EX 3 Evolution
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How are evolution, evolutionary adaptation, and natural selection related?
- change in the genetic composition of a population over time
- adaptation: increase in the frequency of traits better suited to the current
- selection: process which results in evolutionary adaptation
Pre-Darwinian ideas about evolution- Aristotle and LaMarck
- proposed that species are fixed and variation is a mistake
- creatures on scale from ‘low’(plants) to ‘high’(human)
- suggested that life evolves through refinement of traits that equip organisms
- to perform successfully in their environment
What is Lamarckian evolution?
- Traits that’s
- are developed through use or disuse during organisms life and then passed on to
What are the basic requirements for natural selection?
- variation within a population: variation for traits which may be more or less
- advantageous in the environmental context
- of offspring: many individuals die or fail to reproduce in any population
- for existence: survival and breeding rates for any particular individual
- depends on the genetic traits the individual carries
- 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
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
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
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
What kinds of traits are important in natural selection?
Lyell’s contribution to Darwin’s thinking
Earth is very old (~6000 yrs old) Earth was sculpted by gradual geological processes that continue today
What is descent with modification?
Mechanism for natural selection -organisms descended from ancestral species
How is fossil age determined, relatively?
Fossil age is determined by its level of deepness in the strata of rock
What are transitional forms, and how do they support evolution?
Linked groups of animals to one another by having features of each
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
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
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)
What two previously separate fields did the ‘modern synthesis’ combine?
Fusion of genetics and evolutionary biology
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
Be able to use the rules of multiplication and addition to obtain the number of individuals carrying a particularly genotype when given allele frequencies.
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
Ways genetic variation in nature is
Naturalselection is the most important because it is the only process that is based onadaptation to the environment
What is sexual selection?
Naturalselection which occurs within species in competition for breeding opportunities
What is sexual dimorphism?
Differences inthe appearance of males and females of the same species that is associated withsexual selection
Potential exam question: Name and briefly describe the five main lines of evidence for evolution as a scientifically reasonable theory.
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