Question

A fish breeder wishes to develop a silver goldfish. She starts with a diverse mixture of fish, some more silver than others. Generation after generation, she allows only the most silver fish to breed. After 30 years of work she has a new breed of fish with interesting traits, but on average, the fish are no more silvery than other goldfish. Which of the following would be a logical explanation for her failure? There is no variation for the trait (silver coloration). Silver coloration is an environmentally-determined trait. The selection was artificial, not natural, so it did not produce evolutionary change. There was no selection (differential reproductive success) related to silver coloration. The breeder accidentally picked less silver fish when she meant to pick more silver fish.

Answer 1

The answer to the first question should be "There is no variation for the trait" because as far as my knowledge on Goldfishes go, they start off silver gray, turn black, then slowly fade to a light yellow before their color deepens to orange or red, sometimes with patches of white. Metallic Goldfish can start changing color within 3 months of hatching.

Individual features of all organisms are the result of "genetics and the environment"

The first stage during embryonic development is "cleavage". It is actually fertilization but since that is not an option we will have to go with cleavage.

During gastrulation, "A hollow blastula is changed into a hollow embryo that has three tissue layers."