A quick look at Evolution.

Charles Robert Darwin §Charles Robert Darwin (1809 –1882) was an English naturalist who proposed and provided scientific evidence that all species of life have evolved over time from common ancestors.

Darwin §His 1859 book On the Origin of Species established evolution by common descent as the dominant scientific explanation of diversification in nature. §Evolution: the gradual change in a species over time.

Darwin §Darwin figured that a species gradually adapted and changed through the process he called natural selection. §Natural Selection: favorable traits (Adaptations) become more common in younger generations of a species, and unfavorable traits become less common.

Natural Selection §Darwin identified a few major factors that contribute to Natural Selection: l Overproduction. l Competition. l Variation. What do you think these all mean? CD

Natural Selection §Overproduction: l Almost every species produces more offspring than can possibly survive. Frog Eggs Sea Turtles Minnows Insects –Why? CD

Overproduction.

Natural Selection §Variation: Minor differences appear between offspring. l Faster swimmer l Longer necks l Longer noses l Sharper beaks

Variation

Natural Selection §Competition: Since food and resources are limited, offspring must compete with each other. l Faster ones catch faster prey l Stronger shells better defense l Heavier shells make you slow… l Slower might make it easier to catch…hmmm

Natural Selection Tough Grass vs Tender

Natural Selection

Natural Selection Fast vs Slower

Natural Selection

Natural Selection Jumpy vs Clever and Still

Natural Selection Resistant to a new disease

Natural Selection

Natural Selection Warmer coat in a long cold winter

Natural Selection

Natural Selection The Survivors

Video §Evolution and Natural Selection

Filler §Making observations today about evolution makes sense. We can see differences between animals right now in our own neighborhoods. Check out the black squirrels in Princeton…..Why are they black? Any ideas?

More Filler... §Here's why some scientists believe the black squirrels were multiplying: In winter, their dark coats allowed them to retain heat from sunlight, leaving them less desperate for warmth than their lighter-colored cousins. §"If you can do it with solar heat, you don't need quite as much metabolic heat," and, therefore, need less food,

Still More §In some cases, this advantage seems to have outweighed the potential downside of a black coat -- being more conspicuous to hawks and other predators. Scientists believes that black squirrels were slightly more likely to survive and reproduce, and their genes were passed on to succeeding generations.

Enough about today…. §Can we find evidence of past changes…. §Sure!

Fossils §Fossil: The preserved remains or traces of an organism that lived in the past.

Types of Fossils §Petrified fossils: Minerals replace buried remains changing them into rock. l Petrified wood example

Types of Fossils §Molds and Casts: organisms dissolve leaving a hollowed space that fills with minerals. l Ohio stone examples

Types of Fossils §Preserved Remains: Preserved in substances other than sediment. l Amber l Tar pits l Ice

Video §Becoming a fossil

Dating a fossil §Relative dating. l Estimates the order of events by observing where fossil organisms lay in the geological record. §Absolute dating l Using radioactive decay rates. Carbon years Potassium billion years