Abstract # 44:

Scheduled for Saturday, September 19, 2009 06:30 PM-09:00 PM: Session 5 (Mission Bay Ballroom CDE) Poster Presentation


MORPHOLOGICAL CHARACTERIZATION OF A BROWN LEMUR HYBRID ZONE (EULEMUR RUFIFRONS X E. CINEREICEPS) IN SOUTHEASTERN MADAGASCAR

K. E. Delmore1, E. E. Louis Jr.2 and S. E. Johnson1
1Department of Anthropology, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada, 2Center for Conservation and Research, Henry Doorly Zoo, 3701 South 10th Street, Omaha, Nebraska, 68107, USA
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Two models have been proposed to explain the persistence of hybrid zones: the tension zone and ecotone models. The tension zone model predicts that intrinsic selection acts against hybrids. This selection is counteracted by dispersal of parentals into the zone. The ecotone model predicts that environmental selection favors hybrids within transitional habitats and parentals outside the zone. This results in a reduction in gene flow between taxa. A hybrid zone exists between two species of brown lemur, Eulemur rufifrons and E. cinereiceps, at Andringitra in southeastern Madagascar. We used pelage and morphological data to evaluate the latter two models. We established eight sites at 10 km intervals along a north-south transect through the zone and immobilized ten animals at each site [N=80]. We scored animals for their degree of hybridity using pelage characters (Phenotypic Hybrid Index) and measured animals for standard morphological variables. Our results support the ecotone model: the zone consists mostly of hybrids and is relatively large [maximum length of 46.5 km]. Private morphological traits were also identified: body fat scores were highest in E. rufifrons females [ANOVA, p=0.05] and tail length was significantly longer in hybrid males [ANOVA, p=0.02], suggesting that gene flow between hybrid and parental populations is reduced. Although function has not been determined, these traits may indicate local adaptations in these divergent populations.