Biology Reference
In-Depth Information
Offspring Dispersal Distribution
The probability of a maternal plant dispersing a given offspring a certain
distance is specifi ed by the dispersal distribution statements. Together,
these statements defi ne the probability curve of the distances of any seed
producer's seed shadow. They are used to describe a hierarchically nested
series of frames, with a chosen maternal plant at the center of all frames.
In the input statements, the user specifi es the minimum and maximum
dispersal distances from a given offspring-producing maternal plant to
defi ne each frame. When delimiting each frame, the probability of a given
offspring being dispersed to a grid point somewhere within that frame is
also specifi ed. The user can create as many distinct frames as desired. Below,
fi rst we will outline how the offspring dispersal distribution statements
work, and then we will give and explain an example for clarifi cation.
By NEWGARDEN convention, dispersal distribution frame statements
take the form
<functionpoint x=“x value” y=“y value”/>
where the x value designates the x and y distances the offspring can
be dispersed (the actual value of maximum dispersal = x value minus
1), and the y value gives the probability for the frame described by the
statement.
For example, a set of dispersal distribution frame statements must
always begin with the statement:
<functionpoint x=“0” y=“0”/>
which can be interpreted to mean: the probability of being dispersed to an
x or y distance less than 0 is 0.
Thus, in each succeeding statement, subtract 1 from the user-given
“x” value to determine the maximum dispersal distance in both the x and
y directions to which an offspring can be dispersed from a female within
the frame bounded by that statement. Each successively distant frame has
its minimum x and y dispersal distance designated by the “x” value of the
statement defi ning the maximum dispersal distance for the immediately
interior frame. The “y” value given in the input statements denotes the
probability that an offspring will be dispersed within the frame outwardly
bounded with a maximum x and y dispersal distance set by the “x” value
of that statement, and inwardly bounded by the “x” value of the previous
statement. Thus, to defi ne a frame, two consecutive statements must be
consulted.
Perhaps this will be made clearer with an example. Consider the input
statements:
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