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GEOG 1403 Spring 2023 Section 004

1. Niche and Environmental Controls – Donovan, Josh, Asher

I. Niche – A species’ role, tolerance, and limiting factors within an ecosystem.

● Niche Breadth – How “broad” a certain species’ niche is. 

A. Generalists – Species that are able to survive in a wide range of habitats and environmental conditions.

B. Specialists – Species that require a very select habitat or environmental conditions to survive.   

● Competition between species (defined two ways) – A negative interaction between two populations, where the populations of one are indirectly decreased by another (i.e. using the same limited resources).  

C. Fundamental Niche – defined as the niche of a species when no competition is present.

D. Realized Niche – represents the niche of a species when competition for available resources is present.

● Intraspecific Competition - Competition between members of the same species

● Interspecific Competition - Competition between members of different species

    II. Environmental Controls

● Limiting Factor/Limiting Resource - Factor or resource that controls organism growth, species population size, or distribution.

E. Examples of limiting factors are availability of food, existence of predators, and availability of shelter.

F. Influences where an organism can live and alters the carrying capacity of a landscape. 

● Environmental Stress – A pressure for populations to remain within their ideal habitat.

G. Zone of the Optimum – Conditions for survival are easily met and triumphed. Location where a species can survive and flourish extremely well.

H. Zone of Stress – Conditions for survival are nonoptimal, but usually met. Location where a species can survive, but it is less than ideal. Species are pushed back towards the zone of the optimum.

I. Zone of Intolerance – Conditions for survival are unfavorable. All populations within this zone are temporary. They will either be forced back into a zone of stress/the optimum, or die here.

2. Species hybridity and ecological authenticity

Species Hybridity and Ecological Authenticity

I. Species

I. Species breed and continue to mutate genetically to become more fit, with many different variations based on their surroundings.

A. https://aeon.co/essays/why-evolution-is-not-a-tree-of-life-but-a-fuzzy-network

B. https://www.ringgold.org/cms/lib/PA01916235/Centricity/Domain/228/7%20Thory%20of%20Evolution.pdf

II. What makes a species?

A. a species is a population whose members are able to interbreed freely under natural conditions.

B. Lions and Tigers can breed, but do not do it under natural conditions and their offspring can not breed themselves.

6. Population patterns and population growth

I. Exponential population growth

I. Intraspecific/interspecific competition

A. Intra: occurs when members of the same species vie for the same resources in an ecosystem

B. Inter: Competition between different species, can regulate populations of interacting species

II. What are the factors that cause population to fluctuate over time  

A. Birth, dealth, immigration, emigration

B. 

Carrying capacity-based on rates of birth and deaths as they are influenced by population density, happens where the equilibrium takes place (birth and death rate meet)

III. Predator/prey relationships

A. Four types of approaches

a. Generalist: Wide range of environmental tolerance

b. Euryphagous: Broad range of food choice

c. Specialist: Narrow range of environmental tolerance

d. Stenophagous: Narrow range of food choice

i. Larger animals tend to be Euryphagous

B. Lotka-Volterra Model of Predator/Prey Dynamics

a. Predator/prey interactions sometimes appear to behave like a self-regulating system

b. 

Boom and bust cycles: one population increases, another increases and vice versa

c. Top-bottom, bottom-top controls (top-bottom: predators control abundance in lower levels of trophic hierarchy; bottom-top: prey abundance control abundance at higher levels of trophic hierarchy

7. Species Interactions

I. Species Creations

A. Biological Species Concept

1. Definition: Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other similar groups.

2. While the most agreed definition of species follows with the BSC, it must be noted that there is no definitive definition of species. There are at least 26 different definitions of species, and no solid consensus among the biology community ("What is a species?", Henry Taylor, The Conversation and Do species really exist?, Sedeer L. Showk, Scitable: Accumulating Glitches Blog)

B. The Evolutionary Species Concept

1. Definition: Traces ancestor-descendant relationships among groups of closely related organisms

2. North American Bear Phylogeny:

a) 

II. Interactions

A. Interspecific Competition

1. Definition: Occurs when members of different species vie for the same resources

2. Nocturnal vs. Diurnal Owls both hunt the white-footed mouse:

 

B. Intraspecific Competition

1. Definition: Occurs when members of the same species vie for the same resources within an ecosystem

2. Largely occurs in situations involving breeding, like two or more male birds competing for the same female.

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3. STUDENT EXAM QUESTIONS

Below, each group will populate the questions developed for their respective topics.

1. Niche and Environmental Controls – Donovan, Josh, Asher

Short Answer:

- On the graph above, mark in the approximate location of the zones of the optimum, intolerance, and stress for the species shown in the graph.

- A species has a very small zone of tolerance, with a small zone of optimum. Another species begins to move and occupy the same space, and uses the same resources. This species has a very broad range of tolerance and a large zone of optimum. Briefly explain a potential impact on the initial population as a result of this.

Discussion Question:

- The Galapagos finches are birds which survived a plethora of challenges throughout their times on Daphne Major. What would happen if some of the finches had evolved to have shorter beaks, whilst some instead evolved to have larger beaks? How would we expect these two species to interact in terms of competition? What would happen if the finches instead all had the same beak length?

5. Species Hybridity and Ecological Authenticity

1. Name the difference between Homologous, Analogous, and Vestigial structures as it relates to evolution.

- Homologous structures appear differently than each other, but came from the same origin. They also have different functions based on the environment the organism is exposed to.

- Analogous structures do not have the same origin, but serve similar functions.

- Vestigial structures do not have a function in the current version of the organism. However, they can be used to find the origin of the organism and its evolutionary history.

Long Answer:

- Describe how the durability of an ecosystem is maintained in order to support native biodiversity in differing climatic environments.

6. Population Patterns and Population Growth

- Define the difference between intraspecific and interspecific competition, be able to give an example for each. How do each of these types of competition affect the population of a species?

- Suppose you have a population of sheeps and cougars, and there were more sheeps than cougars in the population. Over the course of a few years, the population of sheeps fluctuates. What would happen to the cougar population as the sheep population decreases? Conversely, what would happen to the cougar population after the sheep population increases after a period of population loss?

7. Species Interactions

- Short Answer Question: Referencing Lab 6, why do you think the average beak depth of the G fortis species alone (top graph) is different from when living in the same environment as the G. Fyliginosa species (bottom graph)?

 

- Discussion Question: The Morrell reading discussed the recent discovery that the red wolf (canis rufus) was in fact not diverged from the eastern wolf (canis lycaon), but instead is the result of recent interbreeding of the gray wolf (canis lupus) and coyote (canis latrans). Based on the readings and lectures, discuss whether it is possible to determine a universal method to decide when an animal becomes a new species as opposed to simply a hybrid of already established species.