Evolutionary Biology Quiz

Learning Objectives

• Outline the developments leading to the theory of evolution
• Explain how natural selection causes evolution
• Describe examples of evolution

Evolution

• Evolution is the slow change of species over time.
• A famous quote from Theodosius Dobzhansky: "Nothing in biology makes sense except in the light of evolution."

Antibiotic Resistance

• Antibiotic resistance in bacteria is a consequence of evolution by natural selection.

Natural Selection and Drug Resistance

• Natural selection describes the process where organisms with traits advantageous for survival in a particular environment are more likely to reproduce and pass on those traits to their offspring. Drug resistance arises due to microorganisms with mutations conferring resistance to the drug
• Initial exposure to a drug eliminates the non-resistant microbes. The remaining resistant microbes proliferate. Further drug exposure results in high resistance
• Two specific mechanisms of drug resistance development include drug prematurely termination and immunocompromised host

Artificial Selection

• Artificial selection is a process where humans choose organisms with desired traits to breed to produce offspring with those traits. An example provided is teosinte being bred into corn (maize).

Fitness

• Organisms with traits favorable for survival in a given environment, when competing for resources or avoiding threats, will reproduce more and leave more offspring than organisms lacking these traits
• Higher fitness means more surviving offspring

Fitness and Natural Selection

• Fitness is measured by reproductive success and is thus a relative concept
• Traits are only considered adaptive if they increase fitness

Source of Variation

• Variation in DNA sequences leads to different traits in a population
• Mutations—heritable changes in the DNA sequence—are random events
• Mutations can occur due to errors in DNA replication or exposure to physical, chemical, or biological agents

Natural Selection Is Not Random

• Mutations do not try to supply an organism with what it needs; they're not purposeful or directed.
• Natural selection acts upon these random mutations, determining which traits are advantageous and will be passed on. Nothing about predation, disease resistance, etc. is random.

Evidence of Evolution via Natural Selection

• Island populations often show distinct adaptations to their specific environment conditions, serving as early evidence of natural selection at work. The Galapagos Islands are a prime example.
• Specific examples such as the mockingbird species and the Galapagos finches display examples of adaptation

Descent with Modification

• All organisms are related through descent from common ancestors living in the distant past. This is represented in a branching tree diagram.
• The Galápagos Islands, with their unique species, serve as strong evidence for descent with modification.
• Four mockingbird species display similar characteristics in form but have adapted to different environmental niches

Adaptations

• Species in different environments display different traits; that are inherited characteristics better suited to a specific environment.

Experimental Evolution

• Researchers have conducted experiments to study how populations evolve over time. Generation times of various organisms like bacteria and drosophila contribute as study subjects for evolutionary changes
• The process of evolutionary change in populations can be both fast and slow depending on the rate of mutation and reproduction, and the selection pressures

Transitional Forms in the Fossil Record

• Fossil evidence shows transitional forms in the evolution of species. Fossil records present transitional forms, which include Archaeopteryx, that are intermediate between dinosaurs and birds.
• Birds have paedomorphic dinosaur skulls—meaning their features resemble youthful versions

The Scale of Nature

• Early thinkers like Aristotle, conceptualized a "scale of nature," where organisms are placed in a hierarchy from the simplest to the most complex. The scale implied that life forms were unchanging and created by God.

History of Evolutionary Theory

• Darwin's voyage on the HMS Beagle (1831-1836) profoundly affected his understanding of life's variation.
• Other major thinkers that influenced Darwin's early writings include Cuvier, Lyell, and Malthus.
• Ideas around gradual change in geology (Lyell's uniformitarianism), gradualism in life forms (Hutton) coupled with potential populations exceeding available resources (Malthus) all contributed to the development of Darwin's theory.
• Alfred Russel Wallace independently proposed a similar theory to Darwin's.

Influences on Darwin and Wallace

• Geology, with ideas about gradual changes provided a backdrop for evolution. Cuvier's study of fossils, Hutton's gradualism, and Lyell's idea of consistent geologic rates all influenced this aspect of their theories.

Geographical Distribution

• Biogeographical studies on the similar or widely dispersed species provided evolutionary insights of species distributions over time
• Non-flying mammals were absent from island populations, indicating that evolution is significantly impacted by environmental factors, such as isolation

Morphology

• Similarities in the basic structures of organisms (homologous structures) suggest that they share a common ancestry.
• Vestigial structures, which are seemingly useless body parts, also support the idea of common ancestry.

Lamarck's Theory of Evolution

• Lamarck proposed that organisms could adapt to their environments in their lifetime and pass on those acquired traits to their offspring, implying that simple organisms could evolve into increasingly complex ones

Acquired Characteristics are Not Inherited

• Acquired characteristics, traits developed during an organism's life, are not heritable and have no permanent impact on subsequent generations.

Limitations on Population Growth

• Malthus discussed how populations have the potential for exponential growth, but availability of resources, like food, limit this potential for uncontrolled growth.

Misconceptions about Evolution

• Evolution and natural selection are related but distinct concepts.
• Evolution isn't strictly a gradual, slow process.
• Natural selection acts on individuals; populations change through time.
• Natural selection is not necessarily directional; it acts upon variants within a population rather than a guiding force.

Test your understanding of biological evolution, natural selection, and adaptation. This quiz covers essential concepts such as descent with modification, fitness, and selective pressures. Dive into examples like antibiotic resistance to see evolution in action.