Chapter 7: Adaptations over Time Section 1: Ideas About Evolution

Early Models of Evolution Ideas About Evolution 1 Early Models of Evolution Species a group of organisms that look alike and can reproduce among. Variation – differences within a species Evolution - Changes in inherited characteristics over time.

Hypothesis of Acquired Characteristics Ideas About Evolution 1 Hypothesis of Acquired Characteristics Lamarck – Species evolve by keeping traits developed during the parent lifetime are inherited by its offspring. His hypothesis is called the inheritance of acquired characteristics. The data showed that traits developed during a parent’s lifetime, such as large muscles built by hard work or exercise, are not passed on to offspring.

Darwin’s Observations Ideas About Evolution 1 Darwin’s Observations Darwin observed 13 species of finches on the Galápagos Islands. He noticed that all 13 species were similar, except for differences in body size, beak shape, and eating habits. He also noticed that all the Galápagos finch species were similar to one finch he had seen on the main land.

Darwin’s Observations Ideas About Evolution 1 Darwin’s Observations Darwin reasoned that the Galápagos finches must have come from the mainland and competed for food which caused the changes over time. Finches with beak shapes that allowed them to eat available food survived longer and produced more offspring than finches without those beak shapes. After many generations, these groups of finches became separate species.

Ideas About Evolution 1 Darwin’s Theory Darwin’s theory of evolution natural selection – survival of the fittest. Natural selection means that organisms with traits best suited to their environment are more likely to survive and reproduce.

Ideas About Evolution 1 Darwin’s Theory A population -all of the individuals of a species living in the same area. Members of a large population compete for living space, food, and other resources. Those that are best able to survive are more likely to reproduce and pass on their traits to the next generation.

Variation and Adaptation Ideas About Evolution 1 Variation and Adaptation Variation - a difference between members of the same species. It is an inherited trait that makes an individual different from other members of its species. Some gene changes produce small variations such as differences in the shape of human hairlines.

Adaptations include: specialized features ( traits) which make an animal better suited to survive and reproduce. Such as: changes in the eyes (front facing or sideways) changes (special or different) ways to reproduce changes in bones suited for needs (birds are hollow)

Bacteria show trait changes in the shortest time Natural selection - organisms that are better adapted to their environ will survive and reproduce. According to Darwin they also create more offspring than can survive punctuated equilibrium- species evolve over short periods of rapid change Bacteria show trait changes in the shortest time – punctuated equilibrium Gradualism – evolution happens steadily in tiny changes over a long period of time

Variation and Adaptation Ideas About Evolution 1 Variation and Adaptation If individuals with variations continue to survive and reproduce over many generations, a new species can evolve.

Variation and Adaptation Ideas About Evolution 1 Variation and Adaptation adaptation - any variation that makes an organism better suited to survive in its environment. Camouflage is an adaptation. A camouflaged organism blends into its environment and is more likely to survive and reproduce.

Changes in the Sources of Genes Ideas About Evolution 1 Changes in the Sources of Genes Movement of individuals into or out of a population is a reason for variation in that population Individuals (of the same species) move into or out of an area, bring in or remove variations and genes.

Ideas About Evolution 1 Geographic Isolation Gene mutations add variations to populations. Over time, the two populations can become so different that they no longer can breed with each other.

Ideas About Evolution 1 Gradualism The model that describes evolution as a slow, ongoing process by which one species changes to a new species is known as gradualism. gradualism -- a continuing series of mutations and variations over time will result in a new species. A series of intermediate forms can indicate a gradual change from the earliest species to today’s species.

Punctuated Equilibrium Ideas About Evolution 1 Punctuated Equilibrium According to the punctuated equilibrium model, rapid evolution comes about when the mutation of a few genes results in the appearance of a new species over a relatively short period of time.

Punctuated Equilibrium Today Ideas About Evolution 1 Punctuated Equilibrium Today Evolution can occur over a few thousand or million years, and sometimes even faster. many bacteria have changed in a few decades. The antibiotic penicillin originally came from the fungus Penicillium. But many bacteria species that were once easily killed by penicillin no longer are harmed by it.

Punctuated Equilibrium Today Ideas About Evolution 1 Punctuated Equilibrium Today In four years later a species of bacteria that causes pneumonia and other infections developed resistance to the drug. By the 1990s, several disease-producing bacteria had become resistant to penicillin and many other antibiotics.