Give a present day example of NATURAL SELECTION
The emergence of the super bug MRSA.
Antibiotics kill the susceptible bacteria and the resistant one alon. The survivors multiply producing a new generation of anti-biotic resistant bacteria.
. Genetic change in a population over multiple generations
. Descent with modification
Descent with modification
Descent refers to inheritance
modification refers to changes in the inheritable traits over generations
interbreeding members of the same species living in the same place at the same time
When does evolution happen in a population
when some alleles become more common and others less common from one generation to the next.
These changes in alleles account for both the long term and short term changes in the history of life on Earth
What does evolution not answer
how did life begin in the first place
The idea that of the sudden appearance of organisms on Earth.
Species were fixed and unchangeable
Earth was relatively young
There could be no extinction
The name of Darwins Ship
The HMS beagle
describes the acquisition of the same biological trait in unrelated lineages.
More individuals are produced than survive only those who are able to get the resources were more likely to survive and reproduce
. It occurs when encironmental factors cause the differential reproductive success of individual with a particular phenotype.
when a human chooses one or few desired traits and then allows only the individuals that best expresses those qualities to reproduce
Explain theory of Darwin’s theory natural selection and evolution
His theory of evolution through natural selection
- he observed that individuals in a species are different from one another
- and some of these variations are inheritable
- Competition determines which ones live long enough to reproduce: those with the most adaptive traits would more likely reproduce and pass on thos adptive traits to their offsprings.
- Over many generations natural selectioncoupled with enviromental change or a new habitat could change a populations characteristics or give rise to a new species
MODERN EVOLUTIONARY SYNTHESIS
It suggests that genetic mutations create inheritable variations and that this variation is the raw material upon which natural selection acts
. Mutations are changes in DNA sequence that occur at random in all organisms. Sexual reproduction amplifies the variability by shuffling and reshuffling parental alleles to produce genetically differnt offspringd
The 2 types of biological evolution
1. MICRO EVOLUTION
Evolution and Alleles
Evolution involves changes in alleles. Because an individual ‘s allele does not change: evolution can occur in a population and not in an individual. Individuals do not Evolve they adapt
The relatively short term genetic changes in a population
most common example : Natural Selection
large scale events such as the appearance of a new species
features that provide a selective advantage because they improve an organism’s ability to survive and reproduce.
They are inheritable traits that give an individual a competitive advantage
They include only those structures, behaviors or psychological processes that are inheritable and that contribute to reproductive success
In any population, individuals with the best adaptations are mostlikely to reproduce and pass their advantage to their offspring
Because of this “differential reproductive success” ( natural selection) a population changes over time and the best adaptations to the existing environmentbecome more common with each generation
some features neither increase or decrease reproductive success ( surviving to be able to have offsprings that also survive)
eg certain phenotypes like the color of ones eye or mutations in silent dna that persist but are not subject to natural selection
surviving to be able to have offsprings that also survive)
Is the observable properties of an organism,most of which arise from a combination of environmentalinfluences and the action of multiple genes
How does Natural Selection eliminate phenotypes
By weeding out individuals with poorly adapted phenotypes natural selection indirectly changes allele frequencies in the population
What determines if a phenotype is good
it depends on the environment and time: a trait that is adaptive in one set of circumstances may be a liability in another
Why does evolution never stop
Becauses conditions are always changing
Evolution does not have a goal
What are the factors that combine to prevent natural selection from producing all the traits that a species might find useful
- Every genome has limited potential imposed by evolutionary history
- No population contains every allele needed to confront every possible change in the environment: If the right alleles are not available at the right time an environmental change may wipe out a species
- Disasters such as floods can indiscrimantly eleminate the best alleles combination for that environment by chance
- Genetic traits such as diseases that appear after repoductive age are not affected by natural selection
1.is Reproductive Success. It is surving long enough to reproduce
Adaptations contribute to an organism’s fitness: allowing them to overcome environmetal changes,it also includes
- attracting a mate
3. number of of offsprings a organism produces
- the total number that survives to reproductive age
What is evolution
Evolution is genetic change in a population over time
How did people think that species arose and diversified before Charles Darwin published his theory of evolution by natural selection?
The major belief was in a special creation in which God formed all species and placed them on the earth. Jean Baptiste de Lamarck proposed that acquired characteristics were heritable; differential use and disuse of body parts accounted for changes between generations and species diversification.
What did Darwin observe that led him to develop his ideas about the origin of species?
As Darwin journeyed in the HMS Beagle, he observed the uniformity of geological processes such as volcanism, earthquakes, and erosion. He collected fossils and observed that each continent had animals that were characteristic and different from those on other continents. On the Galapagos, he observed and collected finches from different islands and noted differences in giant tortoises on different Galapagos Islands. These observations led Darwin to the idea of “descent with modification
How is artificial selection different from natural selection
In artificial selection, humans select for the traits they desire in plants or animals. In natural selection, environmental factors favor some traits over others.
How did Darwin’s ideas challenge prevailing beliefs about life’s diversity and the status of humans?
Darwin’s ideas challenged prevailing beliefs about life’s diversity by using natural processes to explain how species arise. Darwin saw humans as just another species and rejected the idea that humans were specially created. He thereby demoted humans from an exalted position, putting them on an equal footing with other species competing for resources.
What is the modern evolutionary synthesis?
The modern evolutionary synthesis combines the work of Darwin with a modern understanding of genes, chromosomes, and the origins of variation.
What is an adaptation, and how do adaptations become more common within a population?
An adaptation is a characteristic that helps an individual survive and reproduce in its environment. Adaptations become more common within a population when they are heritable and when they increase the odds of survival and reproduction.
What is the role of genetic variation in natural selection?
Genetic variation is the raw material that natural selection acts on since genetic variation creates variations in phenotypes, some of which are better suited to the current environment.
How can natural selection favor different phenotypes at different times?
Natural selection can favor different phenotypes at different times because environments are always shifting in dramatic or subtle ways.
Why doesn’t natural selection produce perfectly adapted organisms?
Natural selection does not produce perfectly adapted organisms because each population’s evolution is constrained by its existing gene pool, which limits the possible allele combinations and may not contain every allele necessary to confront every challenge. Chance events may also wipe out adaptive allele combinations. Genetic illnesses that produce symptoms only after reproductive age also can maintain harmful alleles in a population.
What is evolutionary fitness?
Evolutionary fitness is measured by reproductive success