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biology

Terms in this set (20)

Describe Lamarck's mechanism of evolution. Cite a specific example in your explanation.
He thought life must evolve. Right idea but wrong mechanism. He believed individual organisms could change their traits in just one life time in order for their offspring to have a higher success rate. Such as giraffe's long necks evolving in their lifetime to better retrieve higher food sources.
List three different types of animals with unique adaptations that Darwin observed on the Galapagos Islands.
-tortoise - each island had its own distinct variety of tortoise
-finches- beak shapes vary across each island b/c of particular food sources
-marine iguanas developed flattened tails compared to mainland iguanas
What two ideas did the geologist Charles Lyell come up with that resonated with Darwin?
• Earth is very old
• Gradualism the idea that the earth changes very slowly, geologic features such as mountains and river valleys develop over long periods of time
Describe the 3 parts to Darwin's natural selection. Explain how individual variation in populations and a struggle for existence when a population is overproduced lead to changes in populations.
1. Overproduction and struggle for existence - populations have the potential to produce more offspring than the environment can support - limited resources lead to a struggle for existence between individuals
2. Individual Variation - individuals in a population are slightly different, there is variation
3. Survival of the fittest -individuals with traits that are better suited to an environment will have greater success and leave more offspring
Describe adaptation.
Adaptation results from the accumulation of favorable traits for a particular environment over time. An example of this is found in the Marine Iguanas from the Galapagos islands. The Marine Iguanas have adapted flattened tails in order to swim faster underwater. Another example of adaption, (also found in the Galapagos Islands), is the 13 different species of finches that each have different shaped/sized beaks used to consume different types of foods, like cactus fruits or seeds
Darwin used artificial selection as support for natural selection. Describe a specific example of artificial selection and how it supports the idea of natural selection.
Artificial Selection is the selective breeding of plants and animals by humans. Darwin argued that if people can breed dogs to become domestic, these kind of changes can happen naturally over long periods of time.
Why did the population of English Peppered Moth change so dramatically during the industrial revolution in England? How did the variation in color arise?
Pollution from the industrial revolution killed the lichens that the lighter moths used to camouflage, exposing dark and sometimes soot covered bark. The light moths were no longer camouflaged, and the darker moths dominated the species as they were still able to hide from predators by blending in.
Who was Alfred Wallace and what is his connection to Darwin?
Alfred Wallace was a British naturalist who separately came up with the same ideas that Darwin had about evolution and natural selection. They exchanged their findings and information, and soon after published their research together in 1858 where Darwin published On the Origin of Species
Darwin's ideas were influenced by fossils, comparative anatomy, embryology and biogeography. Give examples of each of these areas of study.
Fossils: organisms trapped and preserved such as • Insects in amber, mammoths in ice, bones and teeth from La Brea Tar Pits • Sometimes DNA can be extracted for genetic analysis
Comparative Anatomy:
• Comparing body structures of different species can reveal a common ancestor
• Homologous structures are diversely adapted forms with the same underlying bone structure Ex: human, cat, whale, bat
• Vestigial structures are remnants of features that had a function in ancestors of an organism, but no longer have a function Ex: flightless bird penguin or emu
Embryology: More closely related organisms have similar stages of embryonic development
Biogeography: • Refers to the geographic distribution of plant and animal species • Organisms on the Galapagos Islands are unique, but very similar to mainland organisms • 13 Finch species collected from the Galapagos Islands with different beak
Unfortunately, Darwin did not have access to studies in molecular biology. How do modern scientists use molecular biology to better understand the relatedness of different species?
compare DNA of different organisms and look for homologous DNA sequences
The more similar DNA two organisms have, the more recent their common ancestor
What is sexual selection? Give a specific example.
Sexual selection is a behavorial adaptation.
Sexual selection or (mate choice) based on physical characteristics that represent productive fitness.
Ex: coloration, increased sized, or strike adornments ... such as the male peacock and his feather display
How do individuals in a population have genetic variation?
Random mutation can result in changes in the DNA nucleotide sequence and produce new forms of a gene
Sexual Reproduction - DNA molecules cross-over and recombine in meiosis (more on this later) - this process produces unique combinations of DNA in each sperm/egg cell
Explain how antibiotic resistance in bacteria provides a modern-day example of natural selection.
The overuse and misuse of antibiotics has allowed multi-drug resistance to reproduce. This is an example of natural selection due to a genetic trait they possess which enhances their chances of survival over other bacteria which do not possess these traits.
How does microevolution happen in a population?
There are three mechanisms that can cause microevolution to happen in a population: natural selection, genetic drift, and gene flow. Natural selection leads to adaptation while genetic drift happens by chance.
Describe genetic drift using bottlenecks and founder effects as examples. Know specific examples.
Genetic drift are chance events that cause changes in the allele frequency (an allele is one of multiple versions of a gene) Bottleneck =
Natural disasters like earthquake, flood or fire randomly kill individuals in a population (ex: cheetahs)
Founder effect = When a small population becomes isolated, by chance their gene pool may be different than the parent population (gene disease in small amish village)
Compare allopatric and sympatric speciation. Know examples for each.
• Allopatric - gene flow is blocked by a geographic barrier
Ex: Antelope squirrels on opposite rims of the Grand Canyon can't interbreed
• Sympatric - gene flow is stopped without a geographic barrier
Ex: Very common in plants - go from 2 copies of the genetic material to 4 and no longer be able to breed with the parent population.
Cite examples of prezygotic and postzygotic barriers that prevent closely related species from interbreeding.
• Reproductive barriers (zygote = fertilized egg)
• A prezygotic barrier - prevents mating or fertilization before the sperm fertilizes the egg
Example:
1. Temporal - they mate at different times of year
2. Habitat isolation - they live in two different habitats
3. Behavioral - they have different courtship behavior (birds)
4. Mechanical - they are anatomically incompatible
5. Gamete isolation - species specific molecules on the surface of the egg and sperm don't match and bind together

• A postzygotic barrier - sperm and egg fuse, but development of fertile offspring is prevented
Example:
1. Reduced hybrid viability - offspring are frail and do not live long enough to reproduce
2. Reduced hybrid fertility - offspring is healthy, but sterile (as in the case of the mule)
3. Hybrid breakdown - first hybrid is strong, but the next generation is weak and sterile
Describe Rosemary and Peter Grant's research on Galapagos finches. Include how a drought allowed them to measure natural selection happening in nature. How did the medium ground finch population change? Do the 13 finch species on the islands have a common ancestor? How was this determined? Why do different finch species not interbreed? What type of research did they conduct, discovery or hypothesis-driven or both?
long-term studies demonstrating evolution in action in Galápagos finches
The drought killed off a lot of finches in which they were able to observe/study the evolution through the specimens
After the drought, the medium ground finches that managed to survive had smaller beaks than those that had perished,
Yes all 13 finches have a common ancestor from millions of years ago by studying
They did not interbreed due to different habits such as feeding or nesting
Discovery science
A group of Russian geneticists directed the evolution of tame foxes from a wild fox population. Describe their research. How did they prove that the behavioral changes were genetic rather than learned?
Through selective breeding for 58 generations they domesticated wild foxes
• Selected for a weak "wild-response" the selected foxes were docile around humans
• Cubs wagged tails, whimpered and licked researchers
• Interestingly, selection for tame behavior also changed physical traits including floppy ears, curly tails, and color changes
Experiments
• Scientists implanted domesticated fox embryos into wild female foxes and the pups were born tame
Explain how antibiotic resistance in bacteria provides a modern-day example of natural selection.
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