scholarly journals Additive genetic variance for lifetime fitness and the capacity for adaptation in an annual plant

2019 ◽  
Author(s):  
Mason W. Kulbaba ◽  
Seema N. Sheth ◽  
Rachel E. Pain ◽  
Vince M. Eckhart ◽  
Ruth G. Shaw
Keyword(s):  
Genetic Variance ◽  
Experimental Approach ◽  
Additive Genetic Variance ◽  
Chamaecrista Fasciculata ◽  
Evolutionary Rescue ◽  
Declining Populations ◽  
In The Wild ◽  
Population Sustainability ◽  
Mean Fitness ◽  
Fisher’S Fundamental Theorem

AbstractThe immediate capacity for adaptation under current environmental conditions is directly proportional to the additive genetic variance for fitness, VA(W). Mean absolute fitness, , is predicted to change at the rate , according to Fisher’s Fundamental Theorem of Natural Selection. Despite ample research evaluating degree of local adaptation, direct assessment of VA(W) and the capacity for ongoing adaptation is exceedingly rare. We estimated VA(W) and in three pedigreed populations of annual Chamaecrista fasciculata, over three years in the wild. Contrasting with common expectations, we found significant VA(W) in all populations and years, predicting increased mean fitness in subsequent generations (0.83 to 6.12 seeds per individual). Further, we detected two cases predicting “evolutionary rescue”, where selection on standing VA(W) was expected to increase fitness of declining populations ( < 1.0) to levels consistent with population sustainability and growth. Within populations, interannual differences in genetic expression of fitness were striking. Significant genotype-by-year interactions reflected modest correlations between breeding values across years (all r < 0.490), indicating temporally variable selection at the genotypic level; that could contribute to maintaining VA(W). By directly estimating VA(W) and total lifetime , our study presents an experimental approach for studies of adaptive capacity in the wild.

The Contemporary Evolution of Fitness

2018 ◽  
Vol 49 (1) ◽  
pp. 457-476 ◽  
Author(s):  
Andrew P. Hendry ◽  
Daniel J. Schoen ◽  
Matthew E. Wolak ◽  
Jane M. Reid
Keyword(s):  
Genetic Variance ◽  
Evolutionary Dynamics ◽  
Additive Genetic Variance ◽  
Deleterious Mutations ◽  
Contemporary Evolution ◽  
Evolutionary Potential ◽  
Empirical Estimates ◽  
Evolutionary Rescue ◽  
Proportional Change ◽  
Mean Fitness

The rate of evolution of population mean fitness informs how selection acting in contemporary populations can counteract environmental change and genetic degradation (mutation, gene flow, drift, recombination). This rate influences population increases (e.g., range expansion), population stability (e.g., cryptic eco-evolutionary dynamics), and population recovery (i.e., evolutionary rescue). We review approaches for estimating such rates, especially in wild populations. We then review empirical estimates derived from two approaches: mutation accumulation (MA) and additive genetic variance in fitness (IAw). MA studies inform how selection counters genetic degradation arising from deleterious mutations, typically generating estimates of <1% per generation. IAw studies provide an integrated prediction of proportional change per generation, nearly always generating estimates of <20% and, more typically, <10%. Overall, considerable, but not unlimited, evolutionary potential exists in populations facing detrimental environmental or genetic change. However, further studies with diverse methods and species are required for more robust and general insights.

scholarly journals Variation in founder groups promotes establishment success in the wild

2012 ◽  
Vol 279 (1739) ◽  
pp. 2800-2806 ◽  
Author(s):  
Anders Forsman ◽  
Lena Wennersten ◽  
Magnus Karlsson ◽  
Sofia Caesar
Keyword(s):  
Environmental Changes ◽  
Colour Morph ◽  
Natural Conditions ◽  
Establishment Success ◽  
Evolutionary Rescue ◽  
Reproductive Life ◽  
Declining Populations ◽  
In The Wild ◽  
Colour Morphs ◽  
Founder Group

Environmental changes currently pose severe threats to biodiversity, and reintroductions and translocations are increasingly used to protect declining populations and species from extinction. Theory predicts that establishment success should be higher for more variable groups of dissimilar individuals. To test this ‘diversity promotes establishment’ hypothesis, we introduced colour polymorphic pygmy grasshoppers ( Tetrix subulata ) to different sites in the wild. The number of descendants found at the release sites the subsequent year increased with increasing number of colour morphs in the founder group, and variation in founder groups also positively affected colour morph diversity in the established populations. Since colour morphs differ in morphology, physiology, behaviour, reproductive life history and types of niche used, these findings demonstrate that variation among individuals in functionally important traits promotes establishment success under natural conditions, and further indicate that founder diversity may contribute to evolutionary rescue and increased population persistence.

scholarly journals The Origin of Additive Genetic Variance Driven by Positive Selection

2020 ◽  
Vol 37 (8) ◽  
pp. 2300-2308
Author(s):  
Li Liu ◽  
Yayu Wang ◽  
Di Zhang ◽  
Zhuoxin Chen ◽  
Xiaoshu Chen ◽  
...  
Keyword(s):  
Natural Selection ◽  
Positive Selection ◽  
Fundamental Theorem ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Adaptive Divergence ◽  
Population Admixture ◽  
Simple Explanation ◽  
Additive Variance ◽  
Fisher’S Fundamental Theorem

Abstract Fisher’s fundamental theorem of natural selection predicts no additive variance of fitness in a natural population. Consistently, studies in a variety of wild populations show virtually no narrow-sense heritability (h2) for traits important to fitness. However, counterexamples are occasionally reported, calling for a deeper understanding on the evolution of additive variance. In this study, we propose adaptive divergence followed by population admixture as a source of the additive genetic variance of evolutionarily important traits. We experimentally tested the hypothesis by examining a panel of ∼1,000 yeast segregants produced by a hybrid of two yeast strains that experienced adaptive divergence. We measured &gt;400 yeast cell morphological traits and found a strong positive correlation between h2 and evolutionary importance. Because adaptive divergence followed by population admixture could happen constantly, particularly in species with wide geographic distribution and strong migratory capacity (e.g., humans), the finding reconciles the observation of abundant additive variances in evolutionarily important traits with Fisher’s fundamental theorem of natural selection. Importantly, the revealed role of positive selection in promoting rather than depleting additive variance suggests a simple explanation for why additive genetic variance can be dominant in a population despite the ubiquitous between-gene epistasis observed in functional assays.

scholarly journals Genotype-environment interactions and the maintenance of polygenic variation.

Genetics ◽  
1989 ◽  
Vol 121 (1) ◽  
pp. 129-138 ◽  
Author(s):  
J H Gillespie ◽  
M Turelli
Keyword(s):  
Genetic Variance ◽  
Balancing Selection ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Extensive Literature ◽  
Multilocus Genotype ◽  
Polygenic Inheritance ◽  
Mean Fitness ◽  
The Mean ◽  
Polygenic Variation

Abstract Genotype-environment interactions may be a potent force maintaining genetic variation in quantitative traits in natural populations. This is shown by a simple model of additive polygenic inheritance in which the additive contributions of alleles vary with the environment. Under simplifying symmetry assumptions, the model implies that the variance of the phenotypes produced across environments by a multilocus genotype decreases as the number of heterozygous loci increases. In the region of an optimal phenotype, the mapping from the quantitative trait into fitness is concave, and the mean fitness of a genotype will increase with the number of heterozygous loci. This leads to balancing selection, polymorphism, and potentially high levels of additive genetic variance, even though all allelic effects remain additive within each specific environment. An important implication of the model is that the variation maintained by genotype-environment interactions is difficult to study with the restricted range of environments represented in typical experiments. In particular, if fluctuations in allelic effects are pervasive, as suggested by the extensive literature on genotype-environment interactions, efforts to estimate genetic parameters in a single environment may be of limited value.

scholarly journals Joint phenotypes, evolutionary conflict and the fundamental theorem of natural selection

2014 ◽  
Vol 369 (1642) ◽  
pp. 20130423 ◽  
Author(s):  
David C. Queller
Keyword(s):  
Natural Selection ◽  
Species Interactions ◽  
Fundamental Theorem ◽  
Genetic Variance ◽  
Inclusive Fitness ◽  
Evolutionary Conflict ◽  
Mean Fitness ◽  
The Mean ◽  
Multiple Species ◽  
Fisher’S Fundamental Theorem

Multiple organisms can sometimes affect a common phenotype. For example, the portion of a leaf eaten by an insect is a joint phenotype of the plant and insect and the amount of food obtained by an offspring can be a joint trait with its mother. Here, I describe the evolution of joint phenotypes in quantitative genetic terms. A joint phenotype for multiple species evolves as the sum of additive genetic variances in each species, weighted by the selection on each species. Selective conflict between the interactants occurs when selection takes opposite signs on the joint phenotype. The mean fitness of a population changes not just through its own genetic variance but also through the genetic variance for its fitness that resides in other species, an update of Fisher's fundamental theorem of natural selection. Some similar results, using inclusive fitness, apply to within-species interactions. The models provide a framework for understanding evolutionary conflicts at all levels.

scholarly journals The source of additive genetic variance of evolutionarily important traits

2019 ◽  
Author(s):  
Li Liu ◽  
Yayu Wang ◽  
Di Zhang ◽  
Xiaoshu Chen ◽  
Zhijian Su ◽  
...  
Keyword(s):  
Natural Selection ◽  
Fundamental Theorem ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Adaptive Divergence ◽  
Population Admixture ◽  
Strong Positive Correlation ◽  
Narrow Sense Heritability ◽  
Additive Variance ◽  
Fisher’S Fundamental Theorem

AbstractFisher’s fundamental theorem of natural selection predicts no additive variance of fitness in a natural population. Consistently, observations in a variety of wild populations show virtually no narrow-sense heritability (h2) for traits important to fitness. However, counterexamples are occasionally reported, calling for a deeper understanding on the evolution of additive variance. In this study we propose adaptive divergence followed by population admixture as a source of the additive genetic variance of evolutionarily important traits. We experimentally tested the hypothesis by examining a panel of ~1,000 yeast segregants produced by a hybrid of two yeast strains that experienced adaptive divergence. We measured over 400 yeast cell morphological traits and found a strong positive correlation between h2 and evolutionary importance. Because adaptive divergence followed by population admixture could happen constantly, particularly in some species such as humans, the finding reconciles the observation of abundant additive variances in evolutionarily important traits with Fisher’s fundamental theorem of natural selection. It also suggests natural selection may effectively promote rather than suppress additive genetic variance in species with wide geographic distribution and strong migratory capacity.

scholarly journals The quantitative genetics of fitness in a wild bird population

2021 ◽  
Author(s):  
Maria Moiron ◽  
Anne Charmantier ◽  
Sandra Bouwhuis
Keyword(s):  
Reproductive Success ◽  
Genetic Variance ◽  
Evolutionary Ecology ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Common Tern ◽  
Adult Survival ◽  
Lifetime Fitness ◽  
Mean Fitness ◽  
Change In Mean

Additive genetic variance in fitness equals the change in mean fitness due to selection. It is a prerequisite for adaptation, as a trait must be genetically correlated with fitness in order to evolve. Despite its relevance, additive genetic variance in fitness has not often been estimated in wild populations. Here, we investigate additive genetic variance in lifetime fitness, as well as its underlying components, in common terns (Sterna hirundo). Using a series of animal models applied to 28 years of data comprising ca. 6000 pedigreed individuals, we find nominally zero additive genetic variance in the Zero-inflated component of lifetime fitness, and low but unreliable variance in the Poisson component. We also find low but likely nonzero additive genetic variance in adult annual reproductive success, but not in survival. As such, our study (i) suggests heritable variance in common tern fitness to result mostly from heritable variance in reproductive success, rather than in early-life or adult survival, (ii) shows how studying the genetic architecture of fitness in natural populations remains challenging, and (iii) highlights the importance of maintaining long-term individual-based studies such that a major research aim in evolutionary ecology will come within better reach in the next decade.

scholarly journals A Genome Scan for Quantitative Trait Loci in a Wild Population of Red Deer (Cervus elaphus)

Genetics ◽  
2002 ◽  
Vol 162 (4) ◽  
pp. 1863-1873 ◽  
Author(s):  
J Slate ◽  
P M Visscher ◽  
S MacGregor ◽  
D Stevens ◽  
M L Tate ◽  
...  
Keyword(s):  
Quantitative Trait Loci ◽  
Cervus Elaphus ◽  
Quantitative Trait ◽  
Red Deer ◽  
Wild Population ◽  
Additive Genetic Variance ◽  
Model Organisms ◽  
A Genome ◽  
Trait Loci ◽  
In The Wild

Abstract Recent empirical evidence indicates that although fitness and fitness components tend to have low heritability in natural populations, they may nonetheless have relatively large components of additive genetic variance. The molecular basis of additive genetic variation has been investigated in model organisms but never in the wild. In this article we describe an attempt to map quantitative trait loci (QTL) for birth weight (a trait positively associated with overall fitness) in an unmanipulated, wild population of red deer (Cervus elaphus). Two approaches were used: interval mapping by linear regression within half-sib families and a variance components analysis of a six-generation pedigree of &gt;350 animals. Evidence for segregating QTL was found on three linkage groups, one of which was significant at the genome-wide suggestive linkage threshold. To our knowledge this is the first time that a QTL for any trait has been mapped in a wild mammal population. It is hoped that this study will stimulate further investigations of the genetic architecture of fitness traits in the wild.

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