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PROFESSOR: That
zigzag dance-- I think

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we missed at the very
beginning of the film.

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At least the audio
wasn't working yet.

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But you saw it later with
the movement the male makes.

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Its a fixed action
pattern he makes in order

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to lead a female--
usually a female

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he has picked out from
a group-- to his nest.

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And it's when the female
sees that, if she's

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ready to lay eggs, she
is induced to follow him.

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But the cause of her behavior
is the sight of his behavior.

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So you saw an example of
the use of dummy stimuli

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with the models of females
of different shapes.

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And you saw their
analysis of the purpose.

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They were looking for
why that's adaptive.

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And the fairly obvious reason
was the larger females,

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the larger swollen belly,
and so forth have more eggs.

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So it benefits the male
to choose such a female.

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Because then he can
inseminate larger numbers.

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And it should result in a
greater number of offspring.

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And by the way, the
purpose, I mean--

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if you were dealing with
humans, and you say well,

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if you want to know that
purpose of something,

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just ask the person.

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It doesn't work.

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You don't have to be
aware of the purpose.

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The purpose is the
evolutionary purpose.

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It's what's evolved.

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And you don't have to
be aware of it at all.

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In fact, you may give
totally different reasons.

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You would give
approximate reasons.

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But not the reasons where the
whole behavior pattern evolved.

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And then you saw the
study of development

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where they buried the orphan
on the naturally-reared fish.

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And how they differed in
their anti-predator behavior,

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their escape behavior.

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Apparently, the early experience
plays an important role

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in shaping later responses.

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So it's their patterns of
escape from attacking fish

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is not totally unlearned.

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00:03:03,480 --> 00:03:05,870
It has a learned
component as well.

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And you learned the answers
to these from that film also.

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By looking at the fish that
have evolved in isolation

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from each other for
long enough, they

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were able to see
differences that

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have evolved with that, because
of different-- In one case,

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some of the stickleback
were initially ocean-going.

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And then they became
isolated in the smaller

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lake that became
freshwater lake.

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And you learned why the
male stickleback fish drives

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the female away, because
she's cannibalistic.

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The behavior of these
animals, of course,

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involves the behavior
of both male and female.

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An individual female can
benefit by cannibalizing eggs.

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Because most of the eggs she
will be eating aren't hers.

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00:03:58,910 --> 00:04:01,600
And if she now can
lay a lot more eggs,

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00:04:01,600 --> 00:04:05,400
she has a greater
chance of reproducing.

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00:04:05,400 --> 00:04:07,585
Or reproducing a larger
number of individuals.

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00:04:10,100 --> 00:04:12,340
But of course, that's
not in the male's favor.

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00:04:12,340 --> 00:04:18,570
He wants to preserve those
eggs that he has inseminated.

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00:04:18,570 --> 00:04:22,580
And he is the one in charge
of the safety of those eggs,

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until they hatch.

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The female in this-- Sorry?

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AUDIENCE: So what
does the male eat?

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PROFESSOR: What
does the male eat?

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He doesn't eat eggs.

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They eat very small
organisms and vegetation.

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00:04:42,140 --> 00:04:43,750
But I'm not sure of the details.

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There's plenty online
about sticklebacks.

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00:04:45,490 --> 00:04:48,900
It would be a pretty easy
thing if you want details.

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00:04:48,900 --> 00:04:49,480
OK.

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00:04:49,480 --> 00:04:53,360
So next time, we'll be talking
about Tinbergen's studies

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of birds-- kittiwake gulls.