Evolution Unit Test Review Flashcards
REVIEW QUESTIONS
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Evidence of Change: explain embryology, fossil record, vestigial organs, and homologous structures. How do they contribute to the theory of Evolution?
Embryology: is the branch of biology concerned with the study of embryos and their development. This demonstrates the evidence of evolution because some homologous structures can only be seen in embryo development. Example: all vertebrate animals - from humans to fish to chickens - have a tail during development that does not appear in the fully-grown organism.
Fossil Record: history of life as documented by fossils.
Examples: Bones, shells, exoskeletons. This proves evolution has happened and also proves the extinction of some species. Also, some current species are similar but not the same as previous ones from the past, which illustrates the change over time. They also contain transitional fossils. They show the intermediate anatomy between earlier and late forms. Example from the textbook: North American horses, their fossils, and _________________.
Vestigial Organs: structures with no apparent use and seem to be residual (leftover- think residue) parts from an ancestor. Examples: human appendix, wings in flightless birds, snake pelvic bone. This (also) proves change has occurred in the organism.
Homologous Structures: Anatomically similar but have different functions. Examples: flipper of a whale vs the wing of a bird. Homologous structures provide evidence of common ancestors.
Discuss the three assumptions made by Lamarck and why they are not accepted today. How is the Darwin-Wallace theory different from what Lamarck said?
Lamarck’s assumptions:
a) a desire or need to change
b) the law of use or disuse
c) law of inheritance of acquired traits
His theory is not accepted today because…
The Darwin-Wallace theory is different from Lamarck’s theory because Lamarck thought organisms changed out of need or desire, whereas Darwin thought they changed by natural selection (trait variation).
Explain the requirements for natural selection and how natural selection changes populations over time.
The four conditions of natural selection are:
a) VARIATION (of traits in organisms in populations)
b) INHERITANCE (the passing on of traits from parent to offspring)
c) SURVIVAL OF THE FITTEST (more offspring are produced than are able to survive; resources for survival and reproduction are limited so there’s competition.)
d) TIME (allows changes to happen)
Over time, the individuals with the characteristics that allow them to best compete for resources and mates will survive. Since traits are passed down/inherited from parent to offspring, the next generation will get the same favorable traits, as well as the following, etc.
Discuss the three different kinds of selection: directional, stabilizing and disruptive
Directional Selection: Gradual elimination of one phenotype in favor of another. Example: woodpeckers who can peck holes into tree bark to reach the insects living inside are favored and continues to live, whereas the woodpeckers who cannot reach the insects are eventually eliminated.
Stabilizing Selection: the extremes of the population are both eliminated. Example: spiders in a population that are small, average, and large. Small spiders cannot find food and large spiders might find it hard to hide from predators. The average-sized spider will survive, whereas those on the extremes will die.
Disruptive Selection: Two forms in the middle are gone, forming divergent gene pools.
Example: Imagine a scenario where there are green stick bugs, brown stick bugs, and stick bugs with a mixture of both colors. Green ones can hide in leaves and brown ones can hide on twigs. They are both able to successfully hide. The bugs with both colors will not survive as they cannot blend in, thus will be eaten by predators.
Explain speciation and the different types with your own examples. What key words will you use?
Speciation: the formation of new and distinct species in the course of evolution. There are two kinds of speciation: sympatric and allopatric.
Sympatric: they can meet but cannot mate. Example: female apple maggot flies lay their eggs inside apples. The larvae will then grow up and tunnel through the rotting flesh. However, before apples came to this location, there were hawthorn fruit and hawthorn fruit maggots (which did the same thing to the hawthorn as the apple flies will later do to the apples), which later infected the apples. When the apples arrived, some of the flies chose the apples. Now they are two separate species and cannot mate even if they wanted to (they can still meet/encounter each other).
Allopatric: physically separated from one another and cannot reproduce. Example: a species of salamanders in the US was separated by the Rocky Mountains; one side was humid and the other was a desert. They grew to become two separate species and even if one day, salamanders from one side crossed over to the other, they wouldn’t be able to mate.
Keywords Used:
- Mating
- Separation
- Dispersal (separation of a small group)
- Vicariance (natural and physical separation)
Sexual/Mate Selection (Courtship of animals)
Sexual Selection definition: The process by which individuals compete for access to mates and fertilization opportunities
Courting definition: behavior that results in mating and eventual reproduction.
Examples of animal courting behavior include:
- Dancing
- Singing
Difference between intersexual and intrasexual
what are their respective definitions and how are they different?
intersexual: involves competition between individuals of different sexes (ex: male v. male fighting for a female)
intrasexual: involves competition within a single sex. (ex: individuals of the same sex compete against one another to find a mate)
Differentiate among convergent evolution, divergent evolution and speciation. Give examples.
Convergent evolution: Different organisms independently develop similar traits and produces analogous structures (features of different species similar in function but not necessarily in structure and do not derive from a common ancestral feature). Example: bat vs. insect wings.
Divergent evolution: also known as adaptive radiation, is when a population of organisms is split into two distinctive groups. Also gives rise to homologous traits (similar traits in different organisms due to a common ancestor). Example: elephant vs. wooly mammoth.
Speciation: the formation of new and distinct species in the course of evolution. Two kinds: sympatric and allopatric.
Sympatric: no geographical nor physical barriers to prevent mating; all individuals are close in proximity to one another.
Allopatric: the opposite of sympatric; there is a barrier (like mountains) that prevents mating from happening.
(sympatric and allopatric are reproductively isolated.)
What is genetic drift and how is it different from natural selection? Why does it happen?
Both genetic drift and natural selection are evolutionary mechanisms (both change allele frequencies over time).
Genetic drift: the change in allele frequency due to random chance. There is no “better-prepared” individual, it is completely by chance. Example: A population of ants of different colors is on the sidewalk. Some of each color is crushed by a passing scooter.
Natural selection is NON-RANDOM and allele frequencies change by differential reproductive success, whereas genetic drift IS random and happens by chance.
Genetic drift occurs when there is a bottlenecking event on the population (like the scooter crushing the ants). Natural selection happens over a long time and favors certain traits over others.
Compare the gradual change model with the punctuated equilibrium model of evolution.
Gradual change model (think ladybugs, size and # of dots example): illustrates that change in a population is gradual, and happens slowly and steadily over time.
The punctuated equilibrium model of evolution discusses patterns of long stable periods interrupted by brief changes.
In gradual speciation, species diverge eventually over time in small steps. In the punctuated equilibrium theory, a new species changes quickly from the parent species and then remains largely unchanged for long periods of time afterward.
Explain the role of DNA in evolution (how it affects the organism; think bee activity).
The DNA of an organism can affect everything about it: looks, behavior, and physiology. Sometimes there is a beneficial mutation that causes a change in the individual and gets passed on to/is inherited by the offspring. This positive change is necessary in order for the evolutionary process to happen.
Explain the 5 agents of evolutionary change: mutation, genetic drift, gene flow, non-random mating and natural selection.
Mutation: the source of all genetic variation.
Genetic Drift: is the changing of allele frequencies due to an event that was 100% by chance.
Example: a colony of ants of different colors was on the road when a car drove by and crushed some. Allele frequencies were then altered.
NOTE: affects smaller populations more than it does larger populations; the individuals affected are not equipped for better or worse. It was purely chance.
Gene Flow: involves the movement of genes in or out of a population due to either the mvt of individual organisms or their gametes. Alleles brought into the gene pool can be already existent or new, but they come in different proportions. (CAN BE A STRONG AGENT IN EVOLUTION!!)
Non-Random Mating: Essentially mating with standards; organisms may prefer to mate with others of the same or different genotype. (Non-random mating will NOT create allele frequency change in the population alone.)
NOTE: offspring produced from non-random mating has the traits from both parents, so it’ll “push forward” evolution and favorable traits.
Natural Selection: happens when one or a combination of alleles increases or decreases the fitness level of an organism in a given environment. Should an allele reduce fitness, its frequency tends to drop in the coming/following generations.
TERMS
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Evolution
A process that results in changes in the genetic material of a population. It is the process by which different kinds of organisms are thought to have developed and diversified from their earlier forms during the history of the Earth.
Fitness
Reproductive success, also how well-adapted an organism is to its environment.
How well an organism is able to reproduce and survive in its environment. (?)
Common Descent
An effect of speciation in which multiple species are derived from one ancestral POPULATION.
Two or more species are derived from the same ancestor/ancestral population. (?)
Adaptation
The process of change that adapts an organism better to its environment.
A feature an organism has developed in order to better fit in with its environment/survive. (?)
Fossils
The preserved remains of an organism.
DNA
Short for deoxyribonucleic acid, it is the blueprint of life and codes for an organism’s traits, such as eye color.
Polymer of nucleotides that constitutes the genetic material of most organisms. DNA controls the features of cells (and therefore entire organisms) by containing the chemical recipes for all the proteins the cells produce.
RNA
Short for ribonucleic acid; is the product of DNA transcription. mRNA (messenger RNA) transports genetic message from the nucleus to the ribosomes for the making of protein.
