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CLEMSON / Biology / BIOL 1040 / What is it called when two or more individuals or populations try to u

What is it called when two or more individuals or populations try to u

What is it called when two or more individuals or populations try to u


School: Clemson University
Department: Biology
Course: General Biology II
Professor: William surver
Term: Fall 2016
Cost: 50
Name: Biology 2 Final Exam Study Guide
Description: This study guide covers all of the notes from the chapter 45 and chapter 46 powerpoints discussed in class!
Uploaded: 04/21/2016
11 Pages 184 Views 6 Unlocks

Biology 1040 Final Exam Study Guide

What is it called when two or more individuals or populations try to use the same limited resources?

Chapter 45 – Population and Community Ecology

∙ Introduction

o Population Ecology is concerned with

 The changes in population size

 Factors that regulate populations over time

o Populations

 Increase through birth and immigration to an area

 Decrease through death and emigration out of an area o Population

 A group of individuals of a single species that occupy the  same general area

 A group of individuals that share a common gene pool

o Individuals in a population

 Rely on the same resources

 Are influenced by the same environmental factors

How do you estimate population density by sampling?

 Are likely to interact and breed with each other

o Population may be described by the number and distribution of  individuals

o Population dynamics – the interactions between the biotic and  abiotic factors causes variation in population sizes  

o Human population problems

 46.2 million living in poverty in US – below $27,000

 Most resources are consumed by relatively few people  in developed countries

∙ Density and Distribution Patterns

o Population density is the of individuals of a species per unit area  or volume

o Examples of population density Don't forget about the age old question of What are the three elements that make up music?

 The number of oak trees per square kilometer in a forest  The number of earthworms per cubic meter in forest soil o Ecologists use a variety of sampling techniques to estimate  population densities

What does density mean when referring to wildlife?

o The density of a population is not always easy to determine o Where to find information – how accurate?

 Literature search

 Demographic data

o Animals move about so how can one be confident with density  estimates; only able to sample a small area

o Within a population’s geographic range, local densities may vary  greatly

o Some methods used are

 Capture-recapture

 Quadrants (sample plot method)

o Assumptions in capture-recapture

 Marking has no effect on mortality

 Marking has no effect on the likelihood to being captured  There is no immigration or emigration between the  

sampling times

 The dispersion pattern of a population refers to the way  individuals are spaced within their area

∙ Life Tables and Survivorship Curves

o A life history pattern is a set of adaptations that influence  survival, fertility, and the age at first reproduction

o It is a set of conditions pertaining to an individual’s schedule of  reproduction If you want to learn more check out What is a motor plan?

o Summarized in life tables and survivorship curves

o Life table

 Tracks age-specific patterns

 Population is divided into age categories

 Birth rates and mortality rates are calculated for each age  category

 Each species has a characteristic life span; not all achieve  it

o Ecologists use survivorship curves to plot a cohort’s age-specific  survival in a habitat

o Type I – high survivorship until fairly late in life, then a large  increase in death; elephants and other large mammals; humans o Type II – reflect a fairly constant death  rate at all ages; characteristic of lizards, small mammals, and  large birds

o Type III – death rate that is highest early on; species that produce many small offspring and do little, if any, parenting;  


∙ Population Growth

o Exponential growth model

 The rate of a population increases under ideal conditions  Calculated using the equation G = rN

∙ G is the growth rate of the population

∙ N is the population size

∙ r is the per capita rate of increase-the We also discuss several other topics like What would happen if the moon fell to earth?

∙ average contribution of each individual to population  growth birth rate – death/population size

o carrying capacity levels off population growth

 carrying capacity—what the environment can sustain

o Logistic growth model is a description of idealized population  growth that is slowed by limiting factors as the population size  increases We also discuss several other topics like What are the psychological changes in the elderly?

o G=rN ((K-N)/K)

o K stands for the carrying capacity, the maximum population size  a particular environment can sustain

∙ Density Dependent Factors

o Multiple factors may limit population growth

o The logistic growth model predicts that population growth will  slow and eventuall stop as population density increases

o At higher populations densities density-dependent rates result in  Declining births and/or

 Increase in deaths

o Intraspecific competition (competition between same species) –  compete for limited resources – food, nutrients, nesting sites o Limits growth in natural populations

∙ Density Independent Factors

o Factors unaffected by density – density independent

o Natural disasters

 Fires, storms

 Habitat destruction

 Seasonal changes in weather

 Will occur regardless of population size  

o Some populations fluctuate in density with regularity (still at a  specific carrying capacity)

o Boom and bust cycles may be due to

 Food shortages

 Predator-prey interactions

o Snowshoe hare and lynx populations based on the number of  pelts sold by the Hudson Bay Company over a period or nearly  100 years.

o What causes the boom-and-bust cycles of snowshoe hares?  When hares are abundant they overgraze their winter food  supply resulting in high morality Don't forget about the age old question of What is the meaning of polyploidy?

 Hare population cycles attributed by excessive predation o Using radio collars to track individual hares, it was determined  that Don't forget about the age old question of What are the five kinematic equations?

 90% of hares had been killed by predators and none  had died of starvation

 These results support the predation hypothesis

 However, further experiments showed that although  fluctuating food availability is not the primary factor  

controlling hare population cycles, it does play an  

important role

∙ Climate Change – TED Talk  

o Al Gore

o The sky is a very thin shell of atmosphere surrounding the planet o 110 million tons of greenhouse gases being spewed every day  o We rely on carbon-based school for 85% of fossil fuels o Extremely hot days 150x more common than they were 30 years  ago

o Super storm Sandy 9 degrees warmer than average  


o As temp increases, oceans evaporate more moisture into sky o Moisture is pulled from ground—dry land; vegetation dies;  prevalent fires

o Zika virus – spreads in hot weather

o People are beginning to use batteries, solar power, and wind  power more and more

o We CAN change

o Many proposed US coal plants have been cancelled and many  existing plants have been closed

∙ Life Histories

o Life history – the traits that affect an organism’s reproduction  and death make up its life histories

o Key life history traits include

 Age of first reproduction

 Frequency of reproduction

 Number of offspring

 Amount of parental care

o Populations with r-selected life history

 Found in disturbed or transitory environments

 Have short life spans

 Begin breeding early in life

 Opportunistic

 Short generation times

 Produce large numbers of offspring

o Populations with r-selected life history

 Take little care of their offspring and infant mortality is  high

 Have efficient means of dispersal

 Type III survivorship curve

 Never reach K

o Populations with k-selected life history

 Usually found in stable environments

 Have a long life span

 Begin breeding later in life  

 Usually have long generation times

 Most produce small numbers of offspring

 Have parental care of their young

o Populations with k-selected life history

 Have a type I or II survivorship curve

 Efficient in exploiting an ever-narrower slice of their  


 Tend to reach K

∙ Applications

o Sustainable resource management

 Harvesting crops

 Eliminating damage to a resource

o Cod fishing off Newfoundland

 Over fished, collapsed in 1992 and has not recovered o Resource managers use population ecology to determine  sustainable yields

∙ Human Population

o The human population

 Grew rapidily during the 20th century and currently stands  at over 7 billion

o An imbalance between births and deaths is the cause of  population growth (or decline)

o The human population is expected to conitinue increasing for at  least the next several decades

o Growth rate is slowing

o Demographic transition of a shift from zero population growth, in  which birth rates and death rates are high buy roughly equal to  zero population growth characterized by low but roughly equal  birth and death rates

o Mexico is expected to approach zero population growth with low  birth and death rates in the next few decades

o Developing nations

 Death rates have dropped

 Birth rates are still high

 Populations are growing rapidly

o Age structure

 The proportion of individuals in different age groups

 Affects the future growth of the population

 Population momentum

∙ Ecological Footprint

o Is an estimate of the amount of land required to provide the raw  materials an individual or a nation consumes  

 Food

 Fuel

 Water

 Housing

 Waste disposal

o The United States  

 Has a very large footprint, much greater than its own land  Running on a large ecological deficit

o Some researchers estimate that. if everyone on Earth had the  same standard of living as people in the United States, we would  need the resources of 4.5 planets

∙ Community Ecology

o Community ecology is concerned with factors that

 Influence species composition and distribution of  


 Affect community stability

o Community ecologists seek to understand how abiotic factors  and interactions among populations affect the composition and  distribution of communities

o A biological community is

 An assemblage of all the populations of organisms living  close enough together for potential interaction

 Describe by its species composition

o The boundaries of a community vary with the research question  investigated  

 A pond

 The intestinal microbes of a pond organism

o The place where an organism lives is its habitat

o The habitat of an organism is characterized by physical and chemical features and the array of other species living in it o Directly or indirectly, the populations of all species in the habitat associate with one another as a community

o What are some factors that shape community structure?  Climate and topography

 Available foods and resources

 Adaptations of species in community

 Species interactions

 Arrival and disappearances of species

 Physical disturbances

∙ Niche Concept

o The niche concept

 Niches are sometimes difficult to understand but in reality  they are not

 A niche is the sum of activities and relationships in which a  species engages to secure and use resources necessary for survival and reproduction

 Be sure that you can distinguish between a habitat and a  niche

 Habitat is you address and the niche is your occupation in  that niche

o Fundamental niche

 Theoretical niche occupied in the absence of any  

competing species

o Realized niche

 The niche a species actually occupies

 It is some fraction of the fundamental niche

∙ Competition

o Commensalism

 One benefits other is not affected

 Difficult to determine

o Example-Remora and shark

o Competition may be

 Intraspecific and interspecific

 Intraspecific is usually fiercer and has more several  consequences..why is this so?

o Gause in the 1930’s proposed the Principle of Competitive  Exclusion

 Competition occurs when niches overlap

 The more overlap the greater the competition

 Exclusion occurs when two niches completely overlap…but  do they?

o One way to avoid competition is to locate new resources within  your niche-resource partitioning

o Your niche then becomes slightly different than a competitor ∙ Predator/Prey Interactions  

o Predator is the feeder, prey is the feed

o Predators get their food from prey, but they do not take up  residence on or in the prey (contrast to parasites)

o Many of the adaptations of predators and their victims arose  through coevolution

o Prey do have defenses which protect them from predators  Camouflage

 Warning coloration

 Mimicry

 Moment of truth defenses

o Predator may respond through new adaptations

∙ Ecological Succession

o Communities come into being by ecological succession

o Change in the composition of species over time

o Classical model describes a predictable sequence with a stable  climax community

o Primary succession – new environments; bare rock succession o Secondary succession – communities were destroyed or  displaced

o Climax community

 Stable array of species that persists relatively unchanged  over time

 Succession does not always move predictably toward a  specific climax community, other stable communities may  persist

o The following slides show examples of succession

Chapter 46 – Ecosystems

∙ The Nature of Ecosystems

o An ecosystem is an association of organisms and their physical  environment, interconnected by an ongoing flow of energy and a  cycling of materials through it

o The participants – in order to understand the complexity of  ecosystems it is necessary to know the key participants

 Primary producers are autotrophs that can capture  sunlight energy and incorporate it into organic  


o Consumers are heterotrophs that feed on the tissues of other  organisms

 Herbivores eat plans

 Carnivores eat animals

 Omnivores eat a variety of organisms

 Parasites reside in or on living hosts and extract energy  from them; decomposers are also heterotrophs and  

 include fungi and bacteria that extract energy  

from the remains or products of organisms

o Detritovores include small invertebrates that feed on partly  decomposed particles of organic matter (detritus)

o Ecosystems are complex

 They are open systems through which energy flows and  materials are cycled

 They require energy and nutrient input and generate  

energy (usually as heat) and nutrient output

o Nutrients neither enter nor leave cycle

o Energy is not recycled

 Captured by producers

 Transferred through consumers  

 Each transfer loses energy  

o Diets can change depending upon the availability of food ∙ Trophic Levels

o Trophic levels

 Trophic (feeding) levels are a hierarchy of energy  transfers…”who eats whom”

 Level 1 (closest to the energy source) consists of producers  Level 2 comprises herbivores

 Level 3 and above are carnivores

 Decomposers feed on organisms from all levels

∙ Food Web

o A food wed is a simple sequence of who eats whom is called a  food chain

o Interconnected food chains comprise food webs in which the  same food resource is often part of more than one food chain ∙ Energy Flow Through an Ecosystem

o Energy flow is considered in terms of productivity

 Gross primary productivity is the ecosystem’s total rate of  photosynthesis

 Net primary productivity is the rate of energy storage in  plant tissues in excess of the rate of respiration by the  

plants themselves

o Primary productivity varies

 Seasonal variation

 Variation by habitat

 The harsher the environment, the slower plant growth and  the lower the productivity

o At each trophic level, the bulk of the energy received from the  previous level is used in metabolism

o The energy is released as heat energy and lost to the ecosystem o Eventually all energy is released as heat energy

∙ Biological Magnification

o Biological magnification results when substances become more  and more concentrated in the tissues of organisms at higher  trophic levels of a food web

o DDT is a good example  

o DDT is now banned in the US

Energy Flow, Nutrient Cycling, & Feeding Relationships

Trophic Levels

Food Web

Primary Ecological Succession

Secondary Ecological


Predator/Prey Interactions

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