Natural selection and functional genetic variation in the p53 pathway

Species populations commonly carry a great deal of genetic variation which is not expressed in individual phenotypes. Cryptic variation can be carried in recessive alleles, in cases of heterosis, or where modifier genes inhibit expression of the hidden trait. Other genetic and ecological factors also allow cryptic variation. Stabilizing selection prevents the expression of hidden traits; normalizing selection weeds out the deviants and canalizing selection suppresses their traits. Together the two keep the species near the top of the adaptive peak. Cryptic variation balances a species' need to be well-adapted to its environment and also for it to maintain a reserve of variation for potential environmental change. Expression of cryptic traits is rare and is usually associated with times of greatly reduced natural selection and rapid population growth, when the lower slopes of the adaptive peak are exposed.A possible example of the manifestation of cryptic traits occurs within the lower Trentonian Rafinesquina lineage of New York State. The two most commonly reported species of the genus have been reappraised in terms of cryptic variation. Extensive collections of Rafinesquina “lennoxensis” reveal far more intergrading morphotypes than had hitherto been recognized. The form which Salmon (1942) described is broadly U-shaped with sulcate margins. It grades into very convex forms as well as sharply-defined or convexly geniculate types. Of great importance, all forms grade into the flat, U-shaped, alate R. trentonensis, which is, by far, the most common and widespread lower Trentonian member of the genus. The R. “lennoxensis” assemblage has a very narrow biostratigraphy, being confined to a few locations in the upper Napanee Limestone. This places it in a quiet, protected, low stress, lagoonal setting behind the barrier shoal facies of the Kings Falls Limestone.The R. “lennoxensis” assemblage does not constitute a natural biologic species; it is reinterpreted as an assemblage of phenodeviants occupying a low stress, low natural selection lagoon facies. All such forms should be included within R. trentonensis. Given the evolutionary plasticity of this genus, extensive cryptic variation is not surprising.

Download Full-text

Evolution and evolvability: celebrating Darwin 200

Biology Letters ◽

10.1098/rsbl.2008.0639 ◽

2008 ◽

Vol 5 (1) ◽

pp. 44-46 ◽

Cited By ~ 33

Author(s):

John F.Y Brookfield

Keyword(s):

Genetic Variation ◽

Natural Selection ◽

Time Scales ◽

Evolutionary Change ◽

Adaptive Mutation ◽

Genetic Covariances ◽

The Relationship ◽

The Way

The concept of ‘evolvability’ is increasingly coming to dominate considerations of evolutionary change. There are, however, a number of different interpretations that have been put on the idea of evolvability, differing in the time scales over which the concept is applied. For some, evolvability characterizes the potential for future adaptive mutation and evolution. Others use evolvability to capture the nature of genetic variation as it exists in populations, particularly in terms of the genetic covariances between traits. In the latter use of the term, the applicability of the idea of evolvability as a measure of population's capacity to respond to natural selection rests on one, but not the only, view of the way in which we should envisage the process of natural selection. Perhaps the most potentially confusing aspects of the concept of evolvability are seen in the relationship between evolvability and robustness.

Download Full-text

The genomics of adaptation

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.2322 ◽

2012 ◽

Vol 279 (1749) ◽

pp. 5024-5028 ◽

Cited By ~ 35

Author(s):

Jacek Radwan ◽

Wiesław Babik

Keyword(s):

Genetic Variation ◽

Natural Selection ◽

Royal Society ◽

Genetic Basis ◽

Genomic Data ◽

Evolutionary Change ◽

Introductory Article ◽

Technological Advances ◽

A Genome ◽

Genome Level

The amount and nature of genetic variation available to natural selection affect the rate, course and outcome of evolution. Consequently, the study of the genetic basis of adaptive evolutionary change has occupied biologists for decades, but progress has been hampered by the lack of resolution and the absence of a genome-level perspective. Technological advances in recent years should now allow us to answer many long-standing questions about the nature of adaptation. The data gathered so far are beginning to challenge some widespread views of the way in which natural selection operates at the genomic level. Papers in this Special Feature of Proceedings of the Royal Society B illustrate various aspects of the broad field of adaptation genomics. This introductory article sets up a context and, on the basis of a few selected examples, discusses how genomic data can advance our understanding of the process of adaptation.

Download Full-text

Functional genetic variation in the Rev-Erbαpathway and lithium response in the treatment of bipolar disorder

Genes Brain & Behavior ◽

10.1111/j.1601-183x.2011.00725.x ◽

2011 ◽

Vol 10 (8) ◽

pp. 852-861 ◽

Cited By ~ 61

Author(s):

M. J. McCarthy ◽

C. M. Nievergelt ◽

T. Shekhtman ◽

D. F. Kripke ◽

D. K. Welsh ◽

...

Keyword(s):

Bipolar Disorder ◽

Genetic Variation ◽

Functional Genetic Variation ◽

Lithium Response

Download Full-text

A functional genetic variation of SLC6A2 repressor hsa-miR-579-3p upregulates sympathetic noradrenergic processes of fear and anxiety

Translational Psychiatry ◽

10.1038/s41398-018-0278-4 ◽

2018 ◽

Vol 8 (1) ◽

Cited By ~ 5

Author(s):

L. G. Hommers ◽

J. Richter ◽

Y. Yang ◽

A. Raab ◽

C. Baumann ◽

...

Keyword(s):

Genetic Variation ◽

Functional Genetic Variation ◽

Fear And Anxiety

Download Full-text

Evidence of between-population differences in natural selection on extra-floral nectaries of the shrub Anemopaegma album (Bignoniaceae)

Botany ◽

10.1139/cjb-2015-0201 ◽

2016 ◽

Vol 94 (3) ◽

pp. 201-213

Author(s):

Anselmo Nogueira ◽

Pedro J. Rey ◽

Julio M. Alcántara ◽

Lúcia G. Lohmann

Keyword(s):

Genetic Variation ◽

Natural Selection ◽

Evolutionary Ecology ◽

Common Garden ◽

Phenotypic Selection ◽

Population Differences ◽

Wild Populations ◽

Neotropical Savanna ◽

Foliar Damage ◽

Floral Nectaries

Extra-floral nectaries (EFNs) are thought to represent protective adaptations against herbivory, but studies on the evolutionary ecology of EFNs have seldom been conducted. Here we investigate the patterns of natural selection and genetic variation in EFN traits in two wild populations of Anemopaegma album Mart. ex DC. (Bignoniaceae) that have been previously described as contrasting EFN – ant adapted localities in the Neotropical savanna (Cristália and Grão Mogol). In each population, four EFN descriptors, foliar damage, and reproductive success variables were measured per plant (100–120 plants per population). To estimate the heritability of EFN traits, we crossed reproductive plants in the field, and grew offspring plants in a common garden. The results showed that ant assemblages differed between populations, as did the range of foliar herbivory. Genetic variation and positive phenotypic selection in EFN abundance were only detected in the Cristália population, in which plants with more EFNs were more likely to reproduce. An evaluation of putative causal links conducted by path analysis corroborated the existence of phenotypic selection on EFNs, which was mediated by the herbivory process in the Cristália population. While EFNs could be currently under selection in Cristália, it is possible that past selection may have driven EFN traits to become locally adapted to the local ant assemblage in the Grão Mogol population.

Download Full-text

The crucial role of genome-wide genetic variation in conservation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2104642118 ◽

2021 ◽

Vol 118 (48) ◽

pp. e2104642118

Author(s):

Marty Kardos ◽

Ellie E. Armstrong ◽

Sarah W. Fitzpatrick ◽

Samantha Hauser ◽

Philip W. Hedrick ◽

...

Keyword(s):

Genetic Variation ◽

Environmental Changes ◽

Population Viability ◽

Adaptive Potential ◽

Biodiversity Crisis ◽

Genome Wide ◽

Simulation Based ◽

Functional Genetic Variation

The unprecedented rate of extinction calls for efficient use of genetics to help conserve biodiversity. Several recent genomic and simulation-based studies have argued that the field of conservation biology has placed too much focus on conserving genome-wide genetic variation, and that the field should instead focus on managing the subset of functional genetic variation that is thought to affect fitness. Here, we critically evaluate the feasibility and likely benefits of this approach in conservation. We find that population genetics theory and empirical results show that conserving genome-wide genetic variation is generally the best approach to prevent inbreeding depression and loss of adaptive potential from driving populations toward extinction. Focusing conservation efforts on presumably functional genetic variation will only be feasible occasionally, often misleading, and counterproductive when prioritized over genome-wide genetic variation. Given the increasing rate of habitat loss and other environmental changes, failure to recognize the detrimental effects of lost genome-wide genetic variation on long-term population viability will only worsen the biodiversity crisis.

Download Full-text