Comprehensive Biology Evolution, Taxonomy, and Genetics Key Concepts

What were Linnaeus's key contributions to biology?

Developed taxonomy and binomial nomenclature, grouping organisms by shared physical traits.

How did Malthus influence Darwin's theory?

His argument that populations grow faster than resources provided the basis for Darwin's concept of competition.

What is the difference between Hutton's gradualism and Lyell's uniformitarianism?

Hutton proposed Earth changes gradually over long periods; Lyell expanded this by stating current geological processes operated the same way in the past.

What did Cuvier contribute to the understanding of Earth's history?

He used fossils to prove extinction is real and supported catastrophism.

What was Lamarck's incorrect mechanism for evolution, and what did he get right?

He incorrectly proposed inheritance of acquired characteristics, but correctly argued that species change over time.

How did Darwin use artificial selection in his work?

He used it as a model to demonstrate how selection can change populations by choosing desired traits.

What are the three core observations Darwin made about populations?

Variation within populations, overproduction of offspring, and competition for limited resources.

What is the primary inference Darwin made regarding natural selection?

Individuals with favorable heritable traits survive and reproduce more, increasing the frequency of those traits over generations.

What is the difference between homologous and analogous structures?

Homologous structures share common ancestry; analogous structures share similar functions due to convergent evolution but have different origins.

What are vestigial structures?

Reduced remnants of structures inherited from ancestors that may have little current function.

What does the fossil record demonstrate regarding evolution?

It provides evidence of past organisms, showing change, extinction, and transitional forms over time.

How does biogeography support the theory of evolution?

The geographic distribution of similar species in nearby areas supports descent from common ancestors.

What is the significance of the peppered moth example?

It illustrates natural selection where dark moths were favored in polluted environments due to better camouflage.

How does MRSA demonstrate natural selection?

Antibiotics select for resistant variants already present in the bacterial population, which then survive and reproduce.

What concept is illustrated by the different beak shapes of Galapagos finches?

Adaptive radiation and natural selection based on food sources.

What are the two primary sources of genetic variation?

Mutation and the reshuffling of alleles through sexual reproduction.

What are the five conditions required for a population to be in Hardy-Weinberg equilibrium?

No mutation, random mating, no natural selection, very large population size, and no gene flow.

What is the difference between the founder effect and the bottleneck effect?

The founder effect occurs when a small group starts a new population; the bottleneck effect occurs when a population is suddenly reduced in size.

How does gene flow affect populations?

It involves the movement of alleles between populations, which tends to reduce differences between them.

Compare directional, disruptive, and stabilizing selection.

Directional favors one extreme; disruptive favors both extremes; stabilizing favors intermediate phenotypes.

Why does heterozygote advantage maintain multiple alleles in a population?

Heterozygous individuals have higher fitness than either homozygous genotype, preventing the loss of alleles.

What is frequency-dependent selection?

A process where the fitness of a phenotype depends on how common or rare it is in the population.

What is sexual selection?

Selection for traits that improve mating success, even if those traits reduce overall survival.

What are the primary constraints on natural selection?

Existing heritable variation, history, chance, and changing environments.

What is the goal of modern taxonomy?

To reflect the evolutionary relationships among organisms.

What is binomial nomenclature?

A two-part scientific naming system using genus and species.

What does a polytomy represent on a phylogenetic tree?

A branch point with more than two lineages, indicating unresolved relationships.

What distinguishes morphological homology from molecular homology?

Morphological homology is based on physical structures, while molecular homology is based on DNA, RNA, or protein sequences.

What is the function of an outgroup in a cladogram?

It serves as a reference group to determine which characters are ancestral.

What is the principle of maximum parsimony?

The best tree is the one requiring the fewest evolutionary changes.

What is a molecular clock?

A method using mutation rates to estimate when species diverged from a common ancestor.

What is the Biological Species Concept?

Defining a species as a group that can interbreed in nature and produce viable, fertile offspring.

What is the difference between prezygotic and postzygotic barriers?

Prezygotic barriers prevent fertilization, while postzygotic barriers act after fertilization.

What is the primary cause of allopatric speciation?

Geographic isolation that blocks gene flow.

What are four common factors in sympatric speciation?

Polyploidy, habitat differentiation, sexual selection, and reduced gene flow.

What does the punctuated equilibria model state?

Species remain stable for long periods, interrupted by short bursts of rapid change.

What is adaptive radiation?

The rapid diversification of an ancestral lineage into many species adapted to different niches.

What are the four stages in the origin of life?

Abiotic synthesis of organic molecules, formation of polymers, packaging into protocells, and origin of self-replicating molecules.

What did the Miller-Urey experiment demonstrate?

Organic molecules can be produced from inorganic materials under early Earth conditions.

Why is the RNA-first hypothesis proposed?

RNA can both store genetic information and catalyze chemical reactions.

What was the significance of cyanobacteria in Earth's history?

They were photosynthetic prokaryotes that released oxygen into the atmosphere.

What is the endosymbiotic theory?

The idea that mitochondria and chloroplasts originated as free-living prokaryotes engulfed by ancestral eukaryotic cells.

What evidence supports endosymbiosis?

Mitochondria and chloroplasts have circular DNA, bacterial-type ribosomes, double membranes, and divide by binary fission.

What is secondary endosymbiosis?

A process where a eukaryotic cell engulfs another eukaryotic cell that already contains endosymbiotic organelles.

What are choanoflagellates?

Protists that are the closest living relatives of animals, providing clues to the origin of multicellularity.

How does horizontal gene transfer affect evolutionary study?

It can blur evolutionary relationships by transferring genes between unrelated organisms.

What is natural selection?

The process where individuals with favorable heritable traits survive and reproduce more successfully, increasing those traits' prevalence over time.

What is convergent evolution?

The independent evolution of similar traits in unrelated species due to similar environmental pressures.

What do soapberry beetles demonstrate regarding evolution?

Natural selection, as populations evolved different beak lengths based on the fruit size of their host plants.

What is the evolutionary advantage of the sickle cell allele?

Heterozygote advantage, providing increased resistance to malaria.

What provides the raw material for evolution?

Genetic variation, or differences in DNA sequences among individuals in a population.

What is the Hardy-Weinberg equation for genotype frequencies?

p^2 + 2pq + q^2 = 1

What is the allele frequency equation?

p + q = 1

What is genetic drift?

A random change in allele frequencies due to chance, which is particularly strong in small populations.

What does a phylogenetic tree represent?

Hypotheses about evolutionary relationships based on common ancestry.

What is a basal taxon?

A lineage that diverged early in the history of a group on a phylogenetic tree.

What are sister taxa?

Two lineages that share an immediate common ancestor and are each other's closest relatives.

What is a cladogram?

A branching diagram that groups organisms based on shared derived characters.

What is an ingroup in a cladogram?

The specific group of organisms being studied.

What are derived characters?

Traits that evolved in a lineage after it split from its ancestor and help define clades.

What are ancestral characters?

Traits inherited from a distant ancestor that are older than the derived traits being studied.

What is a paraphyletic group?

A group that includes a common ancestor and some, but not all, of its descendants.

What is a polyphyletic group?

A group made of organisms from different lineages that does not include their most recent common ancestor.

What is reproductive isolation?

Any mechanism that prevents gene flow between populations, allowing them to evolve into separate species.

What is sympatric speciation?

The formation of new species without geographic separation, often through reproductive isolation within the same area.

What are hybrid zones?

Regions where two closely related species meet and interbreed, producing hybrid offspring.

How does radiometric dating determine absolute age?

By measuring the decay of radioactive isotopes in rocks or fossils.

What effect does continental drift have on evolution?

It changes species distributions and can isolate populations.

What are mass extinctions?

Events where a large percentage of species disappear in a relatively short geologic time.

What are stromatolites?

Layered rock structures formed by ancient microbial mats, representing some of the oldest evidence of life on Earth.

What defines a eukaryotic cell?

The presence of a nucleus and membrane-bound organelles.

What is multicellularity?

A condition in which many cells live together, specialize, and cooperate.