Unit 9 Evolution SEE OTHER PART Flashcards
Theory
- Well supported testable explanation of phenomena that have occurred in the natural world
Darwin
- His observations formulated a theory of how species change over time, called natural selection
Lamarck
- Proposed a flawed theory of the inheritance of acquired traits
- Believed that animals were always striving towards perfection
Punctuated Equilibrium
- Jay Gould
- Organisms undergo rapid bursts of speciation followed by long period of time unchanged
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Graduated Equilibrium (general definition)
- Traditional evolutionary view of gradual and continuous change of populations of organisms
Graduated Equilibrium (Explanation 1) Evolutionary Relationships...
- Evolutionary relationships among living organisms and those that inhabited Earth in the past can be understood through
- biochemistry
- developmental stages (cytology, embryology, and anatomy)
- examining the fossil record.
Developmental stages
- Cytology, embryology, and anatomy
Graduated Equilibrium (Explanation 2) Organism similarities...
- Organism similarities (structural and metabolic) are reflected in the similarity in proteins and nucleic acids
Analogous structure
- Different structure, same function
Homologous structure
- Same structure, different function
- Similar characteristics from common ancestry
How do homologous structures develop?
- Homologous structures develop from the same embryo logical tissues and provide strong evidence that all 4 limbed animals w/ backbones have descended from a common ancestor
Vestigial Structure
- Organs so reduced in size that they’re nonfunctional remnants of homologous organs in other species
Relative dating
- The age of the fossil is determined by comparing its placement w/ that of fossils in other layers of rock
Absolute dating
- Some elements in rocks are radioactive; radioactive half- lives determine the age of a sample
Natural Selection
- Process by which organisms w/ traits well suited to an environment survive + reproduce @ a greater rate than those less suited to an environment.
Natural Selection operates in…
- Natural Selection operates in populations over many generations
Adaptation
- Inherited characteristic that increases an organism’s chance of survival
Structural Adaptations…
- Structural adaptations may take millions of years to develop depending on the rate of adaptation, the rate of reproduction, and environmental factors
When do adaptations sometimes arise abruptly?
- Adaptations sometimes arise abruptly in response to strong environmental selective pressure.
Examples of Adaptation
- Bacteria resists antibiotics
- Insects resist pesticide
- Camouflage
- Mimicry
Evolution
- Change IN DNA over time: the process by which modern organisms have descended from ancient organisms
2 main sources of genetic variation
- Mutations and the genetic shuffling that results from sexual reproduction
The change in allele frequency of gene in a given population may lead to…
The change in allele frequency of gene in a given population may lead to a new species
Speciation
Formation of a new species
Reproductive Isolation
- 2 populations can’t interbreed and produce fertile offspring
Geographic isolation
- 2 populations are separated by geographic barriers such as mountains, rivers, etc.
Symbiosis
- Relationship in which 2 species live closely together
According to the endosymbiotic theory…
According to the endosymbiotic theory, eukaryotic cells formed a symbiosis among several different prokaryotic organisms.
Lamarck’s Theory
- Theory of Inheritance of Acquired Characteristics
- If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring.
- Giraffe’s necks
Evolution includes…
- Evolution includes random mutations and nonrandom natural selection
___ are selected, BUT ___ evolve
Individuals are selected, but populations evolve
Evolution 2
- A change in gene frequency caused by mutation + selection
Mutations
- Mutations create variation and changes DNA sequence
Variation
- Variation is the raw material for natural selection
- Frequency of genes passed on to the next generation changes
Bottlenecking cause + effect
- When a large population is drastically reduced by a disaster, not due to fitness
- It narrows the gene pool
Differential survival
- Success traits= adaptations
- Limited quantities of space and resources lead to a struggle for survival results, and as a result those that are the most fit can only survive
Differential reproduction
- Next generation is better than older generation
Modern Example
- Insecticide doesn’t kill all bugs- some bugs survive and reproduce- resistance is inherited- more bugs are resistant/insecticide becomes less effective
Hidden Variation
- Hidden variation can be exposed through natural selection
Analogous structures
- Solving a similar problem w/ a similar solution.
- No evolutionary relationship
Difference between homo vs. analog structures
- Homologous: Show evolutionary related-ness
- Analogous: Don’t show any relation
Comparative Embryology
- Similar embryological development in closely related species
- Ex. Chicken vs. Human embryo look similar
Molecular Similarities
- Comparing DNA + protein structure
- Similar DNA, proteins
- Same genes
Fossil Record
- Layers of sedimentary rock contain fossils
- New layers over older ones
Divergent evolution
- Common ancestor
- Darwin’s finches
Convergent evolution
- Analogous structure
- Same function, but no common ancestor
- Butterflies and birds can fly but no relation
