I think (a good preface for a post on objectivity ) that if there is an objective morality, it would be a biological one as you described. The problem with that is if it is only "do what is best for you species" then when species come into conflict, the victor will be moral in their own eyes, but immoral in the eyes of the defeated. It could be argued that therefore a more overarching objective morality could be "do what is best for all forms of life". But that is almost never going to apply, as the nature of life is that it is in competition with itself. Unless we pool all our resources into balancing all life on earth into some sort of perfect symbiosis (which IMO would be difficult bordering on impossible).