Part I-Jigsaw activity Class Copy-08

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Jan 9, 2024

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Part I -Use the following questions to help you prepare for the Jigsaw activity I-CHARACTERISTICS OF POPULATIONS 1. Differentiate between the terms population size and population density, and crude density and ecological density. a) Population size: This refers to the number of individuals/organisms in a given area. This can be as specific as a certain species of an organism or even divided by Phylum, class, order etc. An example of this would be the population of Ottawa which is about 994,000 people which is the size/hope many people there are in this given area. b) Population density: A measurement of population size per unit area. For example; this would be the population of Ottawa (which is about 994,000) divided by the area where we live(which is about 2778km squared). The population density of Ottawa is about 358 people per square kilometer. c) Crude density: Density is the number of individuals per unit of space . This can include area, volume, etc. Crude density is the total amount of individuals or biomass of the whole space. More specifically, crude density would be looking at how many of a certain animal is living in an area, “2 elephants per km2” or “how many rhinoceros live in this national park?” It is called crude since the number does not necessarily provide us with the proper relationship of the population to the unit of space. d) Ecological density: Instead , ecological density refers to the size of the population in relation to the number of units of habitat space (rather than the whole space). For example, “how much area can be colonized by a population.” 2. Explain the term population dispersion. Describe three patterns of dispersion and give examples of each. Population dispersion: In normal ordinary conditions organisms travel or “distribute” in various different ways such as active movement, migration, and by passive movement through air or water, even sometimes on other organisms. Other organisms on the other hand travel separately alone in a process called dissemination often termed dispersion.

Dispersion is one of the basic attributes in populations that influence multiple different features regarding their organization and structure. Those features include population density, reciprocal relationships, and frequency of encountering members of the same population in a sample unit of area. a) Uniform : In Uniform dispersion, individuals are spaced evenly from one another and take up a predictable pattern. This is best illustrated in various plant species for example sage plant, Salvia leucophylla which secretes a toxin killing all surrounding plants in an almost circular shape. As a result the plant forms a uniform distance from their brethren. b) Random dispersion : In random dispersion, individuals are spaced at random distances from each other. There is no predictable pattern . e.g. plants that have wind-dispersed seeds, such as dandelions: the seeds spread wide and sprout wherever they happen to fall. c) Clumped dispersion : Individuals are clustered in groups. Clumped dispersion often occurs due to an uneven distribution of nutrients or other resources in the environment. It can also be caused by social interactions between individuals. e.g. oak trees, schools of fish: plants that drop their seeds directly to the ground might have offsprings very close to their parents. Animals that live in groups such as schools of fish or herds of elephants. 3. Populations can be measured using quadrats, mark-recapture sampling, and technological tracking. Explain the procedure for each method and the circumstances for which each is used. a) What is a quadrat A small, usually square section of a habitat (often a square meter), that is randomly chosen as a sample for the assessment of distribution of plants and animals. It is used as a way of estimating the amount of different species within a habitat. Within each quadrat, plant and animal populations are counted, and photos are taken. These

photos can be used to monitor growth or changes within populations of a habitat over time. Disadvantages of quadrats include the possibility of them being too small, and missing species. This means that the extrapolation of the quadrat data can be faulty and misleading. b) What is mark recapture sampling ● Mark recapture sampling is a method used when it is impossible to get the exact number of organisms in an area. ● It is used to estimate the size of a population. ● Essentially, it works by capturing a small number of animals, putting marks on them, and releasing them back into the wild. ● Later on, you capture another small group of the same organism and record how many of them have the mark. ● you will find less organisms with the mark in a single sample if the population is bigger, and more if the population is smaller. ● This is based on a few assumptions: ○ The chances for each individual of the population to be caught are equal (it would not work if marked animals were more or less likely to be caught) ○ The proportion of marked to unmarked individuals is the same between captures ○ Enough time is allowed between the captures that the marked population is able to mingle with the unmarked population ○ animals are not affected by the marks, and they do not lose them.

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● There is a mathematical formula for this, which is: N = Mn/m ● M = total number marked, N = total population, m = number of recaptures, n = size of the second sample c) what is technological tracking ● Technological tracking is when biologists attempt to trace the location of populations of a species,. ● This provides important information about their behavior ● They can be tracked using GPS ● They can also be tracked by DNA sampling, collecting and testing their droppings or other biological materials they left behind ● Biologists can use this information about the locations of a population of organisms to determine things like the range in which they live, their migration routes, distribution and population density. II-MEASURING AND MODELLING POPULATION CHANGE

4. What is the carrying capacity of an ecosystem? (Emily) The carrying capacity is the maximum number of individuals within a population that environmental resources can support indefinitely. Carrying capacity varies from species to species and habitat to habitat, depending on the amount of resources needed for survival and the amount of resources available. It is represented by the variable “k” in equations that model population growth. 5. Differentiate between the three types of survivorship curves. (Hailey) Survivorship Curves: a graphic display of the rate of survival of individuals over the lifespan of a species Type 1: The death rate is very low at the beginning and increases as age increases. Large animals that produce few offspring and provide extended care for their young. Taking care of their young for longer reduces juvenile mortality. For example, a Dall mountain sheep will have a few children, care for them for the first year of their life. (Large animals that have few offspring that they generally care for until they are old enough to survive on their own) Type 2: Relatively constant rate of mortality in all age groups. There is a steadily declining survivorship. Some of the reasons for a constant probability of mortality are predation, disease, and starvation at any age. Organisms with a relatively short gestation period usually follow this curve. Examples are lizards , songbirds, and other small mammals. Type 3: A rapid drop at the start, representing a very high death rate early on in life and then the curve flattens as the death rate declines for those that survive the critical stage. There is a high juvenile mortality, and then there is a period of low mortality once they pass the critical age and size. An example of this would be the black crappie fish. The male protects the eggs for a week, then when the young hatch, is the first to feed on the young. Many plants, insects, and marine invertebrates follow this curve.

6. Write the equation for determining the change in population size. Use an example to calculate an increase in population for a fictitious population. (Nour) There are many equations that have been put together in order to account for the increase or decrease a population is facing. Many of which would likely include logistical mathematicians to be able to solve them. This equation is the big picture. Change in population size : dN/dt = (birth + immigration ) - (death + emigration) . (dN, the current population size. dt, over time) What to take from this is that when dN/dt = 0 , the population size has not changed. Similarly, when d (deaths) outweigh b (births), the population is decreasing, and vice versa. Aside from an equilibrium formula for population change, there are other formulas and equations especially for population growth. Example : You're a mayor of a city that has approximately 265000 citizens, and you've recently had a rapid increase in births (50,000 babies)! This is how to see the rate at which your population is increasing. Population growth rate = (births + immigration) - (deaths + emigration) X100 Initial population (50,000 + 2,000) - (8,000 + 2,000) X100 265,000 = 15.85% ← the current population growth rate in your city 7. Differentiate between geometric growth, exponential growth and logistic growth: a) explain the term (Ayesha) Geometric growth, exponential growth and logistic growth are all patterns of data. Geometric growth is when successive changes in a population are different by a constant ratio. Exponential growth is when a population's per capita growth rate remains the same regardless of the population size causing the population to rapidly increase as it gets larger. An example of exponential growth would be placing 100 bacteria in an environment. The population would increase to 200 then 300 and so on however eventually the population would level off because of resource and economic constraints. In addition to geometric growth and exponential growth, logistic growth is when a population's per capita growth rate continues to get smaller as the population size approaches a maximum imposed by limited resources in the environment. This is

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known as carrying capacity. An example of logistic growth would be yeast in a test tube. The growth of the yeast would eventually level off as the population consumes all the nutrients necessary for its growth. b) draw the growth curve (Benjamin) c) describe the calculation involved (Lauren) dN = change in population size N = population size dt = change in time B = Births D = deaths r = per capita growth rates K = carrying capacity Exponential growth

Logistic growth III-FACTORS AFFECTING POPULATION CHANGE 8. Describe how natality, mortality and immigration affect a population. a) Natality: ● Birth rate of a population ● The natality is often the largest influence on a population’s rate of growth. Human Example ❖ Japan’s population is decreasing, their natality rate is 7.3 / 1000 people (Dooley, 2019). ❖ India’s population is growing, their natality rate is 17.4 / 1000 people (Macro Trends, 2021). b) Mortality Death rate of a population One of the four main factors that affects population growth (beside birth-rate, immigration and emigration) Mortality affects the rate of decrease in any given population and is necessary to keep balance in population growth as the rate of natality serves to increase the population. If the rate of mortality is higher than the rate of natality, then the population will begin to decrease. If the mortality rate is less than the rate of natality, then the population will begin to increase.

c) Immigration: → When a species leaves their habitat and moves to a new one permanently it is known as immigration Example: Refugees fleeing war torn countries and coming to a new safer country Canada welcomes about 300,000 immigrants annually → Affects population in two ways: 1. Decreases the population of the habitat they came from 2. Increases the population of new habitat 9. Explain the difference between density-dependent and density-independent factors Density-Dependent Factor - a factor that is influenced by population density, having a greater impact at the population density increases. As the density of a population increases, the effects of density-dependent factors also increase. The magnitude of these factors is directly proportional to the size of the population & vice versa Ex. as a prey population decreases in density, there will be fewer predators because the predators have fewer food resources, therefore, their population will also decrease Examples : Disease- increases when the population increases because it can spread quicker and easier. Diseases can have catastrophic effects on a population as well as ecosystems Competition- can be intense when many individuals are competing for the same resources (food, water, space, & shelter) Predation- when one organism kills and eats another organism, is more competitive when the population density of the predators is high Parasitism- a parasite is an organism that lives on or in a host organism and gets it food from or at the expense of its host. Parasites can influence the hosts behaviour which can regulate host population and have an effect on food webs, biodiversity, and key species. Therefore, parasites are integral components in shaping a community and ecosystem structure Space limitations- crowding affects the growth, size, and survival of individuals in a population. Density independent factors - Any influences on a population’s birth or death rates, regardless of the population density. Simply put, there are limiting factors that affect a population that aren’t related to density. These factors are often physical factors. Examples include:

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Natural disasters Weather problems Eg. extreme temperatures Climate problems Eg. droughts Human activity Eg. Habitat destruction Density independent factor is unrelated to population size. For example natural disasters, hurricanes, tornadoes, floods. Density dependent factor is a limiting factor of a population in which a large and dense population is more affected than the small and less crowded ones. For example, predation, competition, food supply. Density independent factor is a limiting factor that affects all populations regardless of their densities whereas density dependent factor only affects population when they reach a specific density. IV-INTERACTIONS WITHIN COMMUNITIES 10. Differentiate between the terms: ecological niche, fundamental niche, realized niche. Ecological Niche: An ecological niche is the role of a specific organism in its ecosystem. It also describes how a certain species will interact with its ecosystem, which can depend on biotic and abiotic factors. Biotic refers to living factors, such as food abundance and predators, whereas abiotic factors usually refer to factors that are not living, such as temperature and the environment in which the species lives. There are two forms of niches, fundamental and realized. Fundamental Niche: Fundamental niche represents all the environmental conditions where a species could possibly live/ inhabit. It is a set of conditions within which a species can live without any competitors or any other limiting factors that might constrain the population Realized Niche: A realized niche is similar to the fundamental niche. However, competition and interaction between species, and any other limiting factors are taken into consideration. The presence of competing species in an environment is an

example of a limiting factor that restrains an organism's ecological niche. 11. Interactions between species can be classified as competition, predation, or symbiosis. Using your text, make notes on each type of interaction. Be sure to give an example for each. Competition: Competition between species occurs when there is a limited amount of resources in a given area or ecosystem. There are two main types of competition: Interference competition & exploitative competition. ❏ Interference Competition: Based on the concept of survival of the fittest, it occurs when all species have equal access to resources but fitness is the only barrier. ❏ Species can harm each other directly (ex. Lions chase hyenas) ❏ Exploitative Competition: Similar to Interference Competition, however the difference in the ability to gather resources between species is the only barrier ❏ There is the idea of sharing, however, the more species are present, the less available (abundant) a resource will become (ex. The more seed-eating species there are the less seed food supply will be available). This may occur without any encounter or harm to species. Predation: The behavior of one animal killing then feeding on another; a predator and prey relationship to sustain an ecosystem (population). There are 2 principal types: ● Carnivory ○ Consumption of meat by animals ○ Examples would be a wolf eating a bunny or owls hunting mice. ● Herbivory ○ Consumption of plants by animals ○ Examples would be Koalas eating eucalyptus leaves or sheep eating grass Symbiosis:

The close and long term relationship between two dissimilar organisms, there are 3 principal types: ● Mutualism ○ Where both organisms have a net benefit from the interaction ○ Examples are humans and lactobacillus and algae and coral. ● Parasitism ○ Where one organism, the parasite, lives on the other, causing harm to the host but getting personally benefited ○ Examples are fleas and dogs and mosquitoes and humans. ● Commensalism ○ Where one benefits and the other organism either receives benefits or harm ○ Examples are tree frogs and plants and Monarch Butterflies and Milkweed. 12. Differentiate between morphological and chemical defence mechanisms. Give several examples of each. How does Batesian mimicry differ from Mullerian mimicry? Morphological vs Chemical Defense Mechanisms: Morphological Defense Mechanisms: - Also known as mechanical defense mechanisms - Physical adaptations that are specifically meant to lower the chances of predation occurring - Examples include: - Camouflage - Hardened exteriors (i.e. shells, hides, bark, spines, thorns, etc.) - Features that help in combat (teeth, claws, etc.)

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Chemical Defense Mechanisms: - Are substances utilized by prey to reduce predation risk. - Is employed by organisms to avoid consumption by producing toxic or repellent metabolites. - The production of defense chemicals occurs in: - Plants, Fungi, and bacteria Bastian vs Mullerian mimicry: Bastian mimicry: -Form of biological resemblance - When a harmless animal/ organism mimics a harmful animal/organism - Flies that have the same colouring as wasps/ bees and butterflies that mimic monarchs ( monarchs are poisonous) -Helps protect the organism because predators will mistake them for harmful creatures and will stay away Britannica, T. Editors of Encyclopaedia (2011, October 13). Batesian mimicry. Encyclopedia Britannica. https://www.britannica.com/science/Batesian-mimicry

Mullerian Mimicry: - When two or more not closely related harmful animals/organisms have the same defense mechanism - Eg. two venomous snakes have similar patterns/colouring - Predators will learn to stay away from organisms that have these patterns because they associate these colours/ patterns with harm. - Brightly coloured organisms tend to be seen as poisonous in some form - Auditory warnings in snakes Britannica, T. Editors of Encyclopaedia (2019, January 11). Müllerian mimicry. Encyclopedia Britannica. https://www.britannica.com/science/Mullerian-mimicry Differences: Bastian mimicry is when a non harmful organism mimics a harmful organism and Mullerian mimicry is when two harmful organisms exhibit the same traits that predators associate with danger. Viceroy butterfly mimics the monarch butterfly( bastian) Snakes also have auditory warnings to keep predators away (mullerian)

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Part I-Jigsaw activity Class Copy-08

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