Can Evolution Supply What Ecology Demands?

Adaptation to a changing environment is far from simple. 

Ecological demands on populations can vary temporally and spatially.

Likewise, the supply of genetic and epigenetic variation is inherently complex.

Supply and demands can interact and alter evolutionary trajectories.

To track and predict adaptation,we need better integration across disciplines.

1. Supply and Demand in a Changing World
2. Complex and Changing Demands
3. The Supply Side: When and How Does It Work?
4. Genetic Variation
5. Genetic Architecture
6. Epigenetics, Plasticity, and Parental Effects
7. Concluding Remarks

 

遗传结构（Genetic Architecture）可以揭示群体的简化潜力。

Constraints on Evolvability. Fitness gradient from low (blue) to high (yellow) is plotted as a function of two phenotypic traits. Red points correspond to the phenotypic values of individuals currently present in the population and white points refer to the phenotypic values that could result from mutation and recombination. (A) Available and potential supply allows for adaptation. (B) Available supply (red points) is restricted, and adaptation relies on generating new individuals with different trait values (white points), which in turn is dependent on population size and structure, mutation, and recombination rate. (C) Available and potential supply is restricted, for example, due to genetic architecture or antagonistic selection acting on traits, and thus adaptation is constrained. (D) Variation in current and potential phenotypes exist, but not in the direction required for adaptation.

Glossary 

• Additive genetic variation: component of trait variation that is the result of the additive effects of genes.
• Bottlenecks: severe reduction in population size.
• Cryptic genetic variation: standing genetic variation that has little or no effect on phenotypic variation under normal conditions, but generates heritable phenotypic variation under changed environmental or genetic conditions.
• Epiallele: a pair (or group) of identical genes that differ in their methylation.
• Epimutation: a heritable change in gene activity not associated with a change in the DNA sequence but with modification of, for example,methylation status or modification of chromatin.
• Evolvability: the ability of a population to undergo adaptive evolution.
• Genetic drift: changes in allele frequencies due to random sampling from one generation to the next.
• Genetic hitchhiking:allele frequency change of probable neutral locus that is genetically linked to a locus under selection.
• Genetic variation: differences in DNA sequence between individuals. 
• Hill–Robertson effect:the probability of fixation of a beneficial mutation can be limited because it finds itself in linkage disequilibrium with a deleterious mutation.
• Linkage disequilibrium:nonrandom association of alleles at two or more loci.
• Linked selection:change of the allele frequency of loci genetically linked to a locus under selection. Includes allele frequency change due to any action of selection positive selection or negative/purifying selection (also referred to as background selection).
• Locus/Loci:a position in the genome, could be a single nucleotide position or 1000s of base pairs of DNA sequence, it can correspond to a gene or many 100s of genes. 
• Mutation: a permanent change in the DNA sequence of an individual.
• Mutational load: reduction in fitness due to deleterious mutations carried by a population
• Robustness: the ability of a phenotype to resist perturbation by mutations (or the environment).