Science tells us that family certainly does matter | Columns







I’ll never forget my first wild turkey. Although I had hunted them on and off for years, things did not come together until I went out one day with my neighbor, Jack.

Jack was new to turkey hunting, as well, but he has always been a much more experienced hunter than me. You could say he took me under his wing, pun intended, when I arrived in the neighborhood.

We went out together one day on a nearby farm and, amazingly, heard gobbling as soon as we left the truck, and it sounded like two birds, not just one.

Setting up in a nearby field with some sparse trees behind and decoys in front of us, Jack let out a few yelps with his call.

The gobblers immediately ripped back, and they were coming. Within a few minutes they were in front of us, and Jack dropped one immediately.

As the second moved around in confusion, I tried to get a bead on his head. He finally headed right for us, and I was able to take him cleanly.

Jack and I just looked at each other and laughed. I am not sure we have both smiled so much simultaneously before, or since.

At that moment, we thought turkey hunting was easy. Boy, were we wrong. Over the years we have failed many more times than we have been successful trying to lure a gobbler. But each time we go out, we usually learn something new.

What I did not realize on that first fateful day, however, was a lesson I was not even aware of, and did not think about at all until recently.

The question I should have asked at the time was: Why were those two gobblers together?

Male gobblers typically attract harems of hens and defend those harems from rival males. Occasionally, however, you see two or even three gobblers seemingly working together, not fighting each other, and displaying to the hens simultaneously.

This would not seem to make much sense evolutionarily, because gobblers are trying to maximize their reproductive success.

That is, natural selection favors males that pass more of their genes into the next generation, and any competition with other males would reduce their evolutionary fitness.

This is why males often fight each other, using the spurs on their legs and beating each other with their wings, in dominance contests. The winner gets the hens.

Using genetic analysis of these turkeys, scientists have figured out the conundrum of the cooperative gobblers: they are brothers.

As brothers, they share half of their genes with each other. What this means is that even if one brother gets all of the mating, the other brother shares half of the benefits that are passed on to the next generation.

The mating brother gets direct evolutionary benefits, while the second brother gets indirect benefits, but they both benefit from cooperating if that leads to more mated hens. Two gobblers may create a larger and more attractive display, attracting more hens, and two (or three) brothers working together might be less likely to lose the hens to a single-boss gobbler.

It is possible that the brothers share in mating with the hens, and thus each get some direct and some indirect fitness from their cooperative behavior.

This phenomenon is called kin selection, and examples of it are found throughout nature, not just in wild turkeys. Many other bird species, like some species of nuthatches, woodpeckers and jays, have helpers at the nest, which aid the parents in rearing the offspring.

It turns out that helpers are typically offspring from a previous clutch helping to raise their younger siblings, which sounds remarkably similar to how our own older brothers and sisters help to raise us.

It sounds similar because it is; humans are great examples of kin selection in action, as well. Many of us have doting uncles or aunts who have helped us become successful, which are all gaining evolutionarily from their behavior, whether they realize it or not. Other examples include bees and their complex systems of queens and workers; the warning calls of ground squirrels; kin-based cannibalism avoidance in salamanders; and many other examples.

Kin selection works because of how relatedness varies among individuals, and the ability of organisms to recognize these kin differences. In some of these species, it likely occurs because of experience; you know your parents and siblings because of the time you spend with them.

I would bet, but cannot confirm, that groups of jakes (young male turkeys) that we often see together are related, and likely are part of the reason we see gobbler pairs: the jake brothers grow up together.

In other cases, however, such as in many mammals and insects, their sense of smell allows them to discriminate between kin and non-kin.

Not all kin are created equal, however. Siblings share half of their genes with each other, while cousins ​​only share one-quarter of them, and second cousins ​​one-eighth.

What this means is that how organisms behave should depend on the degree to which they are related.

The biologist JBS Haldane was famously asked if he would trade his life to save a drowning man. He is quoted as saying, “No, but I would gladly give up my life for two brothers or eight cousins.”

The direct fitness of one life is worth the same as two siblings or eight first-cousins, from a kin selection point of view.

Scientists have shown that this rule works. For example, ground squirrels are more likely to chase away distant cousins ​​from their burrows than closer kin, and cannibalistic salamanders can tell the difference between cousins ​​and siblings (they are more likely to spit out siblings after they grab them to eat).

Nature is amazing this way. Just when you think you have it all figured out, some new question arises, like why gobblers sometimes cooperate.

The science that helps us understand the answers to these questions is just as amazing, and opens up new doors to reveal relationships in other species, and even our own, that we did not know existed.

That is part of the beauty of science: we never stop learning new things, yet each day brings better understanding of the natural world around us, whether we are hanging out in the backyard or sitting in front of a tree trying to lure a gobbler within range.

HOWARD WHITEMAN, who lives northwest of Paris, is a professor of wildlife and conservation biology in Murray State University’s Department of Biological Sciences and is director of its Watershed Studies Institute. His email address is hwhiteman@murraystate.edu.

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