So, in some species, the father impregnates the mother and is never seen again. In others, he’s has roughly equal involvement with the mother during the pregnancy and possibly when the offspring are born.
What determines the variations of fatherly involvement?
Is K/r selection linked to this in some way? Are K selection species more likely to have a father who sticks around and contributes to the offspring after they are born?
There are species where the father sticks around when the embryos are maturing in the uterus/eggs but then leaves. What determines that?
Are there species where the father is largely absent during the embryonic stage but present and contributing during infancy?
(Moderators: I foresee that some shitspreaders might want to talk about race in this thread. If this occurs, could you split off their cuntribution into a separate GD thread so as not to derail this thread?)
You’re right, although many people might think that “animals” excludes humans which I certainly do not mean to do. I’m not sure how to make it clear that I want to discuss all animals, including humans, but want to avoid discussions of race. I’ll defer to a mod.
Not sure there is any real pattern to it. I would have thought that selection for heavy investment in individual offspring vs. heavy investment in weight of numbers would be the key, but some animals do both - like the stickelback.
One obvious factor is whether the father’s involvement is crucial for feeding the offspring. For example, bears build up a mass of fat to feed themselves (and for mothers, their cubs) during hibernation. Dad involvement is redundant.
Some birds appear to live in food-friendly environments, some others need both parents (IIRC) to feed the chicks. For some other types of animals, there may not be enough food around in the territory to support the father too. Plus too many animals close to the nest may attract predators.
Herd animals, esp. grazers, obviously the whole herd provides the necessary protection, so fatherly involvement is minimal (except in harem arrangements, where the major contribution is to prevent the female from mating with others, plus some protection role.)
In more primitive animals, even identifying one’s own offspring is an issue - in long-term paired animals, the male is relatively confident this is his offspring. In animals that have a courtship display process, and temporary “hookups”, the connection is not direct enough for the father to take an interest in raising the offspring. Ins ome situations, males actively kill existing offspring on the theory that they will get rid of another male’s offspring and replace it with their own - IIRC rats and hamsters, the female actively keeps males away for this reason.
So there you go - the father has to know (be confident) that those are his offspring, and they have to need his help. Otherwise, his best self-interest is to build up his sexual display to attract his next tryst.
Animals often reproduce with one of two strategies for survival: quality or quantity. (Although there are certain species that seem to use a little of both)
The quality approach aims to raise the best offspring and equip them with what they need to survive. This approach often involves smaller litters or groups of offspring and parental involvement.
The quantity approach aims to overwhelm the ecosystem with offspring in the hope that a portion of them will manage to survive to adulthood.
Often, the approach used will depend on the specific adaptations of the species in question. Humans are a great example of the quality approach: we care for our offspring for an extended period of time in order to best prepare them for living in the outside world. A quantity approach might be seen in frogs or sea turtles.
The quality and quantity approaches can both have paternal involvement, to some degree. Caring for young is a significant investment of time and energy however, and so if the benefits of investing these resources into the offspring don’t offset the negative aspects (ie puts the parent in more danger), the parenting will likely be selected out of the species.
In the quantity approach, either or both parents will sometimes guard unhatched eggs. This is a quality aspect being implemented, but in a limited way, as the eggs are stationary. Usually this is to extend the lifespan of the offspring until they are able to move around on their own.
Mammals are often a good example of the quality approach, as most mammalian adaptions are to allow a mother to care for a smaller number of offspring. This doesn’t necessarily require paternal involvement, and in some cases, would make paternal involvement impossible, such as with large apex predators like polar bears. Two adult polar bears require so much food that for a pair to coexist long enough to care for young would likely starve both of them. This is an example of the detriments of paternal involvement greatly dwarfing the benefits.
Other predators like lions do have active paternal involvement, in which male lions defend territory and hunting rights from other prides of lions, to ensure that the lionesses and cubs have a regular supply of prey.
As I’ve detailed in my pigeon thread, the male pigeon of the couple who live on our balcony seems to do most of the child-rearing. Dad is still fooling with the kids once Mom lays some more eggs, which is generally two or three weeks after the previous clutch has hatched. He’ll keep feeding and preening them for a few weeks, while Mama just seems largely to ignore them after that. But she’s fiercely protective before that. Seems to work out okay for them.