Some dinosaurs had small, fluffy feathers called “downy” feathers (similar to down feathers in a pillow), but lacked the type of feathers necessary for flight. These dinosaurs are believed to be the ancestors of modern birds, which have several types of feathers that allow them to fly.  How can we explain the evolution of an “intermediate” trait such as downy feather, if they were functionally useless for flight?

CHOOSE THE BEST ANSWER What molecule is the physical link between the codon in the mRNA and its corresponding amino acid?

Müller’s ratchet is a cost of asexual reproduction and can explain the evolution of sexual reproduction because…

______________ are thought to be a major explanation for rapid macroevolutionary change observed in the fossil record (i.e., patterns of punctuated equilibrium).

In a species of mice, one gene with two incompletely dominant alleles (B, b) influences coat color: BB individuals are blackBb individuals are brownbb individuals are white Researchers studying an isolated population of these mice counted 150 black mice, 100 brown mice, and 250 white mice. Using this information, answer the following questions. What is the frequency of observed genotypes?  What is the frequency of the b allele? Based on their observations, the researcher concluded that the coat color gene in this mouse population…  

Which of the following are required for the evolution of reciprocal altruism? Select two correct answers.

This phylogenetic tree depicts the evolutionary relationships of eight major vertebrate classes.  Tiktaalik is an intermediate fossil that represents an early ancestor of all tetrapods. Specifically, Tiktaalik is known for its wrist, a key feature of the tetrapod limb that made it possible for which major evolutionary transition in animals? If you were to add Tiktaalik to this phylogeny, where would the Tiktaalik branch extend from?

Which statement is true about sexual selection?

Following selection, 80% of individuals with the “AA” genotype survive, all “Aa” individuals survive and 40% of “aa” individuals survive. Their respective relative fitnesses are…

The presence of altruistic behavior in some animals can be explained by kin selection, a theory that maintains that…