Biodiversity Sampling Challenges
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Questions and Answers

What challenges does rarity impose on sampling efforts?

  • Logistical constraints and limited sampling efforts (correct)
  • Complete representation of a community
  • Simplified identification of species
  • Increased availability of species to sample

What do species accumulation curves describe?

  • How species richness changes with population density
  • The increase in species identified with the number of individuals sampled (correct)
  • The decrease in species richness over time
  • The relationship between species abundance and environmental factors

Which statement best describes the shape of species accumulation curves?

  • They remain constant regardless of the number of samples taken
  • They show a random pattern without a clear trend
  • They decrease sharply as more samples are taken
  • They initially rise steeply and then level off (correct)

What does the leveling off of a species accumulation curve indicate?

<p>Most species of the community have been adequately represented (B)</p> Signup and view all the answers

Why is it challenging to determine when enough sampling has been done?

<p>The true state of a community is often unknown (D)</p> Signup and view all the answers

What is a potential consequence of insufficient sampling in community studies?

<p>Overestimating total species richness (C)</p> Signup and view all the answers

What factor does NOT affect the amount of sampling effort researchers can exert?

<p>The presence of numerous species (C)</p> Signup and view all the answers

Sampling effort can be quantified in relation to what specific aspect of a community?

<p>The overall species richness and composition (A)</p> Signup and view all the answers

What does species evenness measure in a community?

<p>The distribution of individuals among species (D)</p> Signup and view all the answers

In the Shannon-Wiener Diversity Index, what does a higher value of H indicate?

<p>Higher species diversity (C)</p> Signup and view all the answers

Which condition leads to a Shannon-Wiener Diversity Index (H) of zero?

<p>A community with exactly one species (A)</p> Signup and view all the answers

How is the Shannon-Wiener Diversity Index affected if species evenness increases while the number of species remains constant?

<p>It increases (D)</p> Signup and view all the answers

What is indicated by the slope (z) of the log-log transformed species-area relationship?

<p>The speed of new species accumulation in added areas (C)</p> Signup and view all the answers

If two communities have the same species richness but different species evenness, how would they compare in terms of diversity?

<p>The one with higher evenness is more diverse (D)</p> Signup and view all the answers

What is a community in ecological terms?

<p>An association of interacting populations of different species in a given area. (D)</p> Signup and view all the answers

Which of the following best describes rank abundance curves in the context of biodiversity?

<p>A tool to compare species evenness and richness across communities (B)</p> Signup and view all the answers

Which component is not part of the widely accepted definition of biodiversity?

<p>The climatic conditions affecting these species. (D)</p> Signup and view all the answers

Which statement is true regarding the relationship between species richness and the Shannon-Wiener Diversity Index when evenness is fixed?

<p>Increasing richness increases H (B)</p> Signup and view all the answers

What is a significant challenge in estimating global species richness?

<p>Reliance on physical and morphological characteristics leading to misclassifications. (C)</p> Signup and view all the answers

Which statement best describes the concept of an ecosystem?

<p>A community of organisms interacting with their physical environment. (D)</p> Signup and view all the answers

What is the estimated range for global species richness?

<p>Between 5 million to several billions of species. (A)</p> Signup and view all the answers

How many species have been documented in scientific literature?

<p>About 2 million species. (B)</p> Signup and view all the answers

Which of the following does not contribute to biodiversity?

<p>The area's human population density. (B)</p> Signup and view all the answers

What might lead to underestimating global species richness?

<p>Misclassifying species due to physical characteristics. (A)</p> Signup and view all the answers

What is one hypothesis explaining latitudinal gradients in diversity?

<p>Differences in diversification rates (C)</p> Signup and view all the answers

Why is species diversity larger in terrestrial tropical systems compared to temperate ones?

<p>Tropical regions have higher primary productivity. (C)</p> Signup and view all the answers

Which hypothesis does NOT relate to latitudinal gradients in diversity?

<p>Carrying capacity (A)</p> Signup and view all the answers

What are the main components of the Equilibrium Theory of Island Biogeography?

<p>Distance to the mainland and island size (B)</p> Signup and view all the answers

What do high productivity levels in tropical regions promote?

<p>Lower extinction risks (B)</p> Signup and view all the answers

Which of the following factors is NOT likely to influence patterns of biodiversity?

<p>Animal behavioral patterns (A)</p> Signup and view all the answers

According to the hypotheses on diversity gradients, what is a key advantage of tropical regions?

<p>Increased population sizes (C)</p> Signup and view all the answers

What type of ecosystem generally has the highest primary productivity?

<p>Tropical forests (C)</p> Signup and view all the answers

What is the relationship between area sampled and the number of species found?

<p>Species richness initially increases steeply with area, then slows. (B)</p> Signup and view all the answers

Which factor does the slope (z) in the species-area relationship power function indicate?

<p>The probability of observing new species as area increases. (B)</p> Signup and view all the answers

In the equation $S = cA^z$, what does the variable 'S' represent?

<p>Number of species in the area. (A)</p> Signup and view all the answers

What is a primary reason hierarchical sampling designs are used?

<p>To understand variations in community composition across different areas. (B)</p> Signup and view all the answers

What mathematical transformation is used to better describe species-area relationships?

<p>Log-log transformation. (B)</p> Signup and view all the answers

In the context of species-area relationships, what does the 'c' represent?

<p>Average number of species per unit area. (D)</p> Signup and view all the answers

As sampled area increases, what pattern is observed in species accumulation?

<p>Steep initial increase, then a slower accumulation rate. (D)</p> Signup and view all the answers

What does the term 'species richness' refer to?

<p>The variety and number of different species in a given area. (D)</p> Signup and view all the answers

What is the relationship between island size and species richness?

<p>Larger islands tend to harbor more species. (C)</p> Signup and view all the answers

How does distance to the mainland affect immigration rates to an island?

<p>Closer islands have higher immigration rates. (A)</p> Signup and view all the answers

What effect does higher species richness have on extinction rates?

<p>Higher species richness results in higher extinction rates. (A)</p> Signup and view all the answers

What primarily drives the rate of new species arrivals on an island according to the theory?

<p>Immigration from other locations. (D)</p> Signup and view all the answers

What happens to the rate of new species arrivals as the species richness of an island increases?

<p>It slows down. (B)</p> Signup and view all the answers

Which of the following factors does NOT affect immigration rates to an island?

<p>Size of the island. (B)</p> Signup and view all the answers

Which of the following statements about species richness and competition is true?

<p>Higher species richness leads to increased competition. (B)</p> Signup and view all the answers

What assumption is made about ecological timescales in relation to evolutionary timescales in the theory?

<p>Ecological timescales are much faster. (A)</p> Signup and view all the answers

Flashcards

Biodiversity

The variety of life on Earth, encompassing species, ecosystems, and evolutionary history.

Global Species Richness

The total number of species on Earth.

Species Richness

The number of species present in a specific area.

Species Description

The scientific documentation and classification of species.

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Morph Misclassification

The potential for misclassifying different species as variations of a single species.

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Species Misclassification

Mistaking individuals from different species as variations of the same species.

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Estimating Species Richness

The challenge of accurately estimating the total number of species on Earth due to limitations in observation and classification.

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Biogeography

The study of the distribution of species across the Earth and the factors influencing their patterns.

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Rarity in Sampling

The challenge of identifying and counting all species in a community due to limited resources, time, and accessibility.

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Species Accumulation Curve

A graph showing how many new species are found as more individuals are sampled. It typically starts steep and levels off.

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Species Accumulation Curve Leveling Off

The point where adding more samples doesn't significantly increase the number of species found, suggesting a good representation of the community.

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Species-Abundance Relationships

Describes how the number of individuals of each species varies in a community.

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Community Composition

The relative proportions of different species in a community.

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Adequate Representation

Determining whether enough samples have been collected to accurately represent the species richness and composition of a community.

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Increased Sampling Effort

Sampling more individuals to improve the representation of species within a community.

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Species-Area Relationship

The study of how the number of species found within a sample increases as the area sampled increases.

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Power Function for Species-Area Relationship

A mathematical equation used to describe the relationship between the number of species and the area sampled, where the slope of the log-log transformed relationship indicates how quickly new species are found as we sample more area.

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c (Average Number of Species)

The average number of species that can be found per unit area in a specific region. Used in the Species-Area relationship equation.

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z (Slope of log-log transformed species-area relationship)

The slope of the log-log transformed species-area relationship. Explains how quickly new species are found when sampling larger areas.

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Hierarchical Sampling

A strategy for sampling ecosystems across different spatial scales to understand how community composition changes within a region.

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Decreased Probability of New Species with Increased Area

The probability of discovering a new species decreases as the area sampled increases. Once an area has been well-sampled, it becomes harder to encounter new species.

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Latitudinal Gradient of Diversity

The observed pattern where species diversity is higher in tropical regions compared to temperate regions.

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Diversification Rate Hypothesis

The idea that species diversity is higher in the tropics because of the higher rate of new species formation.

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Diversification Time Hypothesis

The idea that species diversity is higher in the tropics because the tropics have been evolving for a longer time due to more stable climate.

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Productivity Hypothesis

The idea that species diversity is higher in the tropics because they have higher primary productivity, leading to larger populations and reduced extinction risk.

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Equilibrium Theory of Island Biogeography

A theory explaining the number of species on an island based on its size and distance from the mainland.

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Island Size Effect

The relationship between island size and species richness, where bigger islands tend to have more species.

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Island Distance Effect

The relationship between distance from the mainland and species richness, where closer islands tend to have more species.

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Equilibrium Point

The balance between immigration and extinction rates on an island, determining the number of species it can support.

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What does the slope of the log-log transformed species-area relationship indicate?

A measure of how quickly the number of species increases as the area sampled grows. It tells us about the rate at which new species are discovered when exploring a larger area.

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What is species richness?

The number of species found in a specific area, often used to quantify biodiversity.

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What is species evenness?

A measure of how evenly individuals are distributed among species in a community. It considers the relative abundance of each species.

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What is the Shannon-Wiener Diversity Index?

A mathematical index that quantifies species diversity by combining species richness and evenness. It reflects both the number of species and their relative abundance.

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How does the Shannon-Wiener Diversity Index range?

It ranges from 0 (a community with only one species) to a higher value indicating higher diversity, reflecting both species richness and evenness.

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What are rank abundance curves?

A graphical representation showing the relative abundance of different species in a community, ranked from most abundant to least abundant.

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What are species-abundance relationships?

The relationship that describes how the number of individuals of each species varies in a community. It helps understand the distribution of species abundance.

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What is community composition?

The relative proportions of different species within a community. It describes the specific types of species present.

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Island Size and Species Richness

Larger islands have a higher chance of attracting new species and offer more diverse habitats, leading to lower extinction rates. Thus, larger islands generally have more species.

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Island Distance and Species Richness

Islands closer to a mainland source of species experience higher rates of immigration, leading to greater biodiversity compared to remote islands.

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Immigration rate and Species Richness

As an island accumulates more species, the rate at which new species arrive slows down. Many arriving species are already present, reducing the probability of adding new ones to the island's list.

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Extinction Rate and Species Richness

Higher species richness on an island increases the rate of extinction. This is because more species means more competition for resources and a greater likelihood of some species going extinct.

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Immigration and Evolutionary Timescales

The rate at which new species arrive on an island is primarily driven by immigration from elsewhere, rather than by speciation on the island itself. This is because evolution typically occurs over much longer timescales than the ecological processes involved in immigration and extinction.

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Immigration and Speciation

The theory assumes that new species arrive on islands primarily through immigration from elsewhere, rather than through speciation on the island itself.

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Equilibrium State

The Equilibrium Theory of Island Biogeography predicts a balance between immigration and extinction rates that ultimately determines the number of species on an island.

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Study Notes

Ecology - Fall 2024, Week 10

  • Course: BIOB50H3F
  • Topic: Biodiversity & Biogeography

From Individuals to Populations to Communities and Ecosystems

  • Individual: A single organism
  • Population: A group of individuals of the same species, living and interacting with each other in a particular area
  • Community: An association of interacting populations of different species, living and interacting in the same area
  • Ecosystem: A community of organisms plus their abiotic (physical) environment

Biodiversity

  • Biodiversity is a complex concept, encompassing the variety of life forms
  • It includes genetic diversity (variations within species), species diversity (the number of different species), and ecosystem diversity (the variety of habitats and ecosystems)

Global Species Richness

  • Approximately 2 million species have been described in scientific literature
  • Estimated number of species worldwide ranges significantly from 5 million to several billions
  • Data collection and estimation are challenging, due to biases in sampling efforts (difficulty finding some species, focusing on particular ecosystems, logistical/financial constraints)

Species Richness

  • Data shows a higher estimation of extant insect species
  • Many species are hard to find and studying them takes time and funds.

Estimated Global Species Richness

  • The estimated number of species ranges: May (1988) 10-50 million, Purvis and Hector (2000) 14 million, Chapman (2009) 11 million, Mora et al. (2011) 8.7 million ± 1.3 million, Costello et al. (2013) 5 million ± 3 million, Larsen et al. (2017) 1-6 billion

Challenges of Estimating Global Species Richness

  • A historical reliance on physical and morphological characteristics
  • Biases exist with respect to which species are studied
  • Biases exist with respect to which ecosystems are studied
  • Many species are hard to find due to logistical, time, and funding constraints
  • Many species are going extinct before they are described

Determining Species Richness & Community Composition

  • Determining all species in a community is usually impossible
  • Sampling techniques for determining community composition are similar to those discussed in Lecture 4
  • Rarity in a community poses challenges with sampling as rare species are often missed
  • Species abundance distribution in communities shows that a few species account for most individuals, indicating most species are considered rare

Species-Abundance Relationships

  • Species accumulation curves describe the number of species that are found with increased sampling effort
  • Community composition may vary across different areas

Species-Area Relationships

  • Species-area relationships show that more species are found in larger areas
  • The number of species may increase with the area that is sampled, steeply at first then more slowly as the probability increases that sampled species have already been observed in previous areas
  • Species-area relationships can be described by a power function or equivalence.

Quantifying Diversity

  • The Shannon-Wiener Diversity Index assesses species diversity by incorporating richness and evenness
  • Higher diversity values (H) indicate more diverse communities
  • Species evenness measures how evenly the total number of individuals are spread among species in a community
  • Rank abundance curves show the proportional abundance of species ranked from most to least abundant (comparing different communities, understanding if differences in diversity of communities are due to differences in species richness, evenness or both)

Phylogenetic Diversity

  • Phylogenetic trees depict evolutionary relationships, branch lengths represent time since evolutionary divergence
  • Phylogenetic diversity (PD) measures evolutionary distance- higher PD scores = more divergent species

Functional Diversity

  • Functional traits describe species' ecological roles
  • Functional diversity dendrograms show relationships among species based on functional traits

Global Geographic Patterns of Biodiversity

  • Tropical rainforests and coral reefs have the highest biodiversity
  • Latitudinal gradients show decreasing diversity as latitude increases
  • Different species richness across different locations depend on many interconnected factors
  • Hypotheses for diversity gradients include rates of diversification, diversification time, and primary productivity

The Equilibrium Theory of Island Biogeography

  • Island biogeography suggests that the number of species on an island depends on immigration and extinction rates
  • The number of species is at equilibrium when immigration and extinction are at equal rates
  • Larger islands with greater distances from the mainland have higher species richness
  • Smaller islands with closer proximity to the mainland have higher turnover rates

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BIOB50H3F Ecology Biodiversity & Biogeography Fall 2024 Lecture 10 PDF

Description

This quiz explores the complexities of sampling in biodiversity studies, including the effects of rarity, species accumulation curves, and the Shannon-Wiener Diversity Index. Test your knowledge on how these factors influence community studies and what they reveal about species diversity and evenness.

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