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Antlions organize themselves systematically in response to the
environments where they find themselves.
Individuals attempt to regularize their own pit locations according to
nearby pits and the borders of the living space, and this structure is
affirmed by a statistical test on the uniformity of their distribution.
Using a Monte Carlo simulation of 10,000 randomly distributed patterns
of the same number of pits as observed from each trial, a typical
distribution of the distance to the nearest neighbor was determined.
The distance to the nearest neighbor is approximately independent for
each pit, so a Cram\'er-von Mises statistical test was applied to the
observed distributions, resulting in striking evidence that these pit%'
dsitributions do not conform to a uniformly random independent
distribution of each pit, with all (except one) distributions of
antlions having $p<0.05.$
Several clear patterns were observed throughout various trial sizes and
communication conditions. For starters, a clear increase in the
reclusive population as trial size decreased was observed in every
obstacle condition, as the amount of reclusive increased from one
($24\times24$) to two ($12\times12$) during the trail erasure trial. The
same results are shown across the trial with fake pits, where the number
of reclusive antlions increased from one to four, and the obstacle
trial, where the amount of reclusive antlion increased from zero to
three. In summary, the number of reclusive antlions increased by an
average of 2.333 antlions, or an increase of 233.3\%, which marks quite
a significant change. This change indicates that the introduction of
various obstacles and interference in other modes of communication can
change the natural settlement patterns of the antlions, as a
significantly larger number of reclusive antlions were observed during
trials with artificial pits, indicating that the density of pits in a
given area affects how antlions settle the territory. This analysis
makes biological sense, as by regulating the density of antlions in a
given territory the organisms can reduce intraspecies competition, which
in turn helps the species reproduce more as a whole, thereby explaining
the phenomenon. Along with this, a dramatic change in the cannibalistic
nature of the antlions was noticed once various obstacles were
introduced, as it was noted in the previous study that the number of
cannibalized antlions increased by an average of 13.9785\% when the
trial size was reduced with no obstacles or communication interference.
This differs from the trend in cannibalism noted throughout the
following trials, as the data clearly shows how the rate of cannibalism
tended to decrease across various trials, with the exception of the
first two trials where pits were removed, as shown by graph 1. This
indicates that the antlions' cannibalistic nature is affected by
environmental conditions such as changes in terrain and other obstacles,
which could be a response to an interrupted communication pattern that
results in a closer settlement, which intern would increase the contact
between each antlion, thereby leading to more cannibalism. Finally,
along with a trend in reclusivity and cannibalism, a trend was noticed
in the average pit depth across all trials, as it decreased as trial
size decreased throughout the study, regardless of the obstacles
introduced (Graph 1). This indicates that the size of pits made by
antlions is independent of the mechanisms that govern how they settle,
as the study was able to alter all of the settlement patterns of the
antlions through the introduction of obstacles except for the average
pit depth, which maintained a constant pattern through the introduction
of obstacles and the original trial from a previous year. This indicates
that the average pit depth does not depend on their settlement pattern
of the antlion community as a whole, but rather is dependent on factors
such as time and available resources.
Following the analysis of individual pit patterns, a large scale
analysis of the settlement pattern of the antlion groups as a whole was
conducted in order to determine how the introduction of various
obstacles and environmental conditions altered the group settlement
patterns of the antlions. During this analysis, several key patterns
emerged from the antlions distribution. For starters, the average
nearest neighbor remained relatively constant across all trials and
environmental conditions, except for when a series of fake pits were
introduced to the environment, as the average nearest neighbor ranged
from 2.1-3.9 (graph 2) for all trials except the $24\times24$ trial with
fake pits, where the average nearest neighbor increased to 8.7.
Furthermore, the nearest neighbor varied the most across the fake pit
trial, as it decreased by about 5.5 inches, which differed from the
trial with trail erasure where the nearest neighbor decreased by about
1.95 inches, and the trial where obstacles were introduced, during which
nearest neighbor reminds constantly. This indicated that the spatial
distribution of the antlions is most likely dependent on several
environmental conditions, each of which has a varying impact on the
antlions patterns. Another settlement pattern that became clear
throughout the trial was shown in the Voronoi diagrams, pictured below,
which illustrate the settlement of every pit in a trial and show the
“territory” occupied by each antlion. Based on the aforementioned
Voronoi diagrams, and statistical analysis, it can be effectively
concluded that the antlions maintain a non-random distribution pattern
across all trial sizes and environmental conditions, as the antlions
near the middle of the habitat maintain about five neighbors at all
times, a principal that is clearly shown by examining the centermost pit
in the Voronoi diagrams, as the territory occupied by each antlion
almost always makes a pentagon shape. Finally, a closer examination of
the Voronoi diagrams illustrates how the antlions tended to maintain a
constant pattern across both changes in environment and changes in
habitat size, as the average territory occupied by each antlion remains
statistically constant throughout all trial sizes and environmental
conditions, indicating that the antlions distribute in a way that
maintains a constant proportion between each pit, thereby reducing
cannibalism and competition.
Based on the settlement patterns of the antlions on both, an individual
and group scale several conclusions can be drawn about the environment's
impact on the settlement patterns of the insect along with the
mechanisms that antlions use to settle in a non-random pattern. With
this in mind, one of the most evident patterns in the data was the
impact of fake pits on the antlions settlement, as when fake pits were
introduced to the environment the rate of cannibalism and reclusivity
among the antlion population increased significantly, as shown by graph
1. Along with this, the Vovrinoi diagrams illustrate how the antlions
tended to space themselves away from fake pits when settling,
represented by the abnormally high average nearest neighbor during this
trial, as the average nearest neighbor increased significantly during
the trial with fake pits, as shown by graph 1. The settlement pattern of
the antlions is highly dependent on the existence of pits around them,
as by introducing fake pits into the environment the natural non-random
distribution of the antlions was disturbed the most, thereby showing
that the pits and deformities in terrain that antlions come into contact
with influence where they settle the most. This principle makes
biological sense, as by spacing themselves away from one another the
antlions are allowing for an equal spread of resources, thereby helping
the species as whole progress more efficiently. Along with this the
increase in reclusivity and cannibalism observed during this trial also
indicates that the presence of pits influences the settlement patterns
of the insect, as the sharp increase in extreme behavior patterns
indicates the antlions are attempting to adapt to the introduction of a
new environmental extreme. With this in mind, it can be concluded that
antlions rely on the density of pits in a given region to settle, as
well as the density of trails surrounding a given region, as the
interference with these two environmental conditions disrupted the
antlions the most.
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