Darwin Flashcards
What were the two major points that Darwin made in his published “The Origin of Species by Means of Natural Selection”? What did the book focus on in general?
Focused on the great diversity of organisms.
- Many current species are descendants of ancestral species.
- Natural selection is a mechanism for this evolutionary process.
When was Darwins book published?
1859
How did aristotle view species?
As fixed and unchanging.
How does the old testament view species?
They were individually designed by god and are therefore perfect.
How did Carolus Linnaeus view species? What was Linnaeus the founder of?
Viewed organismal adaptations as evidence that the creator designed each species for a specific purpose.
Founded taxonomy, the branch of biology concerned with classifying organisms.
Was the origin of species controversial for its time?
YES, it challenged a worldwide view that was prevalent for centuries.
What helped to lay the groundwork for Darwins ideas?
Fossils.
What are fossils?
traces of organisms from the past, usually found in seimentary rock. This sedimentary rock appears in layers called STRATA.
Are the strata layers that are closer to the top younger or older?
younger.
What is paleontology? Who developed this?
The study of fossils.
Georges Cuvier
Cuvier did not believe in evolution, he believed that species are unchanging. So how did he explain the difference from current species that was found in older strata as well as the occurrence of new species observed between one layer and the next layer of the strata?
Catastrophism - each boundary between strata represents a catastrophe that destroyed many of the living species in that area.
This explains the existence of the fossil record.
What is gradualism? Who proposed this?
This is the idea that profound change can take place through the cumulative effect of a slow but continuous process.
James Hutton - proposed that changes in the earths surface can result from slow continuous actions.
What is uniformitarianism? Who proposed this?
This is the belief that mechanisms of change are constant over time.
Suggested that mechanisms of gradualism are still at work today and that they are constant over time.
Charles Lyell
Did the views of gradualism and uniformitarianism influence Darwins thinking? How?
YES
He took these views of gradual change to the earths surface that is slow and continuous and asked, does this occur in organisms as well?
What was Lamarcks theory of evolution? Did this have evidence?
Species evolve through:
- Use and disuse - used parts of body are made larger and stronger, while parts that are not used deteriorate.
- Inhertiance of acquired characteristics - these modifications from use and disuse were passed to offspring.
This mechanism was not backed by evidence.
During Darwins time of the Beagle, what did he do?
He gathered specimens of south american plants and animals and observed that they all have adaptations that allowed their survival in their specific environment.
Where did Darwins interest in geographic distribution of species increase?
During his stop at the Galapagos islands near the equator of south america.
What did Darwins observations make clear to him?
Adaptation to environment and the origin of new species were closely related.
Why did Darwin not publish his essay when he first made his findings? What made him finally publish it?
In 1844 Darwin wrote the essay but didnt want to introduce it to the public because he didn;t want to cause an uproar
But in 1858 he received a manuscript from Alfred Russel Wallace who had written about a similar theory.
Darwin then quickly finished and published his Origin of Species papaer the next year.
What were the two main ideas Darwin developed?
- Evolution explains lifes unity and diversity, many current species are descendants of common ancestors.
- Natural selection is a cause of adaptive evolution.
What is meant by the phrase “descent with modification that summarized Darwins percetion of unity of life?
This refers to the view that all organisms are related through descent from an ancestor that lived in the remote past.
The history of life is like a tree with branches that represent lifes diversity.
What is artificial selection? What was the example talked about in lecture?
Modification of species over many generations by selecting and breeding them for their desired traits.
From the same wild mustard species, multiple different species of vegetable we eat today have risen.
What may happens over time between an organism and its environment when it undergoes natural selection? What would happen if the environment changes or the individual moves to a new environment?
Natural selection increases the match between the organism and its environment over time.
If the environment changes or the individual moves to a new environment natural selection may result in adaptations to the new conditions over time, even sometimes giving rise to a new species in the process.
Do most novel biological structures evolve immediately? What is an example?
No, its usually in many stages and from preexisting structures.
The eye has slowly evolved to where it is now, but has had similar function throughout its evolution. Like in the bivalve, their equivalent eye structure doesnt really see, but it detects changes in light intensity.
Describe John Endlers experiments with the guppies and their coloring along with predation. What two evolutionary forces were at play with this experiment? What were his findings?
- Bright colors of males made females prefer them for reproduction.
- Bright color of males made them more vulnerable to predation.
Guppies in pools with fewer predators had a higher population of brightly colored males.
Brightly colored males were transferred to a pool with many more predators and the population became less colored over time.
He also took drab colored guppies from a pool with many predators to a pool with less predators and over time the population became more brightly colored.
Describe the example given in class of the evolution of drug-resistant HIV infection. How did this arise? How do we combat this?
Before HIV was introduced to drugs to combat it, the strain that was resistant to the drug (3TC) werent considered more fit and therefore were not more prevalent, though they did exist.
Once the drug (3TC) was introduced, as the non-resistant virus was killed off the resistant strain that was able to recognize the drug bearing and normal C bearing nucleotide, was able to thrive and become the dominant strain.
This is why we treat HIV with multiple drugs to prevent resistant strains from arising.
Describe the fossil record and how it gives evidence of natural selection.
Darwinian views that evolutionary transitions should be evident in the fossil record.
These transitions have been found in fossils by paleontologists.
What is a vestigial structure?
Remnants of features that served functions in the organisms ancestors.
What are homologous structures?
Characteristics that are shared by related species due to inheritance from a common ancestor
Can we find homology that only exists in embryos?
YES
For example, both humans and chickens are part of the chordata phylum, but both only have post-anal tails when in the embryonic stage.
How are anatomical similarities between species generally reflected?
Their molecules, genes, and gene products.
What is an evolutionary tree? What data is used to make these?
A hypothesis about the relationships among different groups.
Multiple types of data, anatomical and DNA for example.
What is convergent evolution? How do these arise? Does this provide information about ancestry?
The evolution of similar, or analogous, features in distantly related groups.
These arise when groups independently adapt to similar environments in similar ways.
DOES NOT PROVIDE INFORMATION ABOUT ANCESTRY, TYPE OF ANALOGY
Do important geological processes occur at tectonic plate boundaries?
YES
What is pangea? Give an example of how it coming together and spreading apart changed the distribution of eutherians and marsupials.
This was the supercontinent that formed when previously separated continents were brought together
It was thought that marsupials inhabited inhabited what is now asai but traveled to australia when pangea was formed. Then when it spread the marsupials were separated into Australia and the marsupials thrived while the eutherians did not, and the opposite happened in all the other countries.
What is a mass extinction? What are the two that we need to know for class?
This happens when the global environment changes so rapidly and is so disruptive that a majority of species are killed off.
- Permian - the formation of pangea, a time of extreme volcanism. killed 96% of marine animals and 8 of 27 orders of insects.
- Cretaceous - large asteroid struck earth (evidenced by Chicxulub crater), killed off most of the dinosaurs except for birds.
What are adaptive radiations? How do they play into mass extinctions? What is an example of this?
A period of evolutionary change in which organisms form many new species whose adaptations allow them to fill many different ecological roles OR… the evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities.
Adaptive radiation is common after a mass extinction event.
The Hawaiian archipelago is an example. Thought to have all originated from an ancestral tarweed that have spread into different habitats and formed new species.
