Evolution Evidence of Change Standards B 7 A

Evolution Evidence of Change

Standards B. 7 A (RS) analyze and evaluate how evidence of common ancestry among groups is provided by the fossil record, biogeography, and homologies, including anatomical, molecular, and developmental, stasis, and sequential nature of groups in the fossil record B. 7 C (SS) analyze and evaluate how natural selection produces change in populations, not individuals B. 7 E (RS) analyze and evaluate the relationship of natural selection to adaptation and to the development of diversity in and among species

What is evolution? Biological evolution refers to the changes in the genetic makeup of a population of interbreeding organisms of the same species that occur over time. These genetic changes are the result of mutations in the DNA sequence of the organism, which are passed from one generation to the next. Populations change over time. The slow , gradual change in a population of organisms over time.

Charles Darwin Born Feb. 12, 1809 Joined Crew of HMS Beagle, 1831 Naturalist 5 Year Voyage around world Avid Collector of Flora & Fauna Astounded By Variety of Life

The Voyage of the Beagle In 1831, Darwin set sail from England aboard the H. M. S. Beagle for a voyage around the world. Returned 5 years later.

Charles Darwin During his travels, Darwin made numerous observations and collected evidence that led him to propose a hypothesis about the way life changes over time. That hypothesis has become theory of evolution (AKA theory of natural selection).

Darwin’s Observations He observed many plants and animals were well suited to the environments they inhabited. Adaptation – Features that allows the organism to better survive and reproduce in its environment. Adaptations can lead to genetic changes in a population He was impressed by the ways in which organisms survived and produced offspring. Darwin was puzzled by where different species lived and did not live.

Darwin found fossil evidence of species changing over time. In Argentina, he found fossils of huge animals, such as Glyptodon, a giant armadillo. The fact that these fossils looked like living species suggested that modern animals might have some relationship to fossil forms.

Galapagos Island Small Group of Islands 1000 km West of South America Volcanic islands Island species varied from mainland species & from island-to-island species Each island had long or short neck tortoises and shell sizes

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Galapagos Island Finches Darwin extended his observation, proposing the island species most closely resemble species on the nearest mainland. He hypothesized that at some point in the past, some individuals from South American mainland had migrated to the island. Finches on the islands resembled a mainland finch Different types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insect, etc. ) Finches had different types of beaks adapted to their type of food gathering

Evidence of Evolution

Similarities In Embryonic Development The similar features of embryos in very different organisms suggest evolution from a distant common ancestor.

Living Organisms and Fossils Darwin collected the preserved remains of ancient organisms, called fossils. Some of those fossils resembled organisms that were still alive. Others looked completely unlike any creature he had ever seen.

Molecular Evidence The DNA sequences of organisms can show common ancestry.

Structures; Comparing Anatomy Homologous Analogous Physical Characteristics Physical Features Found in related species May not appear similar at first, but they are closely related. Ex. Forelimbs in humans, cats, and whale. Serve same function Do not indicate a shared common ancestor, but they evolved independently. Ex. Wings on insects, bats, and birds.

Homologous Structure Analogous Structure

Vestigial Structures These structures are remnants of organs or structures found in an early ancestor that no longer serve a useful function or may now serve a different function. As vertebrates, snakes share a common ancestor with tetrapods such as lizards and dogs. The tiny pelvic bones and hind limbs in many snakes are homologous to the pelvic bones of tetrapods.

Whales have a number of vestigial structures that would have been fully functional in their land-living ancestors, including the pelvic girdle, the hind limbs and the finger muscles. The forelimbs of whales, which are used for steering, are stiff and paddle like and the muscles of the fingers, although still present, are much reduced, largely non-contractile and act more in the fashion of ligaments.

http: //www. sumanasinc. com/webc ontent/animations/content/evoluti on/evolution. html THE BIG PICTURE

Darwin’s Conclusion • Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals • Only a fraction of offspring survive each generation • Survival of the Fittest • Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals • Called Natural Selection

Darwin’s Theory of Evolution The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) New species evolve

The Origin of Species Darwin’s book written in 1859, which he presented his scientific theory of evolution. Evidence of evolution comes from several sources, including: Fossil record; Anatomical and physiological similarities among living things; Genetic changes in organisms observed over many generations; and Similarities among certain organisms during embryonic development.

Publication of On The Origin of Species Upon His Return To England, Darwin Developed His Observations Into Theory Of Evolution But he did not publish for 25 years Darwin knew that his theory would be extremely controversial and would be attacked His theory challenged established religious & scientific beliefs, particularly about the creation of man He refused to publish until he received an essay from Alfred Wallace Fellow naturalist Independently developed the same theory After 25 years, someone else had come to the same conclusions from their observations of nature

Publication of On The Origin of Species Alfred Russel Wallace Independently came to same Conclusion as Darwin that species changed over time because of their struggle for existence • When Darwin read Wallace’s essay, he knew he had to publish his findings Darwin Presented Wallace’s Essay & Some Of His Work At A Scientific Conference of the Linnaean Society in July of 1858 Then He Started On his book “Origin of Species” It Took Darwin 18 Months To Complete The Book

Opposition to Evolution The upheaval surrounding evolution began with Darwin’s publication of On the Origin of Species By Means of Natural Selection • The debate continues nearly 150 years later

Lamarck's Evolution Hypotheses Jean-Baptiste Lamarck recognized that: living things have changed over time. all species were descended from other species. organisms were adapted to their environments. Copyright Pearson Prentice Hall

Use and Disuse Lamarck proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in a species. Flaws: Tendency toward perfection Use and Disuse

Copyright Pearson Prentice Hall

Lamarck's Hypothesis Here’s an example: A male fiddler crab uses its front claw to ward off predators and to attract mates. This proposed mechanism is shown here applied to fiddler crabs. (1) The male crab uses its small front claw to attract mates and ward off predators. (2) Because the front claw has been used repeatedly, it becomes Copyright Pearson Prentice Hall larger.

Lamarck's Hypothesis Because the front claw is used repeatedly, it becomes larger. This characteristic (large claw) is then passed onto its offspring. Copyright Pearson Prentice Hall

Evaluating Lamarck's Hypotheses Lamarck’s hypotheses of evolution are incorrect in several ways. Lamarck did not know: how traits are inherited. that an organism’s behavior has no effect on its heritable characteristics. However, he paved the way for the work of later biologists. Copyright Pearson Prentice Hall

Important Scientists Four scientists who influenced Darwin and their contributions Hutton – the changes occurring on earth operate extremely slowly Lyell – the processes that shaped the Earth millions of years earlier are still functioning today Lamarck – use and disuse/ trying to reach perfection Malthus – population growth theory

Review Darwin’s Theory

Theory Individual Organisms In Nature Differ From One Another. Some Of This Variation Is Inherited Organisms In Nature Produce More Offspring Than Can Survive, And Many Of These Offspring Do No Reproduce Because More Organisms Are Produced Than Can Survive, Members Of Each Species Must Compete For Limited Resources Because Each Organism Is Unique, Each Has Different Advantages & Disadvantages In The Struggle For Existence

Theory Individuals Best Suited To Their Environment Survive & Reproduce Successfully – Passing Their Traits To Their Offspring. Species Change Over Time. Over Long Periods, Natural Selection Causes Changes That May Eventually Lead To New Species Alive Today Have Descended With Modifications From Species That Lived In The Past All Organisms On Earth Are United Into A Single Tree Of Life By Common Descent

Video http: //www. youtube. com/watch? v=CKPzkxb. Bc. Mg

Standards B. 7 A (RS) analyze and evaluate how evidence of common ancestry among groups is provided by the fossil record, biogeography, and homologies, including anatomical, molecular, and developmental, stasis, and sequential nature of groups in the fossil record B. 7 C (SS) analyze and evaluate how natural selection produces change in populations, not individuals B. 7 E (RS) analyze and evaluate the relationship of natural selection to adaptation and to the development of diversity in and among species