Evolution, Microevolution, Macroevolution, and Systematics Flashcards

Flashcards covering evolutionary mechanisms, population genetics, speciation barriers, and phylogenetic systematics from the course lectures.

What is Charles Darwin's core concise definition of evolution?

Descent with modification.

What three conditions of phenotypic variation must be met for natural selection to operate on a population?

The variation must be heritable, phenotypic, and influence fitness.

How does Jean-Baptiste Lamarck's view of evolution differ from Charles Darwin's theory regarding how giraffes acquired long necks?

Lamarck proposed that individual giraffe ancestors lengthened their necks through stretching during their lifetime and passed this acquired trait to descendants, whereas Darwin proposed that natural selection acted on pre-existing, genetically-based variation in neck length.

According to the 1992 field study by S. P. Carroll and C. Boyd, how did soapberry bugs in central Florida adapt after feeding on the introduced golden rain tree?

Their average beak length decreased relative to museum specimens that fed on native balloon vines in southern Florida.

What pair of animals illustrates convergent evolution between Australian marsupials and North American eutherians?

The sugar glider and the flying squirrel, which independently evolved similar gliding membranes due to similar environmental pressures.

What are the four primary fossil stages in horse evolution spanning from $55\,mya$ to recent times?

Eohippus ($55\text{--}45\,mya$), Mesohippus ($40\text{--}30\,mya$), Hipparion ($23\text{--}2\,mya$), and the Przewalski horse (recent).

What formula describes allele frequencies in a two-allele population under Hardy-Weinberg equilibrium?

$p + q = 1$, where $p$ represents the frequency of the dominant allele and $q$ represents the frequency of the recessive allele.

In the Hardy-Weinberg genotype equation $p^2 + 2pq + q^2 = 1$, what genotype frequency does $2pq$ represent?

The frequency of heterozygous individuals in the population.

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

1. No natural selection; 2. No mutations; 3. No gene flow (migration); 4. Extremely large population size; 5. Random mating.

What specific gene alteration controls the evolutionary loss of pelvic hind fins in freshwater populations of sticklebacks?

Alterations in the expression activity of the Pitx1 gene.

What form of nonrandom mating is exhibited when wild pigeons select mates with plumage phenotypes different from their own?

Disassortative mating.

How does a population bottleneck cause genetic drift?

A severe, drastic reduction in population size leaves a small sample of surviving individuals whose allele frequencies differ strictly by chance from the original population.

Why is the sickle-cell allele maintained at higher frequencies in populations exposed to Plasmodium falciparum?

Heterozygote advantage: individuals heterozygous for the sickle-cell allele have greater fitness because they are resistant to malaria.

How does habitat isolation act as a prezygotic reproductive barrier between Florida cottonmouths and Eastern copperheads?

Florida cottonmouths are primarily aquatic while Eastern copperheads are terrestrial, preventing interbreeding despite geographic overlap in the southeastern United States.

What prezygotic barrier isolates the leopard lily (Iris domestica) from the vesper iris (Iris dichotoma)?

Temporal isolation, because Iris domestica flowers bloom in the morning whereas Iris dichotoma flowers bloom in the afternoon.

Based on seasonal mating activity curves, how are wood frogs and leopard frogs temporally isolated?

Wood frogs reach peak mating activity around late March, whereas leopard frogs reach peak mating activity around mid-April.

What is the defining distinction between allopatric speciation and sympatric speciation?

Allopatric speciation occurs when populations are geographically separated by a physical barrier, whereas sympatric speciation occurs without geographic separation within overlapping ranges.

How did the closing of the Isthmus of Panama $3.5\,mya$ drive allopatric speciation in porkfish?

It formed a land bridge that cut off gene flow between the Atlantic/Caribbean and Pacific oceans, causing divergence into Anisotremus virginicus (porkfish) and Anisotremus taeniatus (Panamic porkfish).

What key morphological innovation facilitated the adaptive radiation of Cichlid fish in Lake Victoria?

The evolution of a second set of pharyngeal jaws, allowing different species to exploit distinct food resources.

How did sympatric speciation occur via allopolyploidy in North American Tragopogon species?

Hybridization among three introduced European diploid species ($2n = 12$) produced new, fertile tetraploid species ($2n = 24$) such as T. miscellus and T. mirus.

Which reducing gases were combined with water vapor in Stanley Miller and Harrold Urey's 1953 early Earth experiment?

Nitrogen ($N_2$), ammonia ($NH_3$), carbon dioxide ($CO_2$), carbon monoxide ($CO$), methane ($CH_4$), and hydrogen ($H_2$).

What substrate clay was shown to catalyze the self-assembly of precursor molecules into organic vesicles?

Montmorillonite clay.

In cladistics, what is a synapomorphy?

A shared derived trait inherited from the most recent common ancestor of a clade.

How does a monophyletic taxon differ from a paraphyletic taxon?

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

What does the principle of maximum parsimony dictate when constructing phylogenetic trees?

It assumes that the tree requiring the fewest evolutionary events (trait changes) is the most likely hypothesis.

What is the key difference between orthologous genes and paralogous genes?

Orthologous genes diverge after a speciation event between separate species, whereas paralogous genes arise from gene duplication within a single species.