asexual species are vulnerable and genetically limited, eventually dying off. they are suited for a fixed environment that they can exploit to rapidly reproduce. their future genetic potential is limited and a deadend. and they are vulnerable to change of that environment.
specialisation and distribution of labour. gestation for example leaves you pretty vulnerable. of course, it's not like it's strictly deterministic, many things could just be kind of coincidental but they continue to exist simply because they manage to continue existing.