BIOA01 - Deck 3 - Q101~Q150

Question 1

What is synapomorphy?

Answer 1

A synapomorphy is a shared derived trait that is unique to a particular group of organisms, indicating a common evolutionary ancestor.

Question 2

Describe the example of species analysis in African and Asian elephants.

Answer 2

They are considered different species based on genetic and morphological differences, supporting the concept of distinct species.

Question 3

What is speciation?

Answer 3

Speciation is the process by which populations diverge and become reproductively isolated, leading to the formation of new species.

Question 4

What is allopatric speciation?

Answer 4

Allopatric speciation occurs when populations become isolated from each other geographically, leading to reproductive isolation and the evolution of separate species.

Question 5

How can we observe allopatric speciation via dispersal? Describe how Darwin’s finches provide an example.

Answer 5

Dispersal allopatric speciation results from a few individuals colonizing a new, isolated area, as seen in Darwin’s finches on different islands, leading to distinct species.

Question 6

How can we observe allopatric speciation via vicariance? Describe how ratite birds provide an example.

Answer 6

Vicariance allopatric speciation occurs when a barrier divides a population, as seen in ratite birds like ostriches and emus due to continental drift.

Question 7

What is Pangaea? What is Laurasia and Gondwana?

Answer 7

Pangaea, around 335-175 million years ago, split into Laurasia (north) and Gondwana (south), shaping the modern continents.

Question 8

What is sympatric speciation? Describe how Rhagoletis pomonella provides an example.

Answer 8

Sympatric speciation happens within the same geographic area. For instance, the apple maggot fly (Rhagoletis pomonella) formed distinct species due to different host plants in one location.

Question 9

How can polyploidy lead to speciation?

Answer 9

Polyploidy, with multiple chromosome sets, can cause speciation by isolating polyploids from diploids, fostering new species formation.

Question 10

What is autopolyploidy? What is allopolyploidy? Why can changes in ploidy essentially lead to “instant speciation”?

Answer 10

Autopolyploidy duplicates an individual’s own chromosomes, whereas allopolyploidy arises from hybridization between two species, followed by chromosome duplication. Ploidy changes can lead to “instant speciation” due to reproductive isolation from parent populations.

Question 11

How can chromosomal alterations lead to speciation?

Answer 11

Chromosomal alterations, such as inversions or translocations, can disrupt the normal reproductive processes, leading to reproductive isolation and the evolution of separate species.

Question 12

What is peculiar about human chromosome 2? What is its relationship to different chromosomes found in chimpanzees and other primates?

Answer 12

Human chromosome 2’s formation from the fusion of ancestral chromosomes in primates, like chimpanzees, provides evidence of shared evolutionary history with other primates.

Question 13

What happens when isolated populations make contact?

Answer 13

When isolated populations make contact, various outcomes are possible, including hybridization, reinforcement of reproductive barriers, or the formation of hybrid zones.

Question 14

What is a hybrid zone? Give an example.

Answer 14

A hybrid zone is where distinct species or populations interbreed, creating hybrids. An example is the gray wolf-coyote hybrid zone in North America.

Question 15

How can we visualize a hybrid zone?

Answer 15

Hybrid zones can be visualized by mapping the distribution of hybrid individuals and examining the gradual transition between traits of the two parent populations.

Question 16

What is reinforcement? Give an example. When does reinforcement evolve?

Answer 16

Reinforcement enhances reproductive barriers, preventing hybridization between species due to reduced hybrid fitness. It arises when there’s selection for stronger prezygotic isolation.

Question 17

What is hybridization?

Answer 17

Hybridization is the process of interbreeding between individuals from different species or populations, resulting in hybrid offspring with a mix of traits from the parent species.

Question 18

What is a phylogeny?

Answer 18

A phylogeny is the evolutionary history and branching pattern of a group of organisms, often represented as a phylogenetic tree.

Question 19

What is a phylogenetic tree? How and why do phylogenetic trees represent hypotheses?

Answer 19

A phylogenetic tree illustrates evolutionary relationships among species or groups, forming hypotheses from existing data subject to revision as new information emerges, reflecting the current understanding of evolution.

Question 20

What is systematics?

Answer 20

Systematics is the study of biodiversity and organism classification based on evolutionary relationships, involving the creation of phylogenetic trees.

Question 21

What are some useful applications of phylogenetic trees?

Answer 21

Phylogenetic trees are used in fields like evolutionary biology, ecology, conservation, and genomics to study evolutionary history, biodiversity, and genetic relationships.

Question 22

What is a clade?

Answer 22

A clade is a group of organisms consisting of an ancestor and all its descendants, representing a single branch on a phylogenetic tree.

Question 23

What is a cladogram? What is a phylogram? How are they similar and how are they different?

Answer 23

A cladogram shows species relationships and divergence order, while a phylogram adds evolutionary change via branch length. Both depict evolution but vary in representing change.

Question 24

What is an outgroup? Describe how an outgroup is important for distinguishing between ancestral and derived traits.

Answer 24

An outgroup is a related taxon that diverged early in the studied group’s evolution, aiding in distinguishing shared ancestral and unique derived traits through comparison.

Question 25

What are the major components of a phylogenetic tree?

Answer 25

A phylogenetic tree consists of nodes (common ancestors), branches (evolutionary links), tips (extant species), and occasionally branch lengths (showing evolutionary change).

Question 26

What is meant by “free rotation at the nodes”?

Answer 26

“Free rotation at the nodes” means that the order in which sister taxa branch off from a common ancestor does not indicate the relative ages of those sister taxa; they are equally related.

Question 27

What are sister taxa?

Answer 27

Sister taxa are species or groups that share a most recent common ancestor and are each other’s closest relatives on a phylogenetic tree.

Question 28

What are characters? What are homologous characters?

Answer 28

Characters are traits or features used in phylogenetics to study evolutionary relationships. Homologous characters are traits that are similar in different species because they share a common ancestor.

Question 29

What is the difference between homology and homoplasy?

Answer 29

Homology refers to traits that are similar due to shared ancestry, while homoplasy refers to traits that are similar but not due to a common ancestor.

Question 30

Describe how homoplasy can be described via analogy and convergent evolution.

Answer 30

Homoplasy is described via analogy when traits evolve independently in different lineages due to similar selective pressures.

Question 31

What is an evolutionary reversal?

Answer 31

An evolutionary reversal is when a trait that was lost in an ancestor reappears in a later descendant.

Question 32

What is a monophyletic clade? Paraphyletic clade? Polyphyletic clade?

Answer 32

A monophyletic clade includes a common ancestor and all of its descendants. A paraphyletic clade includes a common ancestor and some, but not all, of its descendants. A polyphyletic clade includes species that do not share a recent common ancestor.

Question 33

Why are monophyletic clades most important in the context of evolution?*

Answer 33

Monophyletic clades represent true evolutionary relationships, while paraphyletic and polyphyletic clades do not.

Question 34

What is parsimony?

Answer 34

A principle in phylogenetics that favours the simplest explanation or tree with the fewest evolutionary changes.

Question 35

Very briefly, how can we use evolutionary distance (e.g. neighbour joining) and probability (e.g. maximum likelihood and Bayesian analysis) to construct trees?

Answer 35

Evolutionary distance methods like neighbor-joining use genetic distance to construct trees. Probability-based methods like maximum likelihood and Bayesian analysis use likelihood models to estimate tree topologies.

Question 36

What types of characters (traits) are used to construct phylogenetic trees?**

Answer 36

Both molecular (genetic) and morphological characters (traits) are used to construct phylogenetic trees.

Question 37

What is the fossil record? Why is the fossil record incomplete? What are some of the limitations with fossil specimens?

Answer 37

The fossil record is a collection of all known fossils. It’s incomplete due to biases, preservation limitations, and the fact that many organisms didn’t fossilize.

Question 38

Describe some opportunities and limitations in dealing with fossil data: habitat bias, taxonomic bias, tissue bias, temporal bias, abundance bias

Answer 38

• Habitat bias: Fossils are more likely from some environments than others.
• Taxonomic bias: Some organisms are more likely to fossilize than others.
  -Tissue bias: Soft tissues rarely fossilize, leading to a focus on hard body parts.
• Temporal bias: Fossils from some time periods are better preserved.
• Abundance bias: Abundant species are more likely to leave fossils.

Question 39

What is the geological timescale? What is radiometric dating? What is a half-life? What is radioactive decay?

Answer 39

Geological timescale: Divides Earth’s history into eras, periods, and epochs (period of time)
Radiometric dating: Uses radioactive decay of isotopes to determine the age of rocks.
Half-life: The time it takes for half of a radioactive substance to decay.
Radioactive decay: Process where unstable isotopes transform into stable ones, emitting radiation

Question 40

What key events happened in the Precambrian Era? When was the Precambrian Era?

Answer 40

The Precambrian Era is the longest geological era, occurring from about 4.6 billion years ago to 541 million years ago. It includes the formation of Earth, the origin of life, and the development of simple life forms.

Question 41

What is a stromatolite?

Answer 41

Stromatolites are layered structures created by the growth of microbial communities, often found in ancient rocks.

Question 42

How do we know that multicellularity evolved numerous times?

Answer 42

Evidence from the fossil record and molecular phylogenetics suggests that multicellularity evolved independently in various lineages.

Question 43

When was the Phanerozoic Eon? What are the key events that occurred during the Paleozoic Era, Mesozoic Era, and Cenozoic Era?

Answer 43

• The Phanerozoic Eon began about 541 million years ago.
• Paleozoic: Saw the diversification of marine life, land colonization, and the rise of reptiles.
• Mesozoic: The age of dinosaurs and the emergence of mammals and birds.
• Cenozoic: The “Age of Mammals” with diverse mammals and the appearance of primates, including humans.

Question 44

Describe the distinction of Dimetrodon as an ancestor of mammals.

Answer 44

Dimetrodon is not a direct ancestor but belongs to a group of reptiles called synapsids, which includes ancestors of mammals. It shares some characteristics with early mammalian ancestors.

Question 45

When was the Holocene, and what are some notable organisms that existed during that time?

Answer 45

11,700 years ago and continues to the present day. Notable organisms include modern humans and various extant species.

Question 46

Why have researchers proposed the Anthropocene? What is the significance of Crawford Lake in Milton, ON?

Answer 46

The Anthropocene is proposed to mark the era of significant human impact on the Earth’s geology and ecosystems. Crawford Lake contains settling records that help study human impact and environmental changes.

Question 47

What is adaptive radiation?

Answer 47

Adaptive radiation is the rapid diversification of species from a common ancestor into multiple ecological niches.

Question 48

What are the three hallmarks of adaptive radiation?

Answer 48

The hallmarks of adaptive radiation are rapid speciation, divergence into different ecological niches, and an ancestral lineage.

Question 49

Discern between intrinsic factors and extrinsic factors as mechanisms underlying adaptive radiation.

Answer 49

Intrinsic factors involve genetic adaptations within a lineage, while extrinsic factors involve environmental factors that drive diversification.

Question 50

Describe the example of Hawaiian silverswords.

Answer 50

Hawaiian silverswords underwent adaptive radiation in response to different environments, leading to various species with distinct adaptations.