University:
Felician University
Course:
BIO-405 | Genetics
Academic year:

2022
Views:

206

Pages:

8
Author:

StellarStrategist

Selection and Speciation How сап cl1a11ges iп а populacioп resulc in che forшatioп of а new species? Why? На\'е you ever wondered lюw rh e great di"ersity of life on EarrЬ has соте abouc or how а single new spe cies forms? Eпvironmeпtal pressures шау cause populatioпs to cbaoge over time or evoJvc. This is because а.п organism's aЬility со live to adultlюod in its current environment will decermiпe its reproductive suc cess апd ability to pass on its genes. But cl1a11ges wirhin а popt1lation сап оссш· without creating а new species. At what point do sciencists start rhinking of а new name for а species? Model 1 - Тhree Types ofSelection А Disruptive Selection Directional Selection 25 50 75 100 125 BodySiи (g) 150 С 17; О 2; 37.5 50 62.5 75 87.5 100112.; 125 137.5 150 Body Size (g) Stablliz.ing Selection Origiпal populacion Popu!arion after selection о 25 50 100 75 Body Size (g) 125 150 1. What variaЫes do tbe graphs in Model 1 compare? Body 2. #= of ·,ndvicAvals e td Selection and Speciation el �= 1! 6. Refer ro grapЬ С of M odel 1. • • •n al popu1atюn. • diпereпt · � :cr с1rom t h е or1g1 • n that J1as expeпenced selectюn R' /Jl'I >tolr5 Ь. Which individuals in the original population appear to display berter firness? IYI ь Mtd i ttk WJotSS с. As а group, propose sоше characreriscics of rhe environment that could leaci ro rhe population cl1anges illustrared in graph С. 7. As а group, define the following reпns in granнnatically correct seнrences. Each definirion shouJd contain rЪе follo\.ving words: popularioп, seiecrioп, .firness, and environmenr. а. DirectionaJ selection 3 8. 1 11 each of tl1e follow i 11g examples, dcscribc tЬс likcly outcomc d uc to thc cnviro 11mental p ressurc ancl state rhe rype of selecrion. Justify уош choice. • а. Finches with а small beak cannot crack open seeds. , 4 . Extension Questions . Model 3 - Genetic Drift • •• • •. .• • • ••• • • •• • • • • 1st Generation . 2nd Generation •• • • • • •• • •••• • • ••• •• • 3rd Generation 4th Generarion ••• • • 17. Refer to Modd 3. Fill in the taЬle below with the number of alleles of each суре in each generation • 1st Ge11eracio11 Light Medium Da.rk t 4 2nd Ge11eratio11 i. 5 3rd Generation 1 () 5 '5 4 4th Generation [о (, � 18. Compare the frequency of the dнее alleles in rhe 1st geпeration of rhe small popu.lation illu.s� uared in Model 3. 19. ln the scenario illustrated in Model 3 rwo of the light alleles were lost (tlнougЬ the death of the individual who had these two alleles) before reproduction occu.rred in the 1st generation. How did this affect the disrribution of the three alleles in this small populatioп? 20. The phenomenon illustrated in Model 3 is called genetic drift. lt mainly occurs in small, isolared popu.lations. Propose an explanation for why the light allele disappears from the population Ьу the fourth generation. 1,titt