Darwin's Journey
What three patterns of diversity did Darwin observe on his voyage on the HMS Beagle?
Species vary globally
Species vary locally
Species vary over time
What idea did geologists James Hutton and Charles Lyell develop?
Both geologists' ideas combined to state that Earth is a lot older than what was previously theorized and the geological processes that changed Earth in the past are actively happening today ("deep time")
What is the "struggle for existence?"
If all populations have the potential to produce more offspring than can survive, members of a population will compete for a finite supply of resources.
What is biogeography and how does it match Darwin's ideas about adaptation and evolution?
Biogeography is the study of where organisms live now and where they and their ancestors lived in the past.
Darwin believed that related species have adapted to different environments and distantly related species can have similar adaptations if they live in similar environments or face the same struggles.
How can different, yet ecological similar species inhabit separate, but ecologically similar habitats? (Hint: Rheas in South American grasslands and ostriches in Africa).
Similar animals live in similar habitats because they adapted to similar circumstances.
Why was Jean-Baptiste Lamarck's ideas on evolution incorrect?
Lamarck was incorrect about his ideas on acquired traits because evolution does not always mean a species will become more improved, traits are not acquired in a lifetime, and they will not be inherited.
Define and adaptation. What traits could be considered an adaptation?
An adaptation is any heritable characteristic that increases and organism's ability to survive and reproduce in its environment. It can be different body structures, colors, physiological components, and behaviors.
What is the difference between a homologous and analogous structure? How can scientists differentiate the two?
Homologous structures are similar structures that are shared be a related species who share a common ancestor. An analogous structure is a body part that serves similar functions but do not have similar structures or develop the same way.
Scientists look at how that trait develops in an embryo to determine the difference.
What did Darwin notice about the fossils of extinct animals? How did his observations support the theory of evolution?
Darwin noticed that the fossils of extinct animals looked similar to those that were still alive. This suggests that the living animals could be decedents or close relatives of the extinct ones.
What did Darwin gather from studying artificial selection?
Darwin learned that different variations could be inherited. If humans could control who got to survive and reproduce, so could nature.
When does natural selection occur?
Natural Selection occurs when:
- more individuals are born than can survive
-natural heritable variation affects the ability to survive and reproduce
-fitness caries among individuals
How has increasing the fossils in the geological record helped modern scientists support Darwin's idea that species vary over time?
Having more fossils helps us fill in the "gaps" that Darwin was missing. We can use the fossil record to create a clear timeline for how modern species evolved from extinct ancestors.
What did Darwin notice about the finches in the Galapagos islands? How did this observation support his idea of natural selection?
Several of the same species of finches had different beak sizes and shapes. This suggested that the beaks evolved to allow the finches to be successful at eating certain foods. Competition for food likely drove the natural selection process.
What was Thomas Malthus' ideas on human populations? What did Darwin learn from him?
Malthus noticed that more people were being born than dying and believed that war, famine, and disease were tools of population control.
Darwin believed that this could apple to organisms that reproduced a lot of offspring. He also asked himself how did only some survive but not all.
What is descent with modification and what was Hutton and Lyell's contribution?
Descent with modification means that all living things are descended with changes meant to create new adaptations for changing environments. Hutton and Lyell's deep time theory suggest that there is enough time for natural selection to create all of the changes necessary for the evolution of a species.
How did Mendel help to support the idea that traits can be inherited?
Darwin did not know how heredity worked and Mendel later suggested that certain traits can be passed down to offspring. This supports the idea of "descent with modification" as adaptations are passed down through generations.