Who's Your Daddy?

 Who's Your Daddy?

No, seriously... I need to know for record purposes.

Maintaining proper records of parentage is key to successful zoo breeding programs.  Though there is a long tradition of breeding fathers to daughters, brothers to sisters throughout the history of animal husbandry, doing so can have some bad results, as deleterious (bad) gene combinations are expressed.  Think of the royal households of 19th century Europe and all of the resultant medical issues, such as hemophilia.  Or, about white tigers and what a genetic dumpster fire they are.

Of course, to know how related animals are, you have to have an accurate idea of their parentage.  And that can be tricky with a lot of animals.  If you put a male tiger in with a female tiger and get tiger cubs (as one does), you can be pretty sure who mom and dad were - especially if dad is the only male tiger that mom spent any time with in the months preceding the birth.  But it's not always so easy...

For instance, in some social animals, there can be multiple males and multiple females in an enclosure together, all fertile.  Some species, such as many ungulates, have a dominant bull that you may assume is the father of all of the young (not that some subordinate males don't get some sneaky breeding in on the side - which is why many zoos maintain single breeding males per herd).  Other species, such as chimps, are quite promiscuous, and the mother might have mated with many potential fathers.  Even if you witnessed her breeding Male "A," that doesn't preclude her having also spent some quality time with Males "B" and "C."  A genetic test may be necessary... but has to be budgeted for.

Even if a species is monogamous, there are no guarantees.  A study of a colony of ibises at one zoo - consisting of several nominally mated pairs - showed that there was a surprising amount of adultery going on.  Females would sneak off to breed another male, then return to their nest to lay an egg and hatch a chick which the zookeepers assumed to have been sired by her mate.  Her mate assumed so, too.  This probably happens regularly in the wild as well, but no one is keeping a studbook in the wild.

What male was with the female at the suspected time of conception?  Hard to say - because that would imply a concrete answer for how long of a time period there is between mating and laying eggs or giving birth.  Some species can store sperm for lengthy periods of time.   Some mammals show delayed implantation, where the egg is fertilized, then stays in limbo for months before finally starting to develop.

And then there is parthenogenesis, or virgin birth... in which the answer to the question "Who's your daddy?" is... no one.

With other species, you may know dad, but not mom.  With rheas, ostrich-like birds from South America, all of the females dump their eggs in one nest for one male to incubate, while they go off foot-loose and fancy-free.  In that case, the father may be known - because he's usually the only male - but the mother may be one of several females.  Or you may just find an egg in an exhibit of multiple animals and that's all you know - it could be anyone's!

Sometimes you can use some detective work to track down the correct parents.  Sometimes you get lucky and observe the mating, or the egg-laying, or what have you.  Sometimes you can do genetic testing and find the parents that way.

And sometimes it's a mystery.