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.

Assuming that the realized heritability in phlox is relatively high, what factors might account for such a high response?

Answer the following in regard to multifactorial traits in human twins. If the trait is substantially influenced by genes, would you expect the concordance rate to be higher in MZ twins or higher in DZ twins? Explain your reasoning.

Answer the following in regard to multifactorial traits in human twins. If the trait is produced with little contribution from genetic variation, what would you expect to see if you compared the concordance rates of MZ twins versus DZ twins? Explain your reasoning.

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. 

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.

In terms of evolutionary potential, is a population with high heritability likely to be favored compared to one with a low realized heritability? 

Congenital dislocation of the hip is a threshold condition in which the head of the femur (the femoral head) is out of its normal position relative to the bones that will form the socket of the hip (the acetabulum). This misplacement can lead to potentially serious orthopedic problems later in life if the condition is not treated in infancy. Numerous studies have shown that:

(a) Brothers and sisters of infants born with congenital hip dislocation are more likely to develop the condition than are the siblings of those without the condition. These studies also find that

(b) More female infants than male infants have the trait, and

(c) If the affected child is a girl, the risk to her siblings is lower than if the affected infant is a boy.

Explain the meaning of the three observations (a, b, and c) in the context of proposing a threshold model that explains these observations.