How does self-pollination evolve? Inferences from floral ecology and molecular genetic variation

1996 ◽  
Vol 351 (1345) ◽  
pp. 1281-1290 ◽  
Keyword(s):  
Mating System ◽  
Molecular Genetic ◽  
Phenotypic Selection ◽  
Reproductive Assurance ◽  
Floral Ecology ◽  
Automatic Selection ◽  
Self Pollination ◽  
Neutral Genetic Diversity ◽  
Pollen Vectors ◽  
Molecular Genetic Variation

The automatic selection and reproductive assurance hypotheses provide the two most general explanations for the evolution of self-pollination. Under automatic selection, self-pollination is mediated by pollen vectors and the mating system modifier experiences a transmission bias through the pollen that leads to its selection. Under reproductive assurance, self-pollination is autonomous and the mating system modifier is selected as it allows seed production when pollinators are scarce. We present phenotypic selection models that examine the selection of floral traits influencing several modes of selling simultaneously. Inferences from these models suggest that reproductive assurance may be more important than has been appreciated. Additional insight into the importance of automatic selection versus reproductive assurance may be gained by considering the distribution of neutral genetic diversity among populations within selfing species. A number of approaches are outlined for analysing patterns of neutral diversity as they pertain to the mechanism of the evolution of selfing.

Endophenotypes

2018 ◽  
pp. 103-106
Author(s):  
David C. Glahn ◽  
Laura Almasy ◽  
John Blangero
Keyword(s):  
Mental Illness ◽  
Genetic Variation ◽  
Psychiatric Disorders ◽  
Genetic Locus ◽  
Molecular Genetic ◽  
Gene Discovery ◽  
Psychiatric Diagnoses ◽  
Behavioral Syndrome ◽  
Molecular Genetic Variation ◽  
Or Gene

Endophenotypes are traits that, while genetically related to an illness, are not used for diagnoses (e.g., a symptom). It is unlikely that specific genes directly code for any of our current psychiatric diagnoses. Rather, genes influence neurobiological processes that either increase or decrease risk for mental illness. One use of an endophenotype is to help characterize a genetic locus or gene previously identified as conferring risk for a particular illness. In this context, endophenotypes help to bridge the gap between a behavioral syndrome and molecular genetic variation. Alternately, endophenotypes can be used for novel locus or gene discovery, particularly when used in multivariate analyses. In this chapter, we define endophenotypes and describe different ways they have been applied to aid our understanding of the genetic architecture of psychiatric disorders.

Molecular genetic variation and geographical structuring in Fusarium graminearum

2004 ◽  
Vol 145 (3) ◽  
pp. 299-307 ◽  
Author(s):  
PRASHANT K MISHRA ◽  
JALPA P TEWARI ◽  
RANDALL M CLEAR ◽  
T KELLY TURKINGTON
Keyword(s):  
Genetic Variation ◽  
Fusarium Graminearum ◽  
Molecular Genetic ◽  
Molecular Genetic Variation

scholarly journals The demography and population genomics of evolutionary transitions to self-fertilization in plants

2014 ◽  
Vol 369 (1648) ◽  
pp. 20130344 ◽  
Author(s):  
Spencer C. H. Barrett ◽  
Ramesh Arunkumar ◽  
Stephen I. Wright
Keyword(s):  
Mating System ◽  
Population Genomics ◽  
Molecular Data ◽  
Reproductive Assurance ◽  
Evolutionary Transitions ◽  
Cast Doubt ◽  
Self Fertilization ◽  
Loss Of Diversity ◽  
Linked Selection

The evolution of self-fertilization from outcrossing has occurred on numerous occasions in flowering plants. This shift in mating system profoundly influences the morphology, ecology, genetics and evolution of selfing lineages. As a result, there has been sustained interest in understanding the mechanisms driving the evolution of selfing and its environmental context. Recently, patterns of molecular variation have been used to make inferences about the selective mechanisms associated with mating system transitions. However, these inferences can be complicated by the action of linked selection following the transition. Here, using multilocus simulations and comparative molecular data from related selfers and outcrossers, we demonstrate that there is little evidence for strong bottlenecks associated with initial transitions to selfing, and our simulation results cast doubt on whether it is possible to infer the role of bottlenecks associated with reproductive assurance in the evolution of selfing. They indicate that the effects of background selection on the loss of diversity and efficacy of selection occur rapidly following the shift to high selfing. Future comparative studies that integrate explicit ecological and genomic details are necessary for quantifying the independent and joint effects of selection and demography on transitions to selfing and the loss of genetic diversity.

Phenotypic and Molecular Genetic Variation in Tunisian Natural Populations of Sulla carnosa

2013 ◽  
Vol 105 (4) ◽  
pp. 1094-1100 ◽  
Author(s):  
Mohamed Neji ◽  
Wael Taamalli ◽  
Malek Smida ◽  
Chedly Abdelly ◽  
Mhemmed Gandour
Keyword(s):  
Genetic Variation ◽  
Molecular Genetic ◽  
Natural Populations ◽  
Molecular Genetic Variation

Mistletoes on mistletoes: The floral ecology of Amyema miraculosum and its host, Amyema miquelii (Loranthaceae)

1984 ◽  
Vol 32 (1) ◽  
pp. 73 ◽  
Author(s):  
P Bernhardt
Keyword(s):  
Interspecific Hybridization ◽  
Bird Species ◽  
Pollination Ecology ◽  
Interspecific Crosses ◽  
Obligate Parasite ◽  
Floral Ecology ◽  
Pollen Vectors ◽  
First Time ◽  
Nectar Content

In Victoria, self-incompatible Amyema miraculosum may exist as a locally obligate parasite on partially self-compatible Amyema miquelii. For the first time, the pollination ecology of a mistletoe on a mistletoe is analysed. Both species were generalist ornithophiles with overlapping flowering seasons from January to March. Consequently, the hyperparasite was in competition with its congeneric host for pollen vectors belonging to the local nectar bird guild (Meliphagidae and Zosteropidae). Amyema miquelii produced flowers that were longer-lived, and had a higher nectar content, than those of A. miraculosum. From mid February through March, A. miquelii plants offered more inflorescences, with open flowers, than A. miraculosum. There was an average of twice as many flowers on an A. miquelii inflorescence as on an A. miraculosum inflorescence, Not surprisingly, more than 70% of avian foraging bouts observed were to A. miquelii only. Eight bird species foraged for nectar on A. miquelii while only five were recorded on A. miraculosum. While 22% of all foraging bouts were interspecific, no examples of interspecific hybridization were found. This corresponds with previous observation of the reciprocal failure of interspecific crosses in vitro.

The mating system of Acrotriche serrulata (Ericaceae)

2010 ◽  
Vol 58 (2) ◽  
pp. 124 ◽  
Author(s):  
Melanie Schneemilch ◽  
Emma Steggles
Keyword(s):  
Mating System ◽  
Pollen Viability ◽  
Seed Viability ◽  
Corolla Tube ◽  
Morphological Features ◽  
Stigma Receptivity ◽  
Pollination Experiments ◽  
Controlled Pollination ◽  
Cross Pollination ◽  
Self Pollination

Controlled pollination experiments were conducted on Acrotriche serrulata R.Br. (Ericaceae) to determine the mating system for this species. Pollen viability and stigma receptivity were investigated to ensure effective timing and sourcing of material for maximum fertilisation. Stigmas were found to be receptive in mature buds, with receptivity maintained while nectar remained within the corolla tube. Germination testing showed that pollen from within mature buds was viable. The mating system of A. serrulata was found to be predominantly outcrossing, with 49.8% of cross-pollinated flowers developing to fruit, compared with 8.7% of self-pollinated flowers. Seed viability did not differ significantly between fruits produced by cross-pollination and those produced by self-pollination, although this may be attributable to low sample sizes available for self-pollinated fruits. These results in combination with morphological features of the flower suggest that a pollinator is required for this species.

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