The evolution of striped coat patterns in African mammals-what function do the stripes have?

Abstract

Several families of mammals have stripes and many hypotheses have been proposed to explain the evolution of the striped coat patterns. However, there is very limited experimental evidence to support which hypotheses are the most likely to explain the evolution of the striped patterns. Therefore, what adaptive function the stripes serve in all these species is still largely unknown. In this study I investigated the characteristics of stripes such as stripe width for both white and black stripes on 36 striped African mammals’ coats collected in four museums and three countries. My study further revealed that the appearance of stripes on mammalian coats is most likely not involved in sexual selection. There were close similarities in stripes number or stripes width between sexes for Equus grevyi and Tragelaphus imberbis. In order to evaluate the effects of stripes on tabanids attractiveness, two experiments designed to test tabanids attraction were performed. Data on tabanids daily activity revealed that the flies were more active on partly cloudy and sunny weather. Especially, Haematopota pluvialis is known to have a high flight intensity in cloudy weather before an anticipated rain. Using sticky panels and models, tabanids were more attracted to sunny sides in the both experiments. Moreover, the findings revealed that the stripes in all striped patterns were extremely important in stimulating tabanid flies’ repellency. My results suggest that the appearance of stripes on different mammalian coats could be an evolutionary force reducing the attraction of tabanids to many striped animals, consequently, reducing disease transmission risk.