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Extinctions Make Way for New Creatures! Precambrian Extinction Cambrian Explosion Huge diversity of shelled creatures Cambrian extinction New forms of hard-shelled creatures Ordovician extinction New creatures with bones and fish Land plants and forests Devonian extinction Amphibians and advanced fish Permian extinction (biggest) Cretaceous extinction Holocene extinction Dinosaurs! Mammals! What next?
The human tailbone Blind fish with remnants of eyes that are not used
Human wisdom teeth Sexual parts in dandelions They do not use them; they clone themselves.
Virgin whiptail lizards clone themselves and no males are present in the species. The lizards still have sex even though it serves no purpose. Males have nipples and breast tissue although they serve no purpose. The human appendix is used in herbivores to digest plant matter but since humans are not herbivores, the appendix is not used.
All life on this planet has the same DNA bases and the same types of genes.
This indicates that we are all related.
Comparing genes and DNA, comparing amino acids sequences and comparing certain protein sequences all lead to the same conclusion…
As the number of differences decreases, the more related the two animals are.
If you take the gene for making an eye in a fruit fly and put that gene into a developing embryo for a mouse eye, it still produces a regular mouse eye. These are called homeobox genes and they control placement of appendages in all bodies of animals.
Guppies in high predator environments lessen their bright colors for defense. Over time the population becomes lighter and more drab in color. Why does this occur? Brighter colored fish are eaten more often and do not pass their genes to the next generation leaving only the drab colored fish to reproduce. Over time the population changes or evolves.
Coevolution is when two species change together in close association.
Some species cannot live without the other because they are so closely connected.
Convergent evolution is when the environment selects certain features to be similar even though the two animals may not closely related; sharks and dolphins
Divergent evolution is when two or more related populations over time become more different. This usually results in a new species; dogs and wolves.
Divergent evolution is also called adaptive radiation, when the animals adapt to a specific environment and change into new species over time.
Artificial selection is when humans select the traits and cause the evolution; dogs, cats, goldfish, grain crops
Coevolution The Yucca plant and Yucca moth, the plant is only pollinated by that moth. Lichens are a mixture of a fungus and an algae working together. They cannot live without each other.
Coevolution Many flowers like this snapdragon are designed specifically for a certain insect. Darwin actually predicted the existence of a certain moth by measuring the size of a flower opening. 40 years later, the moth was discovered!
Bees see in UV light and flowers evolved to maximize the bees visits by showing where the nectar is located. The flower’s colors glow and the landing strips show the bee where to go. Butterflies have a weak sense of smell. Flowers pollinated by butterflies are usually very fragrant and have bright colors like red or orange. Moths are nocturnal and do not need bright colors to feed. They need a long tube like flower.
This flower, the Rafflesia smells like rotten meat and poo. Who would pollinate this plant?