Simplify the following text for a Grade 11 native English-speaking person.
Original: It is useful to distinguish between `` ecological selection '' and `` sexual selection '' . Ecological selection covers any mechanism of selection as a result of the environment ( including relatives , e.g. kin selection , competition , and infanticide ) , while `` sexual selection '' refers specifically to competition for mates .
Simplified: `` Since Darwinâ s days it has become clear that this kind of selection includes a far wider realm of phenomena , and instead of sexual selection it is better referred to as selection for reproductive success ... genuine selection , not elimination , is involved , unlike survival selection .