Vocabulary

What is a genotype-phenotype map?

A conceptual framework describing how genetic information (genotype) translates into observable traits (phenotype) through development.

Define pleiotropy.

A single gene influencing multiple phenotypic traits.

What is epistasis?

Interaction between genes where one gene affects the expression of another.

What is canalization?

The reduction of phenotypic variation despite genetic and environmental variation.

What is gene duplication?

A mutation that results in two copies of a gene, allowing one to evolve a new function.

What is subfunctionalization?

The process where duplicate genes divide the work of the ancestral gene.

What is neofunctionalization?

The process where a duplicated gene evolves a new function not present in the original gene.

What is antagonistic pleiotropy?

When one gene controls multiple traits that have opposite effects on fitness.

What are Hox genes?

A family of transcription factors that determine the body plan along the anterior-posterior axis in animals.

What does modularity in development refer to?

The organization of traits into modules that can evolve independently.

What is an evolutionary transition in individuality (ETI)?

A shift where a group of individuals evolves into a new evolutionary individual.

What is fitness decoupling?

The fitness of a group becomes independent of the average fitness of its individual members.

What is the germ-soma distinction?

The division between reproductive (germ) and non-reproductive (soma) cells.

Define individuality in an evolutionary context.

An integrated and indivisible entity capable of reproduction and subject to selection.

What is an example of increasing individuality in volvocine algae?

Evolution from Gonium (low individuality) to Volvox (high individuality) via steps like division of labor and germ-soma separation.

What is reorganization of fitness?

A process during ETIs where lower-level units give up some fitness to benefit the higher-level entity.

What is a hypercycle?

A system of cooperating molecular replicators that increase evolutionary individuality.

What is a pseudogene?

A duplicated gene that has lost its function.

What is the paradox of sex?

Sex is costly yet nearly universal among eukaryotes, prompting questions about its evolutionary benefit.

What is the 2-fold cost of males?

In sexual populations, only females bear offspring, effectively halving reproductive output.

What is recombination?

The breakage and rejoining of DNA to create genetic diversity.

What is Muller's Ratchet?

The irreversible accumulation of deleterious mutations in asexual populations.

What is the Fisher-Muller hypothesis?

Sex speeds up evolution by combining beneficial mutations.

What is the Red Queen hypothesis?

Ongoing coevolution with parasites maintains sex by favoring genetic diversity.

What is linkage disequilibrium (LD)?

A non-random association of alleles at different loci.

What is negative epistasis?

When the combined effect of beneficial mutations is less than additive, favoring recombination.

What is the DSBR model?

The double-strand break repair model explaining molecular recombination during meiosis.

Why did meiosis evolve from DNA repair mechanisms?

Recombination during meiosis repairs DNA damage, promoting genetic integrity across generations.

What is co-option?

The process by which an existing gene gains a new function, often due to being expressed in a new developmental context.

What are paralogs?

Genes that arise from duplication events and may evolve new functions.

What is the DDC model (Duplication-Degeneration-Complementation)?

A model explaining subfunctionalization where gene duplicates each retain part of the original gene's functions.

What is dominance in genetics?

The relationship between alleles where one masks the expression of another.

What are norms of reaction?

The range of phenotypes expressed by a single genotype across different environments.

What is an adaptive landscape?

A conceptual model where fitness is plotted as a function of genotype or phenotype.

What is cell inheritance in development?

The passing on of cell states and gene expression patterns through mitosis.

What are Darwinian properties?

Heritability, variation, and fitness — the three prerequisites for natural selection.

What is physiological integration?

The coordination among parts of a group to function as a unified whole.

What is a unicellular bottleneck?

A developmental stage where a multicellular organism passes through a single-cell stage, promoting genetic homogeneity.

What is an evolutionary individual?

A unit that is functionally integrated and has Darwinian properties at its level of organization.

What is the difference between group and individual level fitness?

Group fitness refers to the success of the whole group, while individual fitness refers to each member’s reproductive success.

What is gene conversion?

A non-reciprocal transfer of DNA sequence information during recombination.

What are Holliday junctions?

DNA structures formed during recombination that can lead to crossing over.

What is amphimixis?

The fusion of gametes from two parents during sexual reproduction.

What is negative linkage disequilibrium?

When favorable alleles are associated with unfavorable ones, creating a situation where recombination is beneficial.

What is facultative sex?

Organisms that can reproduce both sexually and asexually depending on environmental conditions.

What is recombinational repair?

Repair of DNA double-strand breaks using homologous sequences as templates, a mechanism also central to meiosis.

What are ROS (reactive oxygen species)?

Molecules that damage DNA and contribute to mutation, often driving the need for DNA repair mechanisms.

What is the “spin cycle” metaphor in sex evolution?

A metaphor for how sex and recombination "clean" genomes of deleterious mutations.