BIEB 154

Question 1

Non-adaptive convergence that can occur through random drift, genetic constraints or other non-selective mechanisms.

Answer 1

Non adaptive convergence example; salamanders have evolved to have four digit toe numbers with no evidence that the evolutionary reaction was driven by natural selection

Question 2

The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. (pt.1)

Answer 2

Gould and Lewontin use the example of architectural spandrels—these are the triangular spaces formed where two arches meet and support a dome. These spandrels aren’t designed for a specific purpose; they just happen to be there because of how the arches are built. Similarly, they suggest that some traits in organisms might not have evolved because they are directly useful, but instead, they appear as side effects of other evolutionary changes.

Question 3

The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. (pt.2 )

Answer 3

is a trait that did not arise in response to selection for the trait itself. It arose as a side effect of some other evolutionary process such as selection got a different trait.

Question 4

Improbable Destinies Chapter 9, pp. 240-246 Divergent evolution

Answer 4

Mutations within different groups of organisms shape their evolutionary paths. The timing and context of these mutations influence whether they become a permanent part of the population’s genetic makeup. Species in different environments might develop different traits if there are multiple ways to adapt, challenging the idea that they will evolve similar traits (convergent evolution).

Question 5

Researchers have used many different organisms to examine population evolution. They used e coli or three different types of pseudomonas cell types. (pt.1)

Answer 5

The process involved spinning the microorganisms at high speeds, causing larger, denser cells to settle at the bottom faster. Travisano collected these larger cells and used them to start new generations. Over successive generations, he observed a significant increase in cell size, demonstrating how organisms can adapt to extreme environments.

Question 6

Researchers have used many different organisms to examine population evolution. They used e coli or three different types of pseudomonas cell types. (pt.2)

Answer 6

Key Measurements
Growth Rate: Tracking changes in the reproductive rates of the populations over generations.
Fitness: Measuring the reproductive success of different bacterial strains to determine advantageous traits.
Mutation Rates: Assessing the rate at which mutations occur to understand the role of genetic variation.
Genetic Diversity: Analyzing changes in genetic diversity within and between populations over time.

Question 7

Researchers have used many different organisms to examine population evolution. They used e coli or three different types of pseudomonas cell types. (pt.3)

Answer 7

Goals of the Study
Investigate whether yeast can evolve from unicellular to multicellular forms.
Explore fundamental questions about evolution, including:
Rates and mechanisms of adaptation
Role of genetic variation in evolutionary processes
Repeatability of evolutionary outcomes

Question 8

Pleiotropy

Answer 8

Pleiotropy is when a single gene influences multiple phenotypic traits. This can lead to non-adaptive convergence if the gene affects traits in ways that are not necessarily beneficial but are a byproduct of its primary function.

Question 9

Carrol. Four Secrets (pt.1)

Answer 9

Tinkering: modification of existing traits→ new structures are modified versions of older structures. Often, the new structures develop via new generations of existing genes/genetic pathways

Question 10

Modularity

Answer 10

Modularity offers an important mechanism for evolutionary flexibility, where changes in one module can occur without affecting the organism’s overall function but yet, it can still lead to the development of new traits or adaptations

Question 11

Carrol. Four Secrets (pt.2)

Answer 11

Multifunctionality: One structure doing multiple jobs. Examples: Lobster legs, early bird wings, tapir noses.

Question 12

Carrol. Four Secrets (pt.3)

Answer 12

redundancy : Multiple structures all doing one job. Example: pairs of walking legs, fingers/toes, insect segments

Question 13

Carrol. Four Secrets (pt.4)

Answer 13

Modularity: one element of a repeated structure (e.eg. one pair of legs out of many) becomes modified or specialized to do a new job (such as grasping food) while the rest of the structures keep doing the old job (such as walking). Genes can be modular too: entire developmental pathways can be switched on or off.

Question 14

“A partition typology of alternatives to the adaptationist programme” (pt.1)

Answer 14

No adaptation and no Selection at all
Genetic drift can lead to differentiation between population, especially via the founder effect.
Drift can also fix (bring up to 100% frequency) harmful alleles or cause beneficial alleles to be lost, especially if the population is small and/or selection is weak (Ns<=1)

Question 15

“A partition typology of alternatives to the adaptationist programme” (pt.2)

Answer 15

No adaptation and no selection on the part at issue.
Allometry (like the antlers of the Irish Elk)
Selection on one trait (e.g., rapid generations) can cause a change in another trait (e.g. maturing at small size or reproducing as a larva).

Question 16

“A partition typology of alternatives to the adaptationist programme” (pt.3)

Answer 16

a) Selection without adaptation
A trait that increases individual fitness relative to others in the population without increasing the population’s fit to its environment.
b) Adaptation without selection Phenotypic plasticity including physiological and cultural adaptations

Answer 17

Adaptations and selection but no selective basis for differences among adaptations
multi solutions to the same problem, or multiple origins of the same solution. Presumably the resulting difference are due to evolving