Zoology Chapter 4 Power Point Notes Ms. K. Cox

Change Many groups of people have considered the idea that organisms change over time. The earliest ideas of evolution originated with the Greeks, including Aristotle

Lamarck Lamarck was the first to describe a coherent, scientific theory of evolution, although an incorrect theory. Lamarck’s theory of inheritance of acquired characteristics assumed that the development, or loss of structures, was due to use, or disuse, of these structures. The problem with his theory is that there was no mechanism by which the characters could be passed to the next generation. Phenotypic change in one generation would not produce genotypic change in subsequent generations.

Darwin The story of Darwin is such an interesting one. He was initially a premedical student, and like many of our students, found himself unsuited to this field. He married his cousin, Emma Wedgewood, and they had 10 children, only 7 of which reached maturity.

Do not copy this slide it is just for information. When Darwin embarked on the voyage on the Beagle, he was only 22 years old. We often emphasize the importance of this voyage, but equally important were the 20 years of studies he conducted later in England that helped shape his ideas. He studied barnacles for 8 years and wrote 4 huge volumes on them! He was the first scientist to discover that barnacles were crustaceans, not molluscs. He also did some experimental crosses on pigeons, but, unlike Mendel, he did not conduct enough crosses to mathematically analyze them.

Darwin’s work Darwin was a well-educated member of the English aristocracy before he took the position of ship’s naturalist on the HMS Beagle. During a 5-year voyage to map the coastlines of South America, Darwin observed a wide variety of living animals, and found many fossils as well.

Darwin’s work During his visit to the Galàpagos Islands, he observed the terrestrial giant tortoises and the various species of finches found within the archipelago. Darwin noticed that the island species exhibited some morphological similarities, as might be the case if they had come from the same starting population, but also exhibited some morphological differences from each other, as might be the case if they had adapted to the different environmental conditions on each island.

Darwin’s work Darwin’s theory of evolution by natural selection has three main parts: 1. Species can produce more offspring than will survive to reproduce. 2. Individuals within a population differ due to random mating, recombination, and mutation, among other sources (Darwin did not know the genetic basis of inheritance, but he could see that offspring resembled parents strongly enough that it was possible to breed for particular types of offspring.)

Darwin’s theory of evolution by natural selection has three main parts: 3. Variation among individuals results in some individuals that are more suited to survive in a particular environment than are other individuals.

Question What is the difference between artificial selection and natural selection.

Darwin was not alone in his ideas. Charles Lyell developed the idea of uniformitarianism. That the forces of wind, rain, rivers, volcanoes, and geological uplift shape the earth today. DO YOU AGREE?

Adaptation When do animals adapt? Name some examples of adaptation?

Types of Evolution Two main types 1. microevolution 2. macroevolution

1. microevolution A change in frequency of alleles in populations over time. Example: the possibility of this in jaguars and leopards. Turn to page 58 in your book. Notice the similarities.

2. macroevolution Large scale changes that result in extinction or the formation of a new species. These are difficult to observe. Evidence however is always left behind.

What areas study this evidence? 1. Biogeography 2. Paleontology 3. analogy 4. homology 5. comparative anatomy 6. phylogeny Break into groups for quick mini presentations.

Evolution What do you think?