Diversity 0The variety of living things that inhabit the Earth is called biological diversity. 0Evolutionary theory is a collection of scientific facts, observations, and hypotheses. 0This theory is a well-tested concept that is supported by multiple evidence.
Voyage of the Beagle 0Charles Darwin contributed more to our understanding of evolution than anyone else. 0On a five-year voyage on the Beagle, Darwin visited several continents and many remote islands. 0Darwin s observations led to a revolutionary theory about the way life changes over time.
Voyage of the Beagle 0Wherever the ship anchored, Darwin went ashore to collect plant and animal specimens. 0At sea, he studied the specimens, read scientific books, and filled notebooks with his observations.
Darwin s Observations 0He saw far more diversity during his travels than he expected. 0He realized that an enormous number of species inhabit the Earth.
Patterns of Diversity 0The plants and animals he observed were remarkably well suited to their own environment. 0He also discovered that some animals only lived on certain continents even though there were similar grassland ecosystems.
Living Organisms and Fossils 0On his journey Darwin also collected fossils. 0Some of those fossils resemble organisms that were still alive. 0Other fossils looked completely different from anything he had ever seen.
The Galapagos Islands 0The Galapagos Islands are a small group of islands that have very different climates from one another. 0Darwin also observed that the characteristics of many animal and plants varied among the Islands.
Galapagos Islands 0 Southern Islands 0Hot and dry 0Sparse vegetation 0Saddle-backed tortoise 0Larger Central Islands 0Greater rainfall 0Assortment of plants and animals 0Rich vegetation 0Dome-shaped tortoise
Galapagos Islands 0Darwin also collected many black birds he found on the Islands. 0He did not find the birds to be very important. 0He noticed that the birds had different shaped beaks.
The Journey Home 0After returning home, Darwin wondered if the animals on the different islands once belonged to the same species. 0According to his hypothesis the different island animals evolved from an original ancestor species.
Publication of On the Origin of Species 0Darwin hesitated to publish any information that filled his notebooks. 0His ideas challenged fundamental beliefs of his day. 0In 1859, 25 years after his voyage, Darwin published the results of his work. 0 On the Origin of Species
Publication of On the Origin of Species 0In his book he proposed a mechanism for evolution he called natural selection. 0Many considered his arguments brilliant and others strongly opposed them.
Inherited Variation and Artificial Selection 0Inherited variation is caused by variations in genes passed from parents to offspring. 0These variations are used today by plant and animal breeders to improve crops and livestock. 0Darwin termed this artificial selection in which nature provides the variation and humans select what they find most useful.
Evolution by Natural Selection 0In the struggle for existence each species competes for resources like food and living space. 0 Faster predators will catch prey 0 Camouflage or protection to avoid being caught
Evolution by Natural Selection 0Some animals have adaptations that increase their chance of survival because they are better suited for their environment. 0 Porcupine quills 0 Plant photosynthesis 0 Hunting in groups
Evolution by Natural Selection 0Darwin referred to the survival of the fittest as natural selection. 0This is because animals compete to survive and produce offspring. 0Natural selection takes place over many generations without human interference. 0It results in changes in the inherited characteristics of a population.
Evolution by Natural Selection 0After many years natural selection produces organisms that have: 0 Different structures 0 Established different niches 0 Occupied different habitats. 0As a result species today look different from their ancestors known as descent with modification.
Evolution by Natural Selection 0If we look far enough back in history we could find the common ancestors of all living things. 0A single tree of life links all living things.
Evidence of Evolution 0Darwin argued that living things have been evolving on Earth for millions of years. 0Evidence for this process could be found in: 0 1.) The fossil record 0Darwin proposed countless species had come into being, lived for a time, and vanished.
Evidence of Evolution 0 2.) The geographical distribution of living species 0Many animals could have descended with modifications from a common mainland ancestor. 0 3.) Homologous structures of living organisms 0Limbs vary greatly in form and function but they are all from the same embryonic tissue.
Evidence of Evolution 0 4.) Similarities in early development 0Embryonic cells develop in similar patterns to produce the tissues and organs of all vertebrates.