New Features in RAMAS Metapop 5.0



	New Features in RAMAS Metapop version 5
	Note: If you are still using version 3 (1998), also see New Features in RAMAS Metapop 4.0
	New Sample Files Dozens of additional sample files are added, so the program now includes sample files for about 60 species. New parameter: Exclude the initial X time steps from risk calculations This option (in the Stochasticity dialog box under the Model menu) makes the program calculate the following risk results only for time steps X+1 through the end of the simulation: Risk of low harvest Interval extinction risk Interval explosion risk Interval percent decline Expected minimum abundance This option is useful when you want to exclude a transition period from calculating risks. If a population is increasing from a low abundance, then excluding the initial time steps from calculating risk of decline will decrease the risk estimates. Note that risk of extinction (reaching a threshold of zero) may not be affected, because once the metapopulation is extinct, it will remain so (unless there is Introduction in Population management or there is dispersal from an extant population that is not included in summation). If the population is decreasing, then excluding the initial time steps from calculating "explosion risk" will decrease the risk estimates. New Result: Average Stage Abundances This result window shows the change in average abundance of each stage of each population through time. It outputs the average number of individuals (over all replications) in each stage of each population. The population and stage for which you want to view the average stage abundances is specified in a population counter on the tool bar and a stage picklist below it. This result is available only for the first 100 populations. New parameter: Relative dispersal (population-specific) This parameter (in Populations dialog box under the Model menu) is used to modify the dispersal rates by multiplying it with the rates from the dispersal matrix, and the stage-specific relative rates from the Stages dialog. You can enter either constants or filenames for these parameters. A constant number multiplies all dispersal rates (for all stages and all time steps). Because the dispersal matrix already gives rates that are specific between any pair of populations, this relative dispersal parameter is mostly used to model deterministic trends (non-random or systematic changes in time), by specifying filenames instead of constant values. The filenames should refer to files that contain time series of these parameters. If you specify a filename, you can also specify a different time series for each stage. Allee Effects on Vital Rates Based on user requests, the operation of Allee effects is changed so that it modifies only selected vital rates, as specified in the "Density dependence affects" parameter (in the Density dependence dialog). For example, if "Density dependence affects fecundities", then only fecundities are multiplied by N/(A+N), where N is the basis for density dependence (i.e., total population size, abundance of selected stages, etc.) at the current time step for this population, and A is the Allee parameter for this population.
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Date modified: 2-28-05