principles of ecology - powerpoint 5

Questions and Answers

What factor limits adaptive evolution at a gene level?

Lack of genetic variation (correct)

Existence of genetic variation

Presence of advantageous alleles

High mutation rates

How does evolutionary history influence traits in organisms?

Natural selection can create characteristics independent of ancestry.

Natural selection operates on traits that already exist due to ancestry. (correct)

Organisms inherit only favorable traits from their ancestors.

It allows for the emergence of new traits beneficial for survival.

What is an example of an ecological trade-off?

A species thriving at greater population densities.

Increased reproduction leading to decreased survival rates. (correct)

The adaptation of predators to increase prey population.

Gaining resistance to pathogens without any loss in fitness.

In the joint effects of ecology and evolution, what is a potential outcome of a predator evolving a new capturing method?

The prey species may go extinct or evolve new adaptations. Signup and view all the answers

What is NOT a factor that affects adaptive evolution?

Cognitive abilities of organisms Signup and view all the answers

What factor is primarily altered by human actions leading to impacts on evolutionary processes?

Environmental selection pressures Signup and view all the answers

Which type of selection is illustrated by soapberry bugs exhibiting directional selection?

Directional selection Signup and view all the answers

Which of the following factors is NOT mentioned as contributing to the current biodiversity crisis?

Traffic pollution Signup and view all the answers

What evolutionary changes were observed in evening primrose populations in relation to ecological interactions?

Increased lifespan and changes in flowering time Signup and view all the answers

What defines the term 'adaptive radiation' in the context of ecological interactions?

The expansion of species into various ecological niches. Signup and view all the answers

How does climate change contribute to future extinctions?

By altering habitats and creating unfavorable conditions for species Signup and view all the answers

What role does genetic drift often play in speciation?

It skews genetic variation leading to divergence. Signup and view all the answers

Which mechanism of evolution can be directly influenced by habitat fragmentation?

Gene flow Signup and view all the answers

Which of the following best describes the influence of ecological interactions on evolution?

Evolution can reshape ecological interactions over time. Signup and view all the answers

What is a consistent result of natural selection on existing traits?

Modification of existing traits for better fit to the environment. Signup and view all the answers

What does the term 'descent with modification' imply in the context of evolution?

Populations accumulate differences over generations while remaining related to their ancestors. Signup and view all the answers

How does natural selection contribute to evolutionary change?

It favors individuals with certain heritable traits that enhance reproductive success. Signup and view all the answers

What is a primary consequence of genetic drift in a population over time?

It reduces genetic diversity by favoring certain alleles at random. Signup and view all the answers

What role do mutations play in evolution?

They provide the raw genetic material necessary for evolutionary change. Signup and view all the answers

What determines the effect of stabilizing selection on a population?

It preserves intermediate phenotypes and may decrease variation. Signup and view all the answers

How can gene flow among populations enhance evolutionary change?

By introducing new alleles which may alter allele frequencies. Signup and view all the answers

What is a significant reason why individuals do not evolve?

Individual traits do not change within a single lifespan. Signup and view all the answers

Which of the following statements about alleles and phenotypes is true?

Alleles arise through mutations affecting an individual's genotype. Signup and view all the answers

Which mechanism of evolution results from random fluctuations in allele frequencies?

Genetic drift Signup and view all the answers

What happens when two populations experience distinct environmental pressures?

Natural selection may favor different characteristics, leading to divergence. Signup and view all the answers

What role does recombination play in evolution?

It produces different genotypes by rearranging alleles. Signup and view all the answers

Which type of natural selection favors intermediate phenotypes?

Stabilizing selection Signup and view all the answers

How does genetic drift primarily affect small populations?

Allele frequencies fluctuate randomly. Signup and view all the answers

Under which condition can mutation rates significantly impact allele frequencies?

When mutations are linked to advantageous traits. Signup and view all the answers

What is a potential outcome of disruptive selection in a population?

Development of distinct phenotypic groups. Signup and view all the answers

Which example illustrates a trait that has reached fixation due to natural selection?

Andean geese possessing hemoglobin with high oxygen affinity. Signup and view all the answers

Which factor does NOT contribute to genetic drift?

Random mating within large populations. Signup and view all the answers

What is a consequence of extreme directional selection?

Fixation of one extreme phenotype. Signup and view all the answers

What typically happens to the frequency of harmful alleles in small populations due to genetic drift?

They can increase even with mild deleterious effects. Signup and view all the answers

Which mechanism of evolution provides raw material for new genetic combinations?

Mutation Signup and view all the answers

What term describes the change in allele frequencies in a population over time?

Evolution Signup and view all the answers

How does trophy hunting primarily affect Bighorn sheep populations?

Removes the largest and strongest males Signup and view all the answers

What is the primary mechanism for adaptive evolution?

Natural selection Signup and view all the answers

Which statement accurately reflects the effect of human activities on evolution?

Human activities can induce evolutionary changes in populations. Signup and view all the answers

What change is observed in fish populations due to commercial fishing targeting larger specimens?

Fish populations develop genetic traits for earlier maturation and smaller sizes. Signup and view all the answers

What is the genotype of an individual with two different alleles for a gene?

Heterozygous Signup and view all the answers

Which of the following best illustrates the concept of speciation?

Two populations of a species becoming reproductively isolated. Signup and view all the answers

What consequence does poaching of African elephants for ivory have on the population?

It decreases the proportion of tusked individuals. Signup and view all the answers

Study Notes

Key Concepts of Evolution

Evolution is defined as genetic change over time or descent with modification.
Natural selection, genetic drift, and gene flow can alter allele frequencies in populations.
Natural selection is crucial for adaptive evolution, while speciation, extinction, and adaptive radiation shape long-term evolutionary patterns.
Interconnectedness exists between ecological interactions and evolution, influencing one another profoundly.

Case Study: Trophy Hunting

Bighorn sheep populations have decreased by 90% due to hunting, habitat loss, and domestic cattle introduction.
Trophy hunting targets large, strong males, resulting in an average decrease in size and horn length over 30 years.
Similar trends have been observed with commercial cod fishing, where larger fish are harvested, leading to smaller fish maturing earlier.
Poaching of African elephants is decreasing the genetic diversity of tusked individuals in the population.

Evolution: Basic Definitions

Genes, made of DNA, consist of alleles which determine an individual's genotype (AA, Aa, aa).
Changes in allele frequencies exemplify evolution: for instance, a shift from 40% to 71% of an allele indicates evolutionary change.
Charles Darwin’s theory emphasizes "descent with modification" via natural selection, favoring certain heritable traits.

Mechanisms of Evolution

Mutation serves as the origin of new alleles, arising from various causes like copying errors or exposure to radiation.
Recombination can create new allele combinations in offspring, enriching genetic diversity.
Background mutation rates are low; however, some mutations, like antibiotic resistance in bacteria, can substantially affect allele frequencies.

Types of Natural Selection

Directional selection favors individuals at one extreme of phenotypic variation (e.g., large beak size in finches during drought).
Stabilizing selection supports intermediate phenotypes (e.g., Eurosta fly galls favored by both parasitic wasps and birds).
Disruptive selection prefers individuals at both phenotypic extremes (e.g., seedcrackers requiring different beak sizes for food sources).

Genetic Drift

Genetic drift leads to random fluctuations in allele frequencies, particularly impactful in small populations.
Consequences include loss of genetic variation, potential increase in harmful alleles, and unpredictable fixation of alleles.

Constraints on Adaptive Evolution

Lack of genetic variation limits potential for beneficial adaptations (e.g., absence of pesticide resistance in mosquitoes).
Evolutionary history may constrain natural selection, as traits evolve from pre-existing characteristics (e.g., dolphins having lungs).
Ecological trade-offs exist where adaptations for one trait may hinder performance in others.

Joint Effects of Ecology and Evolution

Ecological factors, including predation and competition, can precipitate evolutionary changes, leading to speciation.
Evolution affects ecological interactions, potentially causing prey extinction or migration in response to predator adaptations.
Long-term evolutionary changes can significantly impact ecosystem dynamics, such as adaptive radiation of land plants altering nutrient cycling.

Human Impact on Evolution

Human activities, including pollution and habitat fragmentation, have altered environmental selection pressures and evolutionary mechanisms.
Current extinction rates are elevated, 100 to 1,000 times higher than historical averages, attributed to climate change and other human impacts.
Recognizing the intertwined relationship between ecology and evolution is critical for understanding biodiversity crises.

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Description

This quiz covers key concepts in the Principles of Ecology course, focusing on evolution, natural selection, and genetic drift. Students will explore how these mechanisms influence allele frequencies and shape long-term evolutionary patterns. Prepare to test your understanding of ecological and evolutionary principles.