Biology Reference
In-Depth Information
trials dropping from 99% to approximately 98% across the 17 generations.
However, the original founders are present across all generations (little or
no mortality), and thus that is expected. However, if the populations were
more slow-growing, and/or some or all of the founders were lost early on
in population establishment, introducing the founders in the trial a pattern
would be more likely to preserve more unique alleles given its increased
growth rate.
70000
a
60000
5
9
50000
a
5
40000
9
a
5
9
30000
a
5
9
a
20000
5
9
a
5
9
a
5
9
a
10000
5
9
a
5
a
9
a
5
9
a
5
9
a
5
9
5
9
a
5
9
a
a
5
9
5
9
5
9
a
0
5
9
a
0
6
12
18
GENERATION
Fig. 17.15
A comparison of population growth for three populations of perennials that have
identical input conditions, except that trial 5 has two preserves separated by a corridor of
length 1,024 units while trial 9 and trial a lack a corridor and the two preserves are instead
separated by a 50-unit-wide gap (e.g., a river) where no offspring can survive. Trials 5 and 9
have 172 founders placed in a square in one preserve only, while trial a has founders split into
two groups of 86, with the founders in each preserve placed in three lines running parallel
to the river. In all trials, founders have 4 grid units between them, and the shortest distance
from any founder to the corridor or river is 100 units.
Population genetics theory predicts that under a wide range of
conditions, loss of alleles in plant populations will be reduced in perennials
compared to annuals. In
Fig. 17.16,
four trials are compared, two of which
are perennials and the other two annuals, with other conditions held
constant. The perennials are trials a and 9 from the previous example,
including the input conditions: dioecious perennials with a lifespan of 60
years, long-distance pollen and offspring distributions with a maximum of
2,804 units, both lack a corridor and the two preserves are instead separated
by a 50-unit-wide gap where no offspring can survive (e.g., a 50-unit-wide
river). Trials 9 (perennials) and c (dioecious annuals with the same dispersal
distances) have 172 founders placed in a square in one preserve only, while
trials a (perennials) and d (annuals) have founders split into two groups of
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