BIO theme 1

Why are the Galapagos Islands so important in evolutionary biology?

The Galapagos islands are important in evolutionary biology because this is where Darwin observed endemic species, like tree-sized cactuses, giant tortoises and concluded that these species came through biological evolution by natural selection

What is an endemic species?

Species that are found no where else on earth. 

4. What is a fossil and how do they form?

 A fossil is the remains or impressions of plants or animals preserved in rock; it form when organisms are buried by sediments and preserved before they decay.

Why did the discovery of fossils challenge the idea that the Earth was young and unchanging?

Because it showed extinct animals, which contradicted the notion that all animals were made “perfect”. Further, the deeper the rock sediments, the more different the animals looked like, whereas the shallow animals resembled the animals living today more.  

What is the principle of uniformitarianism? Why is it important in our understanding of the age of the Earth?

Uniformitarianism is the principle that geological processes observed today—such as erosion, glaciation, sedimentation, and volcanism—have operated in the same way throughout Earth's history

Why was the new (much older) estimate of the Earth’s age important to the development of the theory of evolution?

Because biological evolution requires a lot of time, with the 6000 year model, it wouldn’t be enough time for evolution to occur.

How did Lamarck propose that organisms changed over time?

Through acquired characteristics (Giraffes stretching their necks)

 What is artificial selection?

 The process by which humans choose and breed individuals with desirable traits (e.g., bigger fruits, faster horses), producing significant changes in domesticated species over just a few generations.

 How is a population defined?

All the individuals of a single species living in a specific area, interacting and potentially interbreeding.

12. What is natural selection?

The differential survival and reproduction of individuals due to heritable trait differences—nature “selects” the variants best suited to the environment.

 Why do we attribute the theory of natural selection to Darwin (mostly) instead of to Wallace?

• Darwin amassed decades of data and published the comprehensive 1859 book On the Origin of Species, laying out detailed evidence and argument.
  Wallace arrived at the idea independently but only shared a brief manuscript. Academic tradition gives primary credit to the more thorough, first major publication.

What is a key point about the importance of populations to the theory of evolution?

Evolution by natural selection is a property of populations, not individuals—only when you look at trait frequencies across many organisms do you see evolutionary change.

What are the five logical statements about the theory of evolution?

1. Overproduction: Species can produce more offspring than can survive.
   
   

2. Stable populations: Despite potential, population sizes remain fairly constant.
   
   

3. Competition: Limited resources force individuals to compete.
   
   

4. Variation: Individuals vary in traits that affect survival/reproduction.
   
   

5. Differential survival: Those with advantageous traits leave more offspring, shifting trait frequencies over generations.
   

How is the idea that populations have restricted growth important to the theory of natural selection?

Because resources are limited, not all offspring survive—this “struggle for existence” is what drives selection, letting only the best-adapted individuals reproduce.

 Why is the variability of traits within a population important for natural selection?

 Without variation, there’s no raw material for selection to favor. Heritable differences in traits are essential for some individuals to outperform others and drive evolutionary change.

What are the examples of natural selection that are outlined in the reading?

• The cactus (North/South America), spurge (Africa), and milkweed (Asia) families developing similar structures like thick stems and spines in desert environments.
  
  

• Lithops ("stone plants") in Africa evolving to resemble rocks to avoid being eaten.
  
  

• Rose-colored orchids mimicking bellflowers to attract pollinators without offering a reward.
  
  

• Evolution of carnivorous plants and protocarnivores like sticky geraniums and potatoes.

 What is comparative anatomy?

It is the examination and comparison of structural details (organs, etc.) in different organisms to reveal evolutionary relationships

What are homologous structures?

Structures that share a common evolutionary origin but may differ in current function. Example: leaf modifications like spines, bracts, or floral parts.

How are homologous structures different from analogous structures?

• Homologous = same origin, different function.
  
  

• Analogous = different origin, same function (e.g., pea tendrils from leaves vs. grape tendrils from stems).
  

 What is mimicry?

An evolutionary adaptation where an organism evolves to resemble another organism or object, often for protection or deception (e.g., orchids mimicking bellflowers).

 If two species have evolved recently, would you expect them to share more or less of their genetic makeup? Why or why not?

More—because they haven't had much time to accumulate genetic differences, so their DNA and proteins remain more similar.

What are large-scale changes in evolutionary history called?

• Macroevolution—these are changes over geological time that result in new species.