descent with modification (bio 2, chp 19)

Be able to recognize/describe how organisms in their adaptations to an environment illustrate key observations about life.

• Organisms adapt to their environment due to the evolutionary process (Fit)

• Shared characteristics in a way for organisms to avoid predation (unity of life)

• Diversity

How does Darwin's phrase "descent with modification" explain evolution as both a process and pattern?

• Darwin noted that current species are descendants of ancestral species. His phrase also viewed evolution as change that happens over time. Therefore, descent with modification illustrates how species evolve through adaptations that enhance survival and reproduction.

What things contributed to Darwin developing his theory of evolution? (This should be as extensive as covered in the notes, including things such as his observations on his travels, influence from other scholars, etc.) What about Wallace?

• Darwin collected various plants and animals to study and describe their features that suited organisms to their environment. He observed that fossils resembled living species from the same region, and living species resembled other species from nearby regions. He was influenced by Geologists and observed with them how fossils of ocean animals ended up in the mountains following a massive earthquake (he also concluded that the Earth must be way more than a couple thousands years old as it was traditionally thought). 

• The Galápagos Islands were important because Darwin hypothesized that species from South America had colonized the islands and diverged on the islands. 

• Wallace developed a theory of natural selection very similar to Darwin that connected natural selection (a process up while individuals with favorable inherited traits are more likely to survive and reproduce) with evolutionary processes. Wallace and Darwin’s work was published together by Lyell. 

How are the finches a good example of adaptation to the environment and speciation

finches arose from an ancestral form by the gradual accumulation of adaptations to different environments.

What are the three broad observations about nature that are explained by descent with modification by natural selection?

• The unity of life

• the diversity of life

• the ways that organisms are suited for life in their environments.

How is Darwin's "tree" of life related to phylogeny? What are the tips? Unlabeled branches? Forks in the diagram? Where do fossils fit in?

• The tree of life relates to phylogeny because it expresses how recent extinct animals are closely related to modern day animals, for example the mammuthus is closely related to the elephant, and the tree also show various common ancestors of the modern day elephant with other extinct animals that share common characteristics. 

• tips of branches: present-day organisms

• unlabeled branches: extinct organisms 

• forks: the most recent common ancestor of the lines that the branch from that point.

• fossils: fossils of extinct species help to fill in the morphological gaps between present-day groups.

How does artificial selection relate to and how did it inform Darwin's theory of natural selection?

• Humans modify other species over generations through selective breeding of individuals with desired traits, a process called artificial selection. Darwin argued that a similar process occurs in nature called natural selection. 

What are Darwin's observations and inferences about populations in nature as related to natural selection?  How will these change the frequency of adaptations in a population? How is this affected by environmental change? Recognize examples of this.

• Darwin reasoned that even if advantages are slight, natural selection should  be able to cause dramatic modifications over many hundreds of generations.

• Over time, the increase in frequency of individuals with favorable adaptations results in organisms becoming  well suited for life in their environment 

• Individuals with certain heritable traits survive and reproduce at a higher rate than other individuals 

• If an environment changes, what might happen? natural selection may result in adaptation to the new conditions, sometimes giving rise to new species

Be able to describe the four types of data that document the pattern of evolution and illuminate how it occurs. Be able to go into the details described in the slides. 

• Direct observations

• homology

• fossil record

• biogeography.

Recognize and give examples of direct observations of evolutionary change, such as the food source experiment and MRSA.

• Example: Beak size has evolved in populations that feed on introduced plants with fruits that are smaller or larger than native fruits. The evolution of beak size in soapberry bugs occurred in less than 35 years. The results of this study demonstrate that natural selection can cause rapid evolution in wild populations.

1. Homology: What is it?

2. What are homologous structures? How do they differ from analogous structures?

3. What is a vestigial structure?

4. What is convergent evolution?

5. Why are analogous structures not evidence for descent with modification/natural selection?

1. Homology is a description of an evolutionary process of descent with modification (the state of having the same or similar relation, relative position, or structure).

2. homologous structures are anatomical resemblances that represent variations on a structural theme present in a common ancestor. Analogous structures is the convergent evolution of similar features in distantly related groups. 

3. Vestigial structures are remnants of features that served important functions in an organism’s ancestors but serve no current purpose.

4. Convergent evolution is when unrelated or distantly related organisms independently evolve similar traits or features (analogous structures) because they adapt to similar environments or ecological niches, not because they inherited them from a recent common ancestor

5. Analogous structures do not provide information about ancestry they arise independently through convergent evolution, where different species develop similar traits due to similar environmental pressures or functions, rather than inheriting them from a recent common ancestor with that specific feature 

How does the fossil record contribute evidence?

• It provides evidence that /species have changed through time and many species have gone extinct. Fossils shed light on the origins of new groups of organisms. 

What is biogeography, and how can it provide evidence of evolution? How does Pangea relate to this?

• Biogeography is the scientific study of geographic distribution of species. Biogeography provides evidence of evolution by showing that the geographic distribution of species aligns with evolutionary history, continental drift, and isolation, demonstrating common descent and adaptation. 

• Pangaea was the single large continent of Earth before the continental drift separated all of the continents. This relates to biogeography because understanding the continental movement and modern distribution of species allows us to predict when and where different groups evolved. 

What does it mean to say that evolution by natural selection is a theory?

• In science, a theory accounts for many observations and explains and integrates a variety of phenomena

• The predictions of a scientific theory are supported by continual observation and experimentation

• Evolution by natural selection is a scientific theory because it's a well-supported, comprehensive explanation for observed facts, built from repeated testing, evidence, and falsifiable hypotheses