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The Comparison of Behavior Convergences among the Mammalian Orders: Carnivora and Rodentia.

Abstract: The purpose of this research is to observe and analyze the behaviors of three different mammalian species from the orders: Carnivora and Rodentia to determine behavioral convergences and the link to evolutionary convergences. The research was broken down into two parts. First, research was conducted analyzing one individual at a time on the video recording and analyzing the individual behaviors. The second part of the research focused on the social dynamics and organization of the organisms and the entire group of animals was observed instead of one individual. Behaviors emphasizing the social nature of the animals were especially taken into consideration during observation and analysis.

Introduction: The research conducted for this project studied the behaviors of species representing different mammalian orders: Carnivora and Rodentia. From the Carnivora order, meerkats (Suricata suricata) were observed, and from the Rodentia order, degus (Octodon Degus) and gerbils (Meriones unguiculatus) were observed. The degus and gerbils can be further categorized into suborders. The degus belong to suborder, Hystricognathi, and the gerbils belong to suborder Sciurognathi. Although the different species belong to different orders, other similarities, including behaviors exhibited by the animals can be seen. All three of the species are primarily native to desert-like habitats, live in social settings, and are burrowing mammals. By observing behavioral convergences of the different species belonging to different orders, it may be possible to like this to an evolutionary convergence as well. For the second part of the research, only the meerkats and degus were observed because it was only necessary to have two representative species, one from each order, instead of having three species total.

Meerkats are found in the Kalahari Desert in South Africa. Meerkats are not able to maintain internal thermoregulation as well as most mammals and make up for this loss of body heat by grouping together in burrows to generate more heat. They fall prey to many predators such as martial eagles, tawny eagles, and jackals. Studies have shown meerkats display certain behavioral traits as an adaptation to protect them from predators. For example, it is common to see roles in a group of meerkats such as one which acts as a sentry and stands guard while other members feed or tend to the young. Certain physiological features aid the animals in expressing the behaviors. The long tail acts as a tripod to support the animal when it needs to spend long hours in the stand position to look out for predators. Also meerkats have dark patches of fur around the eyes to reflect the sun when looking up for aerial predators. (http://www.bio.davidson.edu/people/vecase/Behavior/Spring2004/fitzpatrick/fitzpatrick.htm).

Degus are native to Chile, found in coastal areas and montane regions usually in thick underbrush and hedgerows. Studies on degus have shown they live in social colonies and build extensive tunneling networks. Communication exists between members of the colony. Signals such as sharps barks or squeaks will be given out to warn members that a predator may be near. (Cloyd, E. 2003. "Octodon degus" (On-line), Animal Diversity Web. Accessed November 21, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Octodon_degus.html.)

Gerbils when in the wild are native to open, dry habitats. These can include deserts, mountain slopes, and sandy plains. Gerbils are capable of building complex tunneling systems and also live in family groups. Different noises such as clicks, squeaks or barks have been observed in gerbils as forms of communication among members of a family group. (Poor, A. 2005. "Gerbillinae" (On-line), Animal Diversity Web. Accessed November 21, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Gerbillinae.html.)

Materials and Methods: Video analysis was used to record the behaviors of the meerkats, degus, and gerbils. Due to the nature of this research being an observational study of naturally occurring behaviors, it was important for the recording to have as small an impact as possible on the animal. To achieve this, the video camera was set up to record while the observer vacated the area under surveillance. This provided an opportunity for the animals to act more naturally as if no one was watching them. Once video data collection was completed, the tapes were digitized and downloaded on the computer for analysis. During this process, the film was watched at least two times to determine which behaviors were noticed and chosen for analysis. Significant behaviors such as “stand”, “sit”, and “scan” are some examples of noteworthy behaviors. The behaviors were given one-letter codes to make analysis more time efficient. When recording the behavior of an animal it is crucial to notice even the most subtle behaviors expressed by the animals because they may prove to be just as important as more obvious, elaborate behaviors. Once a list of all behaviors was composed for each species, the data was analyzed using a program called time-line analysis. This program compiled the data to create the frequency of behaviors expressed and the transitions between the different behaviors. From the information provided by time-line analysis, an ethogram was created. (See Figs. 1-A, 2-A, and 3-A). Ethograms are used by ethologists to study and predict behaviors exhibited by animals. The ethogram factors in the frequency of the occurrence of the behavior and the occurrence among transitions from one behavior to the next. The size of the square boxes on the ethogram indicate how frequent a behavior occurs in relation to the other behaviors. A larger box indicates the beahvior in the box occurred more frequently than one in a smaller box. The size of the transition arrows are also proportional to how frequently the transition occurs between certain behaviors. A larger arrow, and the number corresponding with the arrow describe how frequently the transition occurred. Ethograms along with probability are useful in predicting behaviors seen in animals. Graphs of the behavior frequencies using Excel were also created. All of the data was used to compare the different animal species for behavioral and evolutionary convergences. In addition to this, a chi-squared analysis was completed to examine if a significant difference existed between the behaviors of the different species.

Results: The following charts and graphs show the data gathered from analyzing the meerkat, degu, and gerbil behaviors.

RESEARCH I: Individual Behaviors

Data for Meerkats Behaviors:

Fig. 1-A: Frequency of Behaviors Observed in Meerkats

Table 1: Chi-squared analysis among the percentage of behaviors seen in the meerkats, degus, and gerbils, (M=Meerkats, D=Degus, and G=Gerbils).

Discussion: As this research shows, behavioral analysis of an animal can give viable information about the particular animal. Many evolutionary convergences can be seen when examining behaviors. The behaviors observed in the animals give more insight as to why the animal may have certain physiological traits. For example meerkats are found in hot, dry areas where they may be in the sun many hours each day. As seen in the Fig 1-A, the meerkat ethogram, the most frequent behavior exhibited by the animal is the scan behavior. Most of the animal’s time is spent scanning in bright sunlight, and to accommodate, meerkats have dark fur around the eyes to reflect the light. In addition to this, meerkats fall prey to many predators and must scan in an attempt to avoid predators. The same examples can be seen in the degus and gerbils. The largest frequencies exhibited by both species is the sit and scan behaviors. Again, these animals fall prey to many predators and must constantly be aware of potential dangers. All three of the species examined have long tails which can act to help balance the animal during long hours of sitting or standing (behaviors frequently seen in all three species), making it easier to do for long periods. From an evolutionary standpoint, the behaviors aid in survival of the species by making the individuals more attentive to predators.

The behavioral analysis of the different mammalian orders, carnivora and rodentia can be compared to an evolutionary convergence. Based on biological taxonomy, the meerkats are members of the order, carnivora whereas the degus and gerbils both belong to the order rodentia. The degus and gerbils can also be divided into further suborders, Hystricognathi and Sciurognathi, respectively. Based on this, it can be hypothesized that if behaviors correspond to evolutionary factors, then the behaviors seen in the gerbils and degus will be more similar than those seen in the meerkats, but if there are still some similarities between all three species, then this could mean a possible evolutionary convergence among the mammalian orders. Chi-squared analysis was used to determine the significant difference between the behaviors of the three species. As seen in the results from the analysis, whenever the degus and gerbils were compared, there was no significant difference seen in the frequency of the behaviors. (See Table 1). This data corresponds with the fact that these animals are more closely related on an evolutionary scale since they are in the same order. However when comparing the behaviors of the degus, meerkats, and gerbils, the chi-squared analysis shows a significant difference exists between these behaviors. Any other significant differences shown by the analysis occur only when comparing the meerkats to another species, but there are still some examples which show no significant difference between the meerkats and other species. This entails that even though the meerkats are in a different order from the degus and gerbils, there are still behavioral convergences which could also mean evolutionary convergences. In addition to this, the chi-squared analysis shows no significant difference between the degus and gerbils even though they are in different suborders. This convergence can also be linked to an evolutionary convergence.

In part II of the research, more attention was paid to the social organization within the animal groups. In this part, instead of analyzing only one individual at a time, the entire group was observed and only those behaviors seen as social were recorded. Some of the same behaviors from the first part of the research were seen in the second part of the research. Behaviors such as sit, walk tail down, or jump were similar in both the individual and social analysis. One key aspect of the behaviors worth noting is the concept of imitation and mimicking. When observing the meerkats and degus, it was very common that when one animal did a certain behavior, that behavior was duplicated by the rest of the group. This supports previous ideas about the social interactions as well as the group support in response to predation. Other behaviors seen when observing group behaviors are the type of actions seen when one individual encounters another member of the group. Behaviors such as greet or nuzzle were frequent and act as a way for members of the group to reacquaint themselves with one another. Perhaps this is a type of evolutionary defense to make certain strangers are not present in a familiar group. Similarly to the previous research, social behaviors can also be linked to evolutionary convergences as well as explain organization among the group of animals.

All three species examined in this research are unique in the fact that they all are different species in two different orders. However based on the similarities seen in the behaviors exhibited by the animals, they can be more closely linked to one another suggesting an evolutionary convergence.

Cloyd, E. 2003. "Octodon degus" (On-line), Animal Diversity Web. Accessed November

GROUPS, By: Science, 00368075, 01/19/2001, Vol. 291, Issue 5503
Database: Academic Search Premier

Poor, A. 2005. "Gerbillinae" (On-line), Animal Diversity Web. Accessed November 21,

Tietjen, B. “Spider Lab” (On-Line). Accessed Novemer 20, 2005 and April 4, 2006 at

Behavior	Comparison	Chi Square Value	df	Significant Difference	No Significant Difference
Sit	M+D+G	20.294	2	+
Sit	M+D	2.4	1		+
Sit	M+G	4.909	1	+
Sit	D+G	0.461	1		+
Scan	M+D+G	14.764	2	+
Scan	M+D	1.923	1		+
Scan	M+G	4.787	1	+
Scan	D+G	0.675	1		+
Stand	M+D+G	6.442	2	+
Stand	M+D	0.727	1		+
Stand	M+G	0	1		+
Stand	D+G	0.727	1		+
Walk	M+D+G	9.012	2	+
Walk	M+D	0.181	1		+
Walk	M+G	2.793	1		+
Walk	D+G	1.58	1		+