Two Views of AdaptationsTwo Views of AdaptationsPages 109-114Pages 109-114

Ideas About How Adaptations Ideas About How Adaptations OccurOccur

InheritanceInheritance of Acquired of Acquired CharacteristicsCharacteristics

The idea that organisms can change themselves The idea that organisms can change themselves was accepted by scientists in the 1800swas accepted by scientists in the 1800s

Individual parents can try to change, and the Individual parents can try to change, and the changes they make are passed on to the next changes they make are passed on to the next generation (inherited)generation (inherited)

The population then changes over timeThe population then changes over time Individuals acquire characteristics because they Individuals acquire characteristics because they

want or need themwant or need them Jean-Baptiste Lamarck, French scientist, thought Jean-Baptiste Lamarck, French scientist, thought

that change occurred as acquired characteristics that change occurred as acquired characteristics were inheritedwere inherited

Natural Selection: A Population View of AdaptationNatural Selection: A Population View of Adaptation

Charles Darwin and Alfred Russell Wallace presented Charles Darwin and Alfred Russell Wallace presented “natural selection” using the following logic “natural selection” using the following logic More offspring are born than can surviveMore offspring are born than can survive Organisms within a population vary from one another in Organisms within a population vary from one another in

specific characteristicsspecific characteristics Heritable variation – Some variations among individuals Heritable variation – Some variations among individuals

can be passed from parents to offspringcan be passed from parents to offspring

Individuals that have inherited traits that better enable Individuals that have inherited traits that better enable them to survive and reproduce will leave more offspring.them to survive and reproduce will leave more offspring.

The frequency of these traits will increase in future The frequency of these traits will increase in future generationsgenerations

Population will change over timePopulation will change over time Beneficial traits are called adaptations.Beneficial traits are called adaptations.

Describes how POPULATIONS change over timeDescribes how POPULATIONS change over time Characteristics that become more frequent in a Characteristics that become more frequent in a

population are the very ones that help individuals population are the very ones that help individuals survive and reproduce… Natural Selection is not survive and reproduce… Natural Selection is not randomrandom

Natural Selection A Powerful Idea Pages 112-114Natural Selection A Powerful Idea Pages 112-114

Why Scientists accept natural Why Scientists accept natural selectionselection If there are no limits on If there are no limits on

population growth population growth organisms would reproduce organisms would reproduce very rapidly.very rapidly.

Our observations tell us that Our observations tell us that most populations in the wild most populations in the wild stay fairly constant in size. stay fairly constant in size.

Resources available in any Resources available in any natural environment are natural environment are limited.limited.

Specific DNA changes Specific DNA changes cause variation in cause variation in populationspopulations

agriculture has been agriculture has been changed using artificial changed using artificial selectionselection

Used to develop flu vaccine Used to develop flu vaccine and treatment for HIVand treatment for HIV

Explanation for phenomena Explanation for phenomena such as why spiders eat such as why spiders eat their matetheir mate

Why Scientists reject the Why Scientists reject the inheritance of acquired inheritance of acquired characteristicscharacteristics Variations that occur Variations that occur

during an organisms during an organisms lifetime are often not lifetime are often not heritable and can not heritable and can not affect the course of affect the course of evolutionevolution

agriculture in the Soviet agriculture in the Soviet Union did not improve Union did not improve from treatments based on from treatments based on the idea of the inheritance the idea of the inheritance of acquired characteristicsof acquired characteristics

The Finch Scientists of the Galapagos pages 105-The Finch Scientists of the Galapagos pages 105-106106

Daphne Major gets only 10 inches of rain a yearDaphne Major gets only 10 inches of rain a year Many species of plants, insects, birds, tortoises, Many species of plants, insects, birds, tortoises,

iguanas ancestors traveled from other Galapagos iguanas ancestors traveled from other Galapagos islands or traveled 600 miles from South America islands or traveled 600 miles from South America to Daphne Majorto Daphne Major

Darwin’s Finches are a species of bird that all Darwin’s Finches are a species of bird that all have a common ancestor (some 3 million years have a common ancestor (some 3 million years ago) yet they have a variety of beak sizes and ago) yet they have a variety of beak sizes and shapes which are key in allowing them to shapes which are key in allowing them to specialize on certain food during the dry season.specialize on certain food during the dry season. Hard seeds, soft seeds, insects, fruits, cactus pads, etc.Hard seeds, soft seeds, insects, fruits, cactus pads, etc.

Why is Daphne Major an Ideal Place to Conduct Biological Why is Daphne Major an Ideal Place to Conduct Biological StudiesStudies

Species have been evolving undisturbed for several million Species have been evolving undisturbed for several million years on this island.years on this island.

Dr. Rose Mary and Peter Grant did detailed and thorough Dr. Rose Mary and Peter Grant did detailed and thorough studies of Finches on Daphne Major and got a glimpse of studies of Finches on Daphne Major and got a glimpse of evolution in action. evolution in action.

HMS BeagleHMS Beagle

Darwin was 22 years old in 1831 when he boarded the Darwin was 22 years old in 1831 when he boarded the research vessel HMS Beagle for a five year trip.research vessel HMS Beagle for a five year trip.

He was supposed to collect organisms as the boat traveled He was supposed to collect organisms as the boat traveled around the world.around the world.

The mission of the crew was to make a detailed map of the The mission of the crew was to make a detailed map of the coast of South Americacoast of South America

Darwin’s job was to collect as many organisms as possible Darwin’s job was to collect as many organisms as possible and make detailed observations of them on the boat.and make detailed observations of them on the boat. He observed fossils that were much larger than modern He observed fossils that were much larger than modern

species.species. He observed that tortoise shell patterns varied from island He observed that tortoise shell patterns varied from island

to island to island Observations led Darwin to question where some of the Observations led Darwin to question where some of the

organisms came from and how to explain all the variation organisms came from and how to explain all the variation he saw within a species.he saw within a species.

After he returned from his voyage Darwin spent 20 more After he returned from his voyage Darwin spent 20 more years collecting observations and testing his ideasyears collecting observations and testing his ideas

Finally he published “On the Origin of Species”Finally he published “On the Origin of Species” Evolution was not a phrase Darwin used instead he used Evolution was not a phrase Darwin used instead he used

Descent with ModificationDescent with Modification Modification is a change in a feature of an organismModification is a change in a feature of an organism Descent means organisms are linked to the past through Descent means organisms are linked to the past through

their ancestorstheir ancestors

Used Natural Selection as his explanation for how Used Natural Selection as his explanation for how modification occurredmodification occurred

Descent with Modification helped explain the diversity in Descent with Modification helped explain the diversity in organisms he observed and why closely related species organisms he observed and why closely related species tend to be found on the same continenttend to be found on the same continent

Human Skin Color Adaptations

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)

Foods

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

Ultraviolet radiation and Nutrients

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

Skin Color and Ultraviolet Light

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, sunburn, and skin cancer

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

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?