{'fraction_non_alphanumeric': 0.02328201276755539, 'fraction_numerical': 0.012016522718738265, 'mean_word_length': 5.312796208530806, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
An Extension of the Orians-Verner-Willson Model to Account for Mating Systems Besides Polygyny

The most influential model on the evolution of mating systems in birds, the Orians-Verner-Willson model for the evolution of polygyny, is a sexual selection model (Verner 1966; Orians 1969). The applicability of this model to an understanding of mammalian mating systems is suspect (Ralls 1977); nevertheless, the Orians-Verner-Willson formulation has led to further elaboration (Wittenberger 1976) and its assumptions have been supported (Pleszczynska 1978). Here I elaborate and generalize the Orians-Verner-Willson model to account for mating systems other than polygyny. I concentrate primarily on birds; however, I believe the reasoning of the model is applicable to mammals and probably to other vertebrate classes. Like the Orians-Verner-Willson model, the extension of this model is based on the assumption that any mating pattern will usually be more advantageous for one individual than another. Given this assumption, the presence or absence of a particular mating pattern must depend primarily upon the advantages and disadvantages to the least advantaged individual in that particular reproductive unit. It differs from the Orians-Verner-Willson model in that it accounts for the evolution of mating systems besides polygyny. It theoretically predicts the relationship of one mating system to another. It differentiates types of polygyny and polyandry based on the numbers of adults cooperating in parental activities. This model is capable of generating predictions independent of the Orians-Verner-Willson model such as predictions concerning preadaptations for polyandry by adults cooperating at one nest. The model is based on definitions of mating systems that stress the essential competitive nature of many evolutionary aspects of mating interaction between the sexes. Names of mating systems and gametic contribution ratios.-There is no general agreement on what to call or how to differentiate particular mating systems. Common names of mating systems include monogamy, types of polygamy (polygyny and polyandry), and promiscuity. Typically, these terms have been defined with reference to the duration and quality of the pair bond (Lack 1968; Selander 1972) or to resources (Emlen and Oring 1977). Here four names of mating systems and modifiers are used. The modifiers are simultaneous, sequential, and cooperative. Simultaneous refers to breeding and parenting activities with two or more mates at the same time though not at the same nest. Sequential refers to mating and parenting which occurs without significant overlap between successive