scholarly journals Understanding specialism when the jack of all trades can be the master of all

2012 ◽  
Vol 279 (1749) ◽  
pp. 4861-4869 ◽  
Author(s):  
Susanna Remold
Keyword(s):  
Habitat Use ◽  
Recent Work ◽  
Habitat Change ◽  
Directional Selection ◽  
Antagonistic Pleiotropy ◽  
Disease Emergence ◽  
Evolutionary Genetic ◽  
The Face ◽  
Genetic Mechanisms ◽  
Selection For

Specialism is widespread in nature, generating and maintaining diversity, but recent work has demonstrated that generalists can be equally fit as specialists in some shared environments. This no-cost generalism challenges the maxim that ‘the jack of all trades is the master of none’, and requires evolutionary genetic mechanisms explaining the existence of specialism and no-cost generalism, and the persistence of specialism in the face of selection for generalism. Examining three well-described mechanisms with respect to epistasis and pleiotropy indicates that sign (or antagonistic) pleiotropy without epistasis cannot explain no-cost generalism and that magnitude pleiotropy without epistasis (including directional selection and mutation accumulation) cannot explain the persistence of specialism. However, pleiotropy with epistasis can explain all. Furthermore, epistatic pleiotropy may allow past habitat use to influence future use of novel environments, thereby affecting disease emergence and populations' responses to habitat change.

scholarly journals The Evolution of Genomic Imprinting via Variance Minimization: An Evolutionary Genetic Model

Genetics ◽  
2003 ◽  
Vol 165 (1) ◽  
pp. 205-222
Author(s):  
Anton E Weisstein ◽  
Hamish G Spencer
Keyword(s):  
Genomic Imprinting ◽  
Genetic Model ◽  
Genetic System ◽  
Deleterious Mutations ◽  
Variance Minimization ◽  
Genetic Conflict ◽  
Evolutionary Genetic ◽  
The Face ◽  
Alternative Hypotheses ◽  
Selection For

Abstract A small number of mammalian loci exhibit genomic imprinting, in which only one copy of a gene is expressed while the other is silenced. At some such loci, the maternally inherited allele is inactivated; others show paternal inactivation. Several hypotheses have been put forward to explain how this genetic system could have evolved in the face of the selective advantages of diploidy. In this study, we examine the variance-minimization hypothesis, which proposes that imprinting arose through selection for reduced variation in levels of gene expression. We present an evolutionary genetic model incorporating both this selection pressure and deleterious mutations to elucidate the conditions under which imprinting could evolve. Our analysis implies that additional mechanisms such as genetic drift are required for imprinting to evolve from an initial nonimprinting state. Other predictions of this hypothesis do not appear to fit the available data as well as predictions for two alternative hypotheses, genetic conflict and the ovarian time bomb. On the basis of this evidence, we conclude that the variance-minimization hypothesis appears less adequate to explain the evolution of genomic imprinting.

scholarly journals Evolutionary Genetic Models of the Ovarian Time Bomb Hypothesis for the Evolution of Genomic Imprinting

Genetics ◽  
2002 ◽  
Vol 162 (1) ◽  
pp. 425-439 ◽  
Author(s):  
Anton E Weisstein ◽  
Marcus W Feldman ◽  
Hamish G Spencer
Keyword(s):  
Growth Factor ◽  
Genetic System ◽  
Early Embryogenesis ◽  
Genetic Models ◽  
Insulin Like Growth Factor ◽  
Deleterious Mutations ◽  
Trophoblastic Disease ◽  
Evolutionary Genetic ◽  
The Face ◽  
Selection For

Abstract At a small number of loci in eutherian mammals, only one of the two copies of a gene is expressed; the other is silenced. Such loci are said to be “imprinted,” with some having the maternally inherited allele inactivated and others showing paternal inactivation. Several hypotheses have been proposed to explain how such a genetic system could evolve in the face of the selective advantages of diploidy. In this study, we examine the “ovarian time bomb” hypothesis, which proposes that imprinting arose through selection for reduced risk of ovarian trophoblastic disease in females. We present three evolutionary genetic models that incorporate both this selection pressure and the effect of deleterious mutations to elucidate the conditions under which imprinting could evolve. Our findings suggest that the ovarian time bomb hypothesis can explain why some growth-enhancing genes active in early embryogenesis [e.g., mouse insulin-like growth factor 2 (Igf2)] have evolved to be maternally rather than paternally inactive and why the opposite imprinting status has evolved at some growth-inhibiting loci [e.g., mouse insulin-like growth factor 2 receptor (Igf2r)].

Paracelsus’ 16 th Century Philosophy Applied to Current Evolutionary Genetics

2017 ◽  
Author(s):  
Jenna Kewin
Keyword(s):  
Sixteenth Century ◽  
Intimate Relationships ◽  
Genetic Disease ◽  
Genetic Research ◽  
Evolutionary Genetics ◽  
Immunodeficiency Virus ◽  
Evolutionary Genetic ◽  
Health And Disease ◽  
Potential Impact ◽  
Selection For

Paracelsus contributed greatly to medical philosophy in the early sixteenth century, yet his reputation was so tainted by his hypocrisy that he left few followers and is often forgotten. Many aspects of his teachings, however, can be applied to current theories governing evolutionary genetic research. His claim, “Where diseases arise, one can also find the roots of health” hints at the intimate relationships between health and  disease that are the foundations of fascinating research. In many devastating medical cases, it has been  found that expression of one genetic disease can confer resistance for another. Sickle­cell anemia sufferers have an increased resistance to malaria, cystic fibrosis is associated with decreased susceptibility to  influenza, tuberculosis and cholera, and even the human immunodeficiency virus (HIV­1) is theorized to  have stemmed from a selection for resistance to the Bubonic Plague. These examples demonstrate the ambiguities in distinguishing between health and disease. While scientists today would likely scoff at Paracelsus’ dated medical rants, when they discover a disease favoured by natural selection, one of the first questions is how it could have conferred a benefit ancestrally. Applying Paracelsus’ theories to a discipline as contrary to evolutionary genetics demonstrates both the robustness of his claims, and the potential impact philosophy can have on medical, scientific and sociological questions surrounding challenging  epidemics

When and How Implicit First Impressions Can Be Updated

2019 ◽  
Vol 28 (4) ◽  
pp. 331-336 ◽  
Author(s):  
Melissa J. Ferguson ◽  
Thomas C. Mann ◽  
Jeremy Cone ◽  
Xi Shen
Keyword(s):  
Social Cognition ◽  
Recent Work ◽  
Social World ◽  
Theoretical Frameworks ◽  
Ongoing Research ◽  
Real People ◽  
The Social ◽  
The Face ◽  
Contradictory Evidence ◽  
Implicit And Explicit

Human perceivers continually react to the social world implicitly —that is, spontaneously and rapidly. Earlier research suggested that implicit impressions of other people are slower to change than self-reported impressions in the face of contradictory evidence, often leaving them miscalibrated from what one learns to be true. Recent work, however, has identified conditions under which implicit impressions can be rapidly updated. Here, we review three lines of work showing that implicit impressions are responsive to information that is highly diagnostic, believable, or reframes earlier experience. These findings complement ongoing research on mechanisms of changing implicit impressions in a wider variety of groups, from real people to robots, and provide support for theoretical frameworks that embrace greater unity in the factors that can impact implicit and explicit social cognition.

scholarly journals Selection for recombination in a polygenic model – the mechanism

1988 ◽  
Vol 51 (1) ◽  
pp. 59-63 ◽  
Author(s):  
J. Maynard Smith
Keyword(s):  
Linkage Disequilibrium ◽  
Recombination Rate ◽  
Phenotypic Variability ◽  
Directional Selection ◽  
Polygenic Model ◽  
Infinite Population ◽  
Selection For ◽  
Repulsion Linkage

SummaryA polygenic model has been simulated in order to reveal the process whereby selection in an infinite population can lead to an increase in the frequency of alleles causing higher rates of recombination (CH alleles). Directional selection generates repulsion linkage disequilibrium (+ − + −), which is less strong in CH gametes (gametes carrying CH alleles). In consequence, CH gametes contribute greater phenotypic variability, and therefore respond more to directional selection: that is, they accumulate more selectively favoured alleles. CH alleles then increase in frequency by hitch-hiking. In contrast, normalizing selection, or frequent changes in the direction of selection, favour alleles for a low recombination rate.

Holding ground in the face of invasion: native fence lizards (Sceloporus undulatus) do not alter their habitat use in response to introduced fire ants (Solenopsis invicta)

2009 ◽  
Vol 87 (7) ◽  
pp. 626-634 ◽  
Author(s):  
T. Langkilde
Keyword(s):  
Habitat Use ◽  
Solenopsis Invicta ◽  
Native Species ◽  
Fire Ants ◽  
Sceloporus Undulatus ◽  
The Face ◽  
Solenopsis Invicta Buren ◽  
The Usa ◽  
Adaptive Shifts ◽  
The Impact

The introduction of non-native species is becoming increasingly common. Understanding the impact of invaders on native populations is critical for effective management. Red imported fire ants ( Solenopsis invicta Buren, 1972) were introduced to the USA in the 1930s. They will attack, and can kill, native fence lizards ( Sceloporus undulatus (Bosc and Daudin in Sonnini and Latreille, 1801)), which co-occur with these ants across much of their invasive range. I determined whether fence lizards minimize encounters with S. invicta by altering their habitat use following invasion or avoiding cues of the presence of these fire ants. I recorded the habitat use of fence lizards and S. invicta mounds across four sites with different histories of invasion, and quantified lizard avoidance of S. invicta scent. I found that lizards do not alter their habitat use following S. invicta invasion, nor do they spatially avoid their mounds. Fence lizards do avoid S. invicta scent, but this was only evident in naïve or recently invaded populations. The lack of avoidance of S. invicta by fence lizards could be explained by the high prevalence of these fire ants, making them difficult to avoid, and adaptive shifts in the escape behaviour and morphology of these lizards following invasion that permit them to survive fire ant attack.

Habitat selection by the Puerto Rican yellow-chinned anole, Anolis gundlachi

2005 ◽  
Vol 83 (7) ◽  
pp. 983-988 ◽  
Author(s):  
Javier A Rodríguez-Robles ◽  
Manuel Leal ◽  
Jonathan B Losos
Keyword(s):  
Habitat Selection ◽  
Habitat Use ◽  
Puerto Rican ◽  
Visual Cues ◽  
Evolutionary Dynamics ◽  
Males And Females ◽  
Selection For ◽  
Free Ranging ◽  
Woody Substrates ◽  
Selection Of

Habitat selection can directly affect the fitness of an individual and the evolutionary dynamics of the population to which that organism belongs. We studied habitat use of the Puerto Rican yellow-chinned anole (Anolis gundlachi Peters, 1876) to examine whether this arboreal lizard uses its environment in a nonrandom manner. Males and females preferred woody vegetation substrates over nonwoody plants and sierra palms (Prestoea acuminata var. montana (Graham) A. Henderson and G. Galeano) as perching sites, and they also selected wider vegetation than what was randomly available. Selection for minimizing conspicuousness to potential predators and for increased locomotion capacity may help explain the preference for woody substrates and broader surfaces, respectively. Anolis gundlachi relies almost exclusively on visual cues for foraging and social interactions, and using wider perches also increases an individual's ability to scan a larger proportion of its territory. Our findings thus indicate that the nonrandom habitat use of free-ranging A. gundlachi leads to the selection of perching substrates that may increase performance of ecologically relevant capabilities.

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