Assortative mixing is a kind of sexual network characteristic that influences epidemic spread, mainly HIV. It simply means the extent to which individuals choose sexual partners who are similar in age, race, sexual orientation, marital status, socioeconomic status, religion, or locale. A sexual network is a social network that is defined by the sexual relationships between a set of individuals. ... In epidemiology, an epidemic (from Greek epi- upon + demos people) is a disease that appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is expected, based on recent experience (the number of new cases in the population during a... Human immunodeficiency virus, commonly known by the initialism HIV, formally known as HTLV-III and lymphadenopathy-associated virus, is a retrovirus that primarily infects vital components of the human immune system such as CD4+ T cells, macrophages and dendritic cells. ...
Assortative mixing is involved in the phenomenon of "super-spreaders" of sexually transmitted diseases; a small fraction of the population that is very sexually promiscuous can act as a conduit for the disease to spread within the group over wide distances, and from that group to other social groups. An example of this phenomenon is the population subgroup formed by truck drivers and prostitutes in Africa.
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Social network growth with assortative mixing (.pdf format)
Bibliography
Catanzaro, Michele; Caldarelli, Guido; Pietronero, Luciano. Social network growth with assortative mixing. Physica A, vol. 338, July 2004.
He assumed moderately assortativemixing (e.g., injecting drug users have sex with both injectors and non-injectors) and found that HIV saturation in the high-risk group occurred about forty years before saturation in the general population (assumed to be in a low-risk category).
Clearly, the key variable determining the spread of HIV is mixing: the more assortative the pattern of mixing, the less the degree of spread to the general, low-risk population.
However, even limited disassortative mixing (mixing with individuals from a different, or non-risk group) results in a sustained prevalence level in the general population for a period of many years.
Assortative mating.--In 1975, I accumulated 719 observations of pairs; 570 (79.3%) were dark pairs, 135 (18.8%) were light pairs, 10 (1.4%) were mixed pairs, and 4 (0.5%) pairs had 1 intermediate-phase bird (either D x I or L x I).
Both egg dumping and brood mixing could result in imprinting or conditioning by a given chick to an adult of the opposite color phase and thus increase the probability of that chick later seeking a mate of the opposite color phase.
Assortative mating by the polymorphic Snow Goose (Cooch and Beardmore 1959), however, indicates that such a mode of speciation is feasible, although genetic isolation by these geese has not reached a level to suggest speciation or strengthening of isolating mechanisms (Rockwell and Cooke 1977).
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