Sex in the Morning or in the Evening? Females Adjust Daily Mating Patterns to the Intensity of Sexual Harassment

Abstract

Selection on males to mate at a higher rate than females often results in male harassment of females and counteracting female responses. When the reproductive value of copulation changes over time, these mating strategies are expected to be time dependent. Here, we demonstrate that variation in the intensity of male harassment leads to drastic changes in female daily mating patterns. In feral populations of fowl Gallus gallus domesticus, male harassment is intense, particularly in the evening when inseminations are most likely to result in fertilization. We experimentally manipulated the intensity of male harassment through similar-sized groups of different sex ratios. Male mating propensity was always higher than females', particularly in male-biased groups and in the evening, when males were closer to and more likely to approach females. Females counteracted male harassment by escalating resistance to mating and-cruciallyby shifting their daily mating pattern: in strongly female-biased groups with relaxed sexual harassment, females solicited sex in the evening, while in male-biased groups, they solicited sex in the morning, thus avoiding harassment in the evening. Together, these results indicate that intersexual conflict may occur not only over mating rates but also over when in the day to copulate.

A cry for help: female distress calling during copulation is context dependent

“…The comb and status are the only male traits that are consistently demonstrated to affect female mate choice in the fowl Pizzari & Birkhead, 2000;Pizzari, 2001;Pizzari et al, 2002). Female precopulatory mate choice in the species is limited and males initiate most copulations (over 90%), often through sexual coercion (Pizzari, 2001;Løvlie & Pizzari, 2007). To avoid copulations, female fowl can to some extent affect the outcome of a mating attempt by showing direct resistance to males (Pizzari, 2001;Løvlie & Pizzari, 2007).…”

“…Female precopulatory mate choice in the species is limited and males initiate most copulations (over 90%), often through sexual coercion (Pizzari, 2001;Løvlie & Pizzari, 2007). To avoid copulations, female fowl can to some extent affect the outcome of a mating attempt by showing direct resistance to males (Pizzari, 2001;Løvlie & Pizzari, 2007).…”

“…Female remating propensity is clearly reduced when comparing first versus successive days of access to males and matings, after females have been sexually rested and housed without males for 14 days, which is the mean time for which females store sperm (Løvlie et al, 2005;Løvlie & Pizzari, 2007 and references therein). Therefore, females were housed in groups with multiple, sexually active males (more than five males not taking part in the experiment) up until 2 days prior to the experiment.…”

“…because of a lack of stored sperm). Males were sexually rested for a minimum of 2 days prior to the experiments to encourage mating propensity (Parker et al, 1942;Løvlie & Pizzari, 2007). Combs of experimental males (N = 53, see below) were measured with digital callipers to the nearest 0.1 mm up to 1 week before the experiments.…”

“…Males used multiple times were never used twice with the same female or in the same male combinations, and were most typically used in different years. Behavioural observations were conducted at a distance of approximately > 6 m from the aviaries housing the birds, and during the peaks in copulation activity in this population, which is around 0400-0800 and 1600-2100 hours local time (Pizzari & Birkhead, 2001;Løvlie & Pizzari, 2007). Morning observations typically lasted 180 min and began when the female left the roost; evening observations started at 1600 hours and continued until the female had gone to roost, and were thus always longer than 180 min.…”