Biology Chapter 7: Darwinian Evolution
Terms in this set (35)
As a child he spent time observing nature.
Did not like school.
Travels let him compare species.
Spent decades reading, analyzing his specimens.
Origin of Species by Means of Natural Selection.
Introduced evolution and natural selection.
Thought Earth held unrelated and unchanging species.
Fossils discovered suggested otherwise.
Lamarck: First to suggest evolution.
Lyell: Earth changed through slow processes.
Alfred Russel Wallace
Developed ideas of natural selection over decades.
Proposed an idea of natural selection which did not exclude the super-natural.
Wallace was preparing to publish his own ideas of natural selection yet, after sharing his ideas with Darwin, Darwin promptly published his work to the public before Wallace.
Origin of Species
By Charles Darwin
- modern species have descended from common ancestors (evolution).
- natural selection is the mechanism of evolution.
More individuals are bornthan can be supported bythe environment.
The amount of resources(such as food, water,shelter, sunlight) staysrelatively constant.
More offspring are born than can be supported by limited resources; not all individuals survive and reproduce.
Darwin also observed thatno two individuals are alike.
Those individuals with variations that make them best suited to their environment will,on average, be morelikely to survive andreproduce.
The traits of an organismare likely to be passed tothe next generation.
Because traits are passed from one generation to the next, and because certain members are more likely to survive and reproduce, a population will change over time, becoming better suited to its environment.
Individuals Do Not Evolve
Natural selection acts onindividuals, but onlypopulations evolve.
Natural Selection Work with Heritable Traits
Only genetically coded traits are subject to natural selection.
Evolution Does Not have a Goal
Evolution occurs in response to local environmental conditions, not future ones.
Selecting specific traits.
First discovered in the 1940s.
Some have become useless because bacteria have evolved resistance.
Accumulation of favorable traits in a population over time.
Individual with traits that enhance survival and reproduction will have, on average, more offspring.
Provides evidence for evolution.
Form when organisms die, fall into accumulating sediment, and are compressed into rock.
Can be dated using their geological position or through radiometric dating.
Fossil record reveals an ordered appearance of life on Earth, from prokaryotes to today's life forms.
Provide evidence of change within lineages, not the formation of new species.
The study of the geographic distribution of species.
Ex: Austrailian marsupials.
Comparisons of the body structures of modern organisms.
Employs computational tools to process genetic data.
Evolution affects only populations, and not individuals.
Group of individuals of the same species living in the same place at the same time.
Consistsof all versions of all the genes carried by all the individuals in a population.
Traits that enhance survival and reproduction will be represented withincreasing frequency.
Genetic variation in agene pool can arise through mutation.
Ensures that genes are randomly mixed.
A generation-to-generation change in the gene pool; evolution occurring on its smallest scale.
Can result in the gradual adaptation of species to the local environment.
A population that is capable of interbreeding to produce healthy, fertile offspring.
Prevent members of different species from breeding.
1. Behavioral Isolation
2. Mating Time Differences
3. Habitat Isolation
4. Mechanical Incompatibility
5. Gametic Incompatibility
6. Hybrid Weakness
Members of a species often identify each other through specific rituals.
Mating Time Differences
Many species are able to reproduce only at specific times.
If species live in slightlydifferent habitats, they maynever meet.
Members of different speciesoften cannot mate because their anatomies are incompatible.
The gametes (sperm and egg)of different species usuallycannot fertilize each other.
Offspring of two speciesmay be unfit, or they maybe sterile.
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