BIOL1020: Diversity of Life I - Evolution Practice Flashcards

A comprehensive study set covering concepts of evolution, mechanisms of microevolution and macroevolution, speciation models, reproductive barriers, and paleontological evidence.

What is the broad definition of evolution?

The theory that all past and present organisms ultimately descended from a common ancestor through a long series of natural changes.

According to Archbishop James Ussher, on what exact date did creation occur?

Creation occurred on $22\text{ October}, 4004\text{ B.C.}$

What was 'The Great Chain of Being' proposed by Charles Bonnet in $1745$?

A linear arrangement linking human beings at the pinnacle of creation with lower life forms and basic matter based on superficial resemblances.

What theory did Georges Cuvier propose to explain odd fossils while opposing species change over time?

Catastrophism, which proposed that periodic floods and other catastrophes destroyed life in the past, followed by immigration from other regions.

How did Carolus Linnaeus explain the emergence of new plant varieties within his 'fixed' species concept?

He proposed that God created one species per genus, and new species subsequently arose within genera through cross-pollination hybridization.

What is Comte de Buffon's Theory of Degeneration?

The theory that closely related forms derived from a single ancestral population that subdivided through migration, accumulating reversible changes due to different climatic conditions while remaining in the same fixed mold species.

How do James Hutton's geological concepts compare to Charles Lyell's Principle of Uniformitarianism?

Hutton suggested gradual geological mechanisms (such as rivers forming valleys), while Lyell established uniformitarianism—the principle that the same mechanisms of geological change operate at constant rates today as in the past.

What are the core concepts of Jean-Baptiste Lamarck's Theory of Inheritance of Acquired Traits?

Organisms have an innate drive to become more complex, adaptively altering organs through use or disuse during their lifetime, and passing those acquired changes to offspring via soft inheritance.

What were the dates and ship involved in Charles Darwin's survey voyage?

Darwin sailed as a scientific observer aboard H.M.S. Beagle on a five-year world survey from $1831\text{--}1836$.

What key observation did Darwin make regarding finches on the Galápagos Islands?

He observed multiple finch species across the islands with distinct beak shapes that corresponded to specific dietary foods, compared to only one finch species on the South American mainland.

What are the four requirements for evolution to occur by natural selection?

1) Organisms produce more offspring than can survive; 2) Inherited phenotypic variations exist within populations; 3) Existence is a constant struggle for limited resources; 4) Adaptive traits become more common over generations due to differential reproduction.

What six key elements define the modern theory of evolution?

1) Evolution (population allele frequency changes); 2) Gradualism; 3) Common ancestry; 4) Speciation; 5) Natural selection; 6) Non-selective evolutionary forces (such as genetic drift).

How did August Weismann's Germ Plasm Theory refute Darwin's hypothesis of Pangenesis?

Pangenesis proposed body cells shed gemmules into gonads to pass acquired traits, whereas Weismann showed that only germ cells carry hereditary material, while somatic body cells do not influence inheritance.

What three inheritance laws were formulated by Gregor Mendel?

1) Law of equal segregation (allele pairs segregate during gamete formation); 2) Law of independent assortment (alleles for different traits pass independently); 3) Law of dominance (dominant alleles mask recessive alleles).

What is the difference between microevolution and macroevolution?

Microevolution consists of small evolutionary changes in allele frequencies within a species or population over generations, whereas macroevolution refers to evolutionary changes occurring at or above the species level over geologic time.

What is the estimated rate of useful mutations per generation, and what are the two main categories of mutations?

At least $1\text{ in } 10,000$ individuals carries a useful mutation per generation. The two main categories are gene mutations (point mutations, frame shift insertions, or frame shift deletions) and chromosomal mutations (changes in chromosome structure or number).

What are the three fundamental modes of natural selection categorized by their effect on phenotypic distribution?

Directional selection (favors one extreme phenotype), Stabilizing selection (favors intermediate phenotypes), and Disruptive selection (disfavors intermediate phenotypes and favors both extremes).

How did environmental change cause directional selection in the peppered moth (Biston betularia) during the 1850s?

Industrial soot coated trees and killed lichens, granting dark mutant morphs a camouflage advantage over pale morphs, which caused dark morphs to become dominant in industrial areas.

What are the two forms of sexual selection?

Male/Male competition (direct combat between males where the winner gains access to females by driving off rivals) and Female choosiness (indirect competition where females choose mates based on exaggerated traits).

What is genetic drift, and what are its two special promoting situations?

Genetic drift is chance variation in allele frequencies due to random gamete sampling error in small populations. Its two special situations are the Founder Effect (a small colonizing group carries a non-representative gene pool) and the Bottleneck Effect (drastic population reduction leaves a remnant gene pool).

What real-world examples illustrate the Founder Effect and the Bottleneck Effect?

The Eastern Pennsylvania Amish population of $\thicksim 200$ founders shows high frequencies of polydactyly and dwarfism (Founder Effect), while South and East African cheetahs show reduced genetic diversity due to severe population depletion (Bottleneck Effect).

What is the Biological Species Concept, and what are its primary shortcomings?

It defines a species as a reproductively isolated community of populations occupying a specific niche. Its shortcomings are that it does not apply to asexually reproducing organisms (e.g. bacteria), extinct fossil species, or geographically isolated populations.

Which diagram illustrates the geographic patterns of Allopatric, Parapatric, and Sympatric speciation?

Allopatric speciation involves barrier formation isolating populations, Parapatric involves entering an adjacent niche, and Sympatric involves genetic polymorphism arising within the same population.

What are the six pre-zygotic reproductive barriers that prevent interbreeding between species?

Geographic isolation, Temporal isolation, Ecological isolation, Behavioral isolation, Mechanical isolation, and Gametic incompatibility.

What are the four post-zygotic reproductive barriers that block gene flow after fertilization?

Zygotic mortality (zygote fails to develop), Hybrid inviability (hybrid embryo is not viable), Hybrid sterility (hybrid adult is sterile), and Hybrid breakdown (subsequent hybrid generations are inviable or sterile).

How do Phyletic Gradualism and Punctuated Equilibrium differ regarding evolutionary pace?

Phyletic Gradualism posits that evolution is a slow, steady, continuous process accumulating imperceptible changes, whereas Punctuated Equilibrium posits long periods of stasis punctuated by sudden, abrupt evolutionary changes.

What is homology, and what classic anatomical structure demonstrates it?

Homology is the inheritance of a structure with modification from a common ancestor; an example is the vertebrate forelimb skeleton (human, cat, whale, bat), which shares structural bones and connection patterns despite varied functions.

What is a vestigial trait, and how do ostrich wings illustrate it?

A vestigial trait is an ancestral adaptation that has lost its original primary function or been co-opted for new uses. Ostrich wings no longer enable flight but are used for balance while running, shade for chicks, and threat displays against predators.

What anatomical evidence demonstrates vestigial limbs in cetaceans?

Whales retain a vestigial pelvis and leg bones that are completely disconnected from the rest of the skeleton.

What vestigial ear muscles do humans possess, and what is their functional origin?

Humans possess three ear muscles (Auricularis superior, Auricularis anterior, Auricularis posterior) used by other mammals to orient the pinna, but which are useless in most humans except for rare ear-wigglers.

How does an atavism differ from a vestigial trait, and what is a human example?

An atavism is the occasional re-expression of an ancestral trait lost in a species due to gene deactivation (occurring rarely rather than universally); a human example is a baby born with a fleshy, hairy, or moveable tail.

Why is the recurrent laryngeal nerve cited as an example of imperfect evolutionary design?

It loops under the aorta (derived from the $6\text{th}$ branchial arch of fish ancestors), extending $0.9\text{ m}$ in humans and $5\text{ m}$ in giraffes ($4.5\text{ m}$ longer than the direct route) to connect the brain to the larynx.

Why is the fossil record incomplete, and what fraction of all species that ever lived has been discovered as fossils?

Fossilization requires rare conditions (aquatic submersion, sediment burial, mineral infiltration, surviving crust shifts, and discovery). Only $\thicksim 250,000$ fossil species have been discovered, representing $0.006\text{--}1\text{\%}$ of all species that ever lived.

What is the Law of Superposition?

In a vertical sequence of rock layers, the oldest strata lie at the bottom and layers are successively younger toward the top.

How do Uranium-235 and Carbon-14 differ in radiometric dating half-lives and uses?

Uranium-235 has a half-life of $700\text{ million years}$ (used for dating very old rocks), while Carbon-14 has a half-life of $5,730\text{ years}$ (used for dating recent organic material).

What transitional fossil represents the colonization of land from water around $375\text{ MYA}$?

Tiktaalik roseae, discovered in ancient freshwater strata in the Arctic Ocean north of Canada, possessing fish traits (gills, scales, fins) and tetrapod traits (flattened head, neck, sturdy ribs, robust fin bones).

What transitional fossil links theropod dinosaurs to modern birds at $145\text{ MYA}$?

Archaeopteryx lithographica, possessing reptilian theropod features (toothed jaw, long bony tail, clawed wing fingers) and avian features (large feathers, furcula, opposable toe).

What early semi-aquatic artiodactyl from $48\text{ MYA}$ is identified as a close relative of ancient whales?

Indohyus, an artiodactyl that lived near water and shares specialized thick ear bones with cetaceans.

What are the four units of the Geologic Time Scale listed from shortest to longest duration?

Epoch (subdivision of a period), Period (basic unit of rock system formation), Era (two or more periods), and Eon (two or more eras).