Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 22 - Evolution by Natural Selection
Back
Previous problem
Next problem
All textbooksFreeman 8th EditionCh. 22 - Evolution by Natural SelectionProblem 14

Chapter 21, Problem 14

Over half of the world’s human population lives in cities. Are species adapting to life in these novel urban environments? A global team of researchers (including Tiffany Longo, Jesse Bragger, and Summer Shaheed, shown in in the photo) used white clover as a study system to find out. They measured the production of a compound called hydrogen cyanide (HCN) in rural and urban clover plants. Production of HCN deters herbivores and increases tolerance to drought but has a cost: Clover must expend energy to produce HCN.

This study was conducted by a network of 287 scientists who sampled 110,019 white clover plants (Trifolium repens) in 160 cities globally. Why do you think they chose to study white clover instead of other plants like red maples, coconut palms, or redwoods? What’s one advantage and one disadvantage of conducting such a large collaboration?

Verified step by step guidance
1
Identify the unique characteristics of white clover (Trifolium repens) that make it a suitable model organism for studying urban adaptation. Consider its widespread distribution, ease of sampling, and the specific traits like HCN production that can be clearly measured and compared across different environments.
Discuss the reasons why other plants like red maples, coconut palms, or redwoods might not have been chosen for this study. Consider factors such as their geographic distribution, growth rate, size, and the practicality of measuring specific adaptive traits in these species compared to white clover.
Explain one advantage of using a large collaborative network of scientists for this study. Consider aspects such as the ability to collect a vast amount of data across many different urban environments, which can provide a more comprehensive understanding of how species adapt to urban settings globally.
Discuss one potential disadvantage of such a large-scale collaborative effort. Consider challenges like coordinating research efforts across different locations, standardizing data collection methods to ensure consistency, and the complexities of managing and analyzing a large dataset.
Reflect on the implications of the findings from this study for our understanding of urban ecology and the adaptation of species to urban environments. Consider how this research can contribute to conservation efforts and urban planning to support biodiversity in cities.
Previous problemNext problem
Related Practice
Open Question

Over half of the world’s human population lives in cities. Are species adapting to life in these novel urban environments? A global team of researchers (including Tiffany Longo, Jesse Bragger, and Summer Shaheed, shown in in the photo) used white clover as a study system to find out. They measured the production of a compound called hydrogen cyanide (HCN) in rural and urban clover plants. Production of HCN deters herbivores and increases tolerance to drought but has a cost: Clover must expend energy to produce HCN.

Compare how evolution by inheritance of acquired characters and the theory of evolution by natural selection would explain the observation that HCN production is often high in rural environments with many herbivores and low in urban environments with few herbivores.

1
views
Textbook Question

Most mice living on the mainland of Florida are brown, but the mice that live on the sand dunes of the barrier islands have white fur. The differences in color are heritable, determined by genes such as MC1R. It is intuitive that the light color of beach-dwelling mice is an adaptation for blending into their environment—and thus evading predators. What is an evolutionary adaptation? a. a trait that improves the fitness of its bearer, compared with individuals without the trait b. a trait that changes in response to environmental influences within the individual's lifetime c. the ability of an individual to adjust to its environment d. a trait that an individual wants so that it can survive

742
views
Open Question

Over half of the world’s human population lives in cities. Are species adapting to life in these novel urban environments? A global team of researchers (including Tiffany Longo, Jesse Bragger, and Summer Shaheed, shown in in the photo) used white clover as a study system to find out. They measured the production of a compound called hydrogen cyanide (HCN) in rural and urban clover plants. Production of HCN deters herbivores and increases tolerance to drought but has a cost: Clover must expend energy to produce HCN.

The production of HCN is a heritable Mendelian trait controlled by just two unlinked genes (Ch. 14, Section 14.2; clover plants with at least one dominant allele produce HCN, but plants that are homozygous recessive for both genes produce no HCN). Apply Darwin’s four postulates to explain natural selection for low HCN production in a population of clover living in a city with few herbivores and ample water.

1
views
Open Question

Over half of the world’s human population lives in cities. Are species adapting to life in these novel urban environments? A global team of researchers (including Tiffany Longo, Jesse Bragger, and Summer Shaheed, shown in in the photo) used white clover as a study system to find out. They measured the production of a compound called hydrogen cyanide (HCN) in rural and urban clover plants. Production of HCN deters herbivores and increases tolerance to drought but has a cost: Clover must expend energy to produce HCN.

The researchers measured the frequency of clover plants producing HCN along a transect from each city center out to its rural environment. The graph shows one example of results from Münster, Germany: Anna Bucharova and Christian Lampei sampled 765 plants in 40 populations along a 9.87 km transect. What does the data reveal? What was the prediction of the null hypothesis?


2
views
Open Question

Over half of the world’s human population lives in cities. Are species adapting to life in these novel urban environments? A global team of researchers (including Tiffany Longo, Jesse Bragger, and Summer Shaheed, shown in in the photo) used white clover as a study system to find out. They measured the production of a compound called hydrogen cyanide (HCN) in rural and urban clover plants. Production of HCN deters herbivores and increases tolerance to drought but has a cost: Clover must expend energy to produce HCN.

When a statistical test was used to compare the trend in the data to the prediction of the null hypothesis, the 𝑃 value (see BioSkills 3) was <0.001 for Münster, Germany. Does this result increase or decrease your confidence in the result? Explain.

2
views