Limitations of Dichotomous Keys and Alternatives

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Questions and Answers

What are two limitations of using a dichotomous key?

A dichotomous key examines physical characteristics and may use technical terms that can be confusing for users.

Describe a method, other than a dichotomous key, used to classify a species.

One method is making comparisons with specimens in reference collections, where expert taxonomists identify unknown specimens by comparing them to known ones.

How does DNA surveying improve species classification?

DNA surveying improves classification by sequencing DNA and comparing it to known sequences, allowing for more accurate identification when physical characteristics are insufficient.

Define a species in biological terms.

<p>A species is a group of organisms that share common characteristics and can interbreed to produce fertile offspring.</p> Signup and view all the answers

Identify one limitation of the biological species concept.

<p>One limitation is that it does not account for asexually reproducing organisms, making it difficult to classify them as species.</p> Signup and view all the answers

Why might geographically isolated populations be problematic in species classification?

<p>Geographically isolated populations may not interbreed, yet the biological species concept does not clarify if they belong to the same species.</p> Signup and view all the answers

What challenge does the biological species concept face regarding extinct populations?

<p>The biological species concept does not classify extinct populations, making it difficult to apply this definition to fossilized organisms.</p> Signup and view all the answers

What are two abiotic factors that affect terrestrial ecosystems?

<p>Temperature and soil moisture.</p> Signup and view all the answers

How do abiotic factors influence species distribution?

<p>They determine the environmental conditions necessary for survival and reproduction, limiting species to areas where these conditions are met.</p> Signup and view all the answers

Describe the procedure for measuring rainfall using a rain gauge.

<p>Position the rain gauge in an open area and check it daily at the same time, recording the amount of collected rain in a graduated cylinder.</p> Signup and view all the answers

Distinguish between percentage frequency and percentage cover.

<p>Percentage frequency measures the number of organisms of a particular species in an area, while percentage cover measures the proportion of an area covered by that species.</p> Signup and view all the answers

How would you calculate percentage cover using quadrats?

<p>Find the area covered by the organisms in all quadrats, calculate the area of one quadrat as a percentage, and then multiply that percentage by the number of quadrats occupied by the species.</p> Signup and view all the answers

What distinguishes intraspecific competition from interspecific competition?

<p>Intraspecific competition occurs between members of the same species, while interspecific competition takes place between different species.</p> Signup and view all the answers

What is an ecological niche?

<p>An ecological niche describes the specific set of abiotic and biotic conditions and resources an organism or population depends on, including food type and environmental conditions.</p> Signup and view all the answers

Why can't two species occupy the same niche indefinitely?

<p>If two species occupy the same niche, the one with a faster growth rate and more efficient energy use will outcompete the other, potentially leading to the latter's extinction.</p> Signup and view all the answers

What are the main characteristics of a J-population growth curve?

<p>A J-population growth curve shows exponential growth without limiting factors, typical of microbes and small mammals that can experience rapid population increases.</p> Signup and view all the answers

How does an S-population growth curve differ from a J-curve?

<p>An S-population growth curve includes limiting factors that slow growth until the carrying capacity (K) is reached, typical of larger mammals.</p> Signup and view all the answers

Define carrying capacity in an ecosystem.

<p>Carrying capacity (K) is the maximum population size that an ecosystem can sustainably support based on its available resources.</p> Signup and view all the answers

What are limiting factors, and how do they affect population growth?

<p>Limiting factors are conditions that slow down population growth as it approaches carrying capacity, which can be biotic or abiotic.</p> Signup and view all the answers

What role do predators and parasites play in an ecosystem?

<p>Predators kill and eat their prey, while parasites weaken their host without killing them directly, influencing population dynamics.</p> Signup and view all the answers

How do stronger individuals benefit in intraspecific competition?

<p>Stronger individuals have higher reproductive success, leading to a greater share of resources and potentially dominating the population.</p> Signup and view all the answers

Can species coexist if they have overlapping niches?

<p>Species can coexist in overlapping niches if they have different needs, but excessive overlap may lead to competitive exclusion.</p> Signup and view all the answers

What is predation and can you provide an example?

<p>Predation is when one animal, the predator, kills and eats another animal, the prey. An example is lions eating zebras.</p> Signup and view all the answers

How does herbivory differ from predation?

<p>Herbivory involves animals (herbivores) eating plants, while predation involves predators eating other animals. An example of herbivory is cattle feeding on grass.</p> Signup and view all the answers

Define mutualism and give an example.

<p>Mutualism is a relationship where both species benefit. An example is leguminous plants and nitrogen-fixing bacteria.</p> Signup and view all the answers

Explain the role of competition in population interactions.

<p>Competition occurs when two species vie for the same resources, resulting in negative effects on both. An example is lions and hyenas competing for food.</p> Signup and view all the answers

What role do limiting factors play in S-curves of population growth?

<p>Limiting factors slow population growth by causing equilibrium through resource scarcity, disease, waste accumulation, and competition.</p> Signup and view all the answers

What is saprotrophism, and why is it important in ecosystems?

<p>Saprotrophism is the feeding on dead organic material, such as by earthworms. It is important for nutrient recycling in ecosystems.</p> Signup and view all the answers

How do J-curves differ from S-curves in terms of limiting factors?

<p>J-curves experience rapid population decline or crash due to limiting factors like seasonal climate change and overexploited resources, unlike S-curves which stabilize.</p> Signup and view all the answers

Describe the difference between density-dependent and density-independent factors.

<p>Density-dependent factors vary with population size, such as disease and competition, while density-independent factors affect population regardless of size, like extreme weather events.</p> Signup and view all the answers

Using the Lincoln Index, how do you estimate a population size?

<p>Population size is estimated using the formula $\frac{M*N}{R}$, where M is the marked first sample, N is the second sample caught, and R is the recaptured marked individuals.</p> Signup and view all the answers

Why can predation be beneficial for both predator and prey?

<p>Predation helps control prey populations, ensuring resources are sufficient for survival, while predators benefit from a food source. It also maintains a healthy gene pool in prey species.</p> Signup and view all the answers

What method is utilized to gather data for the Lincoln Index?

<p>The method used is capture, mark, release, recapture, which involves marking organisms, releasing them, and then resampling later.</p> Signup and view all the answers

What are the effects of disease as a population interaction?

<p>Disease harms the host species, affecting their function and survival. It can also regulate population sizes and maintain ecological balance.</p> Signup and view all the answers

Compare and contrast predation and parasitism.

<p>Both involve one species benefiting at the expense of another; however, predation results in the death of the prey, while parasitism may not kill the host immediately.</p> Signup and view all the answers

What is a strength of using non-conspicuous marking methods in organism studies?

<p>Non-conspicuous marking helps to prevent predation, ensuring marked organisms survive in their environment.</p> Signup and view all the answers

Identify a potential weakness of marking organisms for study.

<p>Marked organisms may experience stress or altered behavior, potentially affecting their quality of life or the study's outcomes.</p> Signup and view all the answers

What factors could impact the accuracy of the Lincoln Index data gathering method?

<p>Factors include the number of trials, type of traps used, the marking method, and assumptions about organism distribution.</p> Signup and view all the answers

How might 'trap shy' behavior affect the Lincoln Index results?

<p>'Trap shy' behavior could lead to underestimation of the population size if fewer marked organisms are captured during the resampling.</p> Signup and view all the answers

What is the implication of seasonal variations on the accuracy of population size estimation?

<p>Seasonal variations may lead to fluctuations in population density, affecting the number captured and thereby skewing estimates.</p> Signup and view all the answers

In what way does habitat density variation complicate population estimation using the Lincoln Index?

<p>Habitat density variation means that not all areas are equally populated, which can lead to inaccurate assumptions about the population structure.</p> Signup and view all the answers

Flashcards

Dichotomous Key

A tool used in biological classification to identify organisms based on a series of paired choices, leading the user to the correct identification.

Species

A set of organisms sharing common characteristics and the ability to interbreed and produce fertile offspring.

Limitations Of Dichotomous Key

Limitations of using a dichotomous key to classify organisms.

Comparisons With Specimens In Reference Collections

A method of classifying species by comparing unknown specimens to known ones in reference collections maintained in institutions.

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DNA Surveys

A method of classification that uses DNA sequencing to compare genetic information of an unknown organism to known sequences in a database.

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Biological Species Concept

The concept that defines species by their ability to interbreed and create fertile offspring.

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Limitations Of The Biological Species Concept

Limitations of the biological species concept in defining species.

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Predation

A relationship between two species where one species (the predator) kills and consumes another species (the prey).

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Herbivory

A relationship between two species where one species (the herbivore) consumes plants.

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Parasitism

A relationship between two species where one species (the parasite) lives in or on another (the host) and benefits by feeding off of the host.

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Mutualism

A relationship between two species where both species benefit from the interaction.

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Competition

A relationship between two species where both species compete for the same resources.

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Saprotrophism

Organisms that feed on dead organic matter.

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Disease

When one species (pathogen) harms another species (host), affecting its function.

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Density-dependent factors

Factors that limit population growth rate, where the effect increases with increasing population density.

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Density-independent factors

Factors that limit population growth rate, where the effect is independent of population density.

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Limiting factor

A factor that limits the growth of a population, such as food availability, disease, or predation.

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S-shaped growth curve

A type of population growth curve that is shaped like an 'S'. It shows a period of rapid growth followed by a leveling off as the population reaches carrying capacity.

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J-shaped growth curve

A type of population growth curve shaped like a 'J'. It shows a period of exponential growth followed by a sudden crash.

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Carrying capacity

The maximum population size that an environment can support.

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Lincoln Index

A method used to estimate the population size of a species by capturing, marking, releasing, and recapturing individuals.

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M (Lincoln Index)

The number of individuals caught in the first sample and marked.

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N (Lincoln Index)

The number of individuals caught in the second sample.

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R (Lincoln Index)

The number of individuals caught in the second sample that were previously marked.

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Capture, mark, release, recapture

A method used to gather data for the Lincoln Index. It involves capturing, marking, releasing, and recapturing individuals to estimate population size.

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Ethically Acceptable and Non-Conspicuous Marking

The ability of a marking method to be ethical and non-conspicuous so it doesn't harm or disadvantage individuals in the wild.

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Predator-Prey Relationship

A relationship where one organism benefits (predator, parasite) and the other is harmed (prey, host).

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Difference between Parasites and Predators

A parasite doesn't kill its host directly, but weakens it over time. Predators, on the other hand, kill and consume their prey immediately.

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Intraspecific Competition

Competition between individuals of the same species.

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Interspecific Competition

Competition between individuals of different species.

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Ecological Niche

The unique set of conditions and resources that a species needs to survive and reproduce.

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Why Species Cannot Occupy the Same Niche

If two species occupy the same niche, the species with the fastest growth rate and better resource use will outcompete the other, leading to an imbalance in population sizes.

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J-Population Growth Curve

A population growth curve that shows exponential growth without any limiting factors.

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S-Population Growth Curve

A population growth curve that shows a slowdown in growth as it reaches its carrying capacity due to limiting factors.

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Abiotic Factors

The range of environmental conditions a species requires for survival and reproduction. These factors determine if a species can thrive in a particular area.

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Percentage Frequency

A method used to measure the proportion of an area covered by a particular species. Often used when it's difficult to count individuals or sample size is large.

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Percentage Cover

Similar to percentage frequency, but focuses on the actual area covered by a species, usually measured in quadrats.

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Population Density

The number of individuals of a species present in a defined area. Measured by dividing the number of individuals by the total area.

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ACFOR Scale

A technique used to assess the proportion of an area covered by a specific plant species in a quadrat. Uses a scale (e.g., ACFOR) to estimate coverage based on abundance, cover, frequency, and occurrence.

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Study Notes

Limitations of Dichotomous Keys

  • Dichotomous keys identify organisms based on physical characteristics, not behavior.
  • They rely on technical terms, not always available for a given organism.
  • Some organisms change shape during their lifetime, making identification inaccurate.
  • Field observation of some features is not reliable.

Alternative Species Classification Methods

  • Dichotomous Key: A series of paired statements that guides users through a process of questions based on observable features.
  • Comparison with Reference Collections: Experts Compare unknown specimens to similar known specimens in reference collections (museums, zoos, etc.) to find a match.
  • DNA Surveys: Analyzing DNA sequences from an unknown specimen and comparing it to known sequences to identify it more accurately.

Definition of Species

  • A group of organisms sharing a common characteristic, able to successfully interbreed and produce fertile offspring.

Limitations of the Biological Species Concept

  • Inability to determine if geographically isolated populations belong to the same species.
  • Doesn't apply to asexual reproduction or geographically extinct populations.
  • Inconclusive if reproductive barriers are incomplete, such as in ring species.

Types of Population Interactions

  • Predation: One organism (predator) kills and consumes another (prey).
  • Herbivory: An animal (herbivore) consumes plants.
  • Parasitism: One organism (parasite) benefits from another (host) at the host's expense.
  • Mutualism: Both organisms benefit from the interaction.
  • Competition: Two or more organisms compete for limited resources (food, water, etc.).
  • Saprotrophism: Organisms feeding on dead organic matter.
  • Disease: A pathogen harming a host.

Predation Benefits

  • Predators stabilize populations, preventing overpopulation.
  • Predators eliminate weaker and diseased individuals.
  • Predation can reduce competition for prey species resources.
  • Prey are less vulnerable to starvation if predators keep their population in check.

Density-Dependent and Density-Independent Factors

  • Density-dependent factors: Limiting factors affected by population density (e.g., disease, predation, competition).
  • Density-independent factors: Limiting factors not affected by population density (e.g., extreme temperatures, resource availability).

Predation vs. Parasitism

  • Both involve one organism benefiting and the other suffering.
  • Predators directly kill and consume prey, whereas parasites weaken but do not directly kill their host.

Ecological Niche

  • The combination of abiotic (non-living) and biotic (living) conditions and resources an organism needs to survive.

Species and Niche

  • No two species can occupy exactly the same ecological niche.
  • Competition for resources would inevitably lead to one species outcompeting the other.

Population Growth Curves

  • J-curve: Exponential growth with no limiting factors.
  • S-curve: Logistic growth that stabilizes near a carrying capacity (K) as limiting factors come into play.

Carrying Capacity

  • The maximum population size an ecosystem can support.

Limiting Factors

  • Factors, biotic or abiotic, which limit the size of a population.

Lincoln Index

  • A method to estimate population size of mobile animals by using mark-recapture techniques.
  • M = number caught and marked in 1st sample.
  • N = number caught in the 2nd sample.
  • R = number of marked animals in 2nd sample.
  • Estimated population = (M x N) / R

Marking Methods

  • Methods used to mark organisms must be ethically acceptable and non-conspicuous to avoid harming or unsettling them.

Abiotic Factors

  • Influences species distribution
  • Physical conditions needed for survival and reproduction (e.g., temp, moisture, light, pH).

Tools for Measuring Abiotic Factors

  • Use specific tools to measure each abiotic factor accurately and consistently.

Rainfall Measurement

  • Use a rain gauge to measure rainfall amount in an unobstructed area.

Calculating Frequency and Cover

  • Percentage frequency: The percentage of quadrats in the studied area occupied by a given species
  • Percentage cover: The percentage of ground area occupied by a given species within a quadrant.
  • Population density: The number of individuals per unit area.

System Diagrams

  • Visual models showing interactions within a system, displaying storages and flows.
  • Incorporate processes, inputs, and outputs in a system.

Environmental Value Systems (EVS)

  • Different value systems (i.e., ecocentric, anthropocentric, technocentric) perceive carrying capacity in different ways.

Boom-and-Bust Cycles

  • Dramatic population increases followed by rapid collapses - illustrated by cases like the reindeer on St. Matthew Island.

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