Does recent experience affect large male advantage in a sequentially-mating fish?

In many mating systems, large male body size is associated with dominance in direct contests with rivals and females may exhibit preference for larger males. As such, body size is often positively associated with mating success. However, mating experience can influence the potential advantage of large body size through alterations in behaviour and depletion of sperm reserves. In Japanese medaka (Oryzias latipes), males mate with many females each day, and larger males mate more frequently than smaller males. In an observational experiment, we tested the following alternate predictions: (1) recent mating experience may enhance mating success through a carry-over effect of prior mating, whereby small experienced males gain an advantage over large inexperienced rivals in mating contests; or (2) recent mating experience decreases mating success through a reduction in fertilization due to sperm limitation, effectively dampening the large-male advantage against a small inexperienced rival. We examined the interactive effect of size and recent experience on mating behaviour and success. While mating contests were monopolized by large males, recent experience enhanced mating success, especially in small male winners. Experienced males courted more readily than those without recent experience, suggesting that recent prior mating enhances this behaviour. Furthermore, males who had copulated recently did not exhibit sperm depletion when in the presence of a competitor, nor did female behaviour indicate a preference for inexperienced males. This suggests that males can use sexual experience to increase their reproductive success in future mating situations, which may influence the action of sexual selection and alternative tactics in shaping mating systems.

Endometritis in Donkeys Associated with Streptococcus equi subspecies zooepidemicus Infection

Endometritis has recently become one of the most important infectious diseases in donkey breeding farms in China. However, so far, no research has been conducted to confirm the causative agents. In the present study, one breeding farm was selected as a research model for isolation and identification of causative agents and epidemiological investigation. Streptococcus equi subspecies zooepidemicus was isolated from the uterus of symptomatic and asymptomatic donkeys and identified by PCR and MALDI-TOF MS analysis. On the farm, the infection rate was 57.1%, which indicated that endometritis is a severe problem and needs to pay much attention to donkey breeding farms. Moreover, female donkeys without mating experience were all negative which suggested the transmitting route might be artificial insemination or related handlings. This study will lead to a great understanding of the causative agent and epidemiological characteristics for endometritis in intensive donkey breeding farms