The Experts below are selected from a list of 37203 Experts worldwide ranked by ideXlab platform
Kermit Ritland - One of the best experts on this subject based on the ideXlab platform.
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Mating System of yellow starthistle (Centaurea solstitialis), a successful colonizer in North America
Heredity, 1998Co-Authors: Kermit RitlandAbstract:The Mating System of Centaurea solstitialis L. was investigated in relation to its colonization of North America. A preliminary investigation of its reproductive biology suggested that the species is a pollinator-dependent outbreeder, and probably self-incompatible. Quantitative analysis of the Mating System parameters was performed using progeny arrays assayed for nine allozyme markers. Multilocus outcrossing rates (t(m)) ranged from 0.948 to 0.990 among eight populations. Moderate levels of biparental inbreeding (≃6 per cent apparent selfing) were detected in most populations. The correlation of outcrossed paternity within progeny arrays (r(p)) ranged from 0.05 to 0.64 among populations, indicating differences in modes of outcross pollination. A geographically marginal population, San Diego, showed the only significant parental inbreeding coefficient (F = 0.27), as well as highest r(p), suggesting microevolutionary changes of Mating System following founder events. One other population exhibited significant variation of individual plant outcrossing rate, with a correlation of selfing within progeny arrays of r(s) = 0.65, indicating variation of self-incompatibility. Mating System variation in colonizing, self-incompatible species is valuable for understanding the evolution of self-incompatibility Systems.link_to_subscribed_fulltex
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Mating System of yellow starthistle centaurea solstitialis a successful colonizer in north america
Heredity, 1998Co-Authors: Kermit RitlandAbstract:The Mating System of Centaurea solstitialis L. was investigated in relation to its colonization of North America. A preliminary investigation of its reproductive biology suggested that the species is a pollinator-dependent outbreeder, and probably self-incompatible. Quantitative analysis of the Mating System parameters was performed using progeny arrays assayed for nine allozyme markers. Multilocus outcrossing rates (tm) ranged from 0.948 to 0.990 among eight populations. Moderate levels of biparental inbreeding (≈6 per cent apparent selfing) were detected in most populations. The correlation of outcrossed paternity within progeny arrays (rp) ranged from 0.05 to 0.64 among populations, indicating differences in modes of outcross pollination. A geographically marginal population, San Diego, showed the only significant parental inbreeding coefficient (F=0.27), as well as highest rp, suggesting microevolutionary changes of Mating System following founder events. One other population exhibited significant variation of individual plant outcrossing rate, with a correlation of selfing within progeny arrays of rs=0.65, indicating variation of self-incompatibility. Mating System variation in colonizing, self-incompatible species is valuable for understanding the evolution of self-incompatibility Systems.
Liv Antonsen - One of the best experts on this subject based on the ideXlab platform.
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delayed stigma receptivity in collinsia heterophylla plantaginaceae genetic variation and adaptive significance in relation to pollen competition delayed self pollination and Mating System evolution
American Journal of Botany, 2007Co-Authors: Asa Lankinen, Scott W Armbruster, Liv AntonsenAbstract:To increase our knowledge about Mating-System evolution, we need to understand the relationship between specific floral traits and Mating System. Species of Collinsia (Plantaginaceae) vary extensively in Mating System; this variation is associated with variation in floral morphology and development and with the timing of self-pollination. Counterintuitively, large-flowered, more outcrossing species tend to have delayed stigma receptivity, reducing the amount of time that the stigma is receptive to cross-pollination before autonomous self-pollination. To understand how the timing of stigma receptivity is related to Mating-System evolution, we studied in detail the timing of both stigma receptivity and self-pollination (anther-stigma contact) in two greenhouse-grown populations of large-flowered Collinsia heterophylla. Crosses on emasculated flowers at different stages of floral development always produced seeds, suggesting that cross-fertilization can be effected by pollen arriving prior to physiological receptivity. Phenotypic and genetic variation within populations in the timing of stigma receptivity and antherstigma contact was substantial, although slightly less for the contact. Despite strong interspecific and interpopulation correlations, we did not find an among-genet phenotypic correlation between the traits. This indicates that each trait may respond independently to selection, and the trait association may be the result of correlational selection. (Less)
Steinar Engen - One of the best experts on this subject based on the ideXlab platform.
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demographic stochasticity allee effects and extinction the influence of Mating System and sex ratio
The American Naturalist, 2011Co-Authors: Bernterik Saether, Steinar EngenAbstract:Demographic stochasticity has a substantial influence on the growth of small populations and consequently on their extinction risk. Mating System is one of several population characteristics that may affect this. We use a stochastic pair-formation model to investigate the combined effects of Mating System, sex ratio, and population size on demographic stochasticity and thus on extinction risk. Our model is designed to accommodate a continuous range of Mating Systems and sex ratios as well as several levels of stochasticity. We show that it is not Mating System alone but combinations of Mating System and sex ratio that are important in shaping the stochastic dynamics of populations. Specifically, polygyny has the potential to give a high demographic variance and to lower the stochastic population growth rate substantially, thus also shortening the time to extinction, but the outcome is highly dependent on the sex ratio. In addition, population size is shown to be important. We find a stochastic Allee effect that is amplified by polygyny. Our results demonstrate that both Mating System and sex ratio must be considered in conservation planning and that appreciating the role of stochasticity is key to understanding their effects.
Jorg T Epplen - One of the best experts on this subject based on the ideXlab platform.
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Mating System and sexual selection in the scorpionfly panorpa vulgaris mecoptera panorpidae
Naturwissenschaften, 1998Co-Authors: Klaus Peter Sauer, Thomas Lubjuhn, Jorn Sindern, Harald Kullmann, Joachim Kurtz, Conny Epplen, Jorg T EpplenAbstract:has become a model insect for testing theories of sexual selection. This contribution summarizes that which has been learned in recent years and presents new data that clearly show that the Mating System of P. vulgaris is not simply a resource-defense polygyny, as has previously been thought. In P. vulgaris neither the pattern in food exploitation nor the ratio of variance in the lifetime reproductive success of the two sexes is in accordance with that expected in resource defense polygynous Mating Systems. Lifetime Mating duration is the most important proximate determinant of male fitness. Males employing alternative Mating tactics obtain copulations of varying duration in relation to the following sequence: saliva secretion 1 food offering 1 no gift. The number of salivary masses which males provide to females during their lifetime is significantly correlated with the lifetime condition index. The condition index depends on the fighting prowess of males and their ability to find food items. Thus saliva secretion of Panorpa is considered a Zahavian handicap, which can serve as an honest quality indicator used by Mating females. Our results confirm four main predictions of the indicator model of the theory of sexual selection: (a) the indicator signals high ecological quality of its bearer, (b) the indicator value increases with phenotypic quality, (c) the indicator value is positively correlated with the genetic quality affecting offspring fitness in a natural selection context, and (d) the quality indicator is more costly for low- than for high-quality individuals. The evolutionary consequences of the Mating pattern and the sperm competition mechanism in P. vulgaris are discussed in the context the way in which sexual selection creates and maintains sperm mixing and the evolution of a promiscuous Mating System.
Jaco M. Greeff - One of the best experts on this subject based on the ideXlab platform.
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Outbreeding and possibly inbreeding depression in a pollinating fig wasp with a mixed Mating System
Heredity, 2009Co-Authors: Jaco M. Greeff, G J Jansen Van Vuuren, Per Kryger, J. C. MooreAbstract:Outbreeding and possibly inbreeding depression in a pollinating fig wasp with a mixed Mating System
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Mating System and sex ratios of a pollinating fig wasp with dispersing males
Proceedings of The Royal Society B: Biological Sciences, 2002Co-Authors: Jaco M. GreeffAbstract:Recent studies have used sex ratios to quantify the Mating Systems of organisms, the argument behind it being that more female-biased sex ratios are an indication of higher local mate competition, which goes hand-in-hand with higher levels of inbreeding. Although qualitative tests of the effects of Mating Systems on sex ratios abound, there is a dearth of studies that quantify both the Mating System and the sex ratio. I use a colour dimorphism with a simple Mendelian inheritance to quantify the Mating System of an unusual fig-pollinating wasp in which males disperse to obtain Matings on non-natal Mating patches. In qualitative agreement with initial expectations, the sex ratios of single foundresses are found to be higher than those of regular species. However, by quantifying the Mating System, it is shown that the initial expectation is incorrect and this species' sex ratio is a poor predictor of its Mating System (it underestimates the frequency of sib-Mating). The species has a very high variance in sex ratio suggesting that excess males can simply avoid local mate competition (and hence a lowered fitness to their mother) by dispersing to other patches.
