Meeting Abstract

111.7  Tuesday, Jan. 7 09:15  Breeding behavior is associated with sex-biased parasitism in the red-spotted newt HANNINEN, A.F.*; THOMASON, C.B.; GABOR, C.R.; ALTIZER, S.; University of Virginia; Texas Tech University; Texas State University; University of Georgia amanda.hanninen@gmail.com

There are two prevailing hypotheses that have been proposed to explain the persistence of male-biased parasitism among vertebrates. First, males may maintain elevated androgens levels to produce elaborate traits and thus suffer the cost of reduced immunity and increased parasitism. Second, ecological factors can generate sex differences in parasitism. Males are often exposed to more parasites and increased transmission while traveling in search of a mate during the breeding season. We examined the dual role of hormones (physiology) and amplexus (ecology) in promoting male-biased parasitism in the red-spotted newt (Notophthalmus viridescens). We collected 42 newts, including amplectant pairs and solitary males and females, from Mountain Lake Biological Station during the breeding season. Following capture, water-borne hormones were collected and each newt was dissected for parasites. We found that amplectant males harbored significantly more trematode parasites relative to solo males and all females. Our results suggest that actively pursuing and engaging females during the breeding season may play a key role in promoting sex differences in parasitism. Furthermore, trematode-infected newts have higher corticosterone levels than uninfected individuals and those infected with other parasites, suggesting that chronic trematode infection may be energetically costly and stressful. Future analysis of both testosterone levels and immune function can inform how endocrinology and ecology interact to mediate male-biased parasitism.