Two Views of Adaptations Pages 109-114

1. Two Views of AdaptationsPages 109-114 Ideas About How Adaptations Occur

2. Inheritance of Acquired Characteristics • The idea that organisms can change themselves was accepted by scientists in the 1800s • Individual parents can try to change, and the changes they make are passed on to the next generation (inherited) • The population then changes over time • Individuals acquire characteristics because they want or need them • Jean-Baptiste Lamarck, French scientist, thought that change occurred as acquired characteristics were inherited

3. Natural Selection: A Population View of Adaptation • Charles Darwin and Alfred Russell Wallace presented “natural selection” using the following logic • More offspring are born than can survive • Organisms within a population vary from one another in specific characteristics • Heritable variation – Some variations among individuals can be passed from parents to offspring • Individuals that have inherited traits that better enable them to survive and reproduce will leave more offspring. • The frequency of these traits will increase in future generations • Population will change over time • Beneficial traits are called adaptations.

4. Describes how POPULATIONS change over time • Characteristics that become more frequent in a population are the very ones that help individuals survive and reproduce… Natural Selection is not random

5. Why Scientists accept natural selection If there are no limits on population growth organisms would reproduce very rapidly. Our observations tell us that most populations in the wild stay fairly constant in size. Resources available in any natural environment are limited. Specific DNA changes cause variation in populations agriculture has been changed using artificial selection Used to develop flu vaccine and treatment for HIV Explanation for phenomena such as why spiders eat their mate Why Scientists reject the inheritance of acquired characteristics Variations that occur during an organisms lifetime are often not heritable and can not affect the course of evolution agriculture in the Soviet Union did not improve from treatments based on the idea of the inheritance of acquired characteristics Natural Selection A Powerful Idea Pages 112-114

6. The Finch Scientists of the Galapagos pages 105-106 • Daphne Major gets only 10 inches of rain a year • Many species of plants, insects, birds, tortoises, iguanas ancestors traveled from other Galapagos islands or traveled 600 miles from South America to Daphne Major • Darwin’s Finches are a species of bird that all have a common ancestor (some 3 million years ago) yet they have a variety of beak sizes and shapes which are key in allowing them to specialize on certain food during the dry season. • Hard seeds, soft seeds, insects, fruits, cactus pads, etc.

7. Why is Daphne Major an Ideal Place to Conduct Biological Studies • Species have been evolving undisturbed for several million years on this island. • Dr. Rose Mary and Peter Grant did detailed and thorough studies of Finches on Daphne Major and got a glimpse of evolution in action.

8. HMS Beagle • Darwin was 22 years old in 1831 when he boarded the research vessel HMS Beagle for a five year trip. • He was supposed to collect organisms as the boat traveled around the world. • The mission of the crew was to make a detailed map of the coast of South America • Darwin’s job was to collect as many organisms as possible and make detailed observations of them on the boat. • He observed fossils that were much larger than modern species. • He observed that tortoise shell patterns varied from island to island • Observations led Darwin to question where some of the organisms came from and how to explain all the variation he saw within a species.

9. After he returned from his voyage Darwin spent 20 more years collecting observations and testing his ideas • Finally he published “On the Origin of Species” • Evolution was not a phrase Darwin used instead he used Descent with Modification • Modification is a change in a feature of an organism • Descent means organisms are linked to the past through their ancestors Used Natural Selection as his explanation for how modification occurred Descent with Modification helped explain the diversity in organisms he observed and why closely related species tend to be found on the same continent

10. Vitamin D in the Body A nutrient crucial to bone and immune system health Vitamin D deficiency can cause abnormal bone growth called rickets in children Women who had rickets will have abnormal pelvic bone structure and could die during child birth Linked to a high susceptibility to disease and cancer Folate in the Body A nutrient used when the critical molecule DNA makes copies of itself when new cells are being made Supports the growth and development of an embryo/fetus/baby Folate deficiency can cause anemia (a condition where the blood does not make enough red blood cells), infertility (due to a reduced ability to produce mature sperm and egg cells), and birth defects that can be fatal to the fetus (such as malformation of the spine called spina bifida) Human Skin Color Adaptations

11. Vitamin D rich foods Fatty fish, mushrooms, eggs Added to milk, bread, and cereal Folate rich foods Leafy green vegetables, beans, peas Added to some cereals Foods

12. Humans can synthesize (make) their own vitamin D when ultraviolet light penetrates the skin The human body can not make its own folate Exposure to ultraviolet light can cause a 43% drop in folate in the bloodstream Folate that has been broken down by UV exposure is unable to perform it’s biological functions Ultraviolet radiation and Nutrients

13. Darker Skin Colors absorb ultraviolet light before it reaches the bloodstream The darker a person’s skin the less ultraviolet light penetrates deep enough for vitamin D synthesis Lighter Skin Colors do not absorb much ultraviolet light before it reaches the bloodstream where it can destroy folate The lighter a person’s skin the more ultraviolet light penetrates deep enough for vitamin D synthesis Skin Color and Ultraviolet Light

14. Skin is the largest human organ Functions in the regulation of temperature through sweating Severe sunburn can damage the sweat glands and reduce the body’s ability to stay cool Sun-blistered skin can become infected Skin Cancer Caused by exposure to UV radiation over long periods of time Typically appears in older individuals, past their reproductive years If untreated some skin cancers can be fatal Exposure of light-skinned individuals t UV radiation causes sunburn over a short period of time Darker-skinned individuals take more exposure to burn Individuals born in Africa with albinism (complete lack of skin pigment) are at high risk for skin cancer 90% die before the age of 30 Skin color, sunburn, and skin cancer

15. One function of the skin • When do people usually develop skin cancer? • What is the life expectancy of an individual with albinism in Africa? • What health concern might a darker skinned person have? • What health concern might a lighter skinned person have? • What benefit does darker skin give? • What benefit does lighter skin give? • What are health issues with low folate levels? • What are the health issues with low vitamin D levels? • Identify the selective pressure in the human skin color adaptation. • Which nutrient can the skin make? • What foods naturally contain vit D? • What foods naturally contain folate? • What is the function of vit D? • What is the function of folate? • What is anemia? • What is Rickets? • What skin color absorbs more UV radiation letting only some through? • What skin color absorbs less UV radiation letting more through?