 In this module, we will discuss high weight characters. There is a list of characters which can be considered as a high weight character. For example, complexity, consistency, characters which are not affected by ecological shift, apomorphic, not a specific adaptation. Now, we will discuss one by one. First of all, we will discuss complexity. It is thought that the complex characters have more phylogenetic content and their contribution towards systematics and classification is more. For example, if we talk about the genitalia of insects, then genitalia is a complex structure. The structure of the genitalia of insects is unique. And it is very difficult to resemble the structure of a genitalia of a species. Because of this complexity, its weight is more and taxonomically, this character is very important. Therefore, when we talk about the identification of insects, then the structure of the genitalia is preferred. Similarly, consistency is another attribute, it is a second high weight character. These characters who are constant, their weight is more. In comparison, there are such characters who are variable. If we read about the pharise, then the pharise said in 1969 that such characters who are less variable, because the phylogenetic content is more, this is why such characters are called high weight characters. Similarly, such characters who are consistently present in a group and are consistently absent in a group, such characters are called high weight characters. Now, let's talk about such characters that do not change as a logical shift. Such characters who do not change as a logical shift, such characters are also called high weight characters. For example, it is seen that there are many birds who are present in a particular habitat and they feed on a particular prey, for example fish. When they are shifted to a new habitat, when they go to a new habitat, they do not change their feeding habits. If they were consuming fish in the first habitat, then they are still consuming fish. This means that because of ecology, there is no change in the behavior of fish eating in the habitat. This means that because of the ecological shift, they did not change. Such characters are called high weight characters.