Biology Lecture 2 - Exam 1
Biology Lecture 2 - Exam 1 BIO 121 A
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This 3 page Class Notes was uploaded by Devin Mart on Tuesday March 29, 2016. The Class Notes belongs to BIO 121 A at Missouri State University taught by Dr. Durham in Spring 2016. Since its upload, it has received 12 views. For similar materials see General Biology in Biology at Missouri State University.
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Date Created: 03/29/16
Mart 1 Lecture 2: A Darwinian View of Life ● Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring. ○ This view was challenged for centuries because at this time many were very religious (biblical viewpoint). ● Lamarck published theory of evolution (1809). ○ Mechanism of evolution is the use and disuse of parts and inheritance of acquired characteristics. ■ Example: giraffes gradually over time acquired longer necks by reaching for leaves, which is passed on to their offspring. ● Charles Darwin (18091882) ○ Darwin went on the survey ship The Beagle for a voyage around the world. ■ The mission was to chart poorly known stretches of the South American coastline. ○ Thousands of specimens of exotic and diverse flora and fauna of South America were collected. ■ Noted that the plants and animals of South America were very distinct from those of Europe. ○ Galapagos Islands contained animal species that lived nowhere else, yet resembled species living on the South American mainland. ■ The island was colonized by plants and animals from the mainland and was later diversified into the different islands. ○ While on The Beagle Darwin read Lyell’s Principles of Geology and concluded that the Earth was very old and was constantly changing. ■ Darwin saw origin of new species and adaptation of species to environment as closely related processes. ○ Darwin quickly finished The Origin of Species which attributed the essence of evolution by natural selection to Darwin. ○ Central to Darwin’s view of evolution was the idea of descent with modification. ■ All present day organisms are related through descent from unknown ancestors in past. ■ Descendents of ancestors accumulated diverse modification or adaptation that fit them to specific ways of life and habitats. ■ Closely related species share the same line of descent until recent divergence from common ancestor. ○ Another central idea was the theory of natural selection Mart 2 ■ Inference 1: Production of more individuals than environment can support leads to a struggle for existence among individuals of population with only a fraction of offspring surviving each generation. ■ Inference 2: Survival in struggle for existence is not random, it depends in part on hereditary constitution of individuals. ■ Inference 3: This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over the generations. ○ Darwin’s main ideas. 1. Natural selection is differential success in reproduction (unequal ability of individuals to survive and reproduce). 2. Natural selection occurs through interaction between environment and variability inherent among individual organisms making up a population. 3. Produce of natural selection is adaptation of populations of organisms to their environment. ● The Darwinian Revolution. ○ Natural selection in action: insecticide resistance. ■ Insecticides poison that kills insects, pests in crops, swamps, backyards and homes. ■ Most insecticides kill 99% of insects, the 1% of survivors contain the gene that enable them to resist chemical attack. ● These insects that carry the gene pass it on to their offspring, the survival rate will then increase with each generation. ■ Natural selection operates not to create variation, but to edit existing variation. ● Favors characteristics in a variable population that fit current, local environment. ○ Natural selection in action: evolution of drugresistant HIV. ■ Many drugs are used in order to combat human immunodeficiency virus (HIV) because the virus’ drug resistant strains evolve rapidly in HIV population infecting each patient 110 billion new mutant viruses per day. ○ Other evidence of evolution pervades biology. ■ Evidence of evolution can be found in the biological diversity documented by fossil record. ■ In descent with modification, new species descended from ancestral species by accumulation of modifications as populations adapt to new environments. Mart 3 ■ Homology is a similarity in sequence of a protein or nucleic acid between organisms of the same or different species. ■ Vestigial organs is a rudimentary structure found in humans that corresponds to a functional structure or organ in ancestral animals. ○ Biogeography the branch of biology that deals with the geographical distribution of plants and animals. ■ Species that are more closely related to other species from the same area than to other species with the same way of life, but in a different area. ■ Resemblance is an example of endemics the process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. ■ Many species of plants and animals found nowhere else in the world are called endemics . ○ Succession of fossil forms is compatible with major branches of descent in the tree of life. ■ Fossilized fish, amphibians, reptiles, mammals and birds.
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