Studied by 5 people
How do organisms evolve?
They change over time
What did Darwin notice about fossils?
He noticed that some fossilized organisms no longer exist on the planet and that fossils of organisms do not always resemble their modern-day descendants completely
What are fossils?
Remains or traces of organisms from the past
Where are fossils usually found?
Sedimentary rock
Strata
The layers of sedimentary rock in which fossils are found
What did Jean-Baptiste de Lamarck publish?
Theory of Evolution (1809)
What were Lamark’s main ideas?
Use and Disuse, Inheritance of Acquired Traits, Tendency toward Perfection
Explain Lamark’s Use & Disuse idea
Lamark believed that the more parts of the body were used, the stronger and bigger they would get
Explain Lamark’s Inheritance of Acquired Traits idea
Lamark believed that modifications could be passed on
Explain Lamark’s Tendency toward Perfection idea
Lamark believed that species were made to be perfect and tried to be that way always
Were Lamark’s proposals accurate?
No
What can we learn from Lamark?
We can learn about his realization that species evolved, although his explanation was flawed
How would Lamark vs Darwin describe the evolution of giraffes with shorter necks into those with longer necks as trees grew taller?
Lamark: The giraffes had to adapt to reach the trees and get food. The increased use of their necks made it longer, helping them reach the trees.
Darwin: The giraffes with shorter necks died as they could not reach the trees and get necessary food. The longer necked giraffes were able to survive long enough to reproduce, passing their traits onto their offspring, populating the gene pool with the long neck characteristic.
Describe Weissman’s experiment and how it disproves a Lamark theory
Weissman cut the tails off of mice and studied them and their offspring. If Lamark was correct in the assumption that acquired traits were inherited, then the mice wold eventually produce offspring with no tails. This however, did not happen, disproving Lamark’s theory.
Evolution
Change over time in the genetic composition of a population from generation to generation
Organisms DO NOT choose to evolve; it is not purposeful
What is the Darwinian definition of evolution?
Descent with modification
Descent with Modification
Evolutionary change based on the interactions between populations and their environment with results in adaptations to increase fitness
What are adaptations
An inherited characteristic that gives an organism an advantage
What happens when an individual has certain heritable traits that helps them survive?
They reproduce at a higher rate than other individuals
What does natural selection increase?
The adaptation of organisms to their environment over time
What may happen if an environment changes over time?
Natural selection may result in adaptation to these new conditions and may give rise to new species
What are the 5 major points of evolution by natural selection?
Overproduction of offspring
Variation exists among offspring
Offspring struggle to survive (competition)
Survival of the fittest
Best adapted reproduce and pass their genes on to their offspring (high fitness)
What does it mean to be ‘fit’?
To be the best adapted
What causes the variation amongst offspring?
Sexual Reproduction: Meiosis crossing over, independent assortment, independent fertilization
Asexual Reproduction: Random bases changes in DNA sequences = mutations
Do mutations always pass on?
Nope, only if they’re in sex cells
Why would offspring compete?
Compete to get food, mates, territory, shelter, and to hide from predators
What determines which organisms survive and reproduce?
Nature
Did Darwin know about the causes of offspring variation?
Nope
Who is Charles Darwin and what did he do?
An English naturalist that joined a 5-year research voyage around the world to collect and study nature. He studied plant and animal specimens, bones, and fossils.
In what place did Darwin come up with his most brilliant ideas?
The Galápagos Islands
What was the name of the ship Darwin went on?
The HMS Beagle
Do individuals evolve?
No, populations do. Over time
Can natural selection create new traits?
No, it can only increase or decrease heritable traits that vary in a population, editing or selecting traits that already exist
What determines the traits that are selected for or against in any specific population?
Natural selection and the local environment
What does natural selection favor?
The organisms with traits more fit to survive
True or False: All adaptations are the same
False: They vary with different environments
What did Darwin hypothesize about species in the Galapagos?
He hypothesized that species from South America had colonized the Galápagos and speciated on the islands, occupying new environmental niches
What did Darwin conclude about adaptation?
Environmental adaptation was a closely linked process to the origin of new species
What did Darwin notice about Galapagos finches?
They had beaks that were adapted to eating different food sources on different islands
Did Darwin know about artificial selection?
Yes, he noted that humans have modified other species by selecting and breeding individuals with desired traits
What are examples of artificial selection?
Domesticated animals, agriculture
What is artificial selection also called?
Selective breeding
What are the main pieces of evidence for evolution? Which is the most rock-solid?
Fossils
Homologous Structures
Similar Biochemistry: the most solid (used to support other evidences)
Similar Embryo Development
Vestigial Structures
Similar Biochemistry
Similar DNA, RNA, and amino acid sequences
Genes shared among organisms inherited from a common ancestor (molecular level)
Homology
Similarity resulting from common ancestry
Homologous Structures
Anatomical resemblances that represent variations on a structural theme present in a common ancestor (similar anatomy)
What is comparative embryology
The a branch of the study of embryos that reveal anatomical homologies not visible in adult organisms
Vestigial Structures
Remnants of features that served important functions in the organism’s ancestors
Whales have leg bones that are vestigial
Why do vaccines have to keep changing for HIV and Covid but not for chicken pox?
HIV and Covid are RNA viruses, which means there is no proofreader when copying genetic material, resulting in many mutations that change the virus properties
Chicken pox, however, is a DNA virus, which means the proofreader makes sure the DNA copied is the same
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