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Biology EOC Review 3-Evolution and Classification

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Clarissa Caro

on 16 April 2013

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Transcript of Biology EOC Review 3-Evolution and Classification

EOC Review 3 Evolution Evolution is the process through which species change over time.
Natural Selection is a theory proposed by Charles Darwin that explains how evolution occurs.
Inherited variations are differences in traits of individuals of the same species.
 Adaptation is a trait that increases an organism’s chances of survival in its environment, such as white fur increasing an organism’s chances of survival in a snow- covered environment. Evidence for Evolution Natural Selection Taxonomy Evolution & Classification Fossil Record We know a great deal about remains of organisms from the past by looking at the fossil record. In principle, a fossil is formed when an organism dies, its body is enclosed in mud, or sand. The soft parts decay but some of the hard parts (skeleton, shells, seeds) are preserved The mud or sand eventually becomes rock and the hard parts of the organism are mineralized. When the rock is exposed as a result of earth movements or erosion, the fossil remains can be dug out and studied. Comparative Anatomy Fish, amphibia, reptiles, birds and mammals all have vertebral columns, skulls, brains, circulatory systems and many other features in common. This suggests that they all arose from a common ancestral form rather than arising independently. The same reasoning can be applied to other groups of organisms such as insects which have most of their anatomical features in common. Although these features are superficially different there is a basic pattern underlying them all Comparative Embryology Similarities in Development
Closely related organisms share many characteristics as they develop Comparative Biochemistry The basic similarity of all living things suggests that they evolved from a single common ancestor.

As we have already seen, all living things pass on information from generation to generation using the DNA molecule.

All living things also use a molecule called ATP to carry energy around the organism. Comparing DNA sequences If evolution is true then we might also expect that closely related organisms will be more similar to one another than more distantly related organisms.

Comparison of the human genetic code with that of other organisms show that chimpanzees are nearly genetically identical (differ by less than 1.2%) whereas the mouse differs by ≈15%.

Differences in amino acid sequences are greater between species that are more distantly related than between species that are more closely related.

Differences in DNA sequences are greater between species that are more distantly related than between species that are more closely related. Vestigial Structures As evolution progresses, some structures get side-lined as they are not longer of use. These are known as vestigial structures.

The coccyx is a much reduced version of an ancestral tail, which was formerly adapted to aid balance and climbing.

Another vestigial structure in humans is the appendix. Antibiotic resistance We are all familiar with the way that certain bacteria can become resistant to antibiotics This is an example of natural selection in action. The antibiotic acts as an environmental pressure. It weeds out those bacteria with low resistance and only those with high resistance survive to reproduce. (1) Variation exists in natural populations

(2) Many more offspring are born each season than can possibly survive to maturity

(3) As a result, there is a struggle for existence
- competition

(4) Characteristics beneficial in the struggle for existence will tend to become more common in the population, changing the average characteristics of the population
- adaptations

(5) Over long periods of time, and given a steady input of new variation into a population, these processes lead to the emergence of new species Essence of Natural Selection Trait that increases survival

For Example,
Beaks that make it easier to eat insects
Bright flowers to attract pollinators
Vascular tissue in plants to adapt to life on land Adaptations Evolution of a new species
must be isolation between populations Speciation Populations will eventually become resistant to pesticides and antibiotics with overuse Antibiotic and Pesticide Resistance Ex. Flowering plants and their pollinators Two organisms evolve in response to each other Coevolution Patterns of Evolution Gradual divergence over long spans of time assume that big changes occur as the accumulation of many small ones In punctuated equilibrium, the rate of speciation is not constant
rapid bursts of change
long periods of little or no change
species undergo rapid change when they 1st bud from parent population Types of selection Directional-homozygous dominant OR homozygous recessive are selected for

Stabilizing-heterozygous are selected for

Divergent- homozgyous dominant AND homozgyous recessive are selected for Two word naming system
Scientific name
Uses Genus and Species names
Ex. Dogs: Canis familiaris Binomial Nomenclature Taxonomy branch of biology concerned with grouping and naming organisms. Used to identify organisms
Paired set of questions with two choices Dichotomous Keys Levels of Organization Dear King Phillip Cried Out For Good Soup Kingdoms The beautiful thing about learning is that no one can take it away from you.
B.B. King Phylogenetic tree A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics. The taxa joined together in the tree are implied to have descended from a common ancestor. http://en.wikipedia.org/wiki/Phylogenetic_tree
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