Gene Frequency and Natural Selection Team Brainstormers BS
Gene Frequency and Natural Selection Team Brainstormers (BS) Spring Feb 2015
Relationship between Gene Frequency and Natural Selection Gene Frequency ∗ Random genetic mutations occurs ∗ Inherent Variation ∗ Sexual reproduction ∗ ∗ (According to Hardy-Weinberg, changes ∗ in frequency will not occur in a population if these five conditions are not met. ) 1. 2. 3. 4. 5. No mutations No natural selection Very large population Random mating No gene flow ∗ Natural Selection Influences from the surrounding environment Eliminating incompetent individuals Does not produce perfect organisms Highly selective and specific
Natural Selection Methods ∗ ∗ ∗ Different populations of prey Different predators Adaptation by prey and predators Different environments Natural disaster-bottleneck effect Different rates of survival and reproduction of prey populations
Gene Frequency Methods ●A starting population of 50 individuals represented by 100 alleles (beads) were picked out of the cup at random; this essentially signifies random mating. ●Allele pairs were added or removed based on the rate of survival to replicate the introduction of selective pressures. ●The allele pairs were then counted and beads were added depending on the rate of survival and reproduction for each case. ●Beads were picked out in pairs at random again, these signify individuals of the second generation. ●This process was repeated for six generations for all runs except for one case due to a shortage of beads. ○ That run was carried out until the fourth generation; therefore, all comparative analysis can only be carried out to the fourth generation and forecasting was used for the subsequent generations. ●The rates of survival and reproduction for our various runs are greatly exaggerated, with rates rare - if ever found in nature. ○ The exaggeration is so that we can see the explosive/depressive effects of adaptability, or lack thereof, to a given environmental condition.
Gene Frequency Results ● According to the graph, each of the genotype frequencies remain constant, therefore reinforcing the fundamental points outlined in the Hardy Weinberg principle.
● This graph entails the projections of the genotype frequency percentages up for future generations.
Natural Selection Results First Environment Population Size Data G 1 G 2 G 3 G 4 G 5 G 6 Blue 20 28 40 28 12 13 Light Purple 20 33 40 37 28 40 Orange 20 35 40 40 1 1 Yellow 20 32 40 32 1 0 Green 20 16 0 0 Pink 20 21 13 16 9 13 Dark Purple 20 29 40 24 9 9 Aqua 0 0 20 24 Second Environment
● ● The second figure displays the combined representation of all of the species According to the first Figure (Populations with Projected Decay), the population counts in the first 6 generations fluctuated, but mainly had decreased in numbers.
Gene Frequency vs. Natural Selection ● Selection against one genotype can result in an overall positive effect on others by freeing up resources such as food and habitat. ● Fluctuations within subsets of a population are normal, overall change in allele frequency is usually gradual unless a subset completely dies out.
Conclusions ★ Natural selection and allele frequency are closely related, if natural selection is in action, then allele frequencies are changing. ★ The correlation between natural selection and gene frequency can be modeled in the laboratory using simple non-living systems, in living systems with much greater complexity, and can probably be modeled using highly sophisticated computer programs. ★ The allele frequency of the previous generation determines the phenotypic distribution of the current generation. ★ Natural selection acts upon this generation to refine the positive traits, weeding out the negative traits due to selective pressures such as predation, sexual selection, and relative fitness. ★ Therefore natural selection is a direct cause of allele fluctuation within a population.
References ● ● Reece, J. (2011). Campbell biology Jane B. Reece. . . [et al. ]. (9 th ed. ). Boston: Benjamin Cummings. The Paleontological Research Institution and its Museum of the Earth. Types of Natural Selection. NY. Paleontological Research Institution. [cited 2015 Feb 19]. Available from http: //bivalves. teacherfriendlyguide. org/ Philip Mc. Clean. Evolutionary Genetics [Internet]. Bison (ND): North Dakota State University; 1997 [updated 1998; cited 2015 Feb 25]. Available from: http: //www. ndsu. edu/pubweb/~mcclean/plsc 431/popgen 4. htm "Modern Theories of Evolution: Hardy-Weinberg Equilibrium Model. Available from: http: //anthro. palomar. edu/synthetic/synth_2. htm
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