nATURAL selection

Topics: Natural selection, DNA, Genetics Pages: 6 (1271 words) Published: September 24, 2014
CHAPTER 7, SECTION 7.2 PAGES 305 – 310
Natural selection: A process in which results in the characteristics of a population of organisms change over many generations. It occurs because individuals with certain inherited traits survive specific local environmental conditions and through reproduction, pass on their alleles to their offspring. Selective Pressure: environmental conditions that select for certain characteristics of an individual and select against other characteristics It may result from biotic factors as well, such as predators, parasites and competition for resources. Example: population in Staphylococcus aureus, the individual members of the bacteria were selected by their environment. They were able to survive the environmental change around them, and thus through reproduction passed on their genetic information against resistances to a particular antibiotic to their offspring’s. Natural Selection is Situational

IT HAS NO PURPOSE, WILL OR DIRECTION .
A trait that was once not used as an advantage for survival may be used in different times and situations for survival and reproduction Fitness: the ability for an organism to survive and reproduce offspring’s that will live long enough to reproduce. The contribution to the gene pool of the next generation by producing offspring’s that survive long enough to reproduce Described by the number of reproductively viable offspring’s that an organism produces in the next generation Artificial Selection

Type of selective breeding
Artificial selection: exerted by humans on a population by modify or improving particular desirable traits Biotechnology: the use of technology & organisms to produce useful products Artificial selection, huge impact on HUMAN SURVIVAL

Most of our food comes from artificial selection
Artificial selection resulted in cows that produce more milk Chicken are bred to grow quickly and increased amounts of meat Appearance of cats& dogs
KEY DIFFERENCE BETWEEN ARTIFICAL SELECTION& NATURAL SELECTION 1. Natural selection, environmental conditions plays a key role just like how in artificial selection humans play key role. 2. Natural selection, environmental conditions determine the ability for organisms in a population to survive and reproduce in the current conditions. 3. Biotechnology is used in artificial selection, which is the usage of technology and organisms to produce useful products Artificial Selection and Food Crops

Wild mustard plant, has been modified by selective breeding to produce broccoli, cauliflower and bussel sprouts. Traits that are artificially selected varieties all differ from the wild plant, but they are member of the same species We breed crops for harvest yield & nutritional value

CON: grown too quickly may not tolerate poor soil conditions Consequences of Artificial Selection
Genetic engineering – used to introduce new genetic info. Into trained organisms Main goal( above) to produce organism that are all very similar, for this, genetic diversity is reduced. Monoculture- extensive planting of same varieties of a species over large land It’s easier to manage, however, since the plants are so similar, if a new disease is introduced then the entire population will die or be severely damaged due to lack of genetic diversity Gene Bank

Contain populations of early ancestors of modern plants
Most important food sources came from wild ancestors with genetic combinations that enabled them to survive and reproduce in their environment By preserving these organisms their genetic diversity is available for introduction into modern plants if need arises

CHAPTER 7, SECTION 7.1 PAGES 296- 302

Adaptation and Survival
Extinct : disappeared from earth completely
Important to learn about adaptation and survival because it will help explain how populations can change over time and why some species survive while others become extinct

Adaption : the structure, physiological and...
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