4.1 Darwin, Evolution, and Natural Selection U4 Flashcards
What is evolution?
Change over time
When was Darwin on the BEAGLE and for how long?
1831 on the BEAGLE for 5yrs
What did Darwin do on the BEAGLE?
As a naturalist, he made observations of organisms in South America and the Galapagos Islands
What were the two observations that Darwin made on his trip on the BEAGLE?
Species in different parts of the world were sometimes similar as if they had similar habits
Species that lived near one another often adapted for different tasks
How did Jean-Baptiste Lamarck influence Darwin?
Jean proposed the Inheritance of Acquired Characteristics
This was a hypothesis where an existing organism undergoes change during its lifetime based on use or disuse of body parts, and those changes could be passed onto offspring
Later Debunked
How did Thomas Malthus influence Darwin?
Economist who argued that human population growth would lead to food scarcity and overcrowding
“Struggle for existence”
Like Natural Selection
How did Alfred Russel Wallace influence Darwin?
Also sailed around collecting specimens and observing
Came to a very similar conclusion about how species evolved, immediately wrote to Darwin about it
Darwin had already been working on the idea for about 20 years, but had been hesitant to publish them.
They met, discussed and Darwin published The Origin Of Species
What is Natural Selection?
Organisms best suited to their environment will survive, producing changes in populations NOT INDIVS
What is adaptation?
heritable characteristic that increase an organism’s fitness
What is an organisms fitness?
An organism’s ability to survive and reproduce in its environment
What is sexual selection?
Form of selection in which individuals with certain inherited characteristics are more likely than others to obtain mate
What is Intersexual?
Choosing of opposite sex
What is Intrasexual?
Competition amongst the same sex
What does sexual selection often result in?
Sexual dimorphism
What is sexual dimorphism?
Difference in appearance between sexes
What did Darwin propose (Descent with Modification)?
That all living and extinct species are descended from ancient common ancestors, modified over time
What are the four types of evidences for evolution?
Biogeographical
Anatomical
Fossil
Molecular
Explain the biogeographical evidence for evolution?
The environment influences adaptations
Convergent and Divergent Evolution
What is Convergent Evolution?
Evolution of two organisms adapted to similar environments produces similar adaptations even though they are only distantly related (share no recent common ancestor)
What is Divergent Evolution?
Evolution of two organisms that are closely related (share a recent common ancestor) but have adapted to different environments
Examples of Convergent Evolution?
Shad
Dolphin
Ichthyosaur
Puffin
All of these animals have a streamlined body shape adapted for underwater life despite all being different species
Examples of Divergent Evolution
Wolf dog and fox
ancestral canine-like species, yet different based on environment
What is adaptive radiation?
A single ancestral species diverges into several different forms adapted to slightly different environments
What is the fossil evidence?
Fossils link recent species to their ancestral species
What is the anatomical evidence(vestigial structures)?
inherited from common ancestor but reduced in size and function due to changes in selective pressures
What is homologous?
Similar in form but not necessarily in function
What is analogous?
Similar in function but not inherited from common ancestor
What evolution causes homologous?
Divergent Evolution
What evolution causes analogous?
Convergent Evolution
What is the Molecular Evidence?
Same genetic code - DNA/RNA/Protein/Central Dogma
Similar proteins across species
The more closely related the species, the more similar their proteins tend to be
