You want to determine whether short wings in fruit flies are the result of a dominant or recessive mutation. You cross a short-w
inged fly stock with a long-winged fly stock (which is considered to be wild type or / ). The progeny have a 1:1 ratio of short to long wings. You then allow the F1 short-winged flies to mate. The F2 progeny have a phenotypic ratio of 3:1 short to long wings. Short wings are likely the result of:
A monohybrid testcross is a cross-breeding experiment used to determine if an individual exhibiting a dominant phenotype is homo-zygous dominant or heterozygous for a particular phenotypic trait (in this case, wing length). In a monohybrid testcross, a 1:1 phenotypic ratio shows that the dominant parental phenotype was a heterozygote for a single gene that has complete dominance. Moreover, a 3:1 ratio in the F2 is expected of a cross between heterozygous F1 individuals, which means that 75% of individuals with short wings have the dominant allele that masks the expression of the long-wing trait (i.e. the recessive allele).
Competition is an interaction between organisms or species in which both the organisms or species are harmed. Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.
