HR: 09:15h
AN: NB51B-04    [Abstracts]
TI: Life History Variation in an Alpine Caddisfly: Local Adaptation or Phenotypic Plasticity?
AU: * Shama, L N
EM: lisa.shama@eawag.ch
AF: EAWAG/ETH, Department of Limnology, Ueberlandstrasse 133, Duebendorf, ZH 8600 Switzerland
AU: Robinson, C T
EM: christopher.robinson@eawag.ch
AF: EAWAG/ETH, Department of Limnology, Ueberlandstrasse 133, Duebendorf, ZH 8600 Switzerland
AB: Facultative species that inhabit permanent and temporary streams can be locally adapted to their stream of origin or exhibit life history plasticity. Temporary stream populations should respond to environmental cues signalling stream drying, whereas permanent stream populations may not. We used a common garden experiment to test whether males and females of an alpine caddisfly from six populations (3 permanent/3 temporary streams) differed in their life history responses to combined changes in photoperiod (ambient/late) and hydroperiod (constant/drying). Responses varied by sex, time-constraint cue and population. Both sexes shortened development time in the late photoperiod, and males emerged before females in all treatments. Growth rates were higher in the late photoperiod for both sexes, and females had higher growth rates and mass at emergence than males. Growth rate compensation in the late photoperiod resulted in similar masses at emergence for both photoperiods. Population-level differences in responses varied according to microgeographic co-gradient variation. Our results suggest that while stream drying cues may not exert sufficient selection pressure to promote faster development in temporary streams, populations may be locally adapted to differences in growing season length associated with stream-specific environmental characteristics.
DE: 9810 New fields (not classifiable under other headings)
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly