Read the questions below carefully and provide accurate, complete answers. paper
ID: 185886 • Letter: R
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Read the questions below carefully and provide accurate, complete answers. paper if needed. Use extra In an experiment you grow three different experimental plant plots: a control (no herbivores or added nutrients), plants with herbivores only, and plants with added nutrients (herbivores still present). Given these results, describe what accurate conclusions can be drawn given the statistical differences represented. (3pts) 1.) 1.l Control Herbivores Nutrients 2.) Compare and contrast the three different forms of selection. Give specific examples for each. (3pts) 3.) Define evolution and describe, in some detail, four different lines of evidence that support it and how? Give drawings and/or examples for each. Feel free to attach on an additional sheet(s) (6 pt)Explanation / Answer
1) The above statistical observations indicate that in the given three different experimental plant plots, natural selection can occur with or without environmental change.
· Plants with added nutrients and herbivores still present have the highest growth or biomass (~0.08 g). If a new variation arises which is advantageous in nature, this new trait will be adapted by the species for improved evolution.
· The plants with herbivores only have the least amount of biomass (~0.02 g) due to a negative trait the growth has reduced.
· The control plant plot with no herbivores or added nutrients has medium amount of biomass or growth (~0.06 g). The population remains stable and maintains its stability in a constant environment.
2) The three types of natural selection are:
i) Stabilizing selection in which the extremes are selected against. For example: height; average height is more commonly favoured among the population compared to more tall or more short.
ii) Directional selection in which only one extreme value is selected. Example speed: since faster is always advantageous species will tend to get faster over time.
iii) Disruptive selection in which both the extremes are selected. Example: distinct prey-type animal will always move away from the norm in both directions.
3) The changes that occur in heritable characteristics among the biological populations over successive generation is known as evolution. It is a process through which different living organisms have developed from previous forms over a very long period of time.
The four lines of evidence from different areas of biology include:
· Anatomy: similar physical features are shared by species as the particular feature was shared by common ancestors. For example: homologous structures.
· Molecular Biology: The shared ancestry among living organisms is reflected through DNA and the genetic code. For example : DNA fingerprinting and DNA comparisons can indicate a relation between species
· Biogeography: The unique features of island species and the distribution of organisms over the globe signify evolution and geological change
· Fossils: The past species which have become extinct are related to the present species through the documentation of fossils.
4) a) The average size of available seed has increased and reached a constant in value until mid-1977 and the gradually decreased thereof till 1978.
b) Due to the change in available seed size between 1976 to 1978, the growth (beak size) of the finch initially decreased till June 1976, and then gradually started increasing there after (July- august 1976 to 1978)
c) The changes in availability of different sized seeds influenced the evolution of beak size of finches. Since larger seeds were more difficult to crack, during drought years they became more common proportionally, hence it favoured finches with larger beaks. However, due to the competition between the large seed eaters, birds with smaller beaks did better when the smaller seeds became proportionally more common.
d) According to the graph, the seed size in December 1976 and January 1978 lies between 5.3 and 5.5, the difference is statistically not significant.
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