Hmm in the context of the article, I'm not so sure it's a good thing.

Later on they mention that if this genetic trait gets passed on to males, they die. So along with hunting, males are doubly at risk.

It may be advantageous for the survival of an individual to be born without tusks, but it doesn't sound too good for the survival of the species.

The trait may or may not be advantageous. Diversity is. In this case the selective pressure is poaching, but selective pressures are constant. Diversity is a bank of genetics that the population can draw from to adapt and survive.

Traits that are rare, are often rare because of shortcomings. But if environmental changes make that tradeoff worthwhile, it can be made. Meanwhile, evolution doesn't stop. Once the trait/gene is common there is positive selective pressure on complementary genes. Over time, these may mitigate or compensate for the negative traits that have acquired.

Of course, on the timescales that humans tend to selectively pressure species, there isn't time for all this elegance to emerge, usually.

This is all true. You make very good points.

My parent said:

> And this is why genetic diversity is a good thing.

I guess what I meant was: genetic diversity is a good thing. But this particular case is not a great example for illustrating why.

Why do they die? Because they can't protect themselves? Or does the trait come with other less desirable side effects for males?

The trait appears to be lethal to males and they do not make it to birth.

It may be the case that at least one typical X chromosome is necessary for survival, and males only get one X chromosome.

Yes, but in the long run isn't this breeding out this specific diversity? I recall reading that genetic diversity becoming limited in endangered species makes them much more susceptible to being wiped out by disease.