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?

Most species of the community have been adequately represented Signup and view all the answers

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

The true state of a community is often unknown Signup and view all the answers

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

Overestimating total species richness Signup and view all the answers

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

The presence of numerous species Signup and view all the answers

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

The overall species richness and composition Signup and view all the answers

What does species evenness measure in a community?

The distribution of individuals among species Signup and view all the answers

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

Higher species diversity Signup and view all the answers

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

A community with exactly one species 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?

It increases Signup and view all the answers

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

The speed of new species accumulation in added areas 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?

The one with higher evenness is more diverse Signup and view all the answers

What is a community in ecological terms?

An association of interacting populations of different species in a given area. Signup and view all the answers

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

A tool to compare species evenness and richness across communities Signup and view all the answers

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

The climatic conditions affecting these species. 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?

Increasing richness increases H Signup and view all the answers

What is a significant challenge in estimating global species richness?

Reliance on physical and morphological characteristics leading to misclassifications. Signup and view all the answers

Which statement best describes the concept of an ecosystem?

A community of organisms interacting with their physical environment. Signup and view all the answers

What is the estimated range for global species richness?

Between 5 million to several billions of species. Signup and view all the answers

How many species have been documented in scientific literature?

About 2 million species. Signup and view all the answers

Which of the following does not contribute to biodiversity?

The area's human population density. Signup and view all the answers

What might lead to underestimating global species richness?

Misclassifying species due to physical characteristics. Signup and view all the answers

What is one hypothesis explaining latitudinal gradients in diversity?

Differences in diversification rates Signup and view all the answers

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

Tropical regions have higher primary productivity. Signup and view all the answers

Which hypothesis does NOT relate to latitudinal gradients in diversity?

Carrying capacity Signup and view all the answers

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

Distance to the mainland and island size Signup and view all the answers

What do high productivity levels in tropical regions promote?

Lower extinction risks Signup and view all the answers

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

Animal behavioral patterns Signup and view all the answers

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

Increased population sizes Signup and view all the answers

What type of ecosystem generally has the highest primary productivity?

Tropical forests Signup and view all the answers

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

Species richness initially increases steeply with area, then slows. Signup and view all the answers

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

The probability of observing new species as area increases. Signup and view all the answers

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

Number of species in the area. Signup and view all the answers

What is a primary reason hierarchical sampling designs are used?

To understand variations in community composition across different areas. Signup and view all the answers

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

Log-log transformation. Signup and view all the answers

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

Average number of species per unit area. Signup and view all the answers

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

Steep initial increase, then a slower accumulation rate. Signup and view all the answers

What does the term 'species richness' refer to?

The variety and number of different species in a given area. Signup and view all the answers

What is the relationship between island size and species richness?

Larger islands tend to harbor more species. Signup and view all the answers

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

Closer islands have higher immigration rates. Signup and view all the answers

What effect does higher species richness have on extinction rates?

Higher species richness results in higher extinction rates. Signup and view all the answers

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

Immigration from other locations. Signup and view all the answers

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

It slows down. Signup and view all the answers

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

Size of the island. Signup and view all the answers

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

Higher species richness leads to increased competition. Signup and view all the answers

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

Ecological timescales are much faster. Signup and view all the answers

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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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.