Where does dominance collide?

In genetics, dominance is the relationship between two alleles at a locus in which the effect of one, the dominant allele, masks the contribution of the other, the recessive allele, so that a heterozygote resembles one homozygote rather than falling between the two. Wright's 1934 Physiological and evolutionary theories of dominance examined why dominance arises, treating it as a property of how gene products act in a metabolic pathway rather than as a fixed rank of the alleles themselves. The referent is a within-locus relation between alleles, read from the phenotype of a heterozygote, and it has nothing to do with an animal's place in a social order, an ordering of risky options, or the abundance of a species in a community.[1]

Unit

A masking relation between two alleles at one locus, seen in the heterozygote

Recovery means

Not applicable

Measured by

Established from crosses and segregation ratios, or from the phenotype of heterozygotes relative to the two homozygotes

In ethology and behavioural ecology, dominance is an animal's position in a hierarchy of priority of access, established and maintained through repeated agonistic encounters, so that a higher-ranked individual reliably prevails over a lower-ranked one over contested resources. Schjelderup-Ebbe's 1922 Beiträge zur Sozialpsychologie des Haushuhns described this ordering in domestic hens as the pecking order, in which each bird has a settled place relative to the others. The referent is a relational rank between individuals in a group, inferred from who yields to whom, and it is distinct from a relation between alleles, an ordering of uncertain prospects, or the predominance of one species over others.[2]

Unit

A rank in a group's order of priority of access, relative to other members

Recovery means

After disruption, such as removing a member, the order is re-established through renewed encounters, which can change the ranks

Measured by

Scored from the direction and outcome of agonistic interactions, often as a matrix of wins and losses that is then ranked

In decision theory and statistics, stochastic dominance is an ordering between two random prospects that holds when one is at least as good as the other for every decision maker in a broad class, without needing their exact utilities: first-order dominance compares the cumulative distributions at every outcome, and higher orders weaken the requirement. Hadar and Russell's 1969 Rules for ordering uncertain prospects set out these rules for ranking gambles by their whole distributions rather than by mean and variance alone. The referent is a partial order over probability distributions, defined by an integral condition, and it shares nothing with a relation between alleles, a rank in an animal group, or the abundance of a species beyond the word.[3]

Unit

A partial order over two distributions, holding across a class of decision makers

Recovery means

Not applicable

Measured by

Checked by comparing the cumulative distribution functions, or their successive integrals for higher orders, over the range of outcomes

In community ecology, dominance is the degree to which one or a few species account for the bulk of a community's biomass, abundance, or cover, so that the community's structure and function are disproportionately shaped by those dominant species. McNaughton and Wolf's 1970 Dominance and the niche in ecological systems examined how dominant species tend to occupy the broadest niches and how dominance is distributed among the species present. The referent is a property of a whole assemblage, summarising how unevenly abundance is spread across species, and it is unrelated to a masking relation between alleles, a social rank among animals, or an ordering of risky prospects.[4]

Unit

The share of a community's abundance or biomass held by its commonest species

Recovery means

Not applicable

Measured by

Quantified by dominance and evenness indices computed from the relative abundances of the species in a sample