Unit 03 Flashcards
What is a range of tolerance?
The limits to abiotic conditions that a species can tolerate, such as extremes of temperature, humidity, salinity, and pH
What occurs as you move along the range of tolerance curve?
survive < survive and grow = survive, grown, and reproduce = survive and grow > survive
What is a fundamental niche?
The suite of abiotic conditions under which a species can survive, grow and reproduce
What is a realized niche?
The range of abiotic and biotic conditions under which a species actually lives determines whether they are a generalist or specialized species
What are examples of biotic limitations?
competitors, predators, and diseases
What is a niche generalist?
Species that can live under a wide range of abiotic or biotic conditions
What is a niche specialist?
A species that is specialized to live in a specific habitat or to feed on a small group of species
Why do species go extinct?
When environmental conditions change and species are unable to adapt to the changes or to favorable environments, they will eventually go extinct
What is the average life span of a species?
1 million to 10 million years, with 99%of species already extinct on Earth
How does the fossil record help us determine the evolution of life?
Organic material is buried and protected by mud and other sediments. Overtime the sediments build up layers that encompass the material which allows us to get a rough estimate of how long a species lived
What is the definition of a mass extinction?
A large extinction of species in a relatively short period of time
How is the sixth mass extinction different from the other five?
The sixth extinction (2020) is being caused by human activities which will make it difficult for species to move or adapt in time to avoid extinction
What are population growth models?
Mathematical equations that can be used to predict population size at any moment in time
What is population growth rate?
The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period
What is intrinsic growth rate (r)?
- The maximum potential for growth of a population under ideal conditions with unlimited resources
- When conditions are less than idea due to limited resources, a populations growth rate will be lower than its intrinsic growth rate
What is the exponential growth model?
A growth model that estimates a population’s future size (Nt) after a period of time (t) based on the intrinsic growth rate (r) and the number of reproducing individuals currently in the population (N(0))
N(t)=N(0)e^(rt)
What kind of curve is produced in an exponential growth model?
J-Shaped curve that represents an initially small growth rate which rapidly increases over time
What are the flaws in an exponential growth model?
No population can experience exponential growth indefinitely as demonstrated by Gause’s experiments with Paramecium
What is a logistic growth model?
A growth model that describes a population whos growth is initially exponential, but slows as the population approaches the carrying capacity of the environment
What kind of curve is produced in a logistic growth model?
S-Shaped curve that represents the affect of carrying capacity on the population of a species
What does a logistic growth model assume?
The number of offspring produced depends on the current population size and the carrying capacity of the environment. However, it usually depends on the time of the year and the availability of food
What is an overshoot?
When a population becomes larger than the environment’s carrying capacity
When will a population experience a die-off?
A rapid decline in a population due to death which can take the population below carrying capacity of the environment
What are K-selected species?
A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity
What are the typical characteristics of a K-selected species?
Life span - long Reproductive maturity - long Reproduction - few Offspring - few Size of offspring - large Parental Care - present Population growth rate - slow Population regulation - density dependent Population dynamics - stable, near carrying capacity
What are the issues with a K-selected species?
The species cannot respond quickly to extinction
What are R-selected species?
A species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs
What are the typical characteristics of an R-selected species?
Life span - short Reproductive maturity - short Reproduction - many Offspring - many Size of offspring - small Parental Care - absent Population growth rate - fast Population regulation - density independent Population dynamics - highly variable
What are the issues with an R-selected species?
They exhibit rapid population growth that is often followed by overshoots and die-offs
What are survivorship curves?
A graph that represents the distinct patterns of species survival as a function of age
What is a type I survivorship curve?
- A pattern of survival over time where there is high survival throughout most of the life span, but then individuals begin to die off in large numbers as the approach old age
- K-selected species such as elephants, whales, and humans
What is a type II survivorship curve?
- A pattern of survival over time where there is relatively constant decline in survivorship throughout most of the life span
- corals and squirrels
What is a type III survivorship curve?
- A pattern of survival over time where there is low survivorship in early life with few individuals reaching adult hood
- R-selected species such as mosquitoes and dandelions
What are corridors?
Strips of natural habitat that connect populations
What is a metapopulation?
A group of spatially distinct populations that are connected by occasional movements of individuals between them
What is inbreeding depression?
When individuals with similar genotypes breed with each other and produce offspring that have an impaired ability to survive and reproduce
Why are small populations more vulnerable to extinction?
- Inbreeding depression
2. Harsh winters and environmental catastrophes can drive populations to critically low numbers
What are the benefits of metapopulations?
Can provide a species with protection from threats such as disease and extinction
What is carrying capacity?
The maximum population size of the species that the environment can sustain
What are the five levels of complexity and what do they study?
Individual: survival and reproduction - the unit of natural selection
Population: population dynamics - the unit of evolution
Community: interactions among species
Ecosystem: Flow of energy and matter
Biosphere: Global processes
What are the five basic characteristics of populations?
Population size: total number of individuals within a defined area at a given time
Population density: number of individuals per unit area
Population distribution: description of how individuals are distributed with respect to one another
Population sex ratio: ratio of males to females in a population
Population age structure: description of how many individuals fit into a particular age category
What are density dependent factors?
A factor that influences an individuals probability of survival and reproduction in a manner that depends on the size of the population
What is a limiting resource
A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size
What is a density-indepdent factor?
A factor that has the same effect on an individual’s probability of survival and the amount of reproduction at any population size
What did Thomas Malthus believe?
He believed the human population was growing exponentially while the food supply we relied on was growing linearly
What do scientists who disagree with Malthus, believe?
The ability for humans to innovate in the face of challenges, means that we will continue to make technological advances indefinitely
What factors affect human populations?
Population size, birth and death rates, fertility, life expectancy, and migration
What is immigration?
The movement of people into a country or region, from another country or region
What is emigration?
The movement of people out of a country or region
What is crude birth rate (CBR)?
The number of births per 1,000 individuals per year
What is crude death rate (CDR)?
The number of deaths per 1,000 individuals per year
How do you calculate the global population growth rate?
[CBR-CDR]
________
10
How do you calculate the national population growth rate?
[(CBR + immigration) - (CDR + emigration)]
________________________________
10
What is doubling time and how can it be calculated?
The number of years it takes a population to double
70/growth rate
What is total fertility rate (TFR)?
- An estimate of the average number of children that each woman in a population will bear throughout her childbearing years (not calculated per 1,000 people)
- In 2014, the TFR was 1.9 which means each women gave birth to about 2 children
What is replacement-level fertility?
The total fertility rate required to offset the average number of deaths in a population in order to maintain the current population size
What is a developed country?
A country with relatively high levels of industrialization and income
What is a developing country?
A country with relatively low levels of industrialization and income
What kind of replacement-level fertility is typical in a developed country?
About 2
What kind of replacement level fertility is typical in a developing country?
Greater than 2.1 in order to account for the greater mortality in young people
When is a country’s population stable?
When TFR is equal to replacement level fertility and where emigration and immigration are equal
When will a country’s population experience a decrease?
When TFR is less than 2.1 and there is no net increase from immigration
What is life expectancy?
The average number of years an infant is expected to live, given average life span and death rate
In what three ways is life expectancy report?
Overall population of a country, for males, and for females only
Why do men usually have a shorter life span?
Biological factors, hazardous lifestyle choices, and greater danger in the work place
What is infant mortality rate?
The number of deaths of children under 1 year of age per 1,000 live births
What is child mortality?
The number of deaths of children under age 5 per 1,000 live births
What factors affect child survival rates?
Health care, adequate food supply, potable drinking water, sanitation, and moderate level of pollution are ideal
Why might a high life expectancy and low infant mortality country have a high crude death rate
Better standard of living which prolongs the lives of senior citizens and disease
What is net migration rate?
The difference between immigration and emigration in a given year per 1,00 people in a country
What is an age structure diagrams?
A visual representation of the number of individuals within a specific age group and gender
What is a population pyramid?
An age structure diagram that is widest at the bottom and smallest at the top, typical of developing countries
What is population momentum?
Continued population growth after growth reduction measures have been implemented
What kind of population would have a column shaped age structure diagram?
Little difference between the number of individuals in younger age groups and in older age groups
What kind of population would have an inverted pyramid?
- Greater number of older people than younger people
- Total fertility rate below 2.1 and a decreasing number of females within each younger age range (Germany, Russia, Italy)
What is the study of demography?
The study of statistics such as births, deaths, income, or the incidence of disease, which illustrate the changing structure of human populations.
What is stage 1 of demographic transition?
- high birth rate, high death rate
- High birth rate compensates for high infant mortality
- Characteristic of poorer countries
What is stage 2 of demographic transition?
high birth rate, rapidly falling death rate
- Industrialization begins access to food and improved healthcare lowers death rate
What is stage 3 of demographic transition
falling birth rate, falling death rate
- Death drops due to improved medicine and modernization
- Most developed countries are at this stage
What is stage 4 of demographic transition?
low birth rate, low death rate
- Birth rate drops to equal zero population growth
- If birth rate falls below death rate then population will decrease
What is the theory of demographic transition?
The theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a shift in population growth
What is affluence?
The state of having plentiful wealth including the possession of money, goods, or property
What is family planning?
The practice of regulating the number of spacing of offspring through the use of birth control
