Darwin’s Theory of Evolution - Descebt with Modification Flashcards
What we’re Darwin’s general observations?
The rich diversity of life, the many shared characteristics (unity) of life, organisms are suited for their environment
What are the two ways evolution can be viewed in?
As a pattern (observations of living world)
As a process (mechanisms that cause observed patterns)
How did Aristotle use the word ‘evolution’?
He used ‘evolution’ in a descriptive sense, everything in nature having a certain order or purpose
What we’re Aristotles contributions to to our understanding of evolution?
He classified all living organisms hierarchically and he made the Great Chain of Beings
Why didn’t Aristotle address change over time?
He didn’t address change over time because he saw the universe as static and species fixed as they were
What was the 1700’s conventional view of Earth and it’s life?
Most scientists accepted the views of the Greek philosopher Aristotle, who generally held that species are fixed, permanent forms that do not evolve
Judeo-Christian culture taught a literal interpretation of the biblical book of Genesis, that each form of life is individually created in its present-day form
Earlier religious scholars estimated the are of Earth at 6,000 years
Who was Carl Linnaeus?
A botanist who sought to classify life’s diversity “for the greater glory of God”
What was Carly Linnaeus contribution to the understanding of evolution?
He developed a heated classification system, grouping similar species into increasingly general categories - that classification system was: class, order, genus, and species
Who was George Cuvier?
The founding fathers of paleontology - he was a geologist studying Paris stars and is know for his anatomical drawings
Proponent of catastrophism
Sudden cataclysmic events and repopulation of sites by different immigrant species
What is the complexifying force?
The idea that simple organisms were the product of spontaneous generation and that higher life forms were derived from simple forms via some kind of force that drive animals to become more complex over many generations
What is the adaptive force?
The idea that life adapts to the changing conditions at the same time as it progresses up the chain of being and that characteristics are acquired as a result of effort are transmitted to the offspring
What is the ‘Use and Disuse’ idea?
Parts of the body that are used extensively become better - these efforts during the life the individual would be passed to offspring (inheritance of acquired characters)
What did many of Darwin’s observations indicate?
They indicated that geographic proximity is a better predictor of relationships among organisms that similarity of environment
What did Darwin hypothesize about the organisms on the Galapagos Islands?
He hypothesized that species from South America had colonized the Galapagos and speculated on the islands
What did the book Principles of Geology present?
It presented the case that changes in Earth’s surface can result from slow, continuous actions still operating today
What we’re Darwin’s hypothesis’ about adaptation?
1- as the descendants of a remote ancestor spread into new habitats or their habitat changes, they accumulated diverse modifications, or adaptations, that fit them to specific ways of life in their environment
2- that present-day species are the descendants of ancient ancestors that they still resemble in some ways
Did Darwin ever use the word ‘evolution’ in The Origin of Species?
No, he used the phrase ‘descent with modification’ to summarize his perception of the unity of life - the phrase refers to the view that all organisms are related through descent form an ancestor that lived in the remote past
Why did some schools in America not want to teach evolution?
Because they believe evolution is only a theory
Theory
In common usage: a theory is a conjecture, opinion or speculation that is not necessarily based on facts
In science: a theory is well-substantiated explanation of a set of natural phenomena
What were the five lines of evidence for evolution?
Biogeography, fossil record, homologies: comparative anatomy and embryology, molecular biology, and direct observations
Biogeographical evidence for evolution
Species tend to be more closely related to other species form the same area than to species with the same way of life from different area
Fossils
The imprints or remains of organisms that lived in the past
Document differences between part and present organisms
Reveal that many species have become extinct
Homologies evidence for evolution
Evolution is a process of descent with modification - a remodeling process
Characteristics present in an ancestral organism are altered over time by natural selection as its descendants face different environmental conditions
Related species can have characteristics that have an underlying similarity yet function differently
Homology
Similarities resulting from common ancestry
Homologous structures
Anatomical similarities on different organisms
Vestigial structures
Remnants of features that served a function in the organism’s
Do all forms of life use the same genetic language of DNA and RNA?
Yes, the genetic code is essentially universal
Evolutionary tree
Has multiple branches from a common ancestral trunk to the descendant species at the tips of the twigs
What homologous structures are used to determine the branching sequence of an evolutionary tree?
Anatomical structure and/or molecular sequence
What are some examples of direct observation of evolutionary change?
Industrial melanoma in moths, the emergence of pesticide resistance in insects, and the appearance and then spread of new SARS-COV-2 variants
What was Darwin’s greatest contribution to biology?
His explanation of how life evolves - his proposition of natural selection as the mechanism of evolution
What two main observations brought Darwin to the conclusion that natural selection is how life evolves?
1- members of a population often vary in their inherited traits
2- all species can produce more offspring than the environment can support, and many of these offspring fail to survive and reproduce
What is the essence of natural selection?
Unequal reproduction - individuals whose traits better enable them to obtain food or escape predators or tolerate physical conditions will survive and reproduce more successfully, passing these adaptive traits to their offspring
What are three important points to emphasize about evolution by natural selection?
That individuals do not evolve, rather the population (group of organisms) evolves over time
That natural selection can amplify or diminish only heritable traits
That evolution is not goal directed, it results form environmental factors that vary temporally and spatially, traits that are beneficial one season may be detrimental the next
