Heat-altered scent marks of males of a fossorial reptile still allow recognition by females but lose information on male quality

Abstract

The efficacy of sexual signals in communication is often maximized under specific environmental conditions. Anthropic alterations of these conditions might, thus, negatively affect communication during reproductive behavior. In fossorial animals, inhabiting visually restricted environments, chemical senses are very important. We examined whether climatic episodes of heat-waves with unusual high temperatures may affect the information provided to females by the sexual chemical signals of males of a fossorial reptile, the amphisbaenian Blanus cinereus. The results showed that experimentally heat-altered substrate scent marks of males can still provide information to females about the presence of a male. Females spent more time on males’ scent marks, irrespective of the temperature treatment, than on control clean ones. However, heat-altered scent marks did not seem to convey information about the health state (immune response) of the producer. Females spent more time on unaltered scent marks of healthier males (probably indicating mating preferences for these males), while female preferences for some heat-altered scent marks were not related to size or immune response of the same individual males. Chemical analyses indicated that the overall chemical profile of precloacal secretions (used for scent marking) did not change with increased temperatures. However, the relationship between proportions of some compounds in secretions and males’ immune response found in unaltered secretions was lost in heat-altered ones. We conclude that unusual increased environmental temperatures may decrease the efficacy of underground sexual chemical signals in this amphisbaenian (i.e., a loss of information on male quality), and consequently, may negatively affect sexual selection and reproduction.