 in this module we will discuss low weight characters if we talk about low weight characters then low weight characters are such characters whose contribution is very less in terms of classification taxonomists do not use such characters for classification or use them very less because these characters have less phylogenetic content these characters are not reliable and these characters have poor indicators of the relationship of the organisms similarly the low weight characters are highly variable in the last module we saw that such characters whose contribution is very less in terms of classification and such characters whose contribution is very less in terms of classification for example if we talk about hairs then the number of hairs in mammals varies very much one individual's number of hairs other individual's number of hairs varies very much even counting them is very difficult so this is a character whose contribution is very less in terms of classification this character cannot be called a reliable character similarly if we talk about branching pattern of arteries branching pattern of arteries is not only varies from one individual to another but with the same individual the branching pattern of the right and left side is different this character is also a highly variable character so these variable characters are less helpful in terms of classification so these are low weight characters similarly these characters whose monogenic or oligogenic their contribution towards identification is also less along with that these are regressive characters i.e. characters whose contribution is very less in terms of classification these are reducing characters these are also low weight characters for example loss of eyes, loss of wings in birds similarly wing, vein, insects, reduction in them similarly the loss of mammals teeth or reduction in them similarly the loss of segmented animals in their segment all these characters are low weight characters they cannot be very reliable therefore their importance is less in taxonomy now the loss of these characters there are many reasons for this one of them is environmental conditions for example the animals living in caves because there is darkness due to that the eyes of animals can be lost similarly because of their habitat many characters are lost because many characters do not need new habitat similarly if we talk about parasitic organisms such organisms which live in our gut many of them have such parasites whose digestive system, nervous system are all reduced so these are those characters which are highly variable so such variable characters cannot be called reliable characters similarly all those properties which are present in high weight characters are opposite in low weight characters for example these are not constant they have variability whereas high weight characters were constant and they had very little variability similarly these are not consistent low weight characters are not consistent but high weight characters are consistent similarly we saw that the high weight characters because of ecological shift they do not change but the low weight characters because of ecological shift they change similarly the high weight characters we read that they are highly complex but the low weight characters they are less complex so the less complex organisms their phylogenetic contents are less so the contribution of low weight characters and systematics or classification are very less