module 1 - Intermolecular Forces

What did Aristotle believe about species?

He believed species were fixed and unchanging. He wrote Scala Naturae and classified organisms based on level of complexity.

What were Cabinets of Curiosities?

17th-century collections where Europeans began bringing back specimens from global travel (e.g., Olaus Worm's 1655 catalogue of specimens).

Who is considered the Father of Taxonomy?

Carolus Linnaeus.

What did Carolus Linnaeus contribute to biology?

He wrote Systema Naturae (1735) and developed a nested classification system grouping similar species into increasingly inclusive categories, plus the binomial format for naming species (e.g., Homo sapiens).

What is Buffon's Law?

George-Louis Leclerc, Comte de Buffon observed that different regions have distinct plants and animals even when the environment is similar.

What was William Paley's argument in Natural Theology (1809)?

He cataloged the remarkable fit of organisms to their environment as evidence for design, implying a designer. His famous example was the watchmaker.

What was the common view of nature in the mid-1800s?

Life is unchanging, similarities among organisms are not due to relatedness, life was created by a deity, differences were designed by a deity, and the earth is young.

What is catastrophism and who proposed it?

Georges Cuvier proposed catastrophism—the idea that boundaries between strata represent sudden catastrophic events.

Who is the "Father of Geology" and what did he propose?

James Hutton (1726-1797). He proposed gradualism—the idea that earth's geologic features formed gradually (e.g., valleys formed by rivers).

What is uniformitarianism and who popularized it?

Charles Lyell popularized uniformitarianism in Principles of Geology (1830-1833)—the idea that current geologic processes occurring at the same rates and manner observed today could account for all of Earth's geological features. "The present is the key to the past."

What are geological strata?

Layers in sedimentary rock that indicate gradual change. Older fossils are deeper; newer fossils are more shallow.

What did Jean Baptiste de Lamarck propose in 1801?

He published a theory of evolution (Philosophie Zoologique): organisms change to adapt to environment, and these changes are heritable.

What was Lamarck's idea of "use and disuse"?

Body parts used extensively become larger and stronger; unused parts deteriorate.

What was Lamarck's idea of "inheritance of acquired characteristics"?

Modifications acquired in one's lifetime can be passed to offspring.

Why were Lamarck's theories mostly misguided?

Populations, not organisms, adapt to environment. Most changes that happen in an organism's lifetime are not heritable. However, gene expression and DNA can change in an organism (use or damage), and if this happens to a germ cell, the change is inherited.

What did Darwin believe about species before the voyage?

He believed in fixity or immutability of species (each species was a single, unchanging entity). Evolution or transformation of species was unlikely.

What are the two types of islands and how do they differ?

• Continental islands: Formed by breaking of land mass; near mainland; few unique species; species are a subset of mainland

• Oceanic islands: Formed by volcanoes; far from mainland; each island had unique species; species on younger islands are more similar to mainland species

What did Darwin observe about Galapagos finches?

Birds on each island were specialized for certain feeding strategies. He did not even initially recognize them all as "finches."

What is descent with modification?

Extant species are descended from previously living species with slight modifications over time. Each ancestral species could give rise to more than one descendant species.

What was Darwin's "Eureka Moment"?

In October 1838, he read Malthus on Population and realized that under circumstances of struggle for existence, favorable variations would be preserved and unfavorable ones destroyed.

Who was Alfred Russel Wallace?

A naturalist who, in 1858, sent Darwin a manuscript describing a nearly identical hypothesis of natural selection.

What is natural selection?

Individuals that have certain inherited traits survive and reproduce at higher rates.

Does natural selection act on individuals or populations?

Natural selection acts on individuals. Individuals do not evolve. Populations evolve.

What are the four key observations/conclusions of natural selection?

1. Individuals within a population are variable

2. All organisms have a reproductive capacity that exceeds replacement

3. Some variations result in individuals better able to survive and gain resources (struggle for existence)

4. Offspring tend to resemble their parents (heritable)

What is the ultimate source of new variation?

Mutation: change in DNA.

What is the role of sexual reproduction in genetic variation?

Reshuffling alleles during reproduction—a common source of genetic variation within populations.

What is artificial selection?

Humans modify species through artificial selection, breeding only individuals with desired traits.

What is homology?

Similarity resulting from common ancestry—anatomical and molecular.

What is convergent evolution?

Analogous traits (not homologous) caused by similar selective pressure, not common ancestry.

How do we know if a trait is homologous or analogous?

Based on shared ancestry, observed in fossil record or genetic record, and an evolutionary tree can indicate homology versus analogy.

What is developmental homology?

All vertebrate embryos have a tail and pharyngeal arches (gills, parts of ears and throat).

What are vestigial structures?

Anatomical structures no longer in use, or molecular pseudogenes (genes that no longer function due to mutation).

What is an exaptation?

When vestigial structures are repurposed. Example: The appendix is homologous to the cecum in mammals.

What are morphological gaps?

Large gaps between related groups are explained by branching and extinction events (e.g., elephants and their extinct relatives).

What is biogeography evidence for evolution?

Species distributions are influenced by continental drift—the gradual movement of Earth's landmasses (e.g., Pangea 250 million years ago).

Why is evolution "only a theory" and not a law?

A hypothesis becomes a theory when tested multiple times across different disciplines. A scientific law describes what happens; a scientific theory explains why or how it happens.