asymmetries in needs and in capacities to meet them?

What does "to meet them" mean here? As I read, I understand it as "to satisfy the conditions (the asymmetries in the needs and in the capacities)". But I'm not sure. If so, "to meet them" would refer to "will require to be satisfied". But where to put "them"?
Your opinion will be appreciated.


Context:

in the currency of nectar, for the hire of their wings. Birds called
honeyguides can find bees' nests but can't break into them. Honey
badgers (ratels) can break into bees' nests, but lack wings with
which to search for them. Honeyguides lead ratels (and sometimes
men) to honey by a special enticing flight, used for no other
purpose. Both sides benefit from the transaction. A crock of gold
may lie under a large stone, too heavy for its discoverer to move.
He enlists the help of others even though he then has to share the
gold, because without their help he would get none. The living
kingdoms are rich in such mutualistic relationships: buffaloes and
oxpeckers, red tubular flowers and hummingbirds, groupers and
cleaner wrasses, cows and their gut micro-organisms. Reciprocal
altruism works because of asymmetries in needs and in capacities to
meet them. That is why it works especially well between different
species: the asymmetries are greater.