F. Helen Rodd and David N. Reznick. 1997. Variation in the demograhy of guppy populations: the importance of predation and life histories. Ecology 78:405-418.
Supplements
Appendix A: Guppy demographic data.
Ecological Archives E078-001-S1 (ESPS 9601).
Description
Data in the companion document were used in the computer simulation described in our paper. Size-specific survival rates, fecundity, etc. are provided for guppies of both sexes by their mm size class. A description of the source of those data is provided in the paper (or see below).
Data in the companion document were used in the computer simulation described in our paper. Size-specific survival rates, fecundity, etc. are provided for guppies of both sexes by their mm size class. A description of the source of those data is provided in the paper (or see below).
All data used as input for the simulation were obtained from guppies from natural populations, both from the samples collected for this study and from mark-recapture studies (Reznick 1989, Reznick et al. in press, D.N. Reznick and M.J. Butler unpublished data). Since data for some input parameters were only available for the dry season, we used only dry season data for all parameters. The demography of the initial population (numbers of individuals in each size class and their sex and reproductive status) was the average of samples from that predator locality (Supplementary Appendix). The initial population was identical for all runs of a given predator locality, with the exception of the timing of the next brood for mature females (the numbers of days to the production of females' next broods were determined using the random number generator). Survival and growth rates were obtained from the mark-recapture studies (Supplementary Appendix). Because the mark-recapture experiments were run for a 12 day period and because this time period is short enough to avoid numerical artifacts, we used 12 days as the time interval for all simulation runs. Growth and mortality rates were calculated by sex and millimeter size class for each site and then averaged across sites within predator locality. Although growth rates for guppies smaller than 12mm have not been measured in the field, Barlow (1992) has shown that the relationship between growth rate and body size is approximately linear for all size classes. Therefore, we estimated individual growth rates from a linear regression line through the data sets for the three or four sites from a given predator locality that had the most complete representation of all size classes (Supplementary Appendix). Average fecundities, by size class, were obtained from the reproducing females that were dissected for this study (Supplementary Appendix). Here, we used the proportion of females carrying developing embryos as an indicator of maturity because, until embryonic development is initiated, we cannot be certain of when the brood will be produced nor how large it will be. An average interbrood interval for each predator locality was obtained from second generation offspring of guppies held in the laboratory under uniform conditions at temperatures comparable to those observed in the field (Reznick 1982). Male sizes at maturity were determined from the field samples (Reznick 1989).
The original paper or microfiche copies of supplements submitted prior to 1998 are on file in the Publications Office of the Ecological Society of America.
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