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FAU / Process Biology / PCB / What are the five main elements the make up the evolutionary theory?

What are the five main elements the make up the evolutionary theory?

What are the five main elements the make up the evolutionary theory?


Evolution PCB3674 Exam 1 Study Guide  

What are the five main elements the make up the evolutionary theory?

1. Evolution

­ Happens by natural selection

­ a change in the frequencies of the different values of a trait  from one generation to the next

­ Fundamental Definition of Evolution

o change in allele frequencies across generations

2. The five main elements the make up the evolutionary theory ­ Individuals are not identical

o Variation We also discuss several other topics like Whats is the major morphological structures of prokaryotic cells?
Don't forget about the age old question of Describe the theory of functionalism.

­ Individuals resemble their parents

o Heritable

­ In most cases, more individuals are produced than reproduce— often many more

o don’t survive long enough

o not reproductively successful

o Few individuals will live long enough to reproduce  themselves

What are the types of evolution?

­ Reproductive success is not random

o some traits support this better than others

­ Time  

3. Variation

­ Variation is the differences with DNA which either causes  mutations or different genotypes and phenotypes.  If you want to learn more check out The buying and selling of products and services through a computer network is called what?

­ Variation is important to the evolutionary process due to the  need for different types of traits in order for selection to act  properly

­ the most “fit” traits are selected and passes on to the next  generation  

­ It’s beneficial for an individuals to be variable because it allows  them to respond to a dynamic environment.  

4. Decent with Modification

­ As one population produces offspring, there are some  modifications within next generations (variation)

What are three types of variation?

­ Populations are variable

o many aspects of variation are heritable

­All individuals do not survive and/or reproduce with the same  success  

o (RADNOM)  

­ Differences in survival and/or reproductive success are not  random

o Some differences are related to heritable, variable trait

­ The frequency of “advantageous” trait values within  populations over generations

o the population evolves

5. The types of evolution  

­ Microevolution—characteristics of species change over time Example: In a population of birds, the average beak size  may change from one generation to the next Don't forget about the age old question of What are the two types of culture?

o Selective breeding  

o All wolves and dog breeds come from the grey wolf  

o Vestigial structures-Structures or traits that  

evolutionarily once held an important purpose but are  Don't forget about the age old question of Why is dna considered simplistic?

now not used or are used for something else

Example: CMAH protein functional in most  

primates. The gene is disrupted slightly in humans  due to mutation though it is not used

­ Speciation-lineages split and diverge thereby increasing the  number of species

o Two populations diverge to the point that they can no  longer interbreed

o Expansions = divergence= extinction  

o May give arise to New species

­ Macroevolution—new life forms derive from earlier forms Example: Tetrapod’s arose from a lineage of fish

o new species evolve, ancestors disappear

o Fossils  

o the extinction of a former species as a new species  takes its place

o Involve transitional forms

 permit connection between related species We also discuss several other topics like What are the main parts of a bacterial cell?

6. Evidence for Common Ancestry

­ Homology

o The study of likeness

­ Structural homology

o similarity in structures

o tissues, organs, bones, etc.

­ Molecular homology

o similarity in molecular details

o genes / proteins, biochemistry, etc.  

o Explains slightly different form of ancestral structures  ­ Non-Homologues Traits (convergent evolution)

o Two different species that face the same challenged that  evolve to have the same solution (physical structure) to  similar problems

o Not due to heredity  

o Not related  

Example: sharks and whales  

7. Evolution under domestication  

­ One way to study the effects of selection is to create it— artificial selection

1) Identify a desirable trait value (size, color, flavor)

2) Choose as breeders only those individuals with the  

most “ideal” values of the trait

3) Repeat over many generations

­ In this scenario, the breeder is deciding which values of a trait  most supports reproductive success

8. Fitness

­ Success in survival and reproduction

o fitness does not mean more physically fit

o although that may be part of it

­ the capacity to survive and produce offspring that are  themselves able to survive and reproduce

o An individual is not either fit or not fit

o an individual is simply more fit or less fit than other  individuals

9. Galapagos finches contribution to the evolutionary theory  ­ Tremendous variation in beak shape

oeach adapted to exploitation of different primary food source ­ Darwin used finches to demonstrated natural selection,  heritability, and Variability

10. Proteins

­ Many protein coding sequences exist as a set of slightly  different sequences within a population—alleles

­ Proteins with slightly different shapes often have slightly  different properties

­ this often leads to differences in phenotype

­ Alleles—different sequences of the same gene

o differences between alleles are usually very minor

o produce proteins that are functional

o but which differ slightly in some way

11. Sources of Variation

­ Mutations

o Change in DNA sequence

o Different alleles arise when one or more bases in the  sequence of a parental DNA strand is change

o if the change is in a protein coding region, then a new “allele” is created

o Two major sources

 duplications

 damage to DNA

o Occasional changes to DNA sequences benefit a species  over the long-term

­ Gene Duplications

o During replication

 accidental copying of the same sequence more than  once during replication—replication “slips

o During meiotic crossing over

 “misalignment”

 chromosomes don’t align properly  

 one participant experiences a deletion

 the other experiences a duplication

 one of the resulting chromosomes now has two  

copies of one of the alleles involved in the crossover

o Duplicated genes are “free” to mutate

 Because the probability that a mutation will be deleterious is  lower for a duplicated gene  

12. Three types of variation?

­ Genetic variation

o variable phenotype depending on which combination of alleles  are inherited from parents

 parents produce 2 x 2 = 4 alleles

 each offspring inherits only 2

­ Environmental variation

o differences due to exposure to different environmental conditions o this variation is generally not heritable

­ Genotype-environment interaction

o genetically based difference in response to environmental conditions o this variation is heritable  

13. Genetic Variation and Evolution

­ Most variable trait values are the result of variation in  the structure of proteins

­ Protein structures that convey higher “fitness” will automatically  become more common in a population over time. Vice Versa ­ Protein structures leading to decreased fitness will become less  common, may even disappear over time

­ No single protein defines fitness

o some proteins convey only slight differences in fitness o definition of fitness must take into account the  


o and the environment is not static

14. Plasticity (Environment and Evolution)

­ many organisms are able to adopt alternative phenotypes  depending on environmental conditions—Plasticity

­ *Plastic is malleable. Able to bend into alternative forms  ­ often involves some component of the environment serving to  modify gene expression

­ But some types of environmentally-driven changes may be  heritable

o Epigenetic changes

 changes to the shape of the DNA caused by  

environmental factors, alter gene expression

 these changes are inherited in some cases

15. Horizontal Transfers

­ Viruses (within DNA)

o procaryotic and eukaryotic

­ Acquisition of environmental DNA

o almost exclusively prokaryotic

o Good at picking up DNA from other prokaryotes and  implementing it into itself  

­ Sexual reproduction

o primarily eucaryotic

o occasionally prokaryotic

­ Vertical transfer

o parent to offspring

o no “new” genetic material

16. Mutations and Fitness

­ Four types of mutation

o lethal

o Deleterious (bad but not lethal)  

o neutral

o Beneficial

 take a perfectly good gene and put in a mutation that creates a  gene that works better than it did before  


­ Most mutations are “silent”

o lethal

o neutral

 in non-coding region of DNA

 no amino acid change

 amino acid change does not affect protein function

o deleterious

 very few are beneficial

17. Nature of Variation

­ In order to be evolutionarily relevant:

onew variation must affect a germ cell

othat germ cell must be very very lucky in several respects:  become part of the next generation

 remain viable

 contribute to the next generation

18. Genetics and Evolution

­ Mendelian genetics

o detailed observation of selective crosses

­Molecular genetics

o genetic processes at the molecular level

­Population genetics

o changes in the frequencies of alleles across generations

19. Allele Frequecies  

­ Book authors ran picked 200 times to produce 100 zygotes and  achieved the following results:

o 34 AA, 57Aa, 9 aa

o frequency A = 2(34) + 57 = 125 = 62.5%

o frequency a = 2(9) + 57 = 37.5%

20. Calculating Probabilities

­ Probability of two independent events occurring together is  product of their individual probabilities

oflip two coins simultaneously

ochance of one being heads is ½

ochance of the other being heads is ½

ochance of both being heads is 1/2 x 1/2 = ¼

­ Chance of either of two mutually exclusive events (either / or) is the sum of their individual probabilities

o probability of rolling a six = 1/6

o probability of rolling a three = 1/6

o probability of either six or three = 1/6 + 1/6 = 1/3

o probability of getting either heads or tails = 1/2 + 1/2 = 118

∙ Things to review 

­ The important points regarding selection 

­ TAS Variation 

­ Leopard Gecko Gender in regards to environmental variation  ­ Simulation of random mating 

­ How to calculate the probability of two independent events  ­ How to calculate the chance of either of two mutually exclusive events  ­ How to calculate two independent events as mutually exclusive  ­ *** flipping two coins at once 

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