Biology. Evolution: History & Process

Transcription

1 Biology Evolution: History & Process

2 Terms: A species is a group of organisms, or population, that can be interbreed & produce fertile offspring. Variations are the differences found within species. Ex: eye color and hair color. These can be determined by the environment, genetics or both. If inherited, it is the result of a random mutation or recombination. 2

3 Adaptations are inherited traits that increase a population s chances of survival and reproduction in a particular environment. A niche is a habitat and the role a population plays in that habitat. This includes where an organism lives, what & how it eats, how offspring are raised, where predators are, and space, light, moisture, & temperature. 3

4 4 Darwin s Theory of Evolution Darwin wrote The Origin of Species Describes his idea of evolution: Natural Selection Theory based on observations made when traveling on the Beagle around the S. American coastline, specifically the Galapagos Islands. Based theory on current thoughts of the time

5 5 Influences on Darwin Evolution means change over time; process by which populations change in response to their environment Georges Buffon suggested the Earth was older than originally believed (few thousand years). Jean-Baptiste Lamarck (1809) theorized that fossils are extinct forms of living organisms found today (in other words, evolution occurred- the organisms today exist b/c of the fossils; they are the ancestors). His theory includes 3 points.

6 Lamarck s Idea of Evolution: 1. Organisms were striving toward constant improvement. 2. Body parts that were used in life continued to develop whereas unused body parts waste away. This is the idea of use and disuse. 3. Once the structure is modified by use and disuse (#2), the modification is inherited by the offspring. This is called the inheritance of acquired characteristics. Think of Dobermans. res/1/ ece5d347f8fe28 28c8fdb7677/giraffe.gif 6

7 7 Charles Darwin studied finches and many other organisms on the Galapagos Islands. He studied many factors which influenced his theory of evolution by natural selection. Charles Lyell s hypothesis about geological change: it occurs extremely slowly & gradually but it can influence plant and animal life over long periods of time. Thomas Malthus s (an economist) idea of supply and demand and populations: Darwin believed this principle could be applied to the competition of food, water & space and the ability to survive allowed for reproduction.

8 YxmULuo NATURAL SELECTION VIDEO

9 9 Darwin s Theory of Evolution by Natural Selection: Darwin wrote a book, On the Origin of Species by Means of Natural Selection, which explains his theory. His Theory involves: Descent with Modification: 1. Organisms descended from ancestral species & Descendants accumulated different modifications (or adaptations) 2. Natural Selection is the mechanism for evolution

10 Descent with Modification & Natural Selection This means: Variations occur within a population (they are ALREADY there). These are inherited. Understand, all of Darwin s knowledge was based on observations. He knew nothing of genetics. Some variations are favorable. 10

11 11 Not all of the young produced in each generation survive. This may be the result of disease, lack of food, or they may be the victims of predation. Individuals that DO survive and have favorable variations WILL reproduce (and pass on those favorable variations to the next generation). THEREFORE, the next generation will have a larger number of offspring with the favorable variations.

12 12 Darwin stated ALL organisms were related. He used a tree analogy.

13 13 Evidence of Evolution Fossils are preserved remains, or imprints, of ancient organisms found in rocks or sediments. Paleontologists are scientists who study fossils. Biodiversity is the variety & abundance of species that makeup a biological community. 99% of all types of organisms that ever lived are now extinct (no longer exists). Geographic distribution (patterns of life) has provided evidence as well.

14 Structures Homologous structures are traits such as the human arm and whale fin that are similar in different species b/c the 2 species share a common ancestor. In this case, the arm and fin have evolved from the forelimb of a vertebrate ancestor. Analogous structures are characteristics that are similar in function but are different in structure in distantly related organisms. Ex: wings of bats and wings of insects. 14

15 s/img165/7901/homologym y6.jpg 15

16 Structures Vestigial structures are structures that are often small or reduced in size and no longer used but inherited and still present in organisms. Ex: pythons have leg and hip bones, humans have an appendix, manatees have leg bones. hics/manatee-skeleton-lg.jpg 16

17 17 Embryology is the study of early developmental stages of organisms. Scientists use this, along with biochemistry, to study and understand evolution. Structures a.ultranet/biologypages/r/ro manes.jpg

18 Other Evidence Developmental: stages of embryonic devo are similar Molecular: similar DNA sequences 18

19 19 Selective breeding to produce a desired trait is artificial selection (think dog breeding). Example of Natural Selection in Action: Pesticide resistance Pesticides are poisons (kill insects that destroy crops & homes) Some insects are resistant to pesticides (have genes); they survive & reproduce (passing on this trait). Understand, insects do not BECOME resistant; they already had the genes for resistance!

20 Natural Selection & SCA Sickle Cell Anemia (SCA) is a genetic disease affecting the shape of RBCs, creating symptoms of fatigue, body pain, organ damage & sometimes death. There is a high frequency of SCA in Africa and even higher frequency of heterozygous individuals 20

21 21 WHY? Heterozygous SCA have resistance to malaria (plasmodium, organism that causes malaria, does not reproduce well w/in sickleshaped RBCs); this is called the heterozygote advantage.

22 22 Antibiotic Resistance Antibiotics are medications that kill (or inhibit the reproduction of) bacteria Some bacteria are resistant to antibiotics (again, this is b/c they contain genes for the resistance). Antibiotic resistance allows the bacteria that survive the 1 st round of antibiotics to reproduce & pass on the gene(s) for resistance. This is becoming a health concern.