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Conservation Implications of Hybridization Between Two Species of Brown Lemur

   Kira Delmore with 2 Red Fronted Lemurs
  Kira Delmore with 2 red fronted lemurs
she captured and released. (Photo by Margaux Keller)

Kira Delmore

Hybridization, interbreeding between individuals from distinct populations or species, can be either a risk or a benefit to the survival of rare animals. Uncommon species may be overwhelmed by the gene flow from a more abundant animal and the offspring of such pairings runs the risk the of sterile children. But hybridization also serves as a conservation opportunity by introducing variation into a rare animal's gene pool. Variation is important for the survival and adaptability. If a species’ environment changes, the possession of variation will enable it to adapt and compete successfully in their new environment.

We evaluated these two possibilities in a hybrid zone between the red-fronted lemur (Eulemur rufifrons) and the gray headed (E. albocollaris). The red-fronted lemur has a large range; it can be found in both western dry forests and eastern rainforests. The gray-headed lemur has a much more restricted range; it consists of only two isolated populations on the southeastern coast which suffer from fragmentation and hunting. The gray-headed lemur is currently listed as endangered on the IUCN Red List and considered one of IUCN’s Top 25 most endangered primates in the world.

We established 18 sampling sites along transects through the hybrid zone. We captured a minimum of 10 individuals at each site, measured them for standard morphological variables and obtained blood samples for genetic analyses. Results from our analyses suggest that hybridization between red-fronted and gray-headed lemurs is serving as a conservation opportunity. First, there was no evidence of unidirectional gene flow (i.e., the gray-headed lemur is not being swamped by gene flow from the red-fronted lemur). Second, hybrids appear to be equally as fit as parental forms and exhibit unique traits (e.g., longer tails), suggesting that hybrid populations are isolated from the other two species. These findings suggest that evolution restricted to hybrids may be occurring. The remaining forest in the hybrid zone’s range is currently threatened of slash-and-burn agriculture, small-scale mining, logging, hunting and trapping. Given the potential for evolutionary innovation in this hybrid zone and its function as a conservation opportunity for gray-headed lemurs, we encourage the protection of the Andringitra region and its corridors.

 

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