22 Flashcards
evolution
descent with modification
3 key observations about life
- The striking ways in which organisms are suited for their environment
- The many shared characteristics of life
- The rich diversity of life
Evolution, as described by Charles Darwin, has as its base four central ideas:
- Descent with modification
- Common ancestry
- Adaptation
- Natural selection
Pre-Darwin Earth and Life
“scala natura”
aristotle proposed species were organized based on increasing size and complexity
Jean-Baptiste de Lamarck hypothesized that species evolve through:
use and disuse of body parts and the inheritance of acquired characteristics.
descent with modification
explains life’s unity and diversity
– All organisms are related through descent from an ancestor that lived in the remote past
adaptations
Characteristics of organisms that enhance their survival and reproduction in specific environments
natural selection
a process in which individuals have certain inherited traits tend to survive and reproduce at higher rates
produces adaptation.
• Darwin proposed natural selection to explain the observable patterns of evolution
– This is an alternative hypothesis to the one proposed by Lamarck
artificial selection
Darwin found striking evidence for the power of unequal reproductive success in examples of artificial selection
as a result, they have little resemblance to their wild ancestors
– the process in which humans direct the differential reproductive success of individuals in a breeding population
– for example, food and animals we have “domesticated”
Natural selection is not the only mechanism that causes evolution, but it is the ______
ONLY mechanism that produces ADAPTATIONS
evidence for evolution
- Experimental Evidence – direct observations
- Anatomical and Molecular Homologies
- The Fossil Record
- Biogeography
homology
similarities resulting from common ancestry
Vestigial structures
are remnants of features that served a function in the organism’s ancestors
convergent evolution
is the evolution of similar, or analogous, features in distantly related groups
Convergent evolution does not provide information about ancestry
Analogous traits arise when _____
groups independently adapt to similar environments in similar ways
Natural selection observations
- Species tend to produce more offspring than is necessary to replace the parents and maintain the population
Observation 2: Despite all the offspring making, adult populations of species stay fairly constant (plateau effect)
Observation 3: Natural Resources are limited
Observation 4: Individuals in a population vary
Observation 5: Much of this variation is heritable, meaning the offspring got their features from their parents
natural selection inferences
Inference 1: There must be a struggle for existence in nature, with too many individuals and not enough resources.
Inference 2: That struggle for existence is not random, but selective.
• Those individuals with the best set of traits will have the best chance for survival and reproduction (this is also known as the survival of the fittest)
Inference 3: Populations change over time as the frequency of advantageous traits increases (speciation)
analogous
species share features because of convergent evolution, the resemblance is analogous not homologous
these features share similar function but not common ancestry
Define convergent evolution. Why is it a “problem” for building trees?
independent evolution of similar features in different lineages
is the evolution of similar, or analogous, features in distantly related groups
this is problem for building trees because these features share similar function but not common ancestry
biogeography
scientific study of geographic distribution of species
pangea
all of earths landmasses
Natural selection can amplify or diminish only _____
heritable traits
Lamarack evolution
the mechanisms were not supported by evidence
Natural selection acts on ____ where as evolution occurs in ______
individuals; populations
what did Carolus Linneaus do?
adopted a nested classification system
Charles Lyell
Darwin was reading Lyell’s Principles of Geology during the voyage
Thomas Malthus
“Essay on the Principle of Population” (1798), which Darwin read and was inspired by. The central theme of Malthus’ work was that population growth would always overpower food supply growth, creating perpetual states of hunger, disease, and struggle.
Alfred Russel Wallace
was doing very similar studies to Darwin. developed hypothesis of natural selection, but Darwin ended up getting majority of the credit
What does the fossil record reveal and how/why is it evidence for evolution?
Documents patterns of evolution, showing that past organism differed from present day organisms
What type of evidence for evolution has come from molecular biology?
Evolution of drug resistant bacteria
What are some examples of direct observations of evolutionary change?
Data suggest that a change in the size of the soapberry bug’s food source can result in evolution by natural selection for matching “beak” size
Which of the following is not an observation or inference on which natural selection is based?
Poorly adapted individuals never produce offspring.
Which of the following observations helped Darwin shape his concept of descent with modification?
South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.
Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained?
Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency.
The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data?
Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.
DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that
humans and chimpanzees share a relatively recent common ancestor.
Central to evolution is the idea of ______
change over time.
Origin of Species had 2 main ideas
- Descent with modification
2. natural selection
Darwins idea of natural selection was an alternative hypothesis to the one proposed by _____
Lamarck
Darwin found striking evidence for the power of _____ in examples of artificial selection
unequal reproductive success
speciation
In time, favored traits will pile up and unfavored traits will disappear from the population, and a new species may result.
Summary of Natural selection
- overproduction
- variation
- selection
- adaptation
Individuals with certain heritable traits reproduce at a ____ than other individuals
higher rate
related species can have characteristics with underlying similarity even though they may have different functions
this is an example of what?
homology
The ____________(longer/ shorter) that is has been since two organisms shared a common ancestor, the ____________ (smaller/greater) the number of base differences we should see between similar genes.
longer; greater
