Kenneth S. Norris Rancho Marino Reserve

04 Jan, 03 AM - 04 Jan, 09 AM

Geographic variation in the life histories of plant and animal taxa is widespread. Often, parthenogenetic forms are more common as one moves towards the poles, in environments that are characterized as being more extreme. The explanations are usually based on correlative evidence because the species studied cannot easily manipulated in experiments. The rhodophyte seaweed, Mastocarpus papillatus, occurs in the marine rocky intertidal zone from Baja, California to Alaska. It exhibits geographic parthenogenesis in which asexual individuals predominate in the northern part of its range (north of San Francisco) and sexual individuals predominate in the southern part of its range (south of San Francisco). Mastocarpus papillatus provides a model organism for experimentally testing alternative hypotheses that explain geographic parthenogenetic patterns. There are several alternative hypotheses for the trend of decreasing sexuality with increasing latitude, including historic accidents associated with geologic changes like glaciation and post-glacial sealevel changes, differences in dispersal or migration of organisms which require mates and those which don?t and differential selection on nonreproductive characteristics. This research program has two main objectives. The first addresses potential biological limitations to the maintenance of sexual populations at northerly latitudes. We will establish the pattern of reproductive effort and its undelying causes in sexual and asexual life cycle variants with respect to latitude. To carry out this objective, we will collect individual gametophytes and tetrasporophytes from the field and culture them in the laboratory. The second objective uses molecular methods to examine biogeographic history of sexual and asexual variants of M. papillatus. We seek to identify genetic markers to distinguish life cycle variants and establish whether asexuality appeared several times, dispersal barriers in recent geological history affected migration, and if local populations are indeed genetically divergent. Overall, this research will determine what factors cause geographic variation in the life history traits of one common intertidsal organism on Pacific seashores and will test evolutionary theories about the role of biogeographic history and environmental interactions in maintaining both asexual and sexual patterns of reproduction in a single species.

Visit #14106 @Kenneth S. Norris Rancho Marino Reserve

Approved

Under Project # 9228 | Research

Reproductive effort in the life histories of Mastocarpus papillatus

graduate_student - California State University (CSU), Northridge

Reservation Members(s)

Stacy Krueger Jan 4, 2007 (1 days)
Group of 2 Volunteer Jan 4, 2007 (1 days)

Reserve Resources(s) | Create Invoice

Day Use Only 3 Jan 4 (6 hours)