Table of Contents
- Materials and Methods
Animal personality is a collection of behaviors exhibited by an individual in a population. Being an individual, we are all unique and behave in various ways. However, due to evolution and genetics, some traits are correlated with others, meaning, that one trait may influence another. Because of this, we believe that certain similar traits will be positively correlated with each other. For example-boldness and exploration. This is a logical correlation as those who are more willing to take risks would most likely be willing to explore a new environment as well. We tested this by placing a test cricket in an enclosed cup, and measured how long it took it for the cricket to leave. Once the test cricket left, we counted the number of square it crossed in a Tupperware container. We found a strongly significant correlation between the boldness and exploration of crickets when isolated from other individuals (N=1157, p<0.001, Figure 1). Additionally, the sociability of the cricket were subsequently tested, however, no correlation was found.
So what exactly is animal personality? Personality, or sometimes known as “behavioral syndromes”, is a collection of behaviors performed by an individual. Behavior can be broken down into 5 divisions-boldness, exploration, activity, aggression and sociability. Since personality is a collection of behaviors, it is a very difficult thing to quantify.There are many theories of why personalities arose, but there is no explicit evolutionary evidence demonstrating them.(Sih, Bell, & Johnson, 2004). Additionally, it seems that some traits have evolved together. This may cause problems. Evolutionarily, one would think that when a personality type that causes conflict for an individual (such as excessive boldness causes one to be eaten by a predator) exists in a population, it would be selected against, but they may not be. These personality traits may be genetically “coupled” to another personality trait that makes up for its downfalls (Sih, Bell, & Johnson, 2004). We believe that some similar personality traits in crickets will be coupled together such as boldness and exploratory behavior as found in Stuberet al.
Personality also changes upon an individual’s environment. By being around other individuals, one’s personality trait can be influencedby others. For example, one cricket may not be very bold when alone, but when grouped with others, it may be. Brown and Irving looked into situations such as this with guppies. The individuals that make up a shoal of fish influence how the shoal behaves (Brown & Irving, 2013). Again, because individuals’ personality traits may vary situation to situation, it becomes increasingly more difficult to quantify.
Our hypothesis is that when alone, a cricket’s boldness and exploratory behaviors will be coupled. Our experiment will not measure a cricket’s boldness and exploratory behaviors when accompanied by others. We believe that because boldness is defined as the ability to take risks, a cricket that is more bold, will also have more environmental exploration. Additionally,we also would like to look at the sociability with a cricket to see if there is any correlation between it and boldness or exploration.
Materials and Methods
In our setup, we decided to test 3 of the 5 personality traits-boldness, exploration and sociability. To test these 3 personality traits, we used 2 experimental setups. The first setup measured boldness and exploration while the second setup tested sociability. To test boldness and exploration, a subject cricket was placed under a cup inside of a Tupperware arena. The cricket was allowed to habituate under the cup for 2 minutes. The side was then removed and the cricket given 300 seconds to leave the cup. The time taken for the cricket to leave the cup was recorded and subtracted from 300 to give us boldness score. An additional timer began whenever the cricket left, and the cricket was given another 300 seconds to explore its new arena. The Tupperware arena was divided into a grid of roughly 1”x1” squares. The number of unique squares the cricket encountered was counted over the 300 second interval and was recorded as its total exploration score.
For the sociability setup, we placed the cricket (immediately after completing the boldness and exploration portion of the experiment) in the middle of another Tupperware container. This container consisted of 3 equal sized portions separated by 2 see through walls (with holes poked through in various locations). On one end of the container, 3 conspecifics were placed to act as a stimulus for our test cricket. The other side was empty and used as a control. The middle section was further divided into 3 equal sized areas, one close to the conspecifics, one close to the control side and one in between the other two areas. After being placed inside the new arena, the cricket’s location was measured with a scan sample of 5 seconds for 300 seconds. The data was recorded as being in the association zone close to the crickets, being in the avoidance zone close to the control side, or being in the neutral zone. To calculate the sociability score, we discarded the number of scans in the neutral zone and calculated the percentage of time spent in the association zone from the remaining scans. After the cricket was recording for 300 seconds, the cricket was placed into separate container to ensure that it was not experimented upon again. This overall experiment was replicated over a 5 day period for a total of 157 crickets. To determine if there is any correlation between two of the personality traits of a cricket, each of the personality traits were plotted against one another and linear regression was performed. The correlation value and sample size were then taken into an online calculator, and the two-tailed probability was calculated. Additionally, we decided to see if there was any difference in the personality traits between male and female crickets. To determine this, a two sample t-test was performed.
By using the same method as the boldness versus exploration score, we receive a p-value of 0.173 for the exploration versus sociability relationship.
A t-test was also used to determine if there was any difference between the personality traits of male and female crickets. The results are displayed below in Table 1.
Male Crickets (71 total) Female Crickets (85 total) p-value
Average Boldness 195.9859 196.1882 0.9919
Standard Deviation 118.7068 125.4177
Average Exploration 41.8706 41.8706 0.8527
Standard Deviation 18.2619 16.3072
Average Sociability 0.4344 0.4987 0.4854
Standard Deviation 0.3953 0.3672
Statistically, we have found a correlation between the boldness personality trait and the exploration personality trait of crickets. Because the p-value was floored by the calculator used, we would like to consider our probability to be p<0.001. This is an extremely strong correlation, but we would like to further investigate to ensure that our hypothesis is correct.
There are some flaws in our experimental setup. It would be wise to use perfectly healthy crickets, but due to our limited resources, not all of our crickets were in the best shape. Many of them did not even emerge from their cup in the boldness portion of our experiment. They had to be coaxed out by using a pencil. Some crickets were barely able to explore its arena too. We had a cricket that explored a total of 2 squares, meaning it barely moved at all. By using healthy, active crickets, we may be able to further confirm our findings and even perhaps have a stronger correlation between other personality traits.
We also measured to see if there was a difference between the personality traits of male and female crickets. This was done by taking the average and standard deviation of all the male and female crickets and comparing them using a t-test. The results are shown above in Table 1. None of the values were significant meaning that the null hypothesis could not be rejected, meaning that there is not statistical difference between male and female crickets. Again, our data may be flawed because of our unhealthy crickets. By using healthy, active crickets, we may be able to find a difference between the personality traits between male and female crickets.
We would like to further our study of the personality traits of crickets. In the next experiment, we would like to repeat our current setup but with healthy crickets. Additionally, we would like to test the other two personality traits-activity and aggression. To test activity, we would need to place a cricket in a familiar environment. Most likely it would be living amongst other crickets, but to control against interactions with conspecifics, we would like to acclimate a cricket in isolation for two weeks. After the two weeks, we will watch the cricket for 900 seconds using a scan sample of 5 seconds, and tally the behaviors observed into an ethogram. To test aggression, we would like to place two same gendered crickets on opposing sides in an arena, and place a small amount of food in the center and measure the amount of time (if any) that the crickets compete for the food. To ensure that the crickets are hungry, they will be kept in isolate for 3 days, and fed nothing except water. Additionally, we would like to expand upon some of the behaviors that we have already tested. Similar studies such as ours have been performed in the past. A recent example is Dochtermann and Nelson’s exploratory experiment on crickets. They looked at 2 different types of exploratory behavior-one being the ability to run a maze and one being exploring an obstacle course (Dochtermann & Nelson, 2014). We would like to incorporate these two trials in our experiment in order to further expand our exploratory behavior.