Evolution, Systematics, and Population Genetics Review

These flashcards cover major concepts from the lecture notes on phylogeny, systematics, evidence for evolution, mechanisms of microevolution, population genetics, and taxonomy. Each card presents a key question with its concise answer to facilitate exam review.

What does the term "phylogeny" describe?

The evolutionary history of a species or group of related species.

Which discipline classifies organisms and infers their evolutionary relationships?

Systematics.

What are the two lasting features of Linnaeus’s taxonomic system?

Binomial nomenclature and a hierarchical classification of taxa.

List the main taxonomic ranks from most inclusive to least inclusive.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

In a phylogenetic tree, what does a branch point represent?

The divergence of two evolutionary lineages from a common ancestor.

What are sister taxa?

Groups that share an immediate common ancestor not shared by any other group.

What is the key difference between homology and analogy?

Homology is similarity due to shared ancestry; analogy (homoplasy) is similarity not due to common ancestry.

Give the term for DNA sequence similarity produced by a speciation event.

Orthologs.

Which term describes gene similarity caused by a duplication event within a genome?

Paralogs.

Horizontal transfer of genes between unrelated lineages produces what kind of molecular homology?

Xenologs.

State the principle of maximum parsimony.

The simplest explanation (fewest evolutionary events) is preferred when constructing phylogenies.

Name three things phylogenetic trees do NOT show.

Exact times of divergence, amount of change in lineages, or direct ancestor–descendant relationships between neighboring taxa.

Define cladistics.

A method of systematics that groups organisms into clades—monophyletic groups containing an ancestor and all its descendants.

Contrast monophyletic, paraphyletic, and polyphyletic groupings.

Monophyletic includes an ancestor and all descendants; paraphyletic excludes some descendants; polyphyletic lacks the most recent common ancestor.

What is horizontal gene transfer?

The movement of genes from one genome to another by mechanisms other than parent-to-offspring inheritance.

Define convergent evolution.

Independent evolution of similar traits in distantly related lineages due to similar environmental pressures, producing analogies.

What are vestigial structures?

Remnants of features that served important functions in an organism’s ancestors but are reduced or unused in the descendant.

List four lines of evidence for evolution discussed in lecture.

Homology, the fossil record, biogeography, and genetic/molecular evidence.

How are most fossils dated directly?

By radiometric dating of certain rock types encasing the fossils.

Define biogeography.

The scientific study of the geographic distribution of species.

What is an endemic species?

A species found nowhere else in the world except its specific location.

Why is the universal genetic code considered evidence for common ancestry?

Because nearly all known organisms use the same codon system to translate DNA into proteins.

State Darwin’s definition of natural selection.

A process in which individuals with favorable inherited traits are more likely to survive and reproduce.

In evolutionary terms, what is "fitness"?

The relative ability of an individual to survive and produce fertile offspring.

Name Darwin’s three broad observations explained by natural selection.

The unity of life, the diversity of life, and organisms’ fit (adaptation) to their environments.

What two observations led Darwin to his first inference about natural selection?

Variation among individuals and the tendency of species to produce more offspring than the environment can support.

Summarize Lamarck’s (unsupported) mechanism for evolution.

Traits acquired during an organism’s lifetime are inherited by its offspring (use and disuse).

Define artificial selection.

Human-directed breeding that selects for desirable traits in organisms.

At what biological level does evolution actually occur?

Populations evolve, even though natural selection acts on individuals.

What is speciation?

The process by which one species splits into two or more distinct species.

Differentiate microevolution and macroevolution.

Microevolution is change in allele frequencies within a population; macroevolution is evolution above the species level.

List the four mechanisms that cause microevolution.

Natural selection, genetic drift, gene flow, and mutation.

Define genetic drift.

Random changes in allele frequencies due to chance events, often reducing variation.

What is the founder effect?

Genetic drift that occurs when a small group isolates from a larger population, carrying only a subset of alleles.

Describe the bottleneck effect.

A sudden reduction in population size that changes allele frequencies and may lead to inbreeding.

Why does inbreeding reduce population fitness?

It increases homozygosity, raising the chance that harmful recessive alleles will be expressed.

Define gene flow.

The movement of alleles among populations via migration of individuals or gametes.

What is a gene pool?

The complete set of alleles for all loci present in a population.

State the Hardy–Weinberg equation for allele frequencies.

p + q = 1, where p and q represent the frequencies of two alleles at a locus.

Name the five conditions required for Hardy–Weinberg equilibrium.

No mutations, random mating, no natural selection, extremely large population size, and no gene flow.

What is considered the ultimate original source of new alleles?

Mutation.

Define sexual selection.

A process in which individuals with certain traits are more likely to obtain mates.

Contrast intrasexual and intersexual selection.

Intrasexual selection is competition within one sex (often males); intersexual selection is mate choice by the opposite sex (often females).

Explain directional selection.

Selection that favors individuals at one extreme of a phenotypic range.

Explain disruptive selection.

Selection that favors individuals at both extremes of a phenotypic range over intermediate forms.

Explain stabilizing selection.

Selection that favors intermediate phenotypes and acts against extremes.

What does the principle of parsimony (Ockham’s razor) state in phylogenetics?

The simplest tree that fits the data (fewest evolutionary steps) is preferred.

Name the three domains of life.

Bacteria, Archaea, and Eukarya.

Give two key characteristics of the domain Bacteria.

Unicellular prokaryotes with cell walls; reproduce asexually.

Give two key characteristics of the domain Archaea.

Unicellular prokaryotes with cell walls; often inhabit extreme environments.

What distinguishes domain Eukarya from the other two domains?

Cells with nuclei and membrane-bound organelles.

To which class do humans, cats, dogs, and mice belong?

Mammalia.

All monkeys are placed in which taxonomic order?

Primates.

Birds belong to which class?

Aves.

What are the two parts of a scientific name in binomial nomenclature?

Genus name and specific epithet (species name).

What is a holotype?

The single physical specimen designated as the type example of a species.

Define homoplasies.

Analogous structures or molecular sequences that evolved independently in different lineages.

Which two evolutionary mechanisms decrease genetic variation within a population?

Natural selection and genetic drift.

Which two mechanisms typically increase genetic variation within a population?

Gene flow and mutation.

What does the term "phylogeny" describe?

The evolutionary history of a species or group of related species.

Which discipline classifies organisms and infers their evolutionary relationships?

Systematics.

What are the two lasting features of Linnaeus’s taxonomic system?

Binomial nomenclature and a hierarchical classification of taxa.

List the main taxonomic ranks from most inclusive to least inclusive.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

In a phylogenetic tree, what does a branch point represent?

The divergence of two evolutionary lineages from a common ancestor.

What are sister taxa?

Groups that share an immediate common ancestor not shared by any other group.

What is the key difference between homology and analogy?

Homology is similarity due to shared ancestry; analogy (homoplasy) is similarity not due to common ancestry.

Give the term for DNA sequence similarity produced by a speciation event.

Orthologs.

Which term describes gene similarity caused by a duplication event within a genome?

Paralogs.

Horizontal transfer of genes between unrelated lineages produces what kind of molecular homology?

Xenologs.

State the principle of maximum parsimony.

The simplest explanation (fewest evolutionary events) is preferred when constructing phylogenies.

Name three things phylogenetic trees do NOT show.

Exact times of divergence, amount of change in lineages, or direct ancestor–descendant relationships between neighboring taxa.

Define cladistics.

A method of systematics that groups organisms into clades—monophyletic groups containing an ancestor and all its descendants.

Contrast monophyletic, paraphyletic, and polyphyletic groupings.

Monophyletic includes an ancestor and all descendants; paraphyletic excludes some descendants; polyphyletic lacks the most recent common ancestor.

What is horizontal gene transfer?

The movement of genes from one genome to another by mechanisms other than parent-to-offspring inheritance.

Define convergent evolution.

Independent evolution of similar traits in distantly related lineages due to similar environmental pressures, producing analogies.

What are vestigial structures?

Remnants of features that served important functions in an organism’s ancestors but are reduced or unused in the descendant.

List four lines of evidence for evolution discussed in lecture.

Homology, the fossil record, biogeography, and genetic/molecular evidence.

How are most fossils dated directly?

By radiometric dating of certain rock types encasing the fossils.

Define biogeography.

The scientific study of the geographic distribution of species.

What is an endemic species?

A species found nowhere else in the world except its specific location.

Why is the universal genetic code considered evidence for common ancestry?

Because nearly all known organisms use the same codon system to translate DNA into proteins.

State Darwin’s definition of natural selection.

A process in which individuals with favorable inherited traits are more likely to survive and reproduce.

In evolutionary terms, what is "fitness"?

The relative ability of an individual to survive and produce fertile offspring.

Name Darwin’s three broad observations explained by natural selection.

The unity of life, the diversity of life, and organisms’ fit (adaptation) to their environments.

What two observations led Darwin to his first inference about natural selection?

Variation among individuals and the tendency of species to produce more offspring than the environment can support.

Summarize Lamarck’s (unsupported) mechanism for evolution.

Traits acquired during an organism’s lifetime are inherited by its offspring (use and disuse).

Define artificial selection.

Human-directed breeding that selects for desirable traits in organisms.

At what biological level does evolution actually occur?

Populations evolve, even though natural selection acts on individuals.

What is speciation?

The process by which one species splits into two or more distinct species.

Differentiate microevolution and macroevolution.

Microevolution is change in allele frequencies within a population; macroevolution is evolution above the species level.

List the four mechanisms that cause microevolution.

Natural selection, genetic drift, gene flow, and mutation.

Define genetic drift.

Random changes in allele frequencies due to chance events, often reducing variation.

What is the founder effect?

Genetic drift that occurs when a small group isolates from a larger population, carrying only a subset of alleles.

Describe the bottleneck effect.

A sudden reduction in population size that changes allele frequencies and may lead to inbreeding.

Why does inbreeding reduce population fitness?

It increases homozygosity, raising the chance that harmful recessive alleles will be expressed.

Define gene flow.

The movement of alleles among populations via migration of individuals or gametes.

What is a gene pool?

The complete set of alleles for all loci present in a population.

State the Hardy–Weinberg equation for allele frequencies.

p + q = 1, where p and q represent the frequencies of two alleles at a locus.

Name the five conditions required for Hardy–Weinberg equilibrium.

No mutations, random mating, no natural selection, extremely large population size, and no gene flow.

What is considered the ultimate original source of new alleles?

Mutation.