My friend belies that research is a group effort and --- do I.

Affirmative বাক্যে  agreement করার দুটি structure:

Structure-01:   প্রথম বাক্য+ and so + auxiliary verb + subject + full stop.

Structure-02:  প্রথম বাক্য+and+  দ্বিতীয় বাক্যের  subject + auxiliary verb +too/also + full stop.

For example:

Se works in a factory and so does her father.

She works in a factory and her father does too/also. 

 I will watch the drama and so will you. 

I will watch the drama and you will too.

Time has changed and so have you.

Time has changed and you have also

He is hard working and so am I. 

He is hard working and I am too also.