Evolution

Charles Darwin The modern theory of evolution is the fundamental concept in biology Evolution changes populations over time Charles Darwin ( )- was an English scientist that formed his ideas about evolution around the information found in the fossil record

Charles Darwin It took Darwin years to develop his theory of evolution He began at age 22 when he took a job as a naturalist on the English ship HMS Beagle, which sailed around the world on a five-year scientific journey

Charles Darwin Darwin studied and collected biological and fossil specimens at every port along the route This made Darwin curious about possible relationships among species Darwin visited the Galapagos Islands, group of small islands near the equator

Charles Darwin Darwin collected specimen on those islands that could not be found anywhere else From Darwin observations he considered the possibility that species can change over time

Charles Darwin Upon the return to England, Darwin began to breed pigeons to try and support his theory Breeding organisms with specific traits in order to produce offspring with identical traits is called artificial selection

Natural Selection Darwin hypothesized that there was a force in nature that worked like artificial selection Natural Selection is a mechanism for change in population It occurs when organisms with favorable variations survive, reproduce, and pass their variations to the next generation

Adaptations: Evidence for Evolution An adaptation is a variation that aids an organism’s chances of survival in its environment. Ex. Thorns on a flower According to Darwin’s theory, adaptations in species develop over many generation

Structural Adaptation Mimicry- a structural adaptation that enables one species to resemble another species. Ex. Certain flies will resemble wasps to avoid being eaten Camouflage- an adaptation that enables species to blend with their surroundings. ex. Stick bugs

Physiological Adaptation Physiological adaptations are changes in an organism’s metabolic processes. Ex. Insects that are exposed to years of pesticides, many species become resistant to these chemicals

Anatomy Homologous structures- structural features with a common evolutionary origin, can be similar in arrangement, in function, or in both Ex. The forearm of crocodiles, birds, whales, and humans

Anatomy Analogous structures- body parts of organisms that do not have a common evolutionary origin but are similar in function Ex. Butterfly wings versus bird wings

Anatomy Vestigial structure- a body structure in a present-day organism that no longer serves it original purpose, but was probably useful to an ancestor Ex. Baleen whale pelvic bones

Embryology An embryo is the earliest stage of growth and development of both plants and animals The embryos of a fish, a reptile, a bird, and a mammal are all very similar This helps support evolutionary lines

Biochemistry Nearly all organisms share DNA, ATP, and many enzymes among their biochemical molecules Scientist use DNA and RNA nucleotide sequences to construct an evolutionary diagram