Exam 3 Flashcards
Biological Evolution
Change in the characteristics of a population of organisms that occurs over the course of generations
Species
A group of individuals that regularly breed together and are generally distinct from other species in appearance or behavior
Population
Subgroup of a species that is somewhat independent from other groups
Natural selection
Process by which individuals with certain traits have greater survival and reproduction than individuals who lack these traits, resulting in an increase in the frequency of successful alleles and a decrease in the frequency of unsuccessful ones
Scientific theory
Body of scientifically accepted general principles that explain natural phenomena
Theory of evolution
Theory that all organisms on Earth today are descendants of a single ancestor that arose in the distant past
Common descent
The theory that all living organisms on Earth descended from a single common ancestor that appeared in the distant past
Homology
Similarity in characteristics as a result of common ancestry
Homologous structures
Structures that are so similar that they imply a common ancestor
Analogous structures
Features that serve a similar function but are derived from different ancestors
Example: bee wing and bat wing
Anatomical homology
Anatomical parts are considered to be homologous when they are evolutionarily derived from a single feature in a common ancestor
Example: the same bones in a human’s arm, a cat’s paw, a whale’s fin, and a bat’s wing
Developmental Homology
a comparison between the embryos of different species
Fossils
Remains of plants or animals that once existed, left in soil or rock
Fossil Record
Physical evidence left by organisms that existed in the past
Vestigial Traits
Structures that have no apparent function and appear to be residual parts from a past ancestor are called vestigial structures. Examples of vestigial structures include the human appendix, the pelvic bone of a snake, and the wings of flightless birds.
Traits would not exist unless the organism’s ancestors possessed them; this is strong evidence of common ancestry and change over time
Suboptimal Structures
our knees and spine were not originally meant for walking upright
our respiratory system crosses our digestive system which can cause choking
evolution can only modify existing structures and functions
organisms “make do” with suboptimal designs
Biogeography
The study of the geographic distribution of organisms
Radiometric dating
Technique that relies on radioactive decay to estimate a fossil’s age
Explain the process of evolution by natural selection
natural selection is the mechanism that drives evolution; individuals best suited to the environment survive and produce more offspring, driving change over time
Summarize and explain the evidence supporting the theory of evolution
vestigial traits: traits that are reduced or rudimentary compared to the same traits in an organism’s ancestors or relatives
anatomical homology: same bones in different species - homologous structures derived from a common ancestor
biogeography: organisms in different environments in similar geographic areas are often alike because populations migrate and adapt to new environments but resemble their ancestors
developmental homology: comparative embryology - the comparison of early stages of animal development reveals many similarities between organisms indicating common ancestry
suboptimal structures: evolution can only modify existing structures and functions
molecular homology: primate chromosome composition is quite similar; chimps/gorillas/orangutans have 24 pairs of chromosomes, humans have 23 pairs
also…. the genetic code is essentially universal, suggesting all species descended from a common ancestor
Compare evolution to alternative hypotheses for life’s origin and diversity
Common Descent: species do change over time, and new species can arise. all species derive from a common ancestor
Supported by a wide variety of evidence
Static Model: species arise separately and do not change over time
Rejected; earth is far older than 10,000 years and earth has clearly changed over time
Transformation: species arise separately and change over time in order to adapt to the changing environment
Rejected; evidence of relationships among organisms abound
Separate Types: species change over time, and new species can arise, but not from a common ancestor. each group of species derives from a separate ancestor that arose independently
Rejected; universality of DNA, genetic code, and cell components are evidence of a single origin of life
Tuberculosis
Degenerative lung disease caused by infection with the bacterium Mycobacterium tuberculosis; destroys the lungs ability to provide oxygen to the bdody
Antibiotic-resistant
Characteristic of certain bacteria; a physiological characteristic that permits them to survive in the presence of particular antibiotics
Antibiotics
A chemical that kills or disables bacteria
Fitness
Relative survival and reproduction of one variant compared with others in the same population
Combination Drug Therapy
The use of more than one drug simultaneously to treat a disease. Often used for disease organisms that mutate quickly or are difficult to control to combat the problem of drug resistance
Adaptations
Trait that is favored by natural selection and increases an individual’s fitness in a particular environment
Explain how drug resistant strains of tuberculosis have evolved
spontaneous gene mutations in M. tuberculosis that render the bacteria resistant to the most commonly used anti-TB drugs
evolution of drug-resistant M.tb depends on bacterial fitness, strain’s genetic background and its capacity to adapt to the surrounding environment
Explain the relationship between natural selection and genetics (the modern synthesis)
random gene mutations produce variation
natural selection acts on that variation
ultimately, natural selection acts on the genes
List the four observations that lead to the inference of natural selection
1) individuals within populations vary
2) some variation can be passed on to offspring
3) populations overproduce
4) survival and reproduction are not random
What are the misconceptions about natural selection?
individuals cannot evolve
you can’t evolve on purpose
natural selection does not produce “perfect” organisms
natural selection does not have a goal
Summarize the relationship between natural selection and drug resistance in disease-causing microbes
using one type of drug for too short of a time period selects for antibiotic resistant bacteria
by using combination drug therapy, bacteria are very unlikely to be resistant to multiple drugs, therefore stopping drug resistance
Spatial isolation
A mechanism for reproductive isolation that depends on the geographic separation of populations