1
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Cheptou PO. The evolutionary ecology of inbreeding depression in wild plant populations and its impact on plant mating systems. FRONTIERS IN PLANT SCIENCE 2024; 15:1359037. [PMID: 39315378 PMCID: PMC11416937 DOI: 10.3389/fpls.2024.1359037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 08/21/2024] [Indexed: 09/25/2024]
Abstract
Inbreeding depression, the reduced fitness of inbred relative to outbred individuals was described more than two centuries ago, long before the development of population genetics. Its impact is central to evolutionary ecology and the evolution of mating systems, in particular self-fertilization in hermaphrodites. In the first half of the 20th century, population genetics revealed a mechanism for inbreeding depression through homozygosity. Numerous theoretical studies have modeled inbreeding depression as a function of genetic architecture and analyzed how it varies with population selfing rates. A major concept in these models is purging, i.e., the purging of recessive deleterious mutations through inbreeding. Consequently, inbreeding depression is expected to decrease with increasing population selfing rates. Along with these theoretical studies, many experimental studies, particularly on plants, have measured inbreeding depression using experimental crosses or directly in the field. The results of these studies have revealed that the evolutionary ecology of inbreeding depression is difficult to capture and that empirical data do not exactly match model predictions, specifically purging efficacy. In addition, the lability of inbreeding depression in natural populations can qualitatively affect the selective role of inbreeding depression in the evolution of mating systems. Recently, several studies have demonstrated the role of epigenetics in shedding new light on the dynamics of inbreeding depression in natural populations. This review provides a general overview of the studies on inbreeding depression and how various angles can help capture its selective role in natural populations.
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2
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Toll K, Willis JH. Hybrid inviability and differential submergence tolerance drive habitat segregation between two congeneric monkeyflowers. Ecology 2018; 99:2776-2786. [DOI: 10.1002/ecy.2529] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 09/10/2018] [Accepted: 09/18/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Katherine Toll
- Department of Biology Duke University Durham North Carolina 27708 USA
- Department of Plant Biology Michigan State University East Lansing Michigan 48824 USA
| | - John H. Willis
- Department of Biology Duke University Durham North Carolina 27708 USA
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3
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Pray LA, Goodnight CJ. GENETIC VARIATION IN INBREEDING DEPRESSION IN THE RED FLOUR BEETLE TRIBOLIUM CASTANEUM. Evolution 2017; 49:176-188. [PMID: 28593675 DOI: 10.1111/j.1558-5646.1995.tb05969.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/1993] [Accepted: 04/22/1994] [Indexed: 11/27/2022]
Abstract
Inbreeding depression varies among species and among populations within a species. Few studies, however, have considered the extent to which inbreeding depression varies within a single population. We report on two experiments to provide evidence that inbreeding depression is genetically variable, such that within a single population some lineages suffer severe inbreeding depression, others suffer only mild inbreeding depression, and some lineages actually increase in phenotypic value at higher levels of inbreeding. We examine the effects of population structure on inbreeding depression for two traits in the first experiment (adult dry weight and female relative fitness), and for seven traits in the second experiment (female and male adult dry weight, female and male relative fitness, female and male developmental time, and egg-to-adult viability). In the first experiment, we collected data from 4 families within each of 38 lineages derived from a single ancestral stock population and maintained for four generations of full-sib mating. Both traits demonstrate significant inbreeding depression and provide evidence that even within a single lineage there is significant genetic variability in inbreeding depression. In the second experiment, we collected data from 5 replicates for each of 15 lineages derived from the same ancestral population used in the first experiment; these lineages were maintained for four generations of full-sib mating. We also collected data on outbred control beetles in each generation and incorporated these data into the analyses to account for environmental effects in an unbiased manner. All traits except female and male developmental time show significant inbreeding depression. All traits showing inbreeding depression are genetically variable in inbreeding depression, as is evident from a significant linear lineage-×-f component. For both experiments, the effect of population structure on inbreeding depression is further evident from the increasing amount of variation that can be explained by the models used to measure inbreeding depression when additional levels of population structure are included. Genetic variation in inbreeding depression has important implications for conservation biology and may be an important factor in mating-system evolution.
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Affiliation(s)
- Leslie A Pray
- Department of Biology, University of Vermont, Marsh Life Science Building, Burlington, Vermont, 05405-0086
| | - Charles J Goodnight
- Department of Biology, University of Vermont, Marsh Life Science Building, Burlington, Vermont, 05405-0086
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Stanton ML, Galen C, Shore J. POPULATION STRUCTURE ALONG A STEEP ENVIRONMENTAL GRADIENT: CONSEQUENCES OF FLOWERING TIME AND HABITAT VARIATION IN THE SNOW BUTTERCUP,
RANUNCULUS ADONEUS. Evolution 2017; 51:79-94. [DOI: 10.1111/j.1558-5646.1997.tb02390.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/1995] [Accepted: 08/26/1996] [Indexed: 11/27/2022]
Affiliation(s)
- M. L. Stanton
- Section of Evolution and Ecology and Center for Population Biology University of California Davis California 95616
| | - C. Galen
- Division of Biological Sciences, 105 Tucker Hall University of Missouri Columbia Missouri 65211
| | - J. Shore
- Department of Biology York University 4700 Keele Street North York Ontario M3J 1P3 Canada
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5
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Husband BC, Schemske DW. EVOLUTION OF THE MAGNITUDE AND TIMING OF INBREEDING DEPRESSION IN PLANTS. Evolution 2017; 50:54-70. [PMID: 28568860 DOI: 10.1111/j.1558-5646.1996.tb04472.x] [Citation(s) in RCA: 455] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/1993] [Accepted: 09/12/1994] [Indexed: 11/28/2022]
Affiliation(s)
- Brian C. Husband
- Department of Botany; University of Washington; Seattle Washington 98195
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6
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Latta R, Ritland K. THE RELATIONSHIP BETWEEN INBREEDING DEPRESSION AND PRIOR INBREEDING AMONG POPULATIONS OF FOUR MIMULUS
TAXA. Evolution 2017; 48:806-817. [DOI: 10.1111/j.1558-5646.1994.tb01363.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/1992] [Accepted: 07/12/1993] [Indexed: 11/28/2022]
Affiliation(s)
- Robert Latta
- Department of Botany; University of Toronto; Toronto Ontario M5S 3B2 Canada
| | - Kermit Ritland
- Department of Botany; University of Toronto; Toronto Ontario M5S 3B2 Canada
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7
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Mayer SS, Charlesworth D, Meyers B. INBREEDING DEPRESSION IN FOUR POPULATIONS OF COLLINSIA HETEROPHYLLA
NUTT (SCROPHULARIACEAE). Evolution 2017; 50:879-891. [DOI: 10.1111/j.1558-5646.1996.tb03896.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/1994] [Accepted: 04/05/1995] [Indexed: 12/01/2022]
Affiliation(s)
- Stephanie S. Mayer
- Department of Ecology and Evolution; The University of Chicago; 1101 East 57th Street Chicago Illinois 60637-1573
| | - Deborah Charlesworth
- Department of Ecology and Evolution; The University of Chicago; 1101 East 57th Street Chicago Illinois 60637-1573
| | - Blake Meyers
- Department of Vegetable Crops; University of California; Davis California 95616
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8
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Schultz ST, Ganders FR. EVOLUTION OF UNISEXUALITY IN THE HAWAIIAN FLORA: A TEST OF MICROEVOLUTIONARY THEORY. Evolution 2017; 50:842-855. [DOI: 10.1111/j.1558-5646.1996.tb03893.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/1994] [Accepted: 01/10/1995] [Indexed: 11/27/2022]
Affiliation(s)
| | - Fred R. Ganders
- Department of Botany; University of British Columbia; Vancouver British Columbia V6T 1Z4 Canada
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9
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Carr DE, Fenster CB, Dudash MR. THE RELATIONSHIP BETWEEN MATING‐SYSTEM CHARACTERS AND INBREEDING DEPRESSION IN
MIMULUS GUTTATUS. Evolution 2017; 51:363-372. [DOI: 10.1111/j.1558-5646.1997.tb02423.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/1996] [Accepted: 12/06/1996] [Indexed: 11/30/2022]
Affiliation(s)
- David E. Carr
- Department of Plant Biology University of Maryland College Park Maryland 20742‐5815
| | - Charles B. Fenster
- Department of Plant Biology University of Maryland College Park Maryland 20742‐5815
| | - Michele R. Dudash
- Department of Plant Biology University of Maryland College Park Maryland 20742‐5815
- Maryland Agriculture Experiment Station University of Maryland College Park Maryland 20742‐5815
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Newman D, Pilson D. INCREASED PROBABILITY OF EXTINCTION DUE TO DECREASED GENETIC EFFECTIVE POPULATION SIZE: EXPERIMENTAL POPULATIONS OF CLARKIA PULCHELLA. Evolution 2017; 51:354-362. [PMID: 28565367 DOI: 10.1111/j.1558-5646.1997.tb02422.x] [Citation(s) in RCA: 228] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/1995] [Accepted: 10/07/1996] [Indexed: 11/29/2022]
Abstract
We established replicated experimental populations of the annual plant Clarkia pulchella to evaluate the existence of a causal relationship between loss of genetic variation and population survival probability. Two treatments differing in the relatedness of the founders, and thus in the genetic effective population size (Ne ), were maintained as isolated populations in a natural environment. After three generations, the low Ne treatment had significantly lower germination and survival rates than did the high Ne treatment. These lower germination and survival rates led to decreased mean fitness in the low Ne populations: estimated mean fitness in the low Ne populations was only 21% of the estimated mean fitness in the high Ne populations. This inbreeding depression led to a reduction in population survival: at the conclusion of the experiment, 75% of the high Ne populations were still extant, whereas only 31% of the low Ne populations had survived. Decreased genetic effective population size, which leads to both inbreeding and the loss of alleles by genetic drift, increased the probability of population extinction over that expected from demographic and environmental stochasticity alone. This demonstrates that the genetic effective population size can strongly affect the probability of population persistence.
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Affiliation(s)
- Dara Newman
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812
| | - Diana Pilson
- School of Biological Sciences, 348 Manter Hall, University of Nebraska, Lincoln, Nebraska, 68588-0118
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Willis JH. THE ROLE OF GENES OF LARGE EFFECT ON INBREEDING DEPRESSION IN MIMULUS GUTTATUS. Evolution 2017; 53:1678-1691. [PMID: 28565461 DOI: 10.1111/j.1558-5646.1999.tb04553.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/1998] [Accepted: 06/10/1999] [Indexed: 11/28/2022]
Abstract
Severe inbreeding depression is routinely observed in outcrossing species. If inbreeding load is due largely to deleterious alleles of large effect, such as recessive lethals or steriles, then most of it is expected to be purged during brief periods of inbreeding. In contrast, if inbreeding depression is due to the cumulative effects of many deleterious alleles of small effect, then it will be maintained in the face of periodic inbreeding. Whether or not inbreeding depression can be purged with inbreeding in the short term has important implications for the evolution of mating systems and the probability that a small population will go extinct. In this paper I evaluate the extent to which the tremendous inbreeding load in a primarily outcrossing population of the wildflower, Mimulus guttatus, is due to alleles of large effect. To do this, I first constructed a large outbred "ancestral" population by randomly mating plants collected as seeds from a natural population. From this population I formed 1200 lines that were maintained by self-fertilization and single seedling descent: after five generations of selling, 335 lines had survived the inbreeding process. Selection during the line formation is expected to have largely purged alleles of large effect from the collection of highly inbred lines. Because alleles with minor effects on fitness should have been effectively neutral, the inbreeding depression due to this class of genes should have been unchanged. The inbred lines were intercrossed to form a large, outcrossed "purged" population. Finally, I estimated the fitness of outbred and selfed progeny from the ancestral and purged populations to determine the contribution of major deleterious alleles on inbreeding depression. I found that although the average fitness of the outcrossed progeny nearly doubled following purging, the limited decline in inbreeding depression and limited increase in inbred fitness indicates that alleles of large effect are not the principle cause of inbreeding depression in this population. In aggregate, the data suggest that lethals and steriles make a minority contribution to inbreeding depression and that the increased outbred fitness is due primarily to adaptation to greenhouse conditions.
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Affiliation(s)
- John H Willis
- Department of Biology, University of Oregon, Eugene, Oregon, 97403
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12
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Sakai AK, Weller SG, Chen M, Chou S, Tasanont C. EVOLUTION OF GYNODIOECY AND MAINTENANCE OF FEMALES: THE ROLE OF INBREEDING DEPRESSION, OUTCROSSING RATES, AND RESOURCE ALLOCATION IN
SCHIEDEA ADAMANTIS
(CARYOPHYLLACEAE). Evolution 2017; 51:724-736. [DOI: 10.1111/j.1558-5646.1997.tb03656.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/1995] [Accepted: 11/20/1996] [Indexed: 11/29/2022]
Affiliation(s)
- Ann K. Sakai
- Department of Ecology and Evolutionary Biology University of California Irvine California 92697
| | - Stephen G. Weller
- Department of Ecology and Evolutionary Biology University of California Irvine California 92697
| | - Mei‐Ling Chen
- Department of Ecology and Evolutionary Biology University of California Irvine California 92697
| | - Shian‐Yean Chou
- Department of Ecology and Evolutionary Biology University of California Irvine California 92697
| | - Chirichan Tasanont
- Department of Ecology and Evolutionary Biology University of California Irvine California 92697
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13
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Weeks SC, Marcus V, Crosser BR. INBREEDING DEPRESSION IN A SELF‐COMPATIBLE, ANDRODIOECIOUS CRUSTACEAN,
EULIMNADIA TEXANA. Evolution 2017; 53:472-483. [DOI: 10.1111/j.1558-5646.1999.tb03782.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/1998] [Accepted: 10/20/1998] [Indexed: 11/30/2022]
Affiliation(s)
| | - Vivien Marcus
- Department of Biology University of Akron Akron Ohio 44325‐3908
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14
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Carr DE, Dudash MR. THE EFFECTS OF FIVE GENERATIONS OF ENFORCED SELFING ON POTENTIAL MALE AND FEMALE FUNCTION IN
MIMULUS GUTTATUS. Evolution 2017; 51:1797-1807. [DOI: 10.1111/j.1558-5646.1997.tb05103.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/1996] [Accepted: 08/11/1997] [Indexed: 11/28/2022]
Affiliation(s)
- David E. Carr
- Departments of Plant Biology and Zoology University of Maryland College Park Maryland 20742
| | - Michele R. Dudash
- Departments of Plant Biology and Zoology University of Maryland College Park Maryland 20742
- Maryland Agricultural Experiment Station University of Maryland College Park Maryland 20742
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15
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Dudash MR, Carr DE, Fenster CB. FIVE GENERATIONS OF ENFORCED SELFING AND OUTCROSSING IN
MIMULUS GUTTATUS
: INBREEDING DEPRESSION VARIATION AT THE POPULATION AND FAMILY LEVEL. Evolution 2017; 51:54-65. [DOI: 10.1111/j.1558-5646.1997.tb02388.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/1995] [Accepted: 08/02/1996] [Indexed: 11/29/2022]
Affiliation(s)
- Michele R. Dudash
- Department of Plant Biology University of Maryland College Park Maryland 20742‐5815
- Maryland Agricultural Experiment Station University of Maryland College Park Maryland 20742‐5815
| | - David E. Carr
- Department of Plant Biology University of Maryland College Park Maryland 20742‐5815
| | - Charles B. Fenster
- Department of Plant Biology University of Maryland College Park Maryland 20742‐5815
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Hill R, Loxterman JL, Aho K. Insular biogeography and population genetics of dwarf mistletoe ( Arceuthobium americanum) in the Central Rocky Mountains. Ecosphere 2017. [DOI: 10.1002/ecs2.1810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Roy Hill
- Department of Biological Sciences; Idaho State University; 921 South 8th Avenue Pocatello Idaho 83209 USA
| | - Janet L. Loxterman
- Department of Biological Sciences; Idaho State University; 921 South 8th Avenue Pocatello Idaho 83209 USA
| | - Ken Aho
- Department of Biological Sciences; Idaho State University; 921 South 8th Avenue Pocatello Idaho 83209 USA
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Signorile AL, Lurz PW, Wang J, Reuman DC, Carbone C. Mixture or mosaic? Genetic patterns in UK grey squirrels support a human‐mediated ‘long‐jump’ invasion mechanism. DIVERS DISTRIB 2016. [DOI: 10.1111/ddi.12424] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- A. L. Signorile
- Zoological Society London Institute of Zoology Regent's Park London NW1 4RY UK
- Imperial College London Department of Life Science Silwood Park Campus Buckhurst Road Ascot Berkshire SL5 7PY UK
| | - P. W.W. Lurz
- Royal (Dick) School of Veterinary Studies University of Edinburgh Easter Bush Midlothian EH25 9RG UK
| | - J. Wang
- Zoological Society London Institute of Zoology Regent's Park London NW1 4RY UK
| | - D. C. Reuman
- Department of Ecology and Evolutionary Biology and Kansas Biological Survey University of Kansas Lawrence KS USA
- Laboratory of Populations Rockefeller University 1230 York Ave New York NY 10065 USA
| | - C. Carbone
- Zoological Society London Institute of Zoology Regent's Park London NW1 4RY UK
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Koelling VA, Monnahan PJ, Kelly JK. A Bayesian method for the joint estimation of outcrossing rate and inbreeding depression. Heredity (Edinb) 2012; 109:393-400. [PMID: 22990309 DOI: 10.1038/hdy.2012.58] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The population outcrossing rate (t) and adult inbreeding coefficient (F) are key parameters in mating system evolution. The magnitude of inbreeding depression as expressed in the field can be estimated given t and F via the method of Ritland (1990). For a given total sample size, the optimal design for the joint estimation of t and F requires sampling large numbers of families (100-400) with fewer offspring (1-4) per family. Unfortunately, the standard inference procedure (MLTR) yields significantly biased estimates for t and F when family sizes are small and maternal genotypes are unknown (a common occurrence when sampling natural populations). Here, we present a Bayesian method implemented in the program BORICE (Bayesian Outcrossing Rate and Inbreeding Coefficient Estimation) that effectively estimates t and F when family sizes are small and maternal genotype information is lacking. BORICE should enable wider use of the Ritland approach for field-based estimates of inbreeding depression. As proof of concept, we estimate t and F in a natural population of Mimulus guttatus. In addition, we describe how individual maternal inbreeding histories inferred by BORICE may prove useful in studies of inbreeding and its consequences.
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Affiliation(s)
- V A Koelling
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA
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Weber JJ, Weller SG, Sakai AK, Nguyen A, Tai ND, Domínguez CA, Molina-Freaner FE. Purging of inbreeding depression within a population of Oxalis alpina (Oxalidaceae). AMERICAN JOURNAL OF BOTANY 2012; 99:923-932. [PMID: 22539518 DOI: 10.3732/ajb.1100383] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PREMISE OF THE STUDY Variation among individuals in levels of inbreeding depression associated with selfing levels could influence mating system evolution by purging deleterious alleles, but empirical evidence for this association is limited. METHODS We investigated the association of family-level inbreeding depression and presumed inbreeding history in a tristylous population of Oxalis alpina (Oxalidaceae). KEY RESULTS Mid-styled individuals possessed the greatest degree of self-compatibility (SC) and produced more autogamous capsules than short- or long-styled individuals. Offspring of highly self-compatible mid-styled individuals showed reduced inbreeding depression. Mid-styled plants that produced capsules autogamously exhibited reduced stigma-anther separation compared to mid-styled plants that produced no capsules autogamously. Reduced inbreeding depression was not correlated with stigma-anther separation, suggesting that self-compatibility and autogamy evolve before morphological changes in stigma-anther separation. CONCLUSIONS Purging of inbreeding depression occurred in SC mid-styled maternal families. Low inbreeding depression in SC mid-styled plants may lead to retention of the mid-styled morph in populations, despite the occurrence of higher selfing rates in mid-styled relative to short- or long-styled morphs. Variation among individuals in levels of self-fertilization within populations may lead to associations between inbreeding lineages and lower levels of inbreeding depression, influencing the evolution of mating systems.
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Affiliation(s)
- Jennifer J Weber
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA
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Inbreeding depression in Solanum carolinense (Solanaceae) under field conditions and implications for mating system evolution. PLoS One 2011; 6:e28459. [PMID: 22174810 PMCID: PMC3236180 DOI: 10.1371/journal.pone.0028459] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/08/2011] [Indexed: 11/23/2022] Open
Abstract
The clonal weed Solanum carolinense exhibits plasticity in the strength of its self-incompatibility (SI) system and suffers low levels of inbreeding depression (δ) in the greenhouse. We planted one inbred and one outbred plant from each of eight maternal plants in a ring (replicated twice) and monitored clonal growth, herbivory, and reproduction over two years. Per ramet δ was estimated to be 0.63 in year one and 0.79 in year two, and outbred plants produced 2.5 times more ramets than inbred plants in the spring of year two. Inbred plants also suffered more herbivore damage than outbred plants in both fields, suggesting that inbreeding compromises herbivore resistance. Total per genet δ was 0.85 over the two years, indicating that S. carolinense is unlikely to become completely self-compatible, and suggesting that plasticity in the SI system is part of a stable mixed-mating system permitting self-fertilization when cross pollen limits seed production.
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Hereford J. Does selfing or outcrossing promote local adaptation? AMERICAN JOURNAL OF BOTANY 2010; 97:298-302. [PMID: 21622390 DOI: 10.3732/ajb.0900224] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The degree to which plants self-fertilize may impact their potential for genetic adaptation. Given that the mating system influences genetic processes within and among populations, the mating system could limit or promote local adaptation. I conducted a literature survey of published reciprocal transplant experiments in plant populations to quantify the effect of mating system on the magnitude of local adaptation. Mating system had no effect on local adaptation. I detected no effect when species were categorized as either self-compatible or self-incompatible or when accounting for environmental differences between source populations. The results suggest that, despite limited genetic variation in selfing species and greater potential for gene flow in outcrossing species, mating system has little influence on adaptation of populations.
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Affiliation(s)
- Joe Hereford
- National Evolutionary Synthesis Center, Durham, North Carolina 27705 USA; and University of Maryland, Department of Biology, College Park, Maryland 20742 USA
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22
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PORCHER E, KELLY JK, CHEPTOU PO, ECKERT CG, JOHNSTON MO, KALISZ S. The genetic consequences of fluctuating inbreeding depression and the evolution of plant selfing rates. J Evol Biol 2009; 22:708-17. [DOI: 10.1111/j.1420-9101.2009.01705.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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24
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Cheptou PO, J. Schoen D. Combining population genetics and demographical approaches in evolutionary studies of plant mating systems. OIKOS 2007. [DOI: 10.1111/j.0030-1299.2007.14655.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ishida K. Maintenance of Inbreeding Depression in a Highly Self-Fertilizing Tree, Magnolia obovata Thunb. Evol Ecol 2006. [DOI: 10.1007/s10682-005-5748-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Holeski LM, Kelly JK. MATING SYSTEM AND THE EVOLUTION OF QUANTITATIVE TRAITS: AN EXPERIMENTAL STUDY OF MIMULUS GUTTATUS. Evolution 2006. [DOI: 10.1554/05-637.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Epistasis contributes significantly to intrapopulation variation in floral morphology, development time, and male fitness components of Mimulus guttatus. This is demonstrated with a replicated line-cross experiment involving slightly over 7000 plants. The line-cross methodology is based on estimates for means. It thus has greater power than the variance partitioning approaches historically used to estimate epistasis within populations. The replication of the breeding design across many pairs of randomly extracted, inbred lines is necessary given the diversity of multilocus genotypes residing within an outbred deme. Male fitness is shown to exhibit synergistic epistasis, an accelerating decline in fitness with inbreeding. Synergism is a necessary, but not sufficient, condition for a mutational deterministic hypothesis for the evolutionary maintenance of sexual reproduction. Unlike male fitness measures, flower morphology and development time yield positive evidence of epistasis but not of synergism. The results for these traits suggest that epistatic effects are variable across genetic backgrounds or sets of interacting loci.
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Affiliation(s)
- John K Kelly
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA.
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Charbonnel N, Rasatavonjizay R, Sellin E, Brémond P, Jarne P. The influence of genetic factors and population dynamics on the mating system of the hermaphroditic freshwater snailBiomphalaria pfeifferi. OIKOS 2005. [DOI: 10.1111/j.0030-1299.2005.13537.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Hayes CN, Winsor JA, Stephenson AG. Environmental variation influences the magnitude of inbreeding depression in Cucurbita pepo ssp. texana (Cucurbitaceae). J Evol Biol 2005; 18:147-55. [PMID: 15669971 DOI: 10.1111/j.1420-9101.2004.00785.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We grew inbred and outcrossed Cucurbita pepo ssp. texana plants and measured inbreeding depression for several male and female fitness traits 4 years in a row in adjacent fields at the same field station under the same cultivation conditions. We found that the magnitude of inbreeding depression varied from 0.16 to 0.53 from year to year and that those traits which were most affected tended to vary with year. We also grew inbred and outcrossed C. pepo ssp. texana plants in two adjacent fields differing only in the presence of nitrogen fertilizer to examine the effect of nutrient limitation as a form of environmental stress on the magnitude of inbreeding depression. We found that inbreeding depression was more severe in the unfertilized field. Overall, this study illustrates the notion that any estimate of inbreeding depression represents a single point in a cluster of possible estimates that can vary (often dramatically) with growing conditions.
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Affiliation(s)
- C Nelson Hayes
- Department of Biology, 208 Mueller Lab, The Pennsylvania State University, University Park, PA 16802, USA.
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Hayes CN, Winsor JA, Stephenson AG. MULTIGENERATIONAL EFFECTS OF INBREEDING IN CUCURBITA PEPO SSP. TEXANA (CUCURBITACEAE). Evolution 2005. [DOI: 10.1554/03-740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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32
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Picó FX, Ouborg NJ, Van Groenendael JM. Evaluation of the extent of among-family variation in inbreeding depression in the perennial herb Scabiosa columbaria (Dipsacaceae). AMERICAN JOURNAL OF BOTANY 2004; 91:1183-1189. [PMID: 21653474 DOI: 10.3732/ajb.91.8.1183] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Significantly different maternal line responses to inbreeding provide a mechanism for the invasion of a selfing variant into a population. The goal of this study was to examine the extent of family-level variation in inbreeding depression in the mixed-mating, perennial herb Scabiosa columbaria. Plants from one population were raised, and hand-pollinated to produce selfed and outcrossed progeny, and the effects of inbreeding depression on life-cycle traits were analyzed. Inbreeding depression significantly affected early life cycle traits. The pollination treatment by family interaction was significant for almost all traits, indicating a high family-level variation in inbreeding depression. The correlations between inbreeding depression values (e.g., percentage germination and flowering date, and flowering date and aboveground biomass) exhibited alternate signs, illustrating the type of association between inbreeding depression loci for different traits across the life cycle. Overall, it is concluded that the extent of among-family variation in inbreeding depression might allow a selfing variant of S. columbaria to invade an outcrossing population, though the pattern of correlations between inbreeding depression values might prevent effective purging of the deleterious genetic load.
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Affiliation(s)
- F Xavier Picó
- Department of Ecology, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, Netherlands
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Herlihy CR, Eckert CG. EXPERIMENTAL DISSECTION OF INBREEDING AND ITS ADAPTIVE SIGNIFICANCE IN A FLOWERING PLANT, AQUILEGIA CANADENSIS (RANUNCULACEAE). Evolution 2004. [DOI: 10.1554/04-439] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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34
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Sweigart AL, Willis JH. PATTERNS OF NUCLEOTIDE DIVERSITY IN TWO SPECIES OF MIMULUS ARE AFFECTED BY MATING SYSTEM AND ASYMMETRIC INTROGRESSION. Evolution 2003. [DOI: 10.1554/02-726] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Charles Darwin recognized that flowering plants have an unrivalled diversity of sexual systems. Determining the ecological and genetic factors that govern sexual diversification in plants is today a central problem in evolutionary biology. The integration of phylogenetic, ecological and population-genetic studies have provided new insights into the selective mechanisms that are responsible for major evolutionary transitions between reproductive modes.
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Affiliation(s)
- Spencer C H Barrett
- Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2.
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Carr DE, Eubanks MD. INBREEDING ALTERS RESISTANCE TO INSECT HERBIVORY AND HOST PLANT QUALITY IN MIMULUS GUTTATUS (SCROPHULARIACEAE). Evolution 2002. [DOI: 10.1554/0014-3820(2002)056[0022:iartih]2.0.co;2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fishman L, Kelly AJ, Willis JH. MINOR QUANTITATIVE TRAIT LOCI UNDERLIE FLORAL TRAITS ASSOCIATED WITH MATING SYSTEM DIVERGENCE IN MIMULUS. Evolution 2002. [DOI: 10.1554/0014-3820(2002)056[2138:mqtluf]2.0.co;2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Mimulus guttatus is a wildflower that exhibits substantial genetic variation in flower size. Here, we test the hypothesis that this variation is caused by deleterious mutations maintained through mutation-selection balance. The deleterious-mutation model predicts that rare, partially recessive alleles will be the primary source of variation. We test this prediction by measuring the change in the mean flower size (deltaM) and the directional dominance of flower size (deltaB) within a selection experiment. If variation is due to rare (partially) recessive alleles, deltaB/deltaM is expected to be positive and exceed one. However, we obtain negative values for deltaB/deltaM from three independent selection lines. This result is statistically inconsistent with the deleterious-mutation model.
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Affiliation(s)
- J K Kelly
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence 66045-7534, USA.
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Cheptou PO, Mathias A. Can Varying Inbreeding Depression Select for Intermediary Selfing Rates? Am Nat 2001; 157:361-73. [DOI: 10.1086/319320] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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42
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Goodwillie C. Inbreeding depression and mating systems in two species of Linanthus (Polemoniaceae). Heredity (Edinb) 2000; 84 ( Pt 3):283-93. [PMID: 10762399 DOI: 10.1046/j.1365-2540.2000.00656.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Theory predicts that, at equilibrium, the magnitude of inbreeding depression caused by recessive alleles should decrease as the level of self-fertilization increases, facilitating the evolution of even higher selfing rates. Data are presented on mating systems and inbreeding depression in multiple populations of two annual species in the genus Linanthus (Polemoniaceae). Outcrossing rates were found to be less than 0.075 in populations of a small-flowered species, L. bicolor, and ranged from 0.104 to 0.300 in populations of a larger-flowered species, L. jepsonii. Inbreeding depression for both species was low for all life history stages, with cumulative inbreeding depression less than 0.23 in all populations. Significant inbreeding depression for pollen fertility was found in L. jepsonii populations and may contribute substantially to total inbreeding depression. A competitive treatment had no significant effect on the expression of inbreeding depression for above-ground dry mass. In accordance with theoretical expectations, the magnitude of inbreeding depression was lower in L. bicolor, the more highly selfing species. The magnitude of inbreeding depression in L. jepsonii, although greater than that of L. bicolor, is not sufficient to prevent evolution of increased selfing rates in this species, according to some theoretical models of mating system evolution.
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Affiliation(s)
- C Goodwillie
- Department of Botany, University of Washington, Seattle, WA 98195, USA.
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Willis JH. Inbreeding load, average dominance and the mutation rate for mildly deleterious alleles in Mimulus guttatus. Genetics 1999; 153:1885-98. [PMID: 10581293 PMCID: PMC1460882 DOI: 10.1093/genetics/153.4.1885] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The goal of this study is to provide information on the genetics of inbreeding depression in a primarily outcrossing population of Mimulus guttatus. Previous studies of this population indicate that there is tremendous inbreeding depression for nearly every fitness component and that almost all of this inbreeding depression is due to mildly deleterious alleles rather than recessive lethals or steriles. In this article I assayed the homozygous and heterozygous fitnesses of 184 highly inbred lines extracted from a natural population. Natural selection during the five generations of selfing involved in line formation essentially eliminated major deleterious alleles but was ineffective in purging alleles with minor fitness effects and did not appreciably diminish overall levels of inbreeding depression. Estimates of the average degree of dominance of these mildly deleterious alleles, obtained from the regression of heterozygous fitness on the sum of parental homozygous fitness, indicate that the detrimental alleles are partially recessive for most fitness traits, with h approximately 0.15 for cumulative measures of fitness. The inbreeding load, B, for total fitness is approximately 1.0 in this experiment. These results are consistent with the hypothesis that spontaneous mildly deleterious mutations occur at a rate >0.1 mutation per genome per generation.
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Affiliation(s)
- J H Willis
- Department of Biology, University of Oregon, Eugene, Oregon 97403,
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Rabe AJ, Soltis DE. Pollen tube Growth and Self-Incompatibility in Heuchera micrantha var. diversifolia (Saxifragaceae). INTERNATIONAL JOURNAL OF PLANT SCIENCES 1999; 160:1157-1162. [PMID: 10568783 DOI: 10.1086/314203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A crossing study and an analysis of pollen tube growth were conducted in diploid and autotetraploid Heuchera micrantha var. diversifolia to distinguish between the possible mechanisms that could promote the high outcrossing rates observed and that could also result in the absence of fruit set following self-fertilization. The crossing study indicated that no fruit set occurred after self-pollination, whereas fruit set occurred in all of the hand-pollinated outcrosses. After 4 d, the self-pollinated flowers shriveled and abscised. Pollen tube growth following hand pollination was assessed in selfed and outcrossed flowers using fluorescence microscopy. The self-pollinated flowers exhibited far fewer pollen tubes than did the outcrossed flowers. Furthermore, in self-pollinated flowers, some of the pollen tubes extended into the style; fewer than one-half of the pollen tubes reached the base of the style and still fewer reached the ovules. The variable length of pollen tube growth, the uniform timing of floral abortion after self-pollination, and the absence of variability among individuals in the level of fruit set following self-pollination are all consistent with a system that lies somewhere between classic gametophytic self-incompatibility and late-acting self-incompatibility as the mechanism that is most likely operating in H. micrantha var. diversifolia. A similar "nonstandard" system may be present in other Saxifragaceae, such as Tolmiea and Lithophragma, as well as in Ribes, the sister group of Saxifragaceae. Our data also indicate that ploidal level (diploid vs. autotetraploid) has no influence on the extent or mechanism of self-incompatibiltiy in autopolyploid H. micrantha var. diversifolia.
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Willis JH. The contribution of male-sterility mutations to inbreeding depression in Mimulus guttatus. Heredity (Edinb) 1999; 83 ( Pt 3):337-46. [PMID: 10504432 DOI: 10.1038/sj.hdy.6885790] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The magnitude of inbreeding depression can influence many aspects of a population's ecology and evolution, including the nature of selection acting on the mating system and the chances that the population will go extinct during periods of small population size. If inbreeding depression is caused primarily by recessive mutations of large effect on fitness, such as lethals or steriles, then it is expected to be purged rapidly by selection with moderate amounts of inbreeding. In contrast, inbreeding depression primarily caused by many genes with mild effects on fitness will not be rapidly purged with inbreeding, so it should be a more resilient barrier to the evolution of self-fertilization and a more significant threat to the survival of endangered species. Here I show that recessive male-sterility alleles at individual loci are common in a primarily outcrossing population of the plant Mimulus guttatus. Despite the high frequency of these major mutations, most of the inbreeding depression for male fertility and cumulative measures of lifetime fitness results from more mildly deleterious alleles. Male-sterility alleles contribute to 31% of the inbreeding depression for the fraction of viable pollen grains, and to 26% of the inbreeding depression for total fitness. These results suggest that most of the inbreeding depression for male fertility in this population would not be purged, in the short term, with moderate inbreeding.
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Affiliation(s)
- J H Willis
- Department of Biology, University of Oregon, Eugene, OR 97403, USA.
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47
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Carr DE, Dudash MR. Inbreeding depression under a competitive regime in Mimulus guttatus: consequences for potential male and female function. Heredity (Edinb) 1995. [DOI: 10.1038/hdy.1995.159] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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48
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Kohn JR, Biardi JE. Outcrossing rates and inferred levels of inbreeding depression in gynodioecious Cucurbita foetidissima (Cucurbitaceae). Heredity (Edinb) 1995. [DOI: 10.1038/hdy.1995.106] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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49
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Levels of genetic variation and covariation for Mimulus (Scrophulariaceae) floral traits. Heredity (Edinb) 1994. [DOI: 10.1038/hdy.1994.84] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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50
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Willis JH. Partial self-fertilization and inbreeding depression in two populations of Mimulus guttatus. Heredity (Edinb) 1993. [DOI: 10.1038/hdy.1993.118] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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