Chapter 22

What was the impact of Darwin's "The Origin of Species" (1859)?

It started the scientific revolution in evolutionary biology and challenged traditional views of a young, unchanging Earth.

What is the definition of evolution according to Darwin?

Evolution is the process by which species accumulate differences from their ancestors as they adapt to different environments over time, summarized as "descent with modification."

How can evolution be viewed?

Evolution can be viewed as both a pattern (evidence from scientific data) and a process (mechanisms causing change).

What was Aristotle's view on species?

Aristotle believed species were fixed and arranged them on a scale of increasing complexity called "scala naturae."

What was Carolus Linnaeus' contribution to classification?

Linnaeus developed a nested classification system and the binomial format for naming species, both still in use today.

What are fossils, and where are they found?

Fossils are remains or traces of past organisms, often found in sedimentary rock layers called strata.

What did Georges Cuvier contribute to paleontology?

Cuvier observed that deeper strata contain fossils less similar to modern organisms and speculated that strata boundaries represent catastrophic events.

What did James Hutton and Charles Lyell propose about Earth's changes?

Hutton proposed gradual geological changes, and Lyell suggested these processes continue at the same rate today.

What was Lamarck’s hypothesis of evolution?

Lamarck proposed "use and disuse" (body parts used extensively become stronger) and "inheritance of acquired traits" (modifications passed to offspring), though unsupported by evidence.

How did Darwin’s research shape his ideas?

His observations during the HMS Beagle voyage, such as adaptations in Galápagos finches, led to the concept of natural selection.

What are adaptations?

Inherited traits that enhance an organism’s survival and reproduction in specific environments.

What led Darwin to publish his theory?

Alfred Russel Wallace independently developed a nearly identical theory, prompting Darwin to publish "The Origin of Species."

What are the three broad observations explained by descent with modification?

1. Unity of life, 2. Diversity of life, 3. Organisms’ adaptations to environments.

What is artificial selection?

Humans selectively breed individuals with desired traits, leading to significant differences from wild ancestors.

What are Darwin’s two key observations in natural selection?

1. Population members vary in inherited traits. 2. Species produce more offspring than the environment can support.

What are Darwin’s two inferences from these observations?

1. Individuals with favorable traits reproduce more. 2. Favorable traits accumulate over generations.

How does natural selection drive adaptation?

Over generations, advantageous traits become more common, improving survival and reproduction.

What did Thomas Malthus contribute to Darwin’s thinking?

He observed that human populations grow faster than resource availability, leading Darwin to recognize this in all species.

What are the three key features of natural selection?

1. Acts on individuals, but populations evolve. 2. Can only act on heritable traits. 3. Favorable traits depend on environmental conditions.

What are four types of evidence supporting evolution?

1. Direct observations, 2. Homology, 3. Fossil record, 4. Biogeography.

What is an example of observed natural selection?

Soapberry bugs’ beak lengths evolved to match seed depth in native vs. introduced plants.

What is an example of drug-resistant bacteria evolution?

MRSA evolved resistance to antibiotics like methicillin, demonstrating natural selection.

What is homology?

Similarity due to common ancestry, such as homologous structures (e.g., mammalian forelimbs).

What are vestigial structures?

Remnants of features that served a function in ancestors, such as snake pelvis bones.

What is convergent evolution?

The evolution of similar features in unrelated species due to similar environmental pressures (e.g., sugar glider vs. flying squirrel).

What does the fossil record reveal?

Evidence of species extinction, emergence of new groups, and evolutionary changes within lineages.

How does biogeography support evolution?

Species distribution reflects continental drift and evolutionary history (e.g., Pangaea’s breakup explains similar species on different continents).

What does Darwin’s theory integrate?

It explains diverse biological observations and continues to drive research in evolution.

What is an evolutionary tree?

A diagram that reflects hypotheses about evolutionary relationships among organisms.

What does an evolutionary tree show?

It shows shared common ancestors and patterns of descent, not exact times of divergence.

How does comparative embryology support evolution?

It reveals anatomical homologies not visible in adult organisms, such as vertebrate embryos having tails and pharyngeal arches.

What is the significance of molecular homologies?

All life shares a universal genetic code, with homologous genes found in vastly different organisms.

What is the difference between homologous and analogous traits?

Homologous traits arise from common ancestry, whereas analogous traits arise from convergent evolution due to similar environmental pressures.

What is the role of transitional fossils in evolution?

They provide evidence of intermediary forms, such as the transition from land mammals to marine cetaceans.

How does continental drift relate to evolution?

It explains the geographic distribution of species, as continents shifting separated related species.

What is an example of biogeographical evidence for evolution?

Freshwater fish in South America and Australia share a common ancestor from the time of Pangaea.

How do pesticide-resistant insects illustrate natural selection?

Insects with resistance genes survive pesticide exposure and pass these genes to offspring, increasing resistance over generations.

How does antibiotic resistance evolve in bacteria?

Bacteria with resistance genes survive antibiotics and reproduce, spreading resistance rapidly.

What is the impact of extinction on evolution?

Extinctions remove species, allowing new groups to diversify and fill ecological niches.

How do environmental changes drive evolution?

Species must adapt to changing environments, or they risk extinction.

What is the difference between microevolution and macroevolution?

Microevolution refers to small genetic changes within a population, while macroevolution involves large-scale changes leading to new species.

What are adaptive radiations?

Rapid evolution of many diverse species from a common ancestor, often after mass extinctions or colonization of new habitats.

At what level does evolution happen ONLY

Population level