What we are discussing here is often called "kin selection".
And one important place it happens is among the cells of a multicellular organism. Each one has its own genetic material, so a cell is a sort-of organism. But the large majority of cells ultimately die without leaving any successors.
A blue whale contains around 10^17 cells, but on average, it is survived by only two cells -- all the rest ultimately die. And that whale has many cells that die before that: skin cells, digestive-system lining cells, blood cells, etc.
Likewise, a tree is mostly dead -- the only actively-metabolizing parts of its trunk and branches are the cambium (the thin green growing layer) and some cells that act as valves. All the other wood and bark cells are dead. A giant sequoia may thus contain 10^19 dead cells -- and a much smaller number of active ones.
And many trees drop their leaves in preparation for poor conditions -- dryness or winter. Meaning that all those leaf cells die at the end of a growing season.
[This message has been edited by lpetrich, 04-26-2003]
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