title: Aging in sexual and obligately asexual clones ofDaphniafrom temporary ponds.
abstract: The freshwater crustaceanDaphniais an emerging model system in the biology of aging. Diversity in aging patterns is thought to be caused by ecological variation in selection on age-specific performance. Previous work inDaphniahas shown a strong correspondence between selective differences and genetic variation in aging in theDaphnia pulexspecies complex. However, recent evidence suggests obligate asexuality could account for the more rapid aging found in pond genotypes compared with lake genotypes without invoking differences in selection. Evolutionary biologists have to date assumed equivalent operation of neutral processes when comparing aging across populations, but a shift in the breeding system changes the basic dynamics of neutral evolution. To test the hypothesis that the breeding system could explain the short lifespans of pond-dwellingDaphnia, we compared aging of sexual and asexualDaphniaclones from temporary ponds. Our data contradict the breeding system hypothesis. Differences in aging between the breeding systems were slight, and trended in the opposite direction from that predicted: asexual clones had longer lifespans and appeared to age more slowly than sexual clones. We conclude that divergent selection between habitats remains the best explanation for differences in aging betweenDaphniaspecies.
authors: Department of Biological Sciences , University of South Carolina , Columbia, SC 29204 , USA.
authors: Jeffry L
authors: JL
authors: Dudycha
authors: Christiane
authors: C
authors: Hassel
keywords: Daphnia; life history; mutation accumulation; senescence; sex