Our examples are about sexual selection, so let's take a look. It says, 3 bird populations are described below. For each population, determine which sex is the high investment sex, or if both sexes have equal investment. Then circle whether the intersexual selection, intrasexual selection, or neither type of sexual selection is being described. Alright.
A here says that red-necked phalarope males are responsible for paternal care. While males are caring for the clutch, female red-necked phalaropes will often attempt to mate with other males and will compete with other females for access to mates, leading to larger and more aggressive females. Alright. So as described, which sex sounds like the high investment sex? Well, I'm going to say males, and that's because the males are responsible for paternal care.
Right? So in that single mating, they have a high investment because they got to stick around and raise the young. So knowing that, well, do you see intersexual selection, intrasexual selection, or neither as described in this example? Well, the key thing for me is that the females will compete with other females for access to available mates, and that sounds like intrasexual selection. Remember, intrasexual selection is competition within one sex.
And here we have that competition within the females. And the way I remember it, that raw competition—I'm going to compete and fight and win the mates. Right? So we have the females competing for access to available mates, and so we get that sexual dimorphism leading to larger, more aggressive females.
Now quick note, we said that usually females are the high investment sex. Here we have the males. When you see that, sometimes it's called a sex role reversal. But it's just important to remember that it's not strictly females or males that behave certain ways. It really depends on how much they invest in the offspring, and that's just determined by that species' mating system.
Alright. We'll go on to B now. Scroll down so we can see it a little bit better here. B says that both male and female Laysan albatrosses raise their offspring. Birds typically form a pair bond with one other bird of the opposite sex that they maintain for life.
There is little visible difference between male and female albatrosses. So which sounds like the high investment sex? Well, to me, that's a bit of a trick question. I'm not going to say neither. Right?
It just says right off the top. Right? Both male and female albatrosses raise their offspring, right, at least relatively. They're giving about the same investment. So then as you read it, is this intersexual selection, intrasexual selection, or neither?
Well, I'm going to go with neither. And you know something that backs that up for me, there's little visible difference. There's little sexual dimorphism. So sexual dimorphism is a result of sexual selection. It just doesn't look like that's really going on here.
Alright. Finally, we have C red-capped mannequin males perform impressive dances that females evaluate when deciding whether to mate. Males have a black body with a red head and bright yellow legs, while females who are responsible for caring for the young are dull green and brown. So based on that description, which sex is the high investment sex? Well, it says the females are responsible for caring for the young.
That's a high investment in that mating. So I'm going to say the females here. And then, well, what do you think? Intersexual selection, intrasexual selection, or neither? Well, I'm going with inter, and that's because we have these showy males and choosy females.
And remember, intersexual selection is sexual selection that involves both sexes—one choosing to mate while the other is sort of performing or trying to impress. So the other sort of silly memory way I remember this, I say, uh. Right? And I think of them going like, do I want to mate with you?
Right? Making that choice. Alright. So with that, we've answered the question. Just a quick reminder, these are sort of simplified descriptions.
You can have both intra and intersexual selection going on in the same systems because nature is complex. Alright? We got more practice after this. I'll see you.