739 PMCID: PMC7547974 DOI: 10.1007/s00122-020-03666-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 08/03/2020] [Indexed: 05/28/2023]
Abstract
KEY MESSAGE Paternity assignment and genome-wide association analyses for fertility were applied to a Thinopyrum intermedium breeding program. A lack of progeny between combinations of parents was associated with loci near self-incompatibility genes. In outcrossing species such as intermediate wheatgrass (IWG, Thinopyrum intermedium), polycrossing is often used to generate novel recombinants through each cycle of selection, but it cannot track pollen-parent pedigrees and it is unknown how self-incompatibility (SI) genes may limit the number of unique crosses obtained. This study investigated the potential of using next-generation sequencing to assign paternity and identify putative SI loci in IWG. Using a reference population of 380 individuals made from controlled crosses of 64 parents, paternity was assigned with 92% agreement using Cervus software. Using this approach, 80% of 4158 progeny (n = 3342) from a polycross of 89 parents were assigned paternity. Of the 89 pollen parents, 82 (92%) were represented with 1633 unique full-sib families representing 42% of all potential crosses. The number of progeny per successful pollen parent ranged from 1 to 123, with number of inflorescences per pollen parent significantly correlated to the number of progeny (r = 0.54, p < 0.001). Shannon's diversity index, assessing the total number and representation of families, was 7.33 compared to a theoretical maximum of 8.98. To test our hypothesis on the impact of SI genes, a genome-wide association study of the number of progeny observed from the 89 parents identified genetic effects related to non-random mating, including marker loci located near putative SI genes. Paternity testing of polycross progeny can impact future breeding gains by being incorporated in breeding programs to optimize polycross methodology, maintain genetic diversity, and reveal genetic architecture of mating patterns.
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Affiliation(s)
- Jared Crain
- Department of Plant Pathology, 4024 Throckmorton Plant Sciences Center, Kansas State University, Manhattan, KS, 66506, USA
| | - Steve Larson
- USDA-ARS, Forage and Range Research, Utah State University, Logan, UT, 84322, USA
| | - Kevin Dorn
- Department of Plant Pathology, 4024 Throckmorton Plant Sciences Center, Kansas State University, Manhattan, KS, 66506, USA
- USDA-ARS, Soil Management and Sugarbeet Research, Fort Collins, CO, 80526, USA
| | - Traci Hagedorn
- AAAS Science and Technology Policy Fellow, USDA-APHIS, 4700 River Road, Riverdale, MD, 20737, USA
- Quantitative Scientific Solutions LLC, Arlington, VA, 22203, USA
| | - Lee DeHaan
- The Land Institute, 2440 E. Water Well Rd, Salina, KS, 67401, USA
| | - Jesse Poland
- Department of Plant Pathology, 4024 Throckmorton Plant Sciences Center, Kansas State University, Manhattan, KS, 66506, USA.
- Wheat Genetics Resource Center, Kansas State University, Manhattan, KS, 66506, USA.
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Ismail SA, Kokko H. An analysis of mating biases in trees. Mol Ecol 2019; 29:184-198. [PMID: 31755136 PMCID: PMC7003921 DOI: 10.1111/mec.15312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/01/2019] [Accepted: 11/20/2019] [Indexed: 11/29/2022]
Abstract
Assortative mating is a deviation from random mating based on phenotypic similarity. As it is much better studied in animals than in plants, we investigate for trees whether kinship of realized mating pairs deviates from what is expected from the set of potential mates and use this information to infer mating biases that may result from kin recognition and/or assortative mating. Our analysis covers 20 species of trees for which microsatellite data is available for adult populations (potential mates) as well as seed arrays. We test whether mean relatedness of observed mating pairs deviates from null expectations that only take pollen dispersal distances into account (estimated from the same data set). This allows the identification of elevated as well as reduced kinship among realized mating pairs, indicative of positive and negative assortative mating, respectively. The test is also able to distinguish elevated biparental inbreeding that occurs solely as a result of related pairs growing closer to each other from further assortativeness. Assortative mating in trees appears potentially common but not ubiquitous: nine data sets show mating bias with elevated inbreeding, nine do not deviate significantly from the null expectation, and two show mating bias with reduced inbreeding. While our data sets lack direct information on phenology, our investigation of the phenological literature for each species identifies flowering phenology as a potential driver of positive assortative mating (leading to elevated inbreeding) in trees. Since active kin recognition provides an alternative hypothesis for these patterns, we encourage further investigations on the processes and traits that influence mating patterns in trees.
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Affiliation(s)
- Sascha A Ismail
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Hanna Kokko
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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Brown KE, Kelly JK. Antagonistic pleiotropy can maintain fitness variation in annual plants. J Evol Biol 2017; 31:46-56. [DOI: 10.1111/jeb.13192] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 10/09/2017] [Indexed: 01/24/2023]
Affiliation(s)
- K. E. Brown
- Department of Ecology and Evolutionary Biology; University of Kansas; Lawrence KS USA
| | - J. K. Kelly
- Department of Ecology and Evolutionary Biology; University of Kansas; Lawrence KS USA
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Ison JL, Weis AE. Temporal population genetic structure in the pollen pool for flowering time: A field experiment with Brassica rapa (Brassicaceae). AMERICAN JOURNAL OF BOTANY 2017; 104:1569-1580. [PMID: 29885229 DOI: 10.3732/ajb.1700210] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/11/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Assortative mating by flowering time can cause temporal genetic structure in species with heritable flowering times. A strong temporal structure, when coupled with a seasonal shift in selection, may lead to adaptive temporal clines. We implemented a prospective and retrospective method to estimate the temporal genetic structure in the pollen pool of Brassica rapa. METHODS The prospective method uses flowering schedules to estimate the seasonal shift in the pollen donors' phenotype. By examining the offspring generation, we can get a direct estimate of temporal genetic structure, i.e., a retrospective estimate. However, this estimate is problematic because of the phenotypic correlation of the trait of interest, flowering time, between dam and sire. We developed a novel retrospective method that isolates flowering time by holding the maternal contribution constant and sampled the pollen pool in eight open-pollinated field plots throughout the flowering season. KEY RESULTS We found temporal genetic structure for flowering time in seven of the eight field plots. Interestingly, the direct (retrospective) temporal structure estimate was 35% larger than the prospective estimate based on flowering schedules. Spatial clumping of pollen donors did not affect temporal structure, but structure intensified when heritability was experimentally enhanced. CONCLUSIONS Temporal genetic structure, especially for flowering time, likely occurs in many plant populations and may be underestimated using a prospective method. We discuss the genome-wide consequences of temporal genetic structure and the potential for adaptive temporal clines in plant populations.
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Affiliation(s)
- Jennifer L Ison
- Department of Biology, The College of Wooster, 1189 Beall Avenue, Wooster, Ohio 44691 USA
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
| | - Arthur E Weis
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
- Koffler Scientific Reserve at Jokers Hill, University of Toronto 17000 Dufferin Street, King City, Ontario, L7B 1K5, Canada
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Emms SK, Stratton DA, Snow AA. THE EFFECT OF INFLORESCENCE SIZE ON MALE FITNESS: EXPERIMENTAL TESTS IN THE ANDROMONOECIOUS LILY, ZIGADENUS PANICULATUS. Evolution 2017; 51:1481-1489. [PMID: 28568611 DOI: 10.1111/j.1558-5646.1997.tb01471.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/1996] [Accepted: 05/16/1997] [Indexed: 11/26/2022]
Abstract
We studied the relationship between inflorescence size and male fitness in the andromonoecious lily Zigadenus paniculatus, using experimentally manipulated inflorescences to eliminate possible correlations between flower number, resource availability, and other floral traits. Allozyme markers were used to determine the siring success of large versus small plants in 14 arrays of plants, each array containing five large and five small plants. The inflorescence size of small plants was held constant both within and among arrays; the size of large plants was held constant within an array but was varied among arrays. Large plants sired more than half the seeds in 12 of the 14 arrays, and significantly more than half in six of these 12. However, in eight of the arrays, large plants sired significantly fewer seeds than expected on the basis of their size advantage. Furthermore, there was no significant relationship between relative size and relative siring success in comparisons among arrays. A maximum-likelihood model estimated that 28% of seeds were sired by imported pollen, with 95% confidence limits of 13% and 50%. Within these limits, high import rates tended to mask the relative success of large plants in several arrays. These results suggest that the evolution of inflorescence size in Z. paniculatus is at least partly driven by selection for increased male success, assuming genetic variation for flower number. However, the data also support a growing body of evidence that estimates of male fitness in plants can be highly variable. We discuss the sources of this variability and the possible effects of inflorescence design on the relationship between inflorescence size and fitness.
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Affiliation(s)
- S K Emms
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, 08544-1003.,Department of Plant Biology, Ohio State University, 1735 Neil Avenue, Columbus, Ohio, 43210-1293
| | - D A Stratton
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, 08544-1003
| | - A A Snow
- Department of Plant Biology, Ohio State University, 1735 Neil Avenue, Columbus, Ohio, 43210-1293
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Kohn JR, Barrett SCH. EXPERIMENTAL STUDIES ON THE FUNCTIONAL SIGNIFICANCE OF HETEROSTYLY. Evolution 2017; 46:43-55. [PMID: 28564966 DOI: 10.1111/j.1558-5646.1992.tb01983.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/1990] [Accepted: 06/27/1991] [Indexed: 11/27/2022]
Abstract
Heterostyly has been viewed as both an antiselfing device and a mechanism that increases the proficiency of pollen transfer between plants. We used experimental manipulation of the morph structure of garden populations of self-compatible, tristylous Eichhornia paniculata to investigate the function of floral polymorphism. Outcrossing rates (t), levels of intermorph mating (d), and morph-specific male and female reproductive success were compared in replicate trimorphic and monomorphic populations. In trimorphic populations, t and d averaged 0.81 (2 SE = 0.03) and 0.77 (2 SE = 0.03) respectively, with no difference in either parameter among morphs. Ninety-five percent of outcrossed seeds were therefore the result of intermorph fertilizations. Male reproductive success of the long-styled morph was low, especially in comparison with plants of the short-styled morph. Outcrossing rates for each morph were higher in trimorphic than monomorphic populations where t averaged 0.71 (2 SE = 0.01), 0.30 (2 SE = 0.04) and 0.43 (2 SE = 0.1) for the long-, mid-, and short-styled morphs, respectively. Seed set was lower in monomorphic populations, particularly those composed of the L morph, reflecting reduced pollen deposition. Floral polymorphism therefore increased both outcrossing rate and fecundity but the magnitude of the differences varied among morphs. If the ancestral condition in heterostylous groups resembled the L morph, as has been suggested, data from this study suggests that the selective basis for the establishment of floral polymorphism could have been increased pollen transfer rather than higher levels of outcrossing.
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Affiliation(s)
- Joshua R Kohn
- Department of Botany, University of Toronto, Toronto, ON, M5S 3B2, CANADA
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8
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Jordan CY, Ally D, Hodgins KA. When can stress facilitate divergence by altering time to flowering? Ecol Evol 2015; 5:5962-73. [PMID: 26811768 PMCID: PMC4717339 DOI: 10.1002/ece3.1821] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/28/2015] [Indexed: 01/25/2023] Open
Abstract
Stressors and heterogeneity are ubiquitous features of natural environments, and theory suggests that when environmental qualities alter flowering schedules through phenotypic plasticity, assortative mating can result that promotes evolutionary divergence. Therefore, it is important to determine whether common ecological stressors induce similar changes in flowering time. We review previous studies to determine whether two important stressors, water restriction and herbivory, induce consistent flowering time responses among species; for example, how often do water restriction and herbivory both delay flowering? We focus on the direction of change in flowering time, which affects the potential for divergence in heterogeneous environments. We also tested whether these stressors influenced time to flowering and nonphenology traits using Mimulus guttatus. The literature review suggests that water restriction has variable effects on flowering time, whereas herbivory delays flowering with exceptional consistency. In the Mimulus experiment, low water and herbivory advanced and delayed flowering, respectively. Overall, our results temper theoretical predictions for evolutionary divergence due to habitat‐induced changes in flowering time; in particular, we discuss how accounting for variation in the direction of change in flowering time can either increase or decrease the potential for divergence. In addition, we caution against adaptive interpretations of stress‐induced phenology shifts.
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Affiliation(s)
- Crispin Y Jordan
- Department of Zoology University of British Columbia Vancouver British Columbia V6T 1Z4 Canada
| | - Dilara Ally
- Department of Zoology University of British Columbia Vancouver British Columbia V6T 1Z4 Canada
| | - Kathryn A Hodgins
- Department of Zoology University of British Columbia Vancouver British Columbia V6T 1Z4 Canada
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Jordan CY, Connallon T. Sexually antagonistic polymorphism in simultaneous hermaphrodites. Evolution 2014; 68:3555-69. [PMID: 25311368 DOI: 10.1111/evo.12536] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/09/2014] [Indexed: 12/22/2022]
Abstract
In hermaphrodites, pleiotropic genetic trade-offs between female and male reproductive functions can lead to sexually antagonistic (SA) selection, where individual alleles have conflicting fitness effects on each sex function. Although an extensive theory of SA selection exists for dioecious species, these results have not been generalized to hermaphrodites. We develop population genetic models of SA selection in simultaneous hermaphrodites, and evaluate effects of dominance, selection on each sex function, self-fertilization, and population size on the maintenance of polymorphism. Under obligate outcrossing, hermaphrodite model predictions converge exactly with those of dioecious populations. Self-fertilization in hermaphrodites generates three points of divergence with dioecious theory. First, opportunities for stable polymorphism decline sharply and become less sensitive to dominance with increased selfing. Second, selfing introduces an asymmetry in the relative importance of selection through male versus female reproductive functions, expands the parameter space favorable for the evolutionary invasion of female-beneficial alleles, and restricts invasion criteria for male-beneficial alleles. Finally, contrary to models of unconditionally beneficial alleles, selfing decreases genetic hitchhiking effects of invading SA alleles, and should therefore decrease these population genetic signals of SA polymorphisms. We discuss implications of SA selection in hermaphrodites, including its potential role in the evolution of "selfing syndromes."
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Affiliation(s)
- Crispin Y Jordan
- Ashworth Laboratories, Institute of Evolutionary Biology, The University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh, EH9 3JT, United Kingdom.
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10
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Assortative mating with respect to size in the simultaneously hermaphroditic land snail Bradybaena pellucida. Acta Ethol 2014. [DOI: 10.1007/s10211-014-0211-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Weis AE, Nardone E, Fox GA. The strength of assortative mating for flowering date and its basis in individual variation in flowering schedule. J Evol Biol 2014; 27:2138-51. [DOI: 10.1111/jeb.12465] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 07/21/2014] [Accepted: 07/22/2014] [Indexed: 11/27/2022]
Affiliation(s)
- A. E. Weis
- Koffler Scientific Reserve at Jokers Hill; University of Toronto; King City ON Canada
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto ON Canada
| | - E. Nardone
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto ON Canada
| | - G. A. Fox
- Department of Integrative Biology; University of South Florida; Tampa FL USA
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12
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Daïnou K, Laurenty E, Mahy G, Hardy OJ, Brostaux Y, Tagg N, Doucet JL. Phenological patterns in a natural population of a tropical timber tree species, Milicia excelsa (Moraceae): Evidence of isolation by time and its interaction with feeding strategies of dispersers. AMERICAN JOURNAL OF BOTANY 2012; 99:1453-1463. [PMID: 22912370 DOI: 10.3732/ajb.1200147] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
PREMISE OF THE STUDY Population genetic structuring over limited timescales is commonly viewed as a consequence of spatial constraints. Indirect approaches have recently revealed reproductive isolation resulting from flowering time (so-called isolation by time, IBT). Since phenological processes can be subject to selection, the persistence of flowering asynchrony may be due to opposing selective pressures during mating, dispersal, and regeneration phases. Our study aimed to investigate phenology, fruit handling by animals, and their interaction in a timber tree species, Milicia excelsa. METHODS We analyzed phenological data collected over 6 years on 69 genotyped trees in a Cameroonian natural rainforest complemented by data from germination trials and field observations of dispersers. KEY RESULTS Initiation of flowering was correlated with variation in temperature and relative humidity, but was also affected by genetic factors: pairwise differences in flowering time between nearby individuals correlated with kinship coefficient, and earliness of flowering remained stable over time. A decrease in mean seed production per fruit with increasing flowering time suggests selection against late bloomers. However, germination rate was not affected by seed collection date, and the main seed disperser, the bat Eidolon helvum, seemed to increase in abundance at the end of the reproductive season and preferred trees in open habitats where early and late bloomers are expected. CONCLUSIONS The pairwise approach performs well in detecting IBT. The persistence of different mating pools in such a case may result from a trade off between selective forces during the mating and seed dispersal processes.
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Affiliation(s)
- Kasso Daïnou
- Laboratory of Tropical and Subtropical Forestry, Unit of Forest and Nature Management, GxABT, University of Liege, 2 Passage des déportés, 5030 Gembloux, Belgium.
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13
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Hendry AP, Day T. Population structure attributable to reproductive time: isolation by time and adaptation by time. Mol Ecol 2006; 14:901-16. [PMID: 15773924 DOI: 10.1111/j.1365-294x.2005.02480.x] [Citation(s) in RCA: 206] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many populations are composed of a mixture of individuals that reproduce at different times, and these times are often heritable. Under these conditions, gene flow should be limited between early and late reproducers, even within populations having a unimodal temporal distribution of reproductive activity. This temporal restriction on gene flow might be called "isolation by time" (IBT) to acknowledge its analogy with isolation by distance (IBD). IBD and IBT are not exactly equivalent, however, owing to differences between dispersal in space and dispersal in time. We review empirical studies of natural populations that provide evidence for IBT based on heritabilities of reproductive time and on molecular genetic differences associated with reproductive time. When IBT is present, variation in selection through the reproductive season may lead to adaptive temporal variation in phenotypic traits [adaptation by time (ABT)]. We introduce a novel theoretical model that shows how ABT increases as (i) selection on the trait increases; (ii) environmental influences on reproductive time decrease; (iii) the heritability of reproductive time increases; and (iv) the temporal distribution of reproductive activity becomes increasingly uniform. We then review empirical studies of natural populations that provide evidence for ABT by documenting adaptive temporal clines in phenotypic traits. The best evidence for IBT and ABT currently comes from salmonid fishes and flowering plants, but we expect that future work will show these processes are more widespread.
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Affiliation(s)
- Andrew P Hendry
- Redpath Museum and Department of Biology, McGill University, 859 Sherbrooke St. W., Montréal, Québec H3A 2K6 Canada.
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14
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Abstract
This paper develops methods to partition the phenotypic correlation between mates for a focal trait--the standard measure for assortative mating--into a direct component and additional indirect components. Indirect assortative mating occurs when a nonassorting trait is correlated within individuals to a directly assorting trait. Direct and indirect assortative mating is assessed for flowering phenology in Brassica rapa. The flowering time of pollen recipients (mothers) was strongly correlated (rho=0.67) to that of potential pollen donors (fathers). Similarly, recipients and donors were correlated for duration of their flowering periods (rho=0.32) and stem diameters (rho=0.52). A partitioning of between-mate correlations revealed direct assortative mating for flowering time and period duration. However, assortment for stem diameter is explained solely through its correlation to flowering time. Examination of standard quantitative genetic theory shows that indirect assortative mating inflates genetic variance in a focal trait and the genetic covariance between focal and phenotypically correlated traits.
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Affiliation(s)
- Arthur E Weis
- Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA 92612, USA.
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15
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Weis AE, Kossler TM. Genetic variation in flowering time induces phenological assortative mating: quantitative genetic methods applied to Brassica rapa. AMERICAN JOURNAL OF BOTANY 2004; 91:825-36. [PMID: 21653438 DOI: 10.3732/ajb.91.6.825] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
It has been argued from first principles that plants mate assortatively by flowering time. However, there have been very few studies of phenological assortative mating, perhaps because current methods to infer paternal phenotype are difficult to apply to natural populations. Two methods are presented to estimate the phenotypic correlation between mates-the quantitative genetic metric for assortative mating-for phenological traits. The first method uses individual flowering schedules to estimate mating probabilities for every potential pairing in a sample. These probabilities are then incorporated into a weighted phenotypic correlation between all potential mates and thus yield a prospective estimate based on mating opportunities. The correlation between mates can also be estimated retrospectively by comparing the regression of offspring phenotype over one parent, which is inflated by assortative mating, to the regression over mid-parent, which is not. In a demonstration experiment with Brassica rapa, the prospective correlation between flowering times (days from germination to anthesis) of pollen recipients and their potential donors was 0.58. The retrospective estimate of this correlation strongly agreed with the prospective estimate. The prospective method is easily employed in field studies that explore the effect of phenological assortative mating on selection response and population differentiation.
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Affiliation(s)
- Arthur E Weis
- Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, California 92687 USA
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16
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Ellstrand NC. Current knowledge of gene flow in plants: implications for transgene flow. Philos Trans R Soc Lond B Biol Sci 2003; 358:1163-70. [PMID: 12831483 PMCID: PMC1693201 DOI: 10.1098/rstb.2003.1299] [Citation(s) in RCA: 216] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Plant evolutionary biologists' view of gene flow and hybridization has undergone a revolution. Twenty-five years ago, both were considered rare and largely inconsequential. Now gene flow and hybridization are known to be idiosyncratic, varying with the specific populations involved. Gene flow typically occurs at evolutionarily significant rates and at significant distances. Spontaneous hybridization occasionally has important applied consequences, such as stimulating the evolution of more aggressive invasives and increasing the extinction risk for rare species. The same problems have occurred for spontaneous hybridization between crops and their wild relatives. These new data have implications for transgenic crops: (i) for most crops, gene flow can act to introduce engineered genes into wild populations; (ii) depending on the specific engineered gene(s) and populations involved, gene flow may have the same negative impacts as those observed for traditionally improved crops; (iii) gene flow's idiosyncratic nature may frustrate management and monitoring attempts; and (iv) intercrop transgene flow, although rarely discussed, is equally worthy of study.
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Affiliation(s)
- Norman C Ellstrand
- Department of Botany and Plant Sciences, and Center for Conservation Biology, University of California, Riverside, CA 92521-0124, USA.
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17
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Schuster WS, Mitton JB. Paternity and gene dispersal in limber pine (Pinus flexilis James). Heredity (Edinb) 2000; 84 ( Pt 3):348-61. [PMID: 10762405 DOI: 10.1046/j.1365-2540.2000.00684.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study provides empirical information on intrapopulation gene dispersal via pollen, the size of genetic 'neighbourhoods', and interpopulation gene flow in a long-lived conifer, limber pine (Pinus flexilis). We used allozyme loci for a paternity analysis of 518 seeds produced in an isolated population of limber pine located in north-eastern Colorado, U.S.A., separated by 2 km from the nearest conspecific trees and nearly 100 km from populations in the Rocky Mountains. We also used indirect techniques (FST analyses) to estimate gene flow rates among subdivisions of the study population and among five widely separated populations. Within the main study population limber pine exhibited a polymorphism level of 50%, observed heterozygosity of 0.159, and 2.36 alleles per polymorphic locus. Mountain populations were slightly more variable. The main study population showed significant differentiation in allozymes among neighbouring subpopulations. The mean FST was 0.031 and the gene flow rate among subpopulations was estimated as 7.8 migrants per generation. Among widely separated populations the mean FST was 0.035 and the gene flow rate was estimated as 6.9 migrants per generation. The paternity analysis indicated a best estimate of 6.5% pollen immigration (minimum 1.1%) from populations 2 km to 100+ km away. For 4% of the seeds examined, paternity could be ascribed to a single tree in the study population. Fractional paternity and likelihood methods were used to estimate pollen dispersal distances for the remainder of the seeds. Mean pollen dispersal distance was estimated at 140 m using the fractional method, similar to results from the other techniques. This compares with a mean distance of 172 m between potential mates. These results suggest near-panmictic pollen dispersal over this population, which covers about 15 ha. The observed allozyme differences and surprisingly low estimates of among-subpopulation gene flow are ascribed to a probable restriction of gene dispersal by seeds.
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Affiliation(s)
- W S Schuster
- Department of Environmental, Population and Organismic Biology, University of Colorado, Boulder, CO 80309, USA.
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Gronemeyer P, Dilger B, Bouzat J, Paige K. The Effects of Herbivory on Paternal Fitness in Scarlet Gilia: Better Moms Also Make Better Pops. Am Nat 1997; 150:592-602. [DOI: 10.1086/286083] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Devlin B, Roeder K, Ellstrand NC. Fractional paternity assignment: theoretical development and comparison to other methods. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 1988; 76:369-380. [PMID: 24232200 DOI: 10.1007/bf00265336] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/1987] [Accepted: 03/10/1988] [Indexed: 06/02/2023]
Abstract
There has recently been a burgeoning interest in the analysis of paternity patterns for natural populations because of its relevance to population genetic phenomena such as the distance between successful mates, relative male reproductive success and gene flow. In this paper we develop a method of analyzing populational patterns of paternity, the fractional paternity method, and compare its performance to two other commonly used methods of paternity analysis (simple exclusion and the most-likely methods). We show that the fractional method is the most accurate method for determining populational patterns of paternity because it assigns paternity to all progeny examined, and because it avoids biases inherent in the other paternity analysis methods when model assumptions are met. In particular, it avoids a systematic bias of the most-likely paternity assignment method, which has a tendency to over-assign paternity of progeny to certain male parents with a greater than average number of homozygous marker loci. We also demonstrate the effect of linkage of some of the marker loci on paternity assignment, showing how the knowledge of the linkage phase of male and female parents in the population can significantly improve the accuracy of the estimates of populational patterns of paternity. Knowledge of the linkage phase of individuals in a population is usually unknown and difficult to assess without progeny testing, which involves considerable labor. However, we show how the linkage phase of hermaphroditic individuals in a population can be obtained in conjunction with the paternity analysis if progeny can be obtained from each hermaphroditic individual in the population, thereby avoiding the problem of traditional progeny testing. Applications of the fractional paternity approach developed herein should contribute significantly to our understanding of the mating patterns in, and hence the evolution of, natural populations.
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Affiliation(s)
- B Devlin
- Department of Botany and Plant Sciences and Program in Genetics, University of California, 92521-0124, Riverside, CA, USA
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