Unit 4 Test Flashcards
Describe struggle for existence.
The competition for resources needed to survive
Other than direct observation, what are other pieces of evidence supporting evolution?
Fossil evidence, homologous structures, analogous structures, biogeography, early embryonic similarities
What are homologous structures? Give an example.
Structures on related organisms but have different purposes (hand of a human, wing of bat, flipper of a whale)
What are analogous structures? Give an example.
Structures on unrelated organisms that have the same function (wing on bee, wing on bird)
What is convergent evolution? Give an example.
Organisms that are not related in two different areas of the world, but areas have similar conditions so will evolve the same
Divergent Evolution
Organisms that start as one species and become more dissimilar over time
What are the 3 ways that reproductive isolation happens? For each, define and give an example.
Behavioral (differences in courtship behavior)
Geographical (river/mountain separating them)
Temporal (orchids bloom at different times)
Define gene pool.
The sum of all the genes and their alleles in a population
What does allele frequency mean?
How common an allele is in a population
Differentiate between single gene traits and polygenic traits and give an example of each.
Single Gene Traits
-Polygenic Traits
-One gene
-Two distinct phenotypes
-EX: Bands or no bands on snails
Polygenic Traits
Two or more genes
Many possible phenotypes and genotypes
EX: human height
Define phylogeny.
The representation of the evolutionary history and relationships between groups of organisms.
What is a clade?
A group of organisms that consists of a common ancestor and all of its descendants.
Why were Darwin’s ideas so controversial at the time?
It threatened the views of the church and showed that the earth was more than a few thousand years old
Why do we study Lamarck’s ideas if they are flawed?
He got people to consider that living things can change
What are vestigial organs? Give 3 examples (what they used to do and why we don’t need them anymore). Why do we still have vestigial organs today if they are not useful anymore?
Organs that have no apparent function and are considered to be the residual parts from past ancestors but do not affect our fitness (wisdom teeth; helped grind food but we don’t need them anymore, appendix; helped digest cellulose but we don’t need to digest cellulose anymore, nictitating membrane; third eyelid found in a few animals that protect and keep the eyes moist and also helps in vision. In humans, it is replaced by plica semilunaris.
What did James Hutton propose? What did Charles Lyell propose?
James Hutton proposed the idea that Earth has slowly been shaped by geologic processes over a very long time (deep time) and it must be millions of years old
Charles Lyell proposed that the same processes that have shaped the Earth in the past are still continuing today (erosion, volcanic eruptions), and Earth must be really old if life has changed so much over time
- Describe AND give an example of each of Jean Baptiste Lamarck’s 3 hypotheses about how and why organisms evolve.
Use and Disuse: body parts used a lot to live in an environment will become stronger over time and those not used will deteriorate until they are no longer there
- Ex: birds used front limbs to fly, so they turned into wings. Other winged animals no longer used the wings so they eventually disappeared
Inheritance of Acquired Traits: modifications that an organism acquires during its life can be passed onto offspring
- Ex: a giraffe’s neck elongates over time from stretching, so the necks will naturally be longer and longer through the generations
Tendency toward perfection: all organisms have an inborn tendency towards perfection, so they are constantly developing features that help them be more successful
- Ex: birds had the urge to fly, so over generations their wings got bigger and better for flying
Describe how 13 different species of finches throughout the Galapagos Islands are distributed from a common ancestry in mainland South America. Hint: There are five steps
- Founders arrive
- Geographic isolation
- Changes in the gene pools
- Reproductive (behavioral) isolation
- Continued evolution produces more species
- What are the 3 sources of genetic variation, and for each a) define, and b) give an example
Mutations: a heritable change in the DNA sequence, most have no effect on phenotypes, but when they do, it can affect fitness/survival
Some mutations may lower fitness, and some may result in important adaptations
If they are passed to offspring they must occur in gametes, not somatic cells
- Ex:
Genetic recombination: crossing over can produce genetic recombination, which results in new genotypes
Ex: DNA crossing over during meiosis 1
Lateral gene transfer: when genes pass from individual to another individual that are NOT parent and offspring
Can occur between organisms of the same species or different species
Can increase genetic variation and increase diversity
LGT among single cell organisms is common
Ex: conjugation between bacteria
Miscellaneous: the # of phenotypes that is produced for a particular trait depends on how many genes control that trait
