Navigation » List of Schools » California State University, Northridge » Biology » Bio 322 – Evolutionary Biology » Spring 2022 » Quiz 4 Phenotypic Evolution
Below are the questions for the exam with the choices of answers:
Question #1
A Phenotypic plasticity is the same as standing genetic variation.
B The change of a trait from one generation to another (mutation).
C Variation in phenotypes (color, shape, behaviour, etc) that does not require genetic adaptation, as it is a response to the environment.
Question #2
A A situation where one species can adapt to a changing environment, but constraints all other species (Tyrannosaurus rex).
B A geologic feature that does not allow migration of species from one continent to another.
C A situation where a species cannot adapt to changing environmental conditions, due to e.g. a lack of genetic variation (only giraffes with short necks present), trade-offs (can’t become lighter and stronger), or correlated traits.
Question #3
A We can’t: Natural selection is already nature’s best mechanism for survival of a species.
B By putting a handful of endangered animals in a Zoo, or freeze them to preserve some of their genetic material.
C Among many measures, one consideration is to assure the population has a large gene-pool by enabling migrations and relocations to preventing isolation. That increases the standing genetic variation, and perhaps population size.
Question #4
A Standing variation is the variation already present in a population, so there might be many, many indviduals able to survive the new environmental conditions, and their survival assures the survival of their species.
B Standing genetic variation is not promoting evolution, as change is the most important aspect of it (not standing still).
C Standing genetic variation means that all individuals are already pre-adapted to the future and there is no need for further selection.
Question #5
A A small population is more nimble to adapt to quick environmental change, like for example the small polar bear populations.
B Slow change and a large population size allow enough variation and time for new mutations to occur, and also not enough time for beneficial alleles to spread in the population through many generations.
C Only the speed of the environmental change matters, no other factors such as population size.
Question #6
A They are al different components of fitness.
B They all describe allele frequncies.
C They all describe imminent extinction.
Question #7
A If there is no change, there is no selection acting upon that trait.
B There would be either directional or disruptive selection acting on the populations.
C In that case differential selection occurs.
Question #8
A The convergence upon a specific phentoypic trait value is characteristic for stabilizing selection.
B This would be typical for reverse selection.
C Whenever individuals in a population die, we speak of disruptive selection
Question #9
A Unnatural selection as small individuals usually have the best survival.
B Galapagos selection, as this phenomenon is not found elsewhere.
C Directional selection towards larger beak size
Question #10
A True, but in reality there are often several additive alleles that create further variation, and most of all: environmental variance can smooth out the distribution, so many in-between body sizes are found in the population (with varying frequencies).
B That’s a theoretical assumption, but in nature there are always 4 pairs of alleles that code each phenotypic trait. This is a safeguard against mutations, as a mutation will not have any effect on the phenotype this way.
C Yes, that is the universal rule, if one gene locus determines a phenotypic trait, then there are no “In-between” sizes.