Chapter 24, Problem 29
In 1988, Horst Wilkens investigated blind cavefish, comparing them with members of a sibling species with normal vision that are found in a lake [Wilkens, H. (1988). Evol. Biol. 25:271–367]. We will call them cavefish and lakefish. Wilkens found that cavefish eyes are about seven times smaller than lakefish eyes. F₁ hybrids have eyes of intermediate size. These data, as well as the F₁×F₁ cross and those from backcrosses (F₁×cavefish and F₁×lakefish), are depicted below. Examine Wilkens's results and respond to the following questions: Wilkens examined about 1000 F₂ progeny and estimated that 6–7 genes are involved in determining eye size. Is the sample size adequate to justify this conclusion? Propose an experimental protocol to test the hypothesis.
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Floral traits in plants often play key roles in diversification, in that slight modifications of those traits, if genetically determined, may quickly lead to reproductive restrictions and evolution. Insight into genetic involvement in flower formation is often acquired through selection experiments that expose realized heritability. Lendvai and Levin (2003) conducted a series of artificial selection experiments on flower size (diameter) in Phlox drummondii. Data from their selection experiments are presented in the following table in modified form and content.
In terms of evolutionary potential, is a population with high heritability likely to be favored compared to one with a low realized heritability?
Floral traits in plants often play key roles in diversification, in that slight modifications of those traits, if genetically determined, may quickly lead to reproductive restrictions and evolution. Insight into genetic involvement in flower formation is often acquired through selection experiments that expose realized heritability. Lendvai and Levin (2003) conducted a series of artificial selection experiments on flower size (diameter) in Phlox drummondii. Data from their selection experiments are presented in the following table in modified form and content.
Considering that differences in control values represent year-to-year differences in greenhouse conditions, calculate (in mm) the average response to selection over the three-year period.
Floral traits in plants often play key roles in diversification, in that slight modifications of those traits, if genetically determined, may quickly lead to reproductive restrictions and evolution. Insight into genetic involvement in flower formation is often acquired through selection experiments that expose realized heritability. Lendvai and Levin (2003) conducted a series of artificial selection experiments on flower size (diameter) in Phlox drummondii. Data from their selection experiments are presented in the following table in modified form and content.
Calculate the realized heritability for each year and the overall realized heritability.
In 1988, Horst Wilkens investigated blind cavefish, comparing them with members of a sibling species with normal vision that are found in a lake [Wilkens, H. (1988). Evol. Biol. 25:271–367]. We will call them cavefish and lakefish. Wilkens found that cavefish eyes are about seven times smaller than lakefish eyes. F₁ hybrids have eyes of intermediate size. These data, as well as the F₁×F₁ cross and those from backcrosses (F₁×cavefish and F₁×lakefish), are depicted below. Examine Wilkens's results and respond to the following questions:
Based strictly on the F₁ and F₂ results of Wilkens's initial crosses, what possible explanation concerning the inheritance of eye size seems most feasible?
In 1988, Horst Wilkens investigated blind cavefish, comparing them with members of a sibling species with normal vision that are found in a lake [Wilkens, H. (1988). Evol. Biol. 25:271–367]. We will call them cavefish and lakefish. Wilkens found that cavefish eyes are about seven times smaller than lakefish eyes. F₁ hybrids have eyes of intermediate size. These data, as well as the F₁×F₁ cross and those from backcrosses (F₁×cavefish and F₁×lakefish), are depicted below. Examine Wilkens's results and respond to the following questions:
Based on the results of the F₁ backcross with lakefish, is your explanation supported? Explain.
In 1988, Horst Wilkens investigated blind cavefish, comparing them with members of a sibling species with normal vision that are found in a lake [Wilkens, H. (1988). Evol. Biol. 25:271–367]. We will call them cavefish and lakefish. Wilkens found that cavefish eyes are about seven times smaller than lakefish eyes. F₁ hybrids have eyes of intermediate size. These data, as well as the F₁×F₁ cross and those from backcrosses (F₁×cavefish and F₁×lakefish), are depicted below. Examine Wilkens's results and respond to the following questions:
Based on the results of the F₁ backcross with lakefish, is your explanation supported? Explain.