| title | author | date | output |
|---|---|---|---|
include2.md |
Meera Lee Sethi |
5/6/2019 |
html_document |
For each butterfly specimen, MacLean measured three morphological traits. First, using digital photography and a computer program, she calculated the proportion of scales with dark pigmentation (or “melanism”) in a specific place on the underside of each hind-wing. You’ll see values for wing melanism that range from 0 (all pale scales) to 1 (all dark scales). As an aside, most butterflies bask in the sun by opening their wings flat, like a book, and exposing the top side. But Colias butterflies warm up by exposing the undersides of their wings, known as “lateral basking.” This is a key piece of information about their natural history that helped MacLean understand which parts of their wings to measure!
In addition, MacLean measured two other traits that you might expect to change with climate: Forewing length (remember the discussion of temperature and size above; warmer temperatures might result in smaller forewings) and setae length. Setae are hairs on a butterfly’s body that help to insulate it, like a fur coat. Longer setae keep butterflies warmer.
The image below shows two different Colias species, Colias meadii and a relative that lives at a lower elevation. You can see the differences in wing melanism (absorbtivity is a measure of how much heat each specimen's wing is able to absorb) and in setae thickness (also called "fur").
In this exercise, you can generate figures using the following variables (hover over a variable for an explanation):