The communication techniques of animals belonging to the same species are normally shaped by natural selection and sexual selection. These two factors are very important in influencing the adaptation of organisms to different environments (Jord and Martins, 2006, p. 1). When considering organisms belonging to different species, there was the observation of complicated selection factors that brought about diversifications in several species. The research involved the use of four phylogenetic comparative methods, alternative phylogenetic hypotheses, and the asset of data that had been collected from 50 different sources representing 53 different strata (Jord and Martins, 2006, p. 1). The research was meant to test the relative importance of different ecological variables on the evolution of anal visual displays. The results of the study showed that the change in the different display components could have been a result of selection, but evolution normally shows that the changes that occur during the time of display could be as a result of sexual dimorphism and the number and uniformity of the display. The research also showed that ecomorph differences also affect the display structure’s evolution.
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Various factors have been shown to influence the evolution of communication structures in animals. For instance, signals used by species to attract mates will tend to be favored by selection (Jord and Martins, 2006, p. 2). The properties of the animal’s environment, especially the makeup of the habitat are another factor that influences the evolution of the communication methods. Apart from adaptation, there are other factors such as mutation, random genetical drift, and the genetic correlations between different elements of a given phenotype. It is rather difficult to positively identify the exact evolutionary process responsible for the differences in animal signals. This is because animals normally display more than one signal that could have arisen as a result of varying evolutionary forces (Jord and Martins, 2006, p. 3).
In the study, modern phylogenetic comparative methods were used to study the effect of the ecological and phylogenetic factors on the interspecific diversification of a multifaceted signal and the dynamic visual displays of animals (Jord and Martins, 2006 p. 3). The study aims at showing how data from various sources can be compared to help determine the evolutionary forces that cause the diversity in signals.
Anolis is one of the largest genera in the world and it consists of about 400 species. This could be as a result of adaptive radiation in the islands of the Antilles and the inhabitation of mainland Central America and Northern South America. The genera have been extensively used in research work because it provides an important ecological, evolutionary biology, and island biographic system. In addition, the group has a lot of information concerning its morphological, phylogenetic, and ecological setup (Jord, and Martins, 2006, p. 3). The study capitalized on the group‘s large species diversity and the focus was specifically on the diversified movement features in anole head bob and the dewlap displays.
The investigation started by looking at the relation in evolution between the different signal characteristics that constitute displays. Then the role of the evolutionary processes in determining the display structure using the phylogenetic generalized least squares and the phylogenetic mixed models; to determine the display components that are controlled by phylogeny. Finally, the effect of the ecological setup of the species on the evolution of signals was studied. Apart from the effect of sexual selection, the recognition of species and the role of the organism’s habitat in the evolution of the display structures in anoles were also examined.
The study showed that there was no special choice of females in the iguana lizards but it was shown that sexual selection was shown by the males when they fought over control over the regions that would allow easy access to the females (Jord and Martins,2006 p. 4). Research also shows that the conflicts over territories by males are mainly influenced by the differences in the sexual sizes of the organism. The competition between males in the lizards has been found to cause the evolution of various methods of communication and as a result, several signals are developed, some of which could be in the form of color variations (Jord and Martins, 2006, p. 5). Then the sexual size dimorphism effect on the evolution of the shorter and more complex signals was assessed. In the anoles, sexual selection has been shown to influence the development of the sexual size dimorphism and it normally occurs by pushing the organisms into ecological setups to minimize the conflicts between the same sexes (Jord and Martins, 2006, p. 6). If the divisions of the ecological niche result in sexual size differences, then it means that the sexual size dimorphism could be having a very minimal effect on the development of the signals.
To have animals communicating effectively with each other, it may be important that they produce signals that are capable of conveying messages that are reliable and are understandable to their fellows (Jord and Martins, 2006, p. 7). The efficiency of the signal is normally determined by several factors such as the extent of the vegetation that is blown by the wind that determines the clarity of the motion displayed in the lizards. Another is the availability of visual interferences between the sender and the receiver, the amount of light available in the habitat that determines the clarity of the motion display i.e. the clarity of the head-bobbing lizard is never clear under dim light. Various ecomorphs are associated with peculiar selection forces and this could therefore be the cause of differences in display features.
The intensity of the competition between the males normally gives rise to the development of even more complex and efficient display features to assist in the assessment of the other males for a speedy conflict decree. The diversity in the displays of the sympatric species is found to be higher than in the allopatric species and is normally proportional to the number of congeners each of the species encounters (Jord and Martins, 2006, p. 8). Species in less sunny surroundings always produce longer and more homogenous signals to enhance the identification of that given signal. The arboreal ecomorphs are shown to have developed slow display movements.
The information for the study was collected from the published display action pattern graphs that had information on the motion of head bobs and dewlaps over some time. The data collection was restricted to the signature displays only; the other information collected was on sexual size dimorphism, habitat use, and sympatry and ecomorph class. In the analysis of the study; for the start, the phylogenetic generalized least squares method was used to assess the ancestral states and relationships between the evolutionary changes and the surroundings. The phylogenetic mixed model was then used to assess the relationship between the interspecific phenotypes and evolution.
The sexual size dimorphism and the head bob duration were shown to have a strong negative correlation. The study also found that there was a very little relationship with the other display traits with sexual size dimorphism. The species’ body size was found to be positively related to sexual size dimorphism in the anoles. It was also shown that there was a negative relationship between head-bob homogeneity and the sympatric congeners and that the lizards communicating in a sunny environment used more pulses that stayed in the environment for quite some time (Jord and Martins, 2006 p. 10). The head-bob duration and the dewlap latency were found to be related to the ecomorph categories. The study also showed that the display evolution is a result of multiple forces. The habitat structures were found to affect the varying properties of lizard’s visual displays (Jord and Martins 2006 p. 14).
Communication between organisms is always a very important activity since it enables the organisms to acquire food, avoid danger, and mate among other things. This will enhance the survival of the species. The modes of communication are normally diversified and at times the animals, especially the males exhibit aggression when communicating with other males. The animals can use signals such as color variation and the production of sounds to communicate. These signals normally show a lot of diversification even among members of the same species. This is a result of the nature of the habitat, the amount of illumination in the environment, and sexual selection.
Jord, T. and Martins, E. P. (2006). Tracing the origins of signal diversity in anole Lizards: phylogenetic approaches to inferring the evolution of complex Behavior. London, Elsevier.