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Outi Savolainen - One of the best experts on this subject based on the ideXlab platform.
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Magnitude and Timing of Inbreeding Depression in Scots Pine (Pinus sylvestris L.)
Evolution, 1999Co-Authors: Hans Peter Koelewijn, Veikko Koski, Outi SavolainenAbstract:Inbreeding Depression is a major selective force favoring outcrossing in flowering plants. However, some self- fertilization should weaken the harmful effects of Inbreeding by exposing deleterious alleles to selection. This study examines the maintenance of Inbreeding Depression in the predominantly outcrossing species Pinus sylvestris L. (Scots pine). Open-pollinated and self-fertilized progeny of 23 maternal trees, originating from a natural stand in southern Finland, were grown at two sites. We observed significant Inbreeding Depression in two of the four life stages measured. Inbreeding Depression was largest for seed maturation (delta = 0.74), where seedset in open-pollinated strobili (70.9%) was about four times higher than in selfed strobili (18.3%). Inbreeding Depression in postgermination survival (upto an age of 23 years) was also high (delta = 0.62-0.75). No significant differences in height (delta = 0.05) or flowering (delta = 0.14) of the trees after 23 years were observed. Cumulative Inbreeding Depression was high (delta = 0.90-0.94) and differed significantly among maternal families (range 0.45-1.00). The magnitude of Inbreeding Depression among the 23 maternal parents was not significantly correlated between early (seed maturation) and later (postgermination survival) life stages, suggesting that its genetic basis varies across the life cycle. Size differences among the progeny types diminished in time due to nonrandom size-specific mortality, causing a decrease in the Inbreeding Depression estimates for height over time. Our results indicate that Scots pine exhibits high levels of Inbreeding Depression during both early and later stages of the Life cycle. It is argued that self-fertilization in Scots pine is inefficient in purging the genetic load caused by highly deleterious mutations because of the nearly complete loss of selfed individuals over time. This results in an effectively random mating outcrossing population. [KEYWORDS: deleterious alleles; Inbreeding Depression; purging recessive mutations; selective interference; self-fertilization; size-specific mortality Self-fertilization; outcrossing rates; lethal mutations; genetic-basis; evolution; plants; populations; fitness; coevolution; selection
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GEOGRAPHICAL VARIATION IN THE Inbreeding Depression OF SCOTS PINE.
Evolution; international journal of organic evolution, 1996Co-Authors: Katri Kärkkäinen, Veikko Koski, Outi SavolainenAbstract:The magnitude of Inbreeding Depression caused by recessive mutations in a population is dependent on the mutation rate and on the intensity of selection against the mutations. We studied geographical differences in the level of early Inbreeding Depression of Scots pine in a common garden experiment. The mean abortion rate of experimentally self-pollinated seeds was significantly lower (75.4%) among trees that originated from northern populations (66-69°N) than among trees from more southern (60-62°N) populations (86.5%). Thus, the number of embryonic lethal equivalents was lower in the northern populations (4.5) than in the southern ones (6.9). The outcrossing rate at the mature seed stage was slightly lower in the northern populations (average 0.93) than in the southern one (0.99). The estimated selfing rate at the zygote stage varied from 0-0.28 in the populations. The reduction in the magnitude of Inbreeding Depression in the north may have been caused by increased levels of self-fertilization in the northern populations. The proportion of self-fertilized seedlings and adults was very small in all populations (F ≈ 0), indicating high Inbreeding Depression also in later life stages. The high level of Inbreeding Depression in the partially selfing Scots pine can be explained by mutation-selection balance only if the mutation rate is high.
Patrice David - One of the best experts on this subject based on the ideXlab platform.
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Inbreeding Depression of mating behavior and its reproductive consequences in a freshwater snail
Behavioral Ecology, 2014Co-Authors: Tim Janicke, Nikolas Vellnow, Thomas Lamy, Elodie Chapuis, Patrice DavidAbstract:Inbreeding is expected to impair male and female reproductive performance, but little is known on how Inbreeding Depression varies between sexes and different levels of competition. We studied Inbreeding Depression in mating behavior and its reproductive consequences in a hermaphroditic freshwater snail and demonstrate that Inbreeding depresses mating success in both sex functions. However, the magnitude of Inbreeding Depression does not differ between sex functions and is not affected by the opportunity for mate choice and male-male competition.Theoretical work predicts that the magnitude of Inbreeding Depression is particularly high in traits that are closely related to fitness. Despite the extensive work on Inbreeding Depression of male and female reproductive performance, relatively little is known on how Inbreeding impairs male and female mating behavior. We studied Inbreeding Depression of male and female mating behavior in the simultaneously hermaphroditic freshwater snail Physa acuta to test 1) whether there is Inbreeding Depression of mating behavior, 2) whether the potential of mate competition and mate choice has an effect on the strength of Inbreeding Depression, 3) whether the magnitude of Inbreeding Depression differs between both sex functions, and 4) how Inbreeding Depression of mating behavior translates into Inbreeding Depression of reproductive success. For this, we compared the mating behavior between selfed (inbred) and outcrossed (outbred) focal snails in a series of mating trials, in which we manipulated experimentally the potential of mate competition and mate choice. Our results provide evidence for moderate Inbreeding Depression of the number of copulatory encounters, the number of copulations, and the total time spent mating in both sex functions. The magnitude of Inbreeding Depression did not differ between the levels of competition and between both sex functions. Finally, our results suggest that Inbreeding Depression of mating behavior only explains a small fraction of the observed Inbreeding Depression of reproductive success. We discuss the implications of these findings with respect to precopulatory sexual selection and sex-specific Inbreeding Depression.
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Inbreeding Depression of mating behavior and its reproductive consequences in a freshwater snail
Behavioral Ecology, 2013Co-Authors: Tim Janicke, Nikolas Vellnow, Thomas Lamy, Elodie Chapuis, Patrice DavidAbstract:Theoretical work predicts that the magnitude of Inbreeding Depression is particularly high in traits that are closely related to fitness. Despite the extensive work on Inbreeding Depression of male and female reproductive performance, relatively little is known on how Inbreeding impairs male and female mating behavior. We studied Inbreeding Depression of male and female mating behavior in the simultaneously hermaphroditic freshwater snail Physa acuta to test 1) whether there is Inbreeding Depression of mating behavior, 2) whether the potential of mate competition and mate choice has an effect on the strength of Inbreeding Depression, 3) whether the magnitude of Inbreeding Depression differs between both sex functions, and 4) how Inbreeding Depression of mating behavior translates into Inbreeding Depression of reproductive success. For this, we compared the mating behavior between selfed (inbred) and outcrossed (outbred) focal snails in a series of mating trials, in which we manipulated experimentally the potential of mate competition and mate choice. Our results provide evidence for moderate Inbreeding Depression of the number of copulatory encounters, the number of copulations, and the total time spent mating in both sex functions. The magnitude of Inbreeding Depression did not differ between the levels of competition and between both sex functions. Finally, our results suggest that Inbreeding Depression of mating behavior only explains a small fraction of the observed Inbreeding Depression of reproductive success. We discuss the implications of these findings with respect to precopulatory sexual selection and sex-specific Inbreeding Depression.
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SEX‐SPECIFIC Inbreeding Depression DEPENDS ON THE STRENGTH OF MALE–MALE COMPETITION
Evolution; international journal of organic evolution, 2013Co-Authors: Tim Janicke, Nikolas Vellnow, Violette Sarda, Patrice DavidAbstract:Inbreeding Depression has become a central theme in evolutionary biology and is considered to be a driving force for the evolution of reproductive morphology, physiology, behavior, and mating systems. Despite the overwhelming body of empirical work on the reproductive consequences of Inbreeding, relatively little is known on whether Inbreeding depresses male and female fitness to the same extent. However, sex-specific Inbreeding Depression has been argued to affect the evolution of selfing rates in simultaneous hermaphrodites and provides a powerful approach to test whether selection is stronger in males than in females, which is predicted to be the consequence of sexual selection. We tested for sex-specific Inbreeding Depression in the simultaneously hermaphroditic freshwater snail Physa acuta by comparing the reproductive performance of both sex functions between selfed and outcrossed focal individuals under different levels of male-male competition. We found that Inbreeding impaired both male and female reproductive success and that the magnitude of male Inbreeding Depression exceeded female Inbreeding Depression when the opportunity for sperm competition was highest. Our study provides the first evidence for sex-specific Inbreeding Depression in a hermaphroditic animal and highlights the importance of considering the level of male-male competition when assessing sex differences in Inbreeding Depression.
Juan L. Bouzat - One of the best experts on this subject based on the ideXlab platform.
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Reduced Inbreeding Depression due to historical Inbreeding in Drosophila melanogaster: evidence for purging.
Journal of Evolutionary Biology, 2006Co-Authors: William R. Swindell, Juan L. BouzatAbstract:An important issue in conservation biology and the study of evolution is the extent to which Inbreeding Depression can be reduced or reversed by natural selection. If the deleterious recessive alleles causing Inbreeding Depression can be ‘purged’ by natural selection, outbred populations that have a history of Inbreeding are expected to be less susceptible to Inbreeding Depression. This expectation, however, has not been realized in previous laboratory experiments. In the present study, we used Drosophila melanogaster as a model system to test for an association between Inbreeding history and Inbreeding Depression. We created six ‘purged’ populations from experimental lineages that had been maintained at a population size of 10 male–female pairs for 19 generations. We then measured the Inbreeding Depression that resulted from one generation of full-sib mating in the purged populations and in the original base population. The magnitude of Inbreeding Depression in the purged populations was approximately one-third of that observed in the original base population. In contrast to previous laboratory experiments, therefore, we found that Inbreeding Depression was reduced in populations that have a history of Inbreeding. The large purging effects observed in this study may be attributable to the rate of historical Inbreeding examined, which was slower than that considered in previous experiments.
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SELECTION AND Inbreeding Depression: EFFECTS OF Inbreeding RATE AND Inbreeding ENVIRONMENT
Evolution, 2006Co-Authors: William R. Swindell, Juan L. BouzatAbstract:The magnitude of Inbreeding Depression in small populations may depend on the effectiveness with which natural selection purges deleterious recessive alleles from populations during Inbreeding. The effectiveness of this purging process, however, may be influenced by the rate of Inbreeding and the environment in which Inbreeding occurs. Although some experimental studies have examined these factors individually, no study has examined their joint effect or potential interaction. In the present study, therefore, we performed an experiment in which 180 lineages of Drosophila melanogaster were inbred at slow and fast Inbreeding rates within each of three Inbreeding environments (benign, high temperature, and competitive). The fitness of all lineages was then measured in a common benign environment. Although slow Inbreeding reduced Inbreeding Depression in lineages inbred under high temperature stress, a similar reduction was not observed with respect to the benign or competitive treatments. Overall, therefore, the effect of Inbreeding rate was nonsignificant. The Inbreeding environment, in contrast, had a larger and more consistent effect on Inbreeding Depression. Under both slow and fast rates of Inbreeding, Inbreeding Depression was significantly reduced in lineages inbred in the presence of a competitor D. melanogaster strain. A similar reduction of Inbreeding Depression occurred in lineages inbred under high temperature stress at a slow Inbreeding rate. Overall, our findings show that Inbreeding Depression is reduced when Inbreeding takes place in a stressful environment, possibly due to more effective purging under such conditions.
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ANCESTRAL Inbreeding REDUCES THE MAGNITUDE OF Inbreeding Depression IN DROSOPHILA MELANOGASTER
Evolution, 2006Co-Authors: William R. Swindell, Juan L. BouzatAbstract:The influence of natural selection on the magnitude of Inbreeding Depression is an important issue in conservation biology and the study of evolution. It is generally expected that the magnitude of Inbreeding Depression in small populations will depend upon the average homozygosity of individuals, as measured by the coefficient of Inbreeding (F). However, if deleterious recessive alleles are selectively purged from populations during Inbreeding, then Inbreeding Depression may differ among populations in which individuals have the same Inbreeding coefficient. In such cases, the magnitude of Inbreeding Depression will partly depend on the ancestral Inbreeding coefficient (fa), which measures the cumulative proportion of loci that have historically been homozygous and therefore exposed to natural selection. We examined the Inbreeding Depression that occurred in lineages of Drosophila melanogaster maintained under pedigrees that led to the same Inbreeding coefficient (F = 0.375) but different levels of ancestral Inbreeding (fa = 0.250 or 0.531). Although Inbreeding Depression varied substantially among individual lineages, we observed a significant 40% decrease in the median level of Inbreeding Depression in the treatment with higher ancestral Inbreeding. Our results demonstrate that high levels of ancestral Inbreeding are associated with greater purging effects, which reduces the Inbreeding Depression that occurs in isolated populations of small size.
Tim Janicke - One of the best experts on this subject based on the ideXlab platform.
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Inbreeding Depression of mating behavior and its reproductive consequences in a freshwater snail
Behavioral Ecology, 2014Co-Authors: Tim Janicke, Nikolas Vellnow, Thomas Lamy, Elodie Chapuis, Patrice DavidAbstract:Inbreeding is expected to impair male and female reproductive performance, but little is known on how Inbreeding Depression varies between sexes and different levels of competition. We studied Inbreeding Depression in mating behavior and its reproductive consequences in a hermaphroditic freshwater snail and demonstrate that Inbreeding depresses mating success in both sex functions. However, the magnitude of Inbreeding Depression does not differ between sex functions and is not affected by the opportunity for mate choice and male-male competition.Theoretical work predicts that the magnitude of Inbreeding Depression is particularly high in traits that are closely related to fitness. Despite the extensive work on Inbreeding Depression of male and female reproductive performance, relatively little is known on how Inbreeding impairs male and female mating behavior. We studied Inbreeding Depression of male and female mating behavior in the simultaneously hermaphroditic freshwater snail Physa acuta to test 1) whether there is Inbreeding Depression of mating behavior, 2) whether the potential of mate competition and mate choice has an effect on the strength of Inbreeding Depression, 3) whether the magnitude of Inbreeding Depression differs between both sex functions, and 4) how Inbreeding Depression of mating behavior translates into Inbreeding Depression of reproductive success. For this, we compared the mating behavior between selfed (inbred) and outcrossed (outbred) focal snails in a series of mating trials, in which we manipulated experimentally the potential of mate competition and mate choice. Our results provide evidence for moderate Inbreeding Depression of the number of copulatory encounters, the number of copulations, and the total time spent mating in both sex functions. The magnitude of Inbreeding Depression did not differ between the levels of competition and between both sex functions. Finally, our results suggest that Inbreeding Depression of mating behavior only explains a small fraction of the observed Inbreeding Depression of reproductive success. We discuss the implications of these findings with respect to precopulatory sexual selection and sex-specific Inbreeding Depression.
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Inbreeding Depression of mating behavior and its reproductive consequences in a freshwater snail
Behavioral Ecology, 2013Co-Authors: Tim Janicke, Nikolas Vellnow, Thomas Lamy, Elodie Chapuis, Patrice DavidAbstract:Theoretical work predicts that the magnitude of Inbreeding Depression is particularly high in traits that are closely related to fitness. Despite the extensive work on Inbreeding Depression of male and female reproductive performance, relatively little is known on how Inbreeding impairs male and female mating behavior. We studied Inbreeding Depression of male and female mating behavior in the simultaneously hermaphroditic freshwater snail Physa acuta to test 1) whether there is Inbreeding Depression of mating behavior, 2) whether the potential of mate competition and mate choice has an effect on the strength of Inbreeding Depression, 3) whether the magnitude of Inbreeding Depression differs between both sex functions, and 4) how Inbreeding Depression of mating behavior translates into Inbreeding Depression of reproductive success. For this, we compared the mating behavior between selfed (inbred) and outcrossed (outbred) focal snails in a series of mating trials, in which we manipulated experimentally the potential of mate competition and mate choice. Our results provide evidence for moderate Inbreeding Depression of the number of copulatory encounters, the number of copulations, and the total time spent mating in both sex functions. The magnitude of Inbreeding Depression did not differ between the levels of competition and between both sex functions. Finally, our results suggest that Inbreeding Depression of mating behavior only explains a small fraction of the observed Inbreeding Depression of reproductive success. We discuss the implications of these findings with respect to precopulatory sexual selection and sex-specific Inbreeding Depression.
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SEX‐SPECIFIC Inbreeding Depression DEPENDS ON THE STRENGTH OF MALE–MALE COMPETITION
Evolution; international journal of organic evolution, 2013Co-Authors: Tim Janicke, Nikolas Vellnow, Violette Sarda, Patrice DavidAbstract:Inbreeding Depression has become a central theme in evolutionary biology and is considered to be a driving force for the evolution of reproductive morphology, physiology, behavior, and mating systems. Despite the overwhelming body of empirical work on the reproductive consequences of Inbreeding, relatively little is known on whether Inbreeding depresses male and female fitness to the same extent. However, sex-specific Inbreeding Depression has been argued to affect the evolution of selfing rates in simultaneous hermaphrodites and provides a powerful approach to test whether selection is stronger in males than in females, which is predicted to be the consequence of sexual selection. We tested for sex-specific Inbreeding Depression in the simultaneously hermaphroditic freshwater snail Physa acuta by comparing the reproductive performance of both sex functions between selfed and outcrossed focal individuals under different levels of male-male competition. We found that Inbreeding impaired both male and female reproductive success and that the magnitude of male Inbreeding Depression exceeded female Inbreeding Depression when the opportunity for sperm competition was highest. Our study provides the first evidence for sex-specific Inbreeding Depression in a hermaphroditic animal and highlights the importance of considering the level of male-male competition when assessing sex differences in Inbreeding Depression.
Russell Lande - One of the best experts on this subject based on the ideXlab platform.
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Inbreeding Depression under mixed outcrossing, self-fertilization and sib-mating
BMC evolutionary biology, 2016Co-Authors: Emmanuelle Porcher, Russell LandeAbstract:Biparental Inbreeding, mating between two relatives, occurs at a low frequency in many natural plant populations, which also often have substantial rates of self-fertilization. Although biparental Inbreeding is likely to influence the dynamics of Inbreeding Depression and the evolution of selfing rates, it has received limited theoretical attention in comparison to selfing. The only previous model suggested that biparental Inbreeding can favour the maintenance of stable intermediate selfing rates, but made unrealistic assumptions about the genetic basis of Inbreeding Depression. Here we extend a genetic model of Inbreeding Depression, describing nearly recessive lethal mutations at a very large number of loci, to incorporate sib-mating. We also include a constant component of Inbreeding Depression modelling the effects of mildly deleterious, nearly additive alleles. We analyze how observed rates of sib-mating influence the mean number of heterozygous lethals alleles and Inbreeding Depression in a population reproducing by a mixture of self-fertilization, sib-mating and outcrossing. We finally use the ensuing relationship between equilibrium Inbreeding Depression and population selfing rate to infer the evolutionarily stable selfing rates expected under such a mixed mating system. We show that for a given rate of Inbreeding, sib-mating is more efficient at purging Inbreeding Depression than selfing, because homozygosity of lethals increases more gradually through sib-mating than through selfing. Because sib-mating promotes the purging of Inbreeding Depression and the evolution of selfing, our genetic model of Inbreeding Depression also predicts that sib-mating is unlikely to maintain stable intermediate selfing rates. Our results imply that even low rates of sib-mating affect plant mating system evolution, by facilitating the evolution of selfing via more efficient purging of Inbreeding Depression. Alternative mechanisms, such as pollination ecology, are necessary to explain stable mixed selfing and outcrossing.
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Inbreeding Depression under mixed outcrossing, self-fertilization and sib-mating
BMC Evolutionary Biology, 2016Co-Authors: Emmanuelle Porcher, Russell LandeAbstract:Background: Biparental Inbreeding, mating between two relatives, occurs at a low frequency in many natural plant populations, which also often have substantial rates of self-fertilization. Although biparental Inbreeding is likely to influence the dynamics of Inbreeding Depression and the evolution of selfing rates, it has received limited theoretical attention in comparison to selfing. The only previous model suggested that biparental Inbreeding can favour the maintenance of stable intermediate selfing rates, but made unrealistic assumptions about the genetic basis of Inbreeding Depression. Here we extend a genetic model of Inbreeding Depression, describing nearly recessive lethal mutations at a very large number of loci, to incorporate sib-mating. We also include a constant component of Inbreeding Depression modelling the effects of mildly deleterious, nearly additive alleles. We analyze how observed rates of sib-mating influence the mean number of heterozygous lethals alleles and Inbreeding Depression in a population reproducing by a mixture of self-fertilization, sib-mating and outcrossing. We finally use the ensuing relationship between equilibrium Inbreeding Depression and population selfing rate to infer the evolutionarily stable selfing rates expected under such a mixed mating system. Results: We show that for a given rate of Inbreeding, sib-mating is more efficient at purging Inbreeding Depression than selfing, because homozygosity of lethals increases more gradually through sib-mating than through selfing. Because sib-mating promotes the purging of Inbreeding Depression and the evolution of selfing, our genetic model of Inbreeding Depression also predicts that sib-mating is unlikely to maintain stable intermediate selfing rates. Conclusions: Our results imply that even low rates of sib-mating affect plant mating system evolution, by facilitating the evolution of selfing via more efficient purging of Inbreeding Depression. Alternative mechanisms, such as pollination ecology, are necessary to explain stable mixed selfing and outcrossing.
