APES Unit 2 Content

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The variety of life in the world or in a particular habitat or ecosystem; includes genetic, species, and habitat diversity

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Environmental stressors

Conditions or events in your physical environment that cause you stress, including poverty, pollution, crowding, noise, natural disasters

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environmental stressors

The more genetically diverse a population is the better it can respond to ____________________ _______________.

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Population bottleneck

A type of genetic drift in which population size is sharply reduced due to some catastrophic event -- can lead to a loss of genetic diversity

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Any event that destroys any or all parts of an ecosystem

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Specialist species

Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or use only one type or a few types of food. Are typically more susceptible to extinction.

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Generalist species

Species with a broad ecological niche that can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions. Are typically less likely to become extinct.

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Species richness

Number of species found in an ecosystem

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Types of biodiversity

Genetic, habitat/ecosystem, and species

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Genetic biodiversity

Genetic variation within a population

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Habitat/ecosystem diversity

Number of habitats in a particular area

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Species biodiversity

Number of species in a particular region

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Biodiversity hotspots

Certain areas that have large numbers of endemic species. Many of these areas are heavily threatened by habitat loss and other human activities.

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Endemic species

A species that is found in its originating location and is generally restricted to that geographic area

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Larger, genetically diverse populations

What type of populations respond better to environmental change and stressors?

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Ecosystem Boundaries

Some ecosystems, such as a caves and lakes have very distinctive boundaries. However, in most ecosystems it is difficult to determine where one ecosystems stops and the next begins.

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Species richness and species evenness

What are the two types of species distribution?

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Species evenness

The measure of whether a particular ecosystem is numerically dominated by one species or all represented by similar numbers of individuals

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Community 1

Which community has greater species evenness?

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They have the same - both have 4 species

Which community has greater species richness?

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Group of organisms that are distinct from others

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The evolution and formation of a new species => takes a very long time

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Background extinction rate

Average number of species that go extinct over period of time

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Types of species

  • Specialist

  • Generalist

  • Invasive

  • Native

  • Exotic

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Invasive species

Species that enter new ecosystems and multiply, harming native species and their habitats by taking over - usually generalists

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Native species

Species that have originated, naturally evolved, and lived in the area for a long period of time

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Exotic species

Species that are brought in that are non native to a particular area; also known as alien species

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Number of species on Earth

  • 2 million species have been identified and named.

  • Current estimates range from 5 to 100 million.

  • Most agree that there are about 10 million.

  • 99% of all species that have ever existed are extinct.

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Remains of organisms that have been preserved in rock. Much of what we know about evolution comes from these excavated records.

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Mass extinctions

The extinction of a large number of species within a relatively short period of geological time, thought to be due to factors such as a catastrophic global event or widespread environmental change that occurs too rapidly for most species to adapt.

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5 Global Mass Extinctions

  1. Ordovician-silurian Extinction: 440 million years ago, Small marine organisms died out.

  2. Devonian Extinction: 365 million years ago, Many tropical marine species went extinct.

  3. Permian-triassic Extinction: 250 million years ago, The largest mass extinction event in Earth's history affected a range of species, including many vertebrates.

  4. Triassic-jurassic Extinction: 210 million years ago, The extinction of other vertebrate species on land allowed dinosaurs to flourish.

  5. Cretaceous-tertiary Extinction: 65 million Years Ago, The major extinction that wiped out non-avian dinosaurs

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The Sixth Mass Extinction

  • Scientists feel that we are in our sixth mass extinction occurring in the last two decades.

  • Estimates of extinction rates vary widely from 15% to 37% by 2050.

  • In contrast to previous mass extinctions, scientists agree that this one is caused by humans.

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Categories of endangerment

Extinct, threatened, near-threatened, least concern

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No longer in existence

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Species with a high risk of extinction in the future

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Species that are likely to become threatened in the future

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Least concern

Species are widespread and abundant

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6 Threats to Biodiversity (HIPPCO)

H - Habitat Loss I - Invasive Species P - Pollution P - Population (Human) C - Climate Change O - Overharvesting

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human development

Most habitat loss is due to _________ ____________________.

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When individuals of a species are removed at a rate faster than the population can replace them. Ex: dodo, American bison, passenger pigeon

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Marine Mammal Protection Act

Prohibits the killing of all marine mammals in the U.S. and prohibits the import or export of any marine mammal body parts

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Lacey Act

One of the earliest laws in the U.S. to control the trade of wildlife. First passed in 1900, the act prohibited the transport of illegally harvested game animals, primarily birds and mammals, across state lines.

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Convention on International Trade in Endangered Species of Wild Fauna and Flora Developed in 1973 to control the international trade of threatened plants and animals. Today, CITES is an international agreement between 175 countries of the world.

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Red List

A list of threatened species regulated by the IUCN (International Union for Conservation of Nature and Natural Resources) each country has its own way to monitor and regulate the import and export of animals on the list.

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Endangered Species Act

First passed in 1973, it authorizes the U.S. Fish and Wildlife Service to determine which species can be listed as threatened or endangered and prohibits the harming of these species.

  • Trading these species is also illegal.

  • The act also authorizes the government to purchase habitat that is critical to the species.

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Convention of Biological Diversity

In 1992, nations came together and made a treaty to protect biodiversity. The treaty had 3 objectives:

  • conserve biodiversity

  • sustainably use biodiversity

  • equitably share the benefits that emerge from the commercial use of genetic resources such as pharmaceutical drugs

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Island biogeography

The study of the ecological relationships and distribution of organisms on islands, and of these organisms community structures

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specialists, generalists

Many island species have evolved to be ______________ versus ______________ because of the limited resources, such as food and territory, on most islands

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Any habitat surrounded by uninhabitable (but crossable) areas

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Types of islands

Ocean islands, patch islands, and forest fragments

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Ocean islands

Islands surrounded by seawater

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Patch islands

Sky islands (Alpine communities surrounded by valleys/plains)

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Forest fragmentation

The division of forests that formerly occupied large, unbroken areas into smaller pieces by road, fields, cities, and other land-transforming activities

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A strip of natural habitat that connects two adjacent nature preserves to allow migration of organisms from one place to another; used to combat habitat patches and make a more complete ecosystem

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Edge habitat

The area where two different communities come together, typically forming an abrupt transition. Ex. A grassy field meeting a forest.

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Biosphere reserves

Protected areas consisting of zones that vary in the amount of permissible human impact

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Island Theory Of Biogeography

  • Larger habitats = more species b/c more niches, larger populations, less prone to extinction

  • Many species can disperse short distances, only some can go long if motile

Bigger island = more species Smaller island = less species Further away = less species Closer to = more species ** Colonization Decreases with Distance!! **

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Occurs when individuals with similar genotypes, generally relatives, breed with each other - can lead to mutation and genetic anomalies/disruption

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Genetic Drift

A decrease in diversity; can be through the founder effect or the bottleneck effect

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Founder effect

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.

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Bottleneck effect

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

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A change in the genetic composition of a population over time

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Evolution below the species level

  • EX: Mosquitoes evolving resistance to DDT

  • EX: Gonorrheal bacterial strains evolving resistance to penicillin

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A large-scale evolution which gives rise to new species or new genera, family, class or phyla

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Occur randomly and can add to the genetic variation of a population

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Physical locations on chromosomes within each cell of an organism

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The complete set of genes in an individual (letter in Punnett Square, Ex: BB); = GENETIC MAKEUP

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The actual set of traits expressed in an individual (Ex: brown eyes) = ACTUAL PHYSICAL CHARACTERISTICS

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The genetic process by which one chromosome breaks off and attaches to a different chromosome (no new genes, but maybe new traits)

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Evolution by artificial selection

The process in which humans determine which individuals breed, typically with a preconceived set of traits in mind

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Evolution by natural selection

The process in which the environment determines which individuals survive and reproduce.

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Darwin's Theory of Evolution by Natural Selection

  • Individuals produce an excess of offspring

  • Not all offspring survive

  • Individuals differ in their traits

  • Differences in traits can be passed on from parents to offspring

  • Differences in traits are associated with differences in the ability to survive and reproduce

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Allopatric Speciation

New species are created by geographic or reproductive isolation ** Most common type of speciation. **

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Sympatric Speciation

The evolution of one species into two species in the absence of geographic isolation, usually through the process of polyploidy

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An increase in the number of chromosomes

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Traits that improve an individual's fitness

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The ability to survive & reproduce

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Rate of environmental change

To survive a rapid environmental change, a population must evolve quickly Slow change = more survivors

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Adaption components

Rate of environmental change: Slow change = more survivors Genetic variation: Less variation = less likely to adapt Population size: Beneficial mutations should spread more rapidly Generation time: Shorter generation times = the faster genetic mutations will spread

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Types of ecological succession

Primary and secondary succession

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Keystone species

A species whose activities have a particularly significant role in determining community structure

  • Population control

  • Provides food for community

  • Mutualistic interactions

  • Provide habitats for others

  • Ecosystem engineers

  • EX: Beavers, wolves

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Indicator species

A plant or animal that, by its presence, abundance, scarcity, or chemical composition, demonstrated that some distinctive aspect of the character or quality of an ecosystem is present

  • Sensitive to changes

  • Representative of other organisms

  • Easily found

  • EX: Frogs

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Pioneer members

An early successional species commonly move into unoccupied habitat and overtime adapt to its particular conditions which may result in the origin of new species

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Succession impact

Will affect the total biomass, species richness, and net productivity over time of a disturbed ecosystem

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Primary succession

  • Volcanic activity, glaciers retreating

  • Surfaces that don't have soil

  • Algae, lichen, moses, & fungi are the first to arrive

  • Break up the rocks

  • Pioneer species

  • Beginning of soil formation KEY: NO SOIL TO START!

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Secondary succession

  • Forest fires, flooding, farming

  • Areas that have been disturbed, but still have soil layers

  • First to arrive are usually grasses and wildflowers KEY: DOES HAVE SOIL TO START!

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Pioneer community

The initial community that develops during primary succession, including lichens and mosses IS THE LEAST STABLE AND LEAST DIVERSE!

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Climax community

Stable, mature ecological community with little change in the composition of species STEADY, STABLE, AND THE MOST DIVERSE!

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Aquatic Succession

Occurs when bodies of water eventually turn into land due to the build up of sediment at the bottom of the water over time

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Environmental change

Changes to the environment can...

  • alter the distribution of species

  • cause species extinction

Some species are adapted to only survive in particular environments so changes in the environment can cause those species to move elsewhere or decrease in population.

  • Even if the species could alter their niche and move elsewhere, it might already be fully occupied by other species.

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Intermediate Disturbance Hypothesis

Species diversity is maximized when ecological disturbance is neither too rare nor too frequent. At low levels of disturbance, more competitive organisms will push subordinate species to extinction and dominate the ecosystem. At high levels of disturbance, all species are at risk of going extinct. According to IDH theory, at intermediate levels of disturbance, diversity is thus maximized because species that thrive at both early and late successional stages can coexist

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Types of disturbances

Periodic, episodic, random

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Predicted disturbances, happens frequently, usually ecosystem/populations adapted to it EX: Fires, Hurricanes

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Disturbances that happen, but not fully predicted EX: Tornadoes

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Out of character disturbances, very infrequent EX: Some volcanic eruptions

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How much an ecosystem can take before it is forced to change

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The rate at which an ecosystem returns to its original state after a disturbance

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Range of tolerance

  • The limit to the abiotic conditions they can tolerate is known as the range of tolerance.

  • Just because a species survives, doesn't mean it thrives

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Fundamental Niche

The suite of abiotic conditions where a species can survive, grow, AND reproduce. No competition or predators WHOLE GRAPH

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Realized Niche

The range of abiotic AND biotic conditions where a species actually lives.

  • Middle part of graph

  • This is the most realistic niche

  • Biotic factors also play a role: Competitors, Predators, Disease

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