Dear Siddhharth,

You cannot use a single primer for checking the expression of all species of frogs hsp70. I am assuming that you are going to use SYBR Green chemistry. The primers have to be specific so that it should amplify only a single product because otherwise you will get false positive results. Although, if you design a primer from the conserved sequence you will get amplification. But, scientifically it will be wrong. So try to design primers for each species separately.

Regards.