Essential Question – How can an adaptation for one individual in a species impact the survival of the species?
In class we continued our lesson on Evolution by natural selection. I collected the Natural Selection Gizmo (SEG + AQ) and Peppered Moth Graphing Activity.
Natural Selection Notes:
THEORY OF NATURAL SELECTION
Natural selection is credited to the famous biologist, Charles Darwin. The idea behind this theory is “survival of the fittest”, or the idea that natural causes will eliminate the weakest or least-adaptable members of a species.
FOR EXAMPLE, if a particular species of frog comes in a variety of shades of green, predators may more easily spot the frogs whose natural coloring is not like the foliage around them. Most of the frogs that live long enough to breed will be the specific shade of green found in the surrounding foliage. Because most of the frogs that remain are this shade of green, more of the frogs born in the next generation will be that color. If predators continue to see, catch and eat the frogs that are not this particular color, the process will continue until the frog species is entirely made up of foliage-colored green frogs.
4 PARTS OF NATURAL SELECTION
1. OVERPRODUCTION: Species produce more offspring than will survive.
Examples may include sea turtles and spiders.
2. VARIATION: Individuals in a population have different traits.
An example is the different size beaks of the Finches.
3. ADAPTATION: The various traits that enable an organism to survive.
Examples may include, but not limited to; camouflage, mimicry, speed, toxicity, deception, deterrence, acute perception, etc.
4. SELECTION: Individuals with adaptions best suited for their environment(s) are more likely to survive.
*Artificial, Natural and Sexual
“Survival of the Fittest” This also may include sexual selection in which the organisms choose the best mate in order to carry on the genes to their offspring. (For example, the Peacock or the Bird of Paradise. The more colorful the feathers, the better the mate)
The story of the peppered moth, Biston betularia, is one of the best-known examples of natural selection in action. The peppered moth is common in Europe, North America, and Asia. It shelters on trees during the day and is eaten by birds. Peppered moths are found in three forms, ormorphs:
- Biston betularia morpha typica is light gray in color and speckled.
- Biston betularia morpha carbonaria is dark gray in color.
- Biston betularia morpha insularia is intermediate in color.
Prior to 1800, the typica morph was much more common than the darker carbonariamorph in the English countryside. The speckled-gray moths blended in well with light-colored tree bark and lichens. The dark carbonaria form contrasted with the tree bark, making it easier to spot.
During the 1800s, the Industrial Revolution changed the landscape of England. New coal-powered factories spewed tons of dirty smoke into the air, blanketing the forests with soot. The lichens on tree trunks died, and tree trunks were darkened. When this happened, the typica form was easier to spot than the carbonaria form, and as a result more were eaten. By 1895, dark moths accounted for nearly 100% of the total population in some forests. The pattern of darkening is described by the term industrial melanism.
Throughout the 20th century, air quality improved, trees became lighter in color, and the proportion of typica moths increased. Today, carbonaria is almost as rare as it was before the Industrial Revolution.
Rainfall and Bird Beaks Gizmo (SEG + AQ)