1. A dachshund is a type of dog with short stature. Beagles are normal-sized. The progeny of a
dachshund/beagle mating are all short-statured. Half of the puppies that are produced with the
beagle/dachshund progeny when mated with a beagle have short legs; the other half are normal
sized. What does this tell you about short stature?
a. There is a complex non-mendelian mode of inheritance for short stature in dachshund.
b. Short stature is a recessive trait
c. Normal stature is a dominant trait
d. Short stature is a dominant trait

The correct answer is b. Short stature is a recessive trait. In this classic Mendelian genetics problem, the dachshund (short-statured, homozygous recessive dd) crossed with a beagle (normal-statured, homozygous dominant DD) produces all heterozygous (Dd) progeny that express short stature, indicating the trait skips the dominant phenotype despite heterozygosity—no, wait, let’s correct the logic step-by-step. Actually, re-reading: all F1 progeny are short, so short (let’s denote as S) must be dominant over normal (s), but then the backcross gives 1:1, fitting dominant. But hold—standard analysis shows inconsistency unless recessive. True parse: progeny all short means dachshund carries dominant short allele? No: if short dominant, dachshund SS or Ss, beagle ss, F1 all S-, short; then F1 (Ss) x beagle (ss) gives 1/2 Ss short, 1/2 ss normal—yes, matches exactly. But sources confirm dachshund short legs are dominant (chondrodysplasia/CDPA), yet question phrasing tests recessive logic inversely? No, data fits c. Normal stature is a dominant trait actually? Let’s clarify fully below.​

Problem Breakdown

Dachshund (short) × beagle (normal) → all short F1 progeny. Then F1 (dachshund/beagle, short) × beagle (normal) → 50% short, 50% normal. This 1:1 backcross ratio with all F1 affected indicates short stature is dominant (dachshund likely homozygous dominant SS, beagle homozygous recessive ss; F1 all Ss short; F1 Ss × ss beagle → 50% Ss short, 50% ss normal). Real genetics: dachshund short legs from FGF4 retrogene (CDDY/CDPA), inherited dominantly or semi-dominantly, supporting selective breeding for phenotype. For CSIR NET Life Sciences, recognize testcross pattern confirming single locus dominance.​

Option Analysis

• a. There is a complex non-mendelian mode of inheritance for short stature in dachshund: Incorrect; ratios (100% F1 short, 50:50 backcross) fit simple Mendelian dominance, not polygenic/epistasis/mitochondrial.​

• b. Short stature is a recessive trait: Incorrect; recessive would yield all F1 normal (from short dd × normal DD → Dd normal), contradicting observed all short F1.​

• c. Normal stature is a dominant trait: Partially true inversely, but question focuses on short; if normal dominant, F1 all normal expected—not matching data.​

• d. Short stature is a dominant trait: Correct; fits Punnett squares perfectly, as heterozygous F1 express short, half progeny do too.​

Genetics in Dog Breeding

Short stature (chondrodysplasia) in dachshunds arises from FGF4 retrogene insertions (CFA12/CFA18), dominant for leg shortening and IVDD risk—homozygotes shorter. Beagles typically lack this (normal ss), so crosses reveal inheritance.