title: Longitudinal analysis of Plantago: adaptive benefits of iteroparity in a short-lived, herbaceous perennial.
abstract: Theory suggests that iteroparity may confer greater fitness than semelparity in situations in which temporal environmental variation is high and unpredictable. Variable age-specific mortality, density dependence, and other factors may also favor iteroparity over semelparity. Here, we empirically test the adaptive benefits of greater numbers of reproductive years in a study of reproductive schedules in an experimental population of a short-lived polycarpic perennial, Plantago lanceolata. A large experimental population was established that included four cohorts with similar genetic structure. Individuals were censused for mortality, size, and reproduction for seven years. Plants experienced variable numbers of reproductive years, but one or two years were most common (approximately 46.7% of the population reproduced only once). The probability of flowering at least once prior to death was determined strongly by extrinsic, environmental or intrinsic but environmentally influenced variables, including early-life size, cohort, and block, but also varied with a number of interactions involving paternal lineage. Maternal effects explained small but significant components of the variance in the number of reproductive years among individuals in each cohort, while paternal effects were significant in only two cohorts. Number of reproductive years contributed significantly to fitness in this system, more so than all other variables tested, although most of the variation in relative fitness may be attributed ultimately to environmental influences. We suggest that the high proportion of each cohort composed of plants reproducing only once may be due to environmental constraints on either growth or size. Such environmental influences, particularly on early life size, may result in small but important indirect effects on fitness.
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, Virginia 22904, USA. dormancy@gmail.com
authors.forename: Richard P
authors.initials: RP
authors.lastname: Shefferson
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Roach
mesh_terms: D000222:Adaptation, Physiological; D017753:Ecosystem; D010943:Plantago / Q000502:physiology*; D012098:Reproduction; D013997:Time Factors
references.citation: Am J Bot. 2008 Feb;95(2):258-62
references.pmid: 21632350
references.citation: Am Nat. 2008 Feb;171(2):141-9
references.pmid: 18197767
references.citation: Am Nat. 1999 Dec;154(6):628-651
references.pmid: 10600610
references.citation: J Evol Biol. 2007 Jan;20(1):190-200
references.pmid: 17210012
references.citation: Trends Ecol Evol. 1998 Oct 1;13(10):403-7
references.pmid: 21238360
references.citation: Am J Bot. 2005 Jun;92(6):920-30
references.pmid: 21652475
references.citation: Proc Biol Sci. 2004 Mar 7;271(1538):471-5
references.pmid: 15129956
references.citation: Ecology. 2009 Jun;90(6):1427-33
references.pmid: 19569355
references.citation: Q Rev Biol. 1954 Jun;29(2):103-37
references.pmid: 13177850
references.citation: Trends Ecol Evol. 2001 May 1;16(5):254-260
references.pmid: 11301155
references.citation: Science. 1973 Dec 28;182(4119):1305-14
references.pmid: 17733097
references.citation: Biometrics. 1948 Dec;4(4):254-66
references.pmid: 18108899
references.citation: Evolution. 2002 Nov;56(11):2156-67
references.pmid: 12487346
references.citation: Curr Biol. 2007 Dec 4;17(23):R1000-1
references.pmid: 18054756