Comprehensive Review: Evolution, Speciation, and the History of Life

Flashcards covering key concepts from biology lecture notes on taxonomy, evolutionary processes, speciation mechanisms, phylogenetics, and the historical fossil record.

What process explains the pattern of evolution and drives speciation by causing populations to diverge into new species?

Natural selection

What two core claims define the 'Tree of Life' concept?

1. All species come from pre-existing species and share a common ancestor.
2. Construction of a 'tree' with a single organism at its base is possible.

Who is recognized as the 'Father of Taxonomy' for establishing a system to name species in 1735?

Carolus Linnaeus

What are the rules of binomial nomenclature established by Linnaeus?

Each species receives a two-part scientific name consisting of a capitalized genus name and a lowercase species name, written in Latin or Greek, and always italicized (or underlined when handwritten).

What is the hierarchical sequence of taxonomic groups from least specific to most specific?

Kingdom, Phylum, Class, Order, Family, Genus, Species (KPCOFGS).

What were the five kingdoms proposed by Robert Whittaker in the 1960s?

Kingdom Monera, Kingdom Protista, Kingdom Plantae, Kingdom Fungi, and Kingdom Animalia.

How do homologous structures differ from homoplasic structures?

Homologous structures result from divergent evolution (common ancestor) and have different functions/appearances with the same underlying structure. Homoplasic structures result from convergent evolution (different ancestors) and have similar functions/appearances with different underlying structures.

Who analyzed small subunit rRNA in 1977 to construct a phylogenetic tree of all living organisms?

Carl Woese

What three major domains of life were identified using small subunit rRNA sequences?

Domain Bacteria, Domain Archaea, and Domain Eukarya.

What are the six currently recognized kingdoms of life?

Archaea, Bacteria, Protista, Plantae, Fungi, and Animalia.

What is the fundamental definition of evolution at the population level?

A change in allele frequencies over time.

What are the five evolutionary processes that cause changes in allele frequencies in a population?

1. Mutation
2. Nonrandom mating (sexual selection)
3. Genetic drift
4. Gene flow
5. Natural selection

What is genetic drift, and what two main phenomena produce it?

Genetic drift is a random change in allele frequencies occurring in small populations, caused by the bottleneck effect or the founder effect.

Why is natural selection unique among the five evolutionary processes?

It is the only cause of change in allele frequencies that adapts a population to its specific environment.

How does directional selection alter the phenotype of a population?

It changes the average phenotype of a population in one direction over time due to environmental change.

What is stabilizing selection and how does it affect phenotypic variation?

Stabilizing selection favors phenotypes near the middle of the variation range, maintaining the average phenotypic value and reducing overall genetic variation.

How does disruptive selection affect phenotypic distribution within a population?

It selects against average phenotypes and favors extreme phenotypes at both ends of the phenotypic range.

What two essential steps lead to speciation?

1. Genetic isolation (lack of gene flow)
2. Genetic divergence (caused by mutation, natural selection, and genetic drift)

What is the primary criterion for defining species according to the Biological Species Concept?

Reproductive isolation (members can interbreed and produce viable, fertile offspring).

What five prezygotic barriers prevent mating or fertilization between different species?

1. Temporal isolation
2. Habitat isolation
3. Behavioral isolation
4. Mechanical isolation
5. Gametic isolation

What are the two postzygotic isolation mechanisms?

1. Hybrid inviability (hybrid embryos fail to develop normally and die)
2. Hybrid sterility (hybrids mature but are sterile as adults)

What are the main limitations of the Biological Species Concept?

It cannot be applied to fossil species, asexual species (such as bacteria), or geographically isolated populations whose ranges do not overlap.

How does the Morphospecies concept identify species, and what are its drawbacks?

It identifies species based on physical differences. Disadvantages include misidentifying polymorphic species, missing cryptic species, and relying on subjective criteria.

What is a monophyletic group (or clade)?

An evolutionary unit consisting of an ancestral population, all of its descendants, and no other organisms.

What is a synapomorphy?

A shared derived trait found in a specific group of organisms and their common ancestor, but absent in more distant ancestors.

What is the distinction between allopatry and sympatry?

Allopatry refers to populations living in geographically separated locations, whereas sympatry refers to populations living in the same geographic region close enough to interbreed.

What two events can cause allopatric isolation?

1. Dispersal (a group colonizes a new habitat)
2. Vicariance (physical splitting of a habitat by a geographic barrier)

What two mechanisms can trigger sympatric speciation within a population?

1. Disruptive selection based on different ecological niches
2. Polyploidy (chromosomal mutations)

What is the difference between autopolyploidy and allopolyploidy?

Autopolyploidy involves chromosome duplication derived from a single parent species due to meiotic nondisjunction. Allopolyploidy occurs when parents of two different species mate to form a hybrid, followed by chromosome duplication.

Why are triploid ($3n$) hybrid plants typically sterile and seedless?

Because uneven numbers of homologous chromosomes cannot be evenly segregated during meiosis, producing abnormal gametes.

What is the difference between microevolution and macroevolution?

Microevolution is observable evolution occurring within populations at the allele frequency level, whereas macroevolution refers to evolutionary changes at or above the species level over large time scales.

In cladistics, what does the principle of parsimony state?

The most likely phylogenetic tree is the one requiring the fewest evolutionary changes (traits gaining or losing state).

How did SINES (short interspersed nuclear elements) confirm that whales evolved from an artiodactyl ancestor closely related to hippos?

Whales and hippos share four unique SINE gene insertions at specific loci that are absent in other artiodactyl lineages, serving as shared derived traits (synapomorphies).

What four biases distort the completeness of the fossil record?

1. Habitat bias (organisms in sediment-depositing areas fossilize more easily)
2. Taxonomic bias (organisms with hard structures preserve better)
3. Temporal bias (recent fossils are less likely to be destroyed)
4. Abundance bias (abundant, widespread, or long-lasting species leave more fossils)

What major evolutionary event marks the beginning of the Paleozoic Era?

The Cambrian Explosion (the rapid evolutionary diversification of almost all major animal phyla).

Which plant and animal groups were dominant during the Mesozoic Era versus the Cenozoic Era?

Gymnosperms and dinosaurs were dominant during the Mesozoic Era; angiosperms (flowering plants) and mammals are dominant during the Cenozoic Era.

What is adaptive radiation and what two main mechanisms trigger it?

Adaptive radiation is the rapid diversification of a single lineage into many descendant species with varied adaptive forms. It is triggered by ecological opportunity (new resources/niches) and morphological innovation (key trait evolution).

What caused the End-Permian extinction, the largest mass extinction event in Earth history?

Massive flood basalt eruptions (Siberian traps) released immense heat, CO2, and sulfur dioxide, causing toxic acid rain, global ocean anoxia, global fires, and severe sea-level drops, killing over 90% of multicellular species.

What evidence supports the asteroid impact theory for the End-Cretaceous (K-T) mass extinction?

High concentrations of iridium in sediment at the K-T boundary, shock quartz, microtektites, and a 10 km wide crater off the coast of the Yucatán Peninsula.