Tuesday, December 11, 2012

Discovery Corps Wants to Know – Part 3

This week’s blog post is the final installment in the series, “Discovery Corps Wants to Know,” but it is not the end of the questions or the curiosity that our DC youths have about science. To read the previous articles, go here and here.

How did butterflies evolve? ?

Scientists have some pretty solid theories about butterfly evolution, but do keep in mind that these delicate insects fossilize very rarely, so most of the evidence comes from relationships between modern groups of butterflies.

You can think of butterflies as a day flying branch of the moth family. The moths are quite diverse; the butterflies are specialists, which probably coevolved with flowering plants, perhaps dating back to the Cretaceous period. The earliest butterflies probably coexisted with some of the later dinosaurs!

Butterflies are closely tied to plants at two stages of their life cycle. As caterpillars, they eat the leaves of plants, with each butterfly species having a small group of plants that it will lay its eggs on and feed on.

As adult butterflies, most species are adapted to drink nectar from flowers. These flowers are often a different species of plant from those the caterpillar eats.

The relationship between butterflies and flowers probably explains a great deal about what makes butterflies unique. The bright colors of flowers attract these day flying insects. The butterfly serves the flower by delivering its pollen from one plant to another and in exchange gets nectar to fuel its flight.

Once butterflies evolved color vision to find flowers, it became important in their mating interactions as well, and their many beautiful wing patterns evolved. As they rely more on vision and less on scent, the butterflies lost the branched antennae we see on moths.

Why do butterflies mimic small animals such as snakes?

Butterflies have no real weapons available to them. They don’t have claws or teeth, or any way to fight off a predator.

Some of them taste bad, but most are edible, and rely on flight or camouflage for protection. But in the darker understory of the rain forest, where light is low, mimicry is also possible. If you saw a yellow eye or a snakehead in the gloom of a dark forest, you might not choose to come closer and investigate. The same markings in a sunnier habitat would probably not fool a potential predator, so you will mostly see these kinds of markings on forest dwelling species.

Is there something that butterflies are better at than us human beings?

I’m guessing this means “something other than flying”?

Butterflies see colors that we can’t. They can see into the ultraviolet end of the spectrum. To them, a flower may have a whole additional set of markings we are unaware of.

The butterfly life cycle isn’t “better” than ours, but it is very well adapted to what it does. A butterfly is able to specialize during each stage of its life, in a way that we don’t. Their growth stage eats different food from their adult stage. This lets them exploit one resource fully as caterpillars and have something else to eat when they grow up. And if a caterpillar eats a whole plant, it can grow up, fly away, and it’s babies can eat another plant somewhere else. These are fabulous adaptations.

Being cold blooded would have its down side during the winter, but many butterflies have amazing adaptations to survive extremes of cold – like developing antifreeze –like liquids in their blood, or entering suspended animation until the weather gets nice.

Butterflies also have amazing instincts that let them do things like navigate journeys they’ve never taken before. We rely less on instinct and more on learning and passing down knowledge. Neither way is better.

Good questions, scientists!

Discovery Corps is Pacific Science Center’s youth development program for high school students. For more information contact discovery.corps@pacsci.org or call (206) 443-2884.

1 comment:

  1. Hi,
    are there any news from the Naked Mole Rats? I'd love to read your blog, but there was for a long time nothing from the NMR. Are they all well?

    Many seasons greetings from