Textbook Question
Which of the following is an example of homoplasy?
a. Hair in humans and fur in mice
b. Astragalus ankle bones in hippos and deer
c. Hox genes in humans and flies
d. Streamlined bodies in dolphins and ichthyosaurs
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Ch. 25 - Phylogenies and the History of Life
Freeman8th EditionBiological ScienceISBN: 9780138276263
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Table of contents
- Ch. 1 - Biology: The Study of Life13
- Ch. 2 - Water and Carbon: The Chemical Basis of Life14
- Ch.3 - Protein Structure and Function10
- Ch.4 - Nucleic Acids and the RNA World10
- Ch. 5 - An Introduction to Carbohydrates10
- Ch. 6 - Lipids, Membranes, and the First Cells11
- Ch. 7 - Inside the Cell10
- Ch. 8 - Energy and Enzymes: An Introduction to Metabolism10
- Ch. 9 - Cellular Respiration and Fermentation11
- Ch. 10 - Photosynthesis12
- Ch. 11 - Cell-Cell Interactions12
- Ch. 12 - The Cell Cycle8
- Ch. 13 - Meiosis12
- Ch. 14 - Mendel and the Gene23
- Ch. 15 - DNA and the Gene: Synthesis and Repair15
- Ch. 16 - How Genes Work16
- Ch. 17 - Transcription, RNA Processing, and Translation16
- Ch. 18 - Control of Gene Expression in Bacteria16
- Ch. 19 - Control of Gene Expression in Eukaryotes12
- Ch. 20 - The Molecular Revolution: Biotechnology, Genomics, and New Frontiers15
- Ch. 21 - Genes, Development, and Evolution12
- Ch. 22 - Evolution by Natural Selection16
- Ch. 23 - Evolutionary Processes13
- Ch. 24 - Speciation15
- Ch. 25 - Phylogenies and the History of Life13
- Ch. 26 - Bacteria and Archaea15
- Ch. 27 - Diversification of Eukaryotes16
- Ch. 28 - Green Algae and Land Plants16
- Ch. 29 - Fungi18
- Ch. 30 - An Introduction to Animals9
- Ch. 31 - Protostome Animals15
- Ch. 32 - Deuterostome Animals17
- Ch. 33 - Viruses16
- Ch. 34 - Plant Form and Function16
- Ch. 35 - Water and Sugar Transport in Plants16
- Ch. 36 - Plant Nutrition13
- Ch. 37 - Plant Sensory Systems, Signals, and Responses16
- Ch. 38 - Flowering Plant Reproduction and Development16
- Ch. 39 - Animal Form and Function17
- Ch. 40 - Water and Electrolyte Balance in Animals16
- Ch. 41 - Animal Nutrition16
- Ch. 42 - Gas Exchange and Circulation16
- Ch. 43 - Animal Nervous Systems16
- Ch. 44 - Animal Sensory Systems16
- Ch. 45 - Animal Movement11
- Ch. 46 - Chemical Signals in Animals16
- Ch. 47 - Animal Reproduction and Development16
- Ch. 48 - The Immune System in Animals16
- Ch. 49 - An Introduction to Ecology15
- Ch. 50 - Behavioral Ecology16
- Ch. 51 - Population Ecology16
- Ch. 52 - Community Ecology20
- Ch. 53 - Ecosystems and Global Ecology17
- Ch. 54 - Biodiversity and Conservation Ecology18
Chapter 25, Problem 7
Describe one similarity between the End-Cretaceous Extinction and the Sixth Mass Extinction, and one difference.
Verified step by step guidance1
Identify the common factor between the End-Cretaceous Extinction and the Sixth Mass Extinction: Both events are characterized by significant biodiversity loss, impacting numerous species across various ecosystems.
Examine the causes of the End-Cretaceous Extinction, which is widely believed to be triggered by a catastrophic asteroid impact that led to drastic environmental changes.
Explore the causes of the Sixth Mass Extinction, which is currently ongoing and primarily driven by human activities such as habitat destruction, pollution, climate change, and overexploitation of species.
Highlight the similarity: Both extinctions demonstrate how abrupt changes in the environment can lead to massive losses in biodiversity.
Point out the difference: The primary cause of the End-Cretaceous Extinction was a natural event (asteroid impact), whereas the Sixth Mass Extinction is largely the result of anthropogenic (human-induced) factors.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
End-Cretaceous Extinction
The End-Cretaceous Extinction, occurring around 66 million years ago, is one of the most significant mass extinctions in Earth's history, famously known for the demise of the dinosaurs. It is believed to have been caused by a combination of volcanic activity, climate change, and a catastrophic asteroid impact, leading to drastic environmental changes that wiped out approximately 75% of species.
Recommended video:
04:55
Cretaceous Extinction
Sixth Mass Extinction
The Sixth Mass Extinction refers to the ongoing extinction event primarily driven by human activities, such as habitat destruction, pollution, climate change, and overexploitation of species. Unlike previous mass extinctions, which occurred over geological timescales, the current extinction is happening at an accelerated rate, with estimates suggesting that species are disappearing 100 to 1,000 times faster than the natural background rate.
Recommended video:
02:29Sixth Extinction
Comparative Analysis of Extinctions
When comparing mass extinctions, one can identify similarities such as the widespread loss of biodiversity and significant shifts in ecological dynamics. However, differences often arise in their causes and the timeframes over which they occur. For instance, the End-Cretaceous Extinction was a rapid event triggered by external factors, while the Sixth Mass Extinction is a gradual process largely influenced by anthropogenic factors.
Recommended video:
04:48Extinctions
Related Practice
Textbook Question
What important assumption does parsimony make when assessing which phylogenetic tree is most accurate? Why was parsimony misleading in the case of the astragalus during the evolution of artiodactyls?
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Textbook Question
You can use a 'one-snip test' to identify monophyletic groups—meaning that if you 'cut' any branch on a tree, everything that 'falls off' is a monophyletic group. Why is this valid?
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Textbook Question
Use the fossil evidence shown in Figure 25.6 to determine whether flight evolved earlier in insects or in birds. Is flight an example of homology or convergent evolution? Explain.
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Textbook Question
The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria, but so few in others, such as Ctenophora? Based on your reading of this chapter, propose at least five traits that you think might have been most important in triggering diversification within phyla (examples: origin of hearing, origin of internal fertilization).
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Textbook Question
The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora? Jezkova and Wiens used a type of graph called a linear regression to find correlations between variables such as the proportion of species per phylum with legs (on the y-axis) and the diversification rate per phylum (on the x-axis). Sketch a graph to show what a strong positive correlation between these two variables would look like and what the absence of a correlation would look like.
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