| Question 1 |
Inbreeding leads to:
Increased homozygosity.
Increased expression of recessive traits.
Decreased expression of dominant traits.
Increased heterozygosity.
| Question 2 |
An allele:
Is one of possibly many variations of a gene.
Can be recessive.
Can be dominant.
Is a synonym of “gene.”
| Question 3 |
A gene:
Is a unit of heredity that is transferred from parent to offspring.
Controls the transmission and expression of one or more traits.
Can code for multiple and otherwise unrelated phenotypic effects.
Codes only for a single discernible phenotypic effect.
Can be dominant or recessive.
| Question 4 |
If an individual has inherited the same allele for a gene from both parents, they are said to be:
Homozygous.
Hemizygous, Nullizygous, Allozygous, Heterozygous.
| Question 5 |
Phenotype refers to:
The set of observable characteristics of an individual.
The morphology, behavior, and development of an individual.
The genetic makeup of an individual.
Both expressed and unexpressed genetic variation.
| Question 6 |
Which of the following trait types can “breed true?” To “breed true” means that two organisms with a particular heritable phenotype produce only offspring with that same phenotype.
Recessive traits. (e.g. brown coloring, rough coats, tri-color, etc.)
Dominant traits. (e.g. black coloring, smooth coats, etc.)
Heterozygous Semi-Dominant traits. (e.g. Merle, Bobtail, Chinese Crested Hairless, German Shepherd Panda, etc.)
Heterozygous Co-Dominant traits. (e.g. AB blood type, red-white Roan in horses, etc.)
| Question 7 |
What mode of inheritance do the following traits have in common: Merle, Bobtail, Harlequin, Panda (German Shepherds), Hairlessness (Xolo, Chinese Crested, etc.) ?
They are Lethal. Lethal genes are capable of causing death.
They are all semi-dominant. When the heterozygote has a different, intermediate phenotype compared to the homozygous dominant or homozygous recessive individuals, it is said to be “semi-dominant.”
They are all recessive.
They are all dominant.
They are sex-linked.
They are all co-dominant.
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Q1. Mathematically, I’d think that increasing expression of recessive traits requires decreased expression of dominants. Eg, with Labs, more yellow and/or chocolates = fewer blacks.
Jen – You’re absolutely right. An error on my part. Inbreeding doesn’t change allele frequencies, it changes hetero/homozygosity, pushing like-with-like and thus the recessive alleles are increasingly uncovered by dominant alleles and thus recessive traits increase in expression. Likewise, dominant alleles move from being expressed in heterozygotes to being redundant in homozygotes, and thus we see less expression of dominants. Extra credit for you. 🙂
Yet agree as we all view old theory such as a merle is a merle isn’t it. As the math does not add up.
If you recognize the theory versus scientific fact in breeding sable collies being adopted in collies as well in my personal studies and supported by yet another old Dr. theories eext in my breed.
It seems that all breeds divisions and arguments center in old theory as Little’s postulations being proven not substainted by current breeding or old color charts. Kathy
Chris indeed like the Border Collie many pure bred breeds suffered. Collie breeders of England wanted to get their best out of harm’s way to the safety of America. So therefore, during that period some of the best quality collies arrived in North America.
Invasions dating back to the Vikings, and the Romans likewise affected the herding breeds of England, Scotland and Ireland.
The Akita color breeding program in Japan changed to only red and white after the War with Japan.
Much excitement and pride of country when they were able to reveal their National Dog in red and white to match their Nation’s flag colors. It seems the foundations of the Akita in North America came prior to the war with Japan. I read where Helen Keller brought back an Akita from Japan.
Our military personnel returning from these wars with pure bred breeds of dogs was another portion of impact of North American canines. Kathy Bittorf
Chris: I reviewed earlier replies before you opened the discussion with the answers. The clicker trainer asked a question about the brown. You gave an excellent answer. Likewise there was a reply from a Lab person. Having come from Lab country this first took my interest due to friendships in dogs. Easy genetics study the Lab.
The history in U.S. is quite different as far as I have read. Smoky black, and charocoal black was not the practice of those who used this breed as a water dog.
The fashion for yellow labs began the problem for conservative breeders. Then was the chocolate lab. Now they have another recessive to cope that gives them smoky black and charcoal. The AKC agreed to registered this pattern under Chocolate.
Well arguments arose and verbal assaults arose well this is dilute chocolate. Hope this helps my many Lab friends out there. Kathy