BackWhat 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
How can the Darwinian concept of descent with modification explain the evolution of such complex structures as an eye?
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. Apply Darwin's four postulates to a population of mice living on sand dunes in coastal Florida.
A population of snails is preyed on by birds that break the snails open on rocks, eat the soft bodies, and leave the shells. The snails occur in both striped and unstriped forms. In one area, researchers counted both live snails and broken shells. Their data are summarized below: Which snail form seems better adapted to this environment? Why? Predict how the frequencies of striped and unstriped snails might change in the future.
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.
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.
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?
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?
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.
The global “One Health” movement fosters collaborations at the intersection of human health, veterinary health, and environmental health. Explain why “One Health” seeks to reduce the use of antibiotics in farm animals to improve human health.
Which organism will have the highest fitness?
Which statement would be supported by the concept of common descent?
What is one reason population thinking is so important in biology?