Lecture 18 Flashcards
What is the first main idea proposed by Darwin in “The Origin of Species”?
Today’s organisms descended from ancestral species that were different from modern species
What does evolution explain?
Evolution explains life’s unity and diversity
What does this process lead to?
leads to an accumulation of inherited traits that enhance an organism’s ability to survive and reproduce in its environment.
What does natural selection allows for populations?
it allows populations to change over time if individuals with certain heritable traits produce more offspring
What is the second main idea proposed by Darwin in “The Origin of Species”?
Natural selection is the mechanism for evolutionary change, resulting in adaptive evolution.
What did Aristotle believe about species?
He viewed species as fixed and unchanging.
How did Aristotle categorize life?
He arranged life on a scale of increasing complexity
How did he name this scale?
“scala naturae”
What did the Old Testament of the Bible suggest about species?
species were designed by God
Who was Carolus Linnaeus and what did he do?
He was a founder of taxonomy, grouping similar species into increasingly greater categories.
How did Linnaeus explain similarities among species?
He attributed similarities to the pattern of their creation, not to evolutionary kinship.
What are fossils?
Remains or traces of organisms from the past
Where are fossils usually found?
found in sedimentary rock.
What do we call the study of fossils?
Paleontology
How do fossils help determine the sequence of events in Earth’s history?
They are found in layers (strata) which shows that a succession of organisms have
populated Earth throughout time
What did Cuvier observe about fossils?
He noted that the older the strata, the more dissimilar the fossils were from modern life.
What theory did Cuvier propose to explain the boundaries between strata?
He proposed the theory of catastrophism
What was he speculating about (the catastrophism theory)?
speculating that local floods or droughts destroyed the species present instead of evolution
What did Lamarck believe about the evolution of organisms?
He believed a life force drove organisms toward greater complexity and perfection over time (so more complex & perfected)
Were Lamarck’s mechanisms supported by evidence?
nope
What was Lamarck’s theory about how traits are passed to offspring?
Traits are passed through use and disuse; parts used extensively become stronger and larger, while unused parts deteriorate.
Give an example of Lamarck’s idea of evolution through use and disuse (giraffe)
A giraffe developed a long neck because its short-necked ancestor stretched its neck to eat leaves on trees.
Who came before Darwin?
Hutton & Lyell
What theory did Hutton propose?
Gradualism
What is Gradualism?
profound change through slow, continuous processes.
What did Lyell perceive about changes in Earth’s surface?
Changes result from slow, continuous actions still operating today.
How did Hutton and Lyell’s ideas contrast with the biblical inference of Earth’s age?
They suggested Earth is older than the 6,000 years estimated by biblical inference.
What implication did their ideas have for the evolution of living organisms?
Slow and subtle processes over long periods can produce substantial changes in living organisms.
Darwin developed his theory based on 4 important things, name them:
i) Malthus’ essay: Struggle for existence
ii) Lyell’s Principles of Geology
iii) Principles of artificial selection
iv) His data (what he saw in the Galapagos)
i) who talked about the Struggle for Existence
Thomas Robert Malthus
What did Malthus believe about population growth?
Population growth is not always desirable.
What conflicts arise from population growth, according to Malthus?
The conflict between population growth and food supply generates famine, disease, and war, which break population growth.
ii) who talked about the Principles of Geology?
Lyell
What geologic change did Darwin experience?
Earthquakes that thrust rocks upward by several feet.
How did this geologic change influence Darwin?
It reinforced his acceptance of Lyell’s ideas.
What doubt did Lyell’s ideas and Darwin’s observations create?
Doubt about the traditional view of a young and static Earth.
What is artificial selection?
The process where humans modify domesticated plants and animals by selecting individuals with desired traits for breeding.
What conclusion did Darwin draw from artificial selection?
large changes in a short period, natural selection should be capable of modification over thousands of generations.
iv) Finish the sentence: Darwin’s Data from WHAT?
from Galapagos
What was the purpose of Darwin’s voyage on the H.M.S. Beagle?
A 5-year exploration of South America and the South Pacific.
What did Darwin observe during his voyage?
Various adaptations of plants and animals in diverse environments.
What comparison did Darwin make with animals?
Compare animals on islands (e.g., Galapagos) with those on the mainland.
What impressed Darwin about the animals he studied?
The similarities/differences b/w island and mainland species.
What fascinated Darwin about the organisms he found? (Darwinian Evolution)
The unusual organisms on the islands.
What did Darwin hypothesize about the colonization of the islands?
Islands were colonized by plants and animals from the mainland that diversified on different islands.
How are the origin of new species and adaptation related?
They are closely related processes.
What example did Darwin use to illustrate adaptation?
Differences in the beaks of the 13 species of finches in the Galapagos, adapted to the specific foods on their home islands.
When did Darwin write his essay on the origin of species and natural selection?
1840s
Why was Darwin initially reluctant to publish his essay?
He was hesitant despite having written it.
Who sent Darwin a manuscript with a similar theory in 1858?
Alfred Russel Wallace
What did Darwin do after receiving Wallace’s manuscript?
He quickly finished and published “The Origin of Species” the next year.
Why is the theory attributed to Darwin instead of Wallace?
Darwin developed his ideas earlier and supported the theory more extensively.
What is the first key concept of natural selection?
Species are capable of producing more offspring than the environment can support.
What would happen to population sizes if not for limiting factors?
Population sizes would increase exponentially.
Despite the potential for exponential growth, what is observed about population sizes?
Populations tend to be stable in size.
What leads to a struggle for existence among individuals?
Production of more individuals than the environment can support.
What results from the struggle for existence?
Competition for limited resources.
What are some examples of limited resources? (4)
Food, water, light, space.
What factors can kill individuals in a population?
Predators, disease, environmental conditions.
How do members of a population differ?
they vary extensively in their characteristics
Are any two individuals exactly alike?
no
Are variations heritable?
yes
What does survival depend on?
Survival depends in part on inherited traits.
What is differential reproductive success?
individuals with inherited traits that give them a high probability of surviving and reproducing.
What happens to individuals with favorable traits?
more likely to leave more offspring
What does differential reproductive success lead to in a population?
It leads to a gradual change, with favorable characteristics accumulating over generations.
What is the scope of natural selection?
It occurs through interactions between individual organisms and their environment.
Do individuals evolve?
no
Evolution occurs at what level?
at the population level
What is the smallest group that can evolve?
population
How is evolutionary change measured?
It is measured as changes in the relative proportions of heritable traits in a population over successive generations.
What types of traits can natural selection act on?
Natural selection can act only on heritable traits, those passed from organisms to their offspring.
How do environmental factors affect natural selection?
a trait that is favorable in one environment may be useless or detrimental in another environment.
Does natural selection create perfect organisms?
no
What does Natural selection allow?
it allows organisms to adapt to their environment (‘edits’ existing variations)
What are the 5 evidences fro Darwin’s Theory?
a) Natural Selection in action
b) Homology
c) Convergent evolution
d) Biogeography
e) Fossils
What do soapberry bugs use their “beak” for?
to feed on seeds within fruits
How do soapberry bugs in South Florida differ from those in Central Florida?
Soapberry bugs in South Florida feed on larger fruit and have longer beaks,
Those in Central Florida feed on smaller, introduced fruit and have shorter beaks.
How does natural selection influence beak length in soapberry bugs?
Beak length matches the depth at which the seeds are found in fruit, demonstrating natural selection in action.
What was the situation regarding the peppered moth before the Industrial Revolution?
Before the Industrial Revolution, birds ate the black moths more easily seen against white trees
What would this lead to for white moths?
leading to an increased proportion of white moths.
How did the Industrial Revolution affect the environment of the peppered moth?
The Industrial Revolution darkened the white birch trees
Darkened the white birch trees due to what?
due to soot
What happened to the proportion of moths after the environment changed?
White moths became more easily seen, and birds ate more of them, increasing the proportion of black moths
What are examples of drug-resistant pathogens?
Antibiotic-resistant bacteria and drug-resistant HIV.
How does the selection for drug-resistant pathogens contribute to adaptive evolution?
it favors the survival/reproduction of organisms with traits that make them resistant to drugs.
How do researchers’ efforts to combat HIV contribute to the selection for drug-resistant viruses?
The use of medications selects for viruses that are resistant to the drugs
What does the use of medications lead to?
it leads to the development of drug-resistant strains.
b) What is homology?
Homology is the similarity resulting from common ancestry.
How are homologous structures defined?
Homologous structures are anatomical resemblances that represent variations on a structural theme present in a recent common ancestor but diverged to have different functions.
(similar structures with diff functions)
Provide an example of homologous structures.
Human arm, cat forelimb, whale front flipper, and bat wing are examples of homologous structures
How come they have homologous structures?
b/c they exhibit similar arrangements of bones, muscles, and nerves
What are vestigial organs?
useless organs or structures
What are they considered to be?
considered “leftovers from ancestors”
What do vestigial organs indicate about an organism’s evolutionary history?
indicates that the organism evolved from ancestors in which the organ was functional.
Provide an example of a vestigial organ and its significance.
Vestigial hind limb bones in large snakes and whales
What do these bones indicate?
indicate that they both evolved from tetrapod ancestors.
Why do vestigial organs tend to persist in organisms?
b/c there is no selective pressure to eliminate them.
What are pharyngeal pouches?
gill slits
Where are pharyngeal pouches found?
n the throat of vertebrate embryos during some stage of their development
How do embryonic structures like pharyngeal pouches demonstrate homology?
Although they develop into different adult structures, such as fish gills and parts of the human ear, they are still homologous, showing divergent evolution.
What is remarkable about the embryonic development of all vertebrates?
Despite differences in adult forms, embryonic development shows remarkable similarities among all vertebrates.
What is the universal genetic code?
sequence of nucleotides in DNA and amino acids in proteins across different organisms
How does the genetic code work?
A sequence of three nucleotides in DNA, called a triplet, codes for a specific codon in mRNA, which in turn codes for a particular amino acid.
What does the example AAA (DNA) → UUU (mRNA) represent?
coding for the amino acid phenylalanine (for shrimp, bacteria, humans, and tulips)
What does the universal genetic code suggest about organisms?
common ancestry among organisms
What do the numbers represent in the context of proteins?
The numbers represent the number
of amino acid differences between
the beta polypeptide chain of
human hemoglobin and the beta
hemoglobins of the other species.
How many amino acids does the human polypeptide chain contain, and how does it compare to most other species?
The human polypeptide chain contains 146 amino acids
How is the number of amino acid differences related to the closeness of kinship?
the number of amino acid differences is inversely proportional to the closeness of kinship
c) Convergent Evoultion
When you think of convergent evolution, what should you associate it with?
Analogous
What are analogous features?
similar but NOT derived from a common ancestor
What do analogous features demonstrate about organisms?
organisms with separate ancestors may adapt in similar ways to similar environments.
What does independent evolution of similar structures in distant related organisms suggest?
It suggests that similar environments can lead to the evolution of similar structures, even in organisms with different ancestors.
d) Biogeography
What does the tendency for species to be more closely related to other species from the same area suggest?
It suggests that a common ancestor adapted to various habitats.
What is Pangea?
Pangea was a supercontinent where continents were once joined together.
What happened over time?
Over time, each continental plate moved due to plate tectonics.
How did the movement of continental plates affect populations?
becoming isolated in different environments, leading to their evolution in different ways
What is an example of the impact of isolation on evolution?
Australia’s marsupials are a diverse group of animals that developed in isolation on a separate landmass for millions of years.
e) Fossil Record
How is the succession of forms observed in the fossil record consistent with other inferences about the major branches of descent in the tree of life?
It suggests that prokaryotes are the ancestors of all life and should precede all eukaryotes in the fossil record.
What is one example of evidence supporting this inference?
The oldest known fossils are prokaryotes
What is the oldest known fossils are prokaryotes?
stromatolites
What are stromatolites?
layered structures formed by the growth of prokaryotes in shallow water environments (providing evidence of ancient life forms)
How is a theory defined in science?
many observations and data and attempts to explain and integrate a great variety of phenomena.
What supports Darwin’s theory of natural selection?
Massive amounts of data support Darwin’s theory of natural selection.
Can the effects of natural selection be observed and tested?
YES
What is Neo-Darwinism?
modern version of Darwinian evolutionary theory
What does Neo-Darwinism incorporate?
Mendelian genetics
What does Neo-Darwinism postulate about natural selection?
Neo-Darwinism postulates that natural selection acts on the heritable (genetic) variations within individuals in populations
Mutations are the main source of these genetic variations
