When we hear the word "evolution" we often
think about Charles Darwin and natural
selection. But some of the most stunning
examples in nature are actually brought
to us by a related concept that Darwin
introduced: sexual selection. And while
natural selection favors the animals
that are best suited to their
environment,
sexual selection favors the animals who
are best suited to get a mate. Instead of
blending in, these are the animals that
stand out. They might fight better or
stronger with antlers, or horns, or like
the animals that you see behind me. Or
that you might see on a night downtown.
They're showier, they're brighter, they
sing better songs and they do better dances.
Darwin discussed the now famous
example of the peacock. He suggested that
its beautiful plumes were the result of
females mating with the most beautiful
males, even if he didn't know why females
might do that.
He also wrote about this fish, the
Peacock molly. He was trying to make a
point that these female mating
preferences might drive speciation. They
might shape species in ways that would
cause those species to be different
because the females had preferences for
certain traits, like this males big
beautiful colorful fins. 150 years later
we're still learning about this. We're
still trying to figure out how sexual
selection shapes and creates new species.
Why do organisms have preferences for
the ornaments and the armaments of a
potential mate? Why might humans have
preferences for symmetry, certain
pheromones, or cues that could indicate
intelligence or fidelity? What makes an
animal "swipe right"?
If we can understand why animals make
these choices — why snails or flies or
fish make the choices they do, then we
can start to understand broader
questions of biological diversity. If we
can start to understand why these two
fish choose each other then we can
understand how those choices might shape
the creation of a new species. We can
start to understand why Sailfin mollies
evolved from Shortfin mollies, and why
there's not one species of
Sailfin molly, but four, and how sexual
selection shaped those. When we look at
the species around us ,when we think
about their beauty and their grandeur,
some of the questions that we're asking
are about what caused those species to
form and why they're all there. Why all
of that diversity, and that's what sexual
selection allows us to do. It allows us
to start to understand these little
biological questions and put them in
that broader context to answer the big
biological problems. In addition, it can
help us smile at our own mate choices. It
can help us look at a Friday night and
better appreciate the songs, the dances,
and the courtship displays and
everything that makes that weekend
night so much more interesting. Thank you.
