Unit 7 - Ecology

Population?

A group of organisms of the same species living in the same area at the same time

Why is random sampling used to estimate population size?

• Gives practical and reliable estimates

• Unbiased and effective

Capture-mark-release-recapture?

A technique used to estimate population size by capturing, marking and releasing and recapturing individuals

Lincon index?

A mathematical formula used to estimate population sized based on marked individuals

Carrying capacity?

The maximum population size an environment can sustain indefinitely without degrading the habitat

What is negative feedback?

A process where changes trigger responses that counteract change

Density dependent factors?

Factors that increase with population density

Examples of density dependent factors?

• Predation

• Disease and paratistim

• Competition for resources

Density independent factors?

Factors that have the same effect whatever the population size

Trophic levels?

A positon in a food chain representing an organisms feeding relationships

What factors affect the change in population?

• Natality

• Mortality

• Immigration

• Emigration

What does sigmoids graph show?

The population grow in the exponential, transitional and plateau phases

Exponential phase?

Population is established at and ideal unlimited environment

Transitional phase?

Population growth slows as carrying capacity is reached

Plateau phase?

Something (a factor) has limited population

Cooperation?

Individuals in a population may cooperate in a variety of ways

Competition?

Members of a population have the same ecological niche and require similar resourcces

Relationships between species in close associations?

• Mutualism - Both species benefit in interactions

• Pathogenicity - One species live in another

• Paratism - One species uses another to obtain food

Relationships between species not living in close association?

• Herbivory - Primary consumer feed on producers

• Predation - One consumes another

• Interspecific competition - Two or more species require the same resources reducing the amount available

Example of mutalisim?

• Legumes and nitrogen fixing bacteria that live in root noodles

• Orchids and fungi mycorrhiza which help orchid obtain water and nutrients

• Hard corals and zooxanthellae algae living within coral tissues providing energy for photosynthesis

Endemic species?

Species native to specific locations and found nowhere else

Invasive species?

Non-native species that establish and spread in a new environment

Competitive exclusion principle?

Two species cannot occupy the same ecological niche and will eventually outcompete each other

How do invasive species succed?

• Lack of predators

• High reproductive rates

• Broad ecological niches

• Resistance to environmental stressors

What challenges do invasive species create?

• Predation and poisoning

• Resource competition

• Habitat alteration

• Disease transmission

How to study interspecific competing?

• Field manipulation

• Lav experiments

• Tests for association between species through random sampling

Predator-prey interactions?

Fundamental ecological relationships where one organisms hunts and consumes another

Why are predator prey relationships important?

• Maintains ecological balance

• prevents overpopulation

• Promotes biodiversity

• Drives natural selection

Top- down control?

Regualtion by predators or higher trophic levels

Bottom up control?

Regulation by resources availability or lower trophic levels

Chemical competition?

The use of chemicals by organisms to reduce competition for resources lie space, nutrients or light

Allelopathy?

The release of chemical by plants that negatively affect the growth of plants

Antibiotic secretion?

The release by microorganisms that inhibit the growth of other mcrobes

How does antibiotic secretion work

1. Production: Antibiotics are produced under stress or competition.

2. Release: They diffuse into the surrounding environment.

3. Effect: They kill or inhibit competing microorganisms.

Mechanisms of allelopathy?

• Leaching: Chemicals wash off leaves into the soil.

• Root exudation: Chemicals are released directly from roots.

• Decomposition: Dead plant material releases chemicals as it breaks down.

What resources limit population growth in plants and for animals?

ANIMALS

• Food

• Water

• Space

  PLANTS

• Light

• Water

• Nutrients

Biodiversity?

The total variety of life on earth including all living organisms the ecosystems they live in and genetic difference between and within a population

Ecosystem diversity?

The variety of combinations within a region or across the globe

Species diversity?

The number and variety of species in a give ecosystem

Genetic diveristy?

The variation of genes within and between populations and species

DNA barcoding?

The process allowing scientists to identify species based of genetic diffrences

Fossil records?

Help get information on past biodiversity levels

Anthropogenic?

Caused or influenced by human activity

Examples of anthropogenic extinction

Giant moa (Ovreharvesting for meat)

White rhino (Poaching for horns)

Caribbean monk seal (over hunting due to lack of fear)

What are the 8 direct or indirect causes of ecosystem loss?

1. Agriculture

2. Urbanization (for infrastructure to support the increasing population and its affluence)

3. Overexploitation of natural resources (hunting, fuel wood, fishing…, knock-on effects of “keystone species”)

4. Mining and smelting (esp. tropical rainforest)

5. Water management (dam/reservoir/irrigation)

6. Drying of wetlands (drained for agriculture ++)

7. Leaching (+ eutrophication from fertilizers washing off agricultural land)

8. Climate change (more in Theme B and D)

9. Alien species being introuduced to the enviroment

Keystone species?

A species that has large effects on its enviroment by maintaing its structure and stability

Examples of direct or indirect ecosystem loss?

The areal sea due to water diversion and salinity which cause less inflow from rivers extinict fish due to increased salinity and an economic decline

Asian mixeddipterocarp forest logging and palm oil, rising sea levels from global warming (+ drainage leads to peat decomposition)

Change of land use/ land cover in Kenya greater population and more land usage, isolated wildlife populations can lose genetic diversity which can lead to extinctions

Species richness?

The total number of species in an area

Species evenss

Relative abundance of individual amount different species

Degradation?

Reduced ecosystem health

Destruction?

Total conversion to another land use (Wildlife land to house)

The bidoversity crisis?

The rapid loss of species and their habitats, resulting in significant declines in biodiversity across ecosystems.

Natural extinction?

The natural rate of extinction were one ecosystems is replaced by another

In situ conservation?

focuses on protecting animals in designated nature reserves/national parks

Ex situ conversation?

Preserve species out of the natural habitat eg in captive breeding or seed banks

Active managment?

When humans take steps in the envrioment to help protect animals

Implications of biodiversity crisis?

ECOLOGICAL - loss of keystone species leading to ecosystem collapses

ECONOMIC - Declines in fisheries, agriculture and tourism

ETHICAL- our responsibility to preserve the natural world for future generations

Benefits on in stu conservation?

Natural habitat conserved

Maintains the animal normal behaviour

Food webs maintained

Limitations on in stu conservation?

Captive breeding doesnt alway work

Benefits of ex situ conservation?

Will work if habitat is lose

Easy to isolate the animal from threat

Captive breeding can increase the number and help with reintroduction

Habitat can be used for reintroduction

Evolutionarily Distinct (EDge)?

Species that are evolutionary distinct and have high risks of evolution

Globally Endangered (edGE)?

The species is likely to go extinct because all remaining populations

What two criterias are used for identifying species conservation priorites?

If they are:

Evolutionarily distinct

Globally endangered

limitations of ex situ conservation?

Species may be too rare to breed/ maintain population in the wild

conservation examples?

Grey wolves in the us

Axolotl in Mexico through captive breeding

3-Toed sloth in Panama recovered through habitat protection

Ecosystem?

A community of living organisms interacting with their psychical environment including biotic and abiotic components

Open system?

Where resources can enter or exit including chemical substance and e
energy

Closed system?

Where energy can enter or exit including chemical subatance’s and energy

What direction does energy flow follow?

A one way path from the sun onwards

What is the primary source of energy for most ecosystems?

The sun

Decomposers?

An organism that breaks down dead organic matter releasing energy 

Food chain?

A linear flow of food chains in a community

Food web?

A model that summarizes all of the possible food chains in a community

Energy flow?

The transfer of energy from one organsims to another through a feeding relationship

How much energy is passed on at one trophic level?

10%

What is energy lost at?

Heat

What are the two main types of decomposers?

• Saprotrophs

• Detrivores

Saprotrophs?

Organsims like bacteria and fungi that digest organic matter by secreting enzymes

Autotroph?

An organism that uses carbon dioxide to synthesis carbon compounds from simple inorganic substances

Types of autotrophs?

• Chemoautotrophs (Use energy in oxidation reactions to produce organic compounds)

• Photoautotrophs (use light energy to convert co2 and water to glucose)

Carbon fixation?

The process of converting inorganic carbon into organic compounds 

Why do autotrophs fix carbon?

The cannot get organic molecules they need by consuming other organisms

Example of photoautotrophs and chemoautotrophs?

• photoautotrophs- Algae, plants

• Chemoautotrophs - Sulfur bacteria, Nitrifying bacteria

How iron oxidizing bacteria uses oxidation reaction for energy?

• Oxidation of iron

• Energy extraction

• ATP production

• Carbon fixation

Heterotrophs?

Organisms that obtain energy and carbon by consuming other organisms

What are the stages of obtaining and using food in heterotrophs?

• Ingestion 

• Digestion 

• Absorption 

• Assimilation 

• Egestion 

How do all living organisms produce ATP?

Cellular respiration 

The process in which carbon compounds are broken down through oxidation?

Cell respiration

Oxidation?

The loss of electrons from a substance

Outline the process of cellular respiration as an oxidation reaction?

• Glycolysis - Glucose is broken down to give away 2 ATP and 2 NAD in the cytoplasm 

• COA is oxidized to produce CO2, ATP, NADH AND FADH2

• Electrons are transfered through a series of proteins driving production of ATP in the mitochondrial membrane

How do autotrophs obtain carbon compounds?

converts solar to chemical energy through photosynthesis

How do Heterotrophs obtain carbon compounds?

Consume other organism or organic matter

Trophic level?

How ecologists classify organism based on how they obtain food

The trophic levels of organism in a food chain?

• Producers - 1 (autotrophic)

• Primary consumers - 2 (producers)

• Secondary consumers - 3 (consumers)

• Tertiary consumers - 4 (consumers)

Energy pyramid?

A graphical representation showing the flow of energy at each trophic level in an ecosystem with energy decreasing at each increasing level

How is energy measured in an energy pyramid?

Kilojoules per square meter per year

Why are there only 4-5 trophic levels?

Because energy decreases about 90% at each level

Give 3 reasons why energy decreases at each trophic level?

• Incomplete consumption 

• Incomplete digestion 

• Cell respiration 

How much energy is passed at each trophic level?

10%

How does second law of thermodynamics explain why heat is created and lost?

Some energy is always lost as heat and cannot be recycled