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How are evolution, evolutionary adaptation, and natural selection related?
- 1.
- Evolution:
- change in the genetic composition of a population over time
- 2.
- Evolutionary
- adaptation: increase in the frequency of traits better suited to the current
- environment
- 3.
- Natural
- selection: process which results in evolutionary adaptation
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Pre-Darwinian ideas about evolution- Aristotle and LaMarck
- Aristotle:
- proposed that species are fixed and variation is a mistake
- -viewed
- creatures on scale from ‘low’(plants) to ‘high’(human)
- LaMarck:
- suggested that life evolves through refinement of traits that equip organisms
- to perform successfully in their environment
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What is Lamarckian evolution?
- Traits that’s
- are developed through use or disuse during organisms life and then passed on to
- offspring
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What are the basic requirements for natural selection?
- 1.
- genetic
- variation within a population: variation for traits which may be more or less
- advantageous in the environmental context
- 2.
- overproduction
- of offspring: many individuals die or fail to reproduce in any population
- 3.
- struggle
- for existence: survival and breeding rates for any particular individual
- depends on the genetic traits the individual carries
- 4.
- unequal
- success in passing genetics to the next generation: the traits of
- individuals with high survival and
- breeding rates are more highly representing by the next generation
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What is relative fitness, and how does it relate to natural selection?
It is the contribution an individual makes to the genes pool of the next generation -fitness is determined solely by the number and quality of offspring in the next generation, not size or appearance, or abilities which do not relate to reproduction -reproductive advantages or fitness is judges relative to others in the population, and it depends strongly on the environmental context, which could change
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How is it that evolution can only work at the population, rather than individual level?
Genetic variation: not all individuals produce offspring in the same quantities -variation in traits I slinked to offspring production
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Why do we have to wait for a new generation to declare the evolution has taken place in a population?
The only variation that can be inherited matter to evolution
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What kinds of traits are important in natural selection?
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Lyell’s contribution to Darwin’s thinking
Earth is very old (~6000 yrs old) Earth was sculpted by gradual geological processes that continue today
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What is descent with modification?
Mechanism for natural selection -organisms descended from ancestral species
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How is fossil age determined, relatively?
Fossil age is determined by its level of deepness in the strata of rock
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What are transitional forms, and how do they support evolution?
Linked groups of animals to one another by having features of each
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What is the difference between homologous structures and analogous structures?
Homologous structures: the similarity in structures due to common ancestor -same bones, different functions Analogous structures: different set of bones (different origin), used for the same function
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What does a cladogram or evolutionary tree show? Where are the common ancestors in a cladogram, and how do they show relatedness?
- -base trunk is
- the common ancestor to all organisms on tree
- -each fork
- represents the last common ancestor for all branches from the fork
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How is the principle of parsimony used to arrange cladograms?
Explains the patterns of characteristics or sequences with the fewest changes, using the PRINCIPLE OF PARSIMONY (simplest explanation Is preferred)
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What two previously separate fields did the ‘modern synthesis’ combine?
Fusion of genetics and evolutionary biology
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What is the gene pool? How do we describe it?
- Gene pool is the total collection of alleles in a population at a particular time
- -the frequency of each allele in a population can be counted
- -when the relative frequency of alleles changes over a number of generations, MICROEVOLUTION has occurred
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Be able to use the rules of multiplication and addition to obtain the number of individuals carrying a particularly genotype when given allele frequencies.
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Causes of microevolution other than
natural selection- ID and explain. Are they adaptive?
Genetic drift:sampling error-leading to changes in allele frequencies which particularlyaffects small populations. Random andnot adaptive
Gene flow:movement of allele from one population or sub-population to another, notadaptive
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Ways genetic variation in nature is
maintained
Naturalselection is the most important because it is the only process that is based onadaptation to the environment
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What is sexual selection?
Naturalselection which occurs within species in competition for breeding opportunities
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What is sexual dimorphism?
Differences inthe appearance of males and females of the same species that is associated withsexual selection
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Potential exam question: Name and briefly describe the five main lines of evidence for evolution as a scientifically reasonable theory.
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