Module 3: Biome and Ecosystem Ecology

Chapter 13-19

Ecology

study of the interactions among living organisms and with their environment

• examines how organisms interact with each other and their environment

• seeeks to idenitify and explain patterns

• levels:

  • organisms, population, community, ecosystem

Organismal Ecology

adaptation that enable individuals to live in specific habitats

• can be morphological, physiological, and behavioral

Population Ecology

a group of interbreeding organisms that are members of the same species living in the same area at the same time

• identified by where it lives, and if area has natural or artificial boundary

• focuses on the number of individuals in an area and how and why population size changes over time

conspecifics

Organisms that are all members of the same species

Community Ecology

consists of the different species within an area, typically a 3D space, and the interactions within and among these species

• interested in the process driving these interactions tons and their consequences

Heterospecifics

members of different species

Ecosystem Ecology

composed of all the biotic components in an area along with the abiotic components of that area

Biome

a major type of terrestrial community distributed according to climate, which determines the predominant vegetation

Biosphere

all parts of Earth inhabited by life

Biodiversity

describes a community’s biological community, number and kinds of species in a locaiton

• measured by the number of different species in a particular area and their relative abundance

• tends to be higher at lower latitudes

• more complex environments provide more habitats

Species richness

refers to the number of species present in an area

• how many different species are there

Relative species abundance

number of individuals in a species relative to the total number of individuals in all species within a habitat, ecosystem, or biome

• just number of species

Species eveness

refers to how close in numbers each species in an environment is

• takes into account the relative abundance of each species

• Pielou’s evenness index

  • J=H/H_max

  • _{higher the value, higher the evenness}

Abiotic

non-biological

• Climate, Geology Disturbance (Natural, human, etc.)

Biotic

biological

• species interactions, distribution and quantity of individual, species of gorups of species, invasive or keystone species

Simpson’s Biodiversity Index

the probability that if you randomly select 2 individuals, they will be the same species

• summed over the number of species in the community

• ranges 0-1

  • 0: two species, maximum diversity

  • 1: same species, no diversity

• D=E (n/N)²

  • N: total number of individuals of all species

  • n: number of individuals in species

Shannon’s diversity index

the certainty that we can know of the identity of a randomly selected individual

• Ranges 0-variable

  • 0: no diversity

  • higher value: higher diversit

• H=-E (p_i x lnp_i)

  • p_i: proportion of individuals of species i (1 species/ total )

• summed over the number of species in the community

Prokaryotic Diversity

• first forms of life

• bacteria and archea

• lack nucleus and true membrane bound organelles

Extremophiles

grow under extreme conditions

Bioflims

a microbial community held together in a gummy-textured matrix, consisting primarily of polysaccharides secreted by the organisms, together with some proteins and nucleic acids.

• Biofilms grow attached to surfaces.

• biofilms are very difficult to destroy, because they are resistant to many of the common forms of sterilization

Characteristics of Prokaryotes

have 3 categories:

• cocci, bacilli, and spirilla

unicellular, lack organelles

have a nucleoid: single chromosome

cell wall: protective layer and shapes

flagella (locomotion) and pili (attachment)

Plasmids (bacteria): small, circular pieces of DNA outside of the main chromosome

Bacteria and Archaea differ in lipid composition

Characteristics Of Archaea

isolated from all places rich with bacteria

monolayer plasma membrane

glycerol and side chain are linked by an ether

fatty acids are isoprenoid chains

semi-rigid cell wall or some lack a cell wall

don’t have peptidoglycan

Organize their DNA using histones

Cell membrane has highly branched hydrocarbons and other chemical differences (promote stability in extreme environments)

tend to be chemoautotrophs, doesn’t do glycolysis

reproduce via binary fission

Characteristics of Bacteria

• Prokaryotic

• reproduce via binary fission

• Cell wall made of peptidoglycan

• Ester-link fatty acid

• Eenrgy and carbon metabolism

Plants

Land plants

• all multicellular

• photosynthetic and immobile

• monophyletic group

• all have chloroplasts

Animals

belong to a group called the opisthokonts

• multicellular

• blastula stage of development

• heterotrophic

Fungi

belong to the opisothokonts

• all absorptive heterotrophic

  • must eat other organisms but digest before ingesting

  • Cells walls are composed of chitin

  • Immobile

Fungal Hyphase

Thread of cells,

One cell thick

High surface area to volume ratio

Protists

• any eukaryote thats not a plant, animal, fugus

• mostly microscopic, unicullular eukaryotic

• live in soil, freshwater, marine water, in animal digestive tracts, within plant vascular tissue

What makes something alive?

• reproduction (virus replicates through host)

• cellular (virus is acellular)

• maintain homeostasis (virus can shift between lytic and lysogenic stages)

• ability to grow and develop (virus assemble virion particle)

• evolve and adapt (virus evolve through mutation, genetic sequences)

• originated from a single ancestor (virus has multiple origins)

Biome

large, distinctive complex of plant communities created and maintained by climate

• determined by temperature and rainfall

Rainforest

• plants need lots of water and warm temp

  • lots of sunlight

  • lots of plant diversity

• Highest precipitation

• 2 types of rainforest:

  • Tropical: high consistent temp, near equator

  • Temperate: cooler temp, coastal higher latitude

How does Earth receive light?

The equator get the more intense light

• light comes from an angle

• Either gets less direct light (cold) or more direct light (hot)

Desert

• contains xeric plant (adapted to dry conditions) and ephemeral plants

• lowest precipitation

• temperatures fluctuate daily

• between 15-35 latitude

• caused by Hadley cells of air circulation

Grassland

• open and continuous, fairly flat areas of grass

• limited tree growth

• Precipitation varies, dry season and wet season

• Temperature largely depends on latitude; savannas are hot

  all year, temperate grasslands have hot summers and cold

  winters

Shrubland

• contain shrubs (woody plants smaller than trees)

• no trees

• dormant during dry summers

• Very seasonal: hot dry summers, cool wet winters

• Intermediate amount of rain, more than deserts an grasslands but less than forests

• 30 - 40 latitude

Temperate deciduous forest

• dominated by deciduous trees (drops leaves in winter)

• less diversity than rainforests

• 4 distinct seasons: hot summers, sold winters

• moderate rainfall throughout year

• located in the mid-latitude areas

Taiga

• dominated by coniferous (evergreen, pine) trees

• slow-growing, long lived trees

• high biomass, low primary productivity

• seasonal variation in temp

• cold, dry winters and short, cool, wet summers

• little evaporation due to cold temps

• high northern latitudes, between tundras and devious forests

Tundra

• low above-ground biomass

• low species diversity

• Permafrost: soil is frozen, roots cannot grow long

• coldest biome, in the arctic

• very short growing season (10-12 weeks), 24 hrs of daylight and plant growth

• low precipitation

• highest latitudes

Biogeochemical cycles

moves materials between ocean, land, life, and atmosphere reservoirs

Water Cycle

Evaporation → Sublimation → Transpiration → Condensation → Deposition → Precipitation → Infiltration & Runoff → Percolation

Evaporation

The sun heats water in oceans, lakes, and rivers, turning it into water vapor that rises into the atmosphere

Sublimation

Solid ice or snow turns directly into water vapor, skipping the melting phase

Transpiration

Plants release water vapor into the air through their leaves

Condensation

Water vapor in the air cools and changes back into liquid, forming clouds

Deposition

the phase change where water vapor (gas) turns directly into ice (solid) without passing through a liquid phase

Precipitation

Water falls back to Earth's surface as rain, snow, sleet, or hail

Infiltration

Water moves across the land surface (runoff) oraks into the ground (infiltration), replenishing oceans, rivers, and groundwater

Percolation

the downward movement of water through soil and rock layers to become groundwater

Phosphorus

Key component of: DNA, Cell membranes, ATP

• limiting nutrient in aquatic ecosystems

• enter the biosphere form weathering of rocks and human activity

• Plants remove phosphorus from soil

Nitrogen

Key component of: DNA, proteins

enters the world via free-living and symbiotic bacteria

• Bacteria free living in the soil are in a mutualism relationship with plants to fix nitrogen for them to use

Nitrogen fixation

the process through which N₂ gas is converted into a bioavailable form, ammonia (NH₃)

• process: ammonification, nitrification, denitrification

Released by combustion of fossil fuels (releases different nitrogen oxides) and use of artificial fertilizers

Ammonification

converts nitrogenous waste from living animals or from the remains of dead animals into ammonium by certain bacteria and fungi

Nitrification

the ammonium is converted to nitrites (NO₂⁻) by nitrifying bacteria

Denitrification

whereby bacteria convert the nitrates into nitrogen gas, allowing it to reenter the atmosphere

Rhizobia

soil bacteria that symbiotically interact with legume roots to form nodules

nodules

specialized structures where nitrogen fixation occurs in the roots

mycorrhizae

fungi that associate with plant roots

• absorb nutrients (nitrogen & phosphorus) and water from the soil and pass them on to the plant

• plants feed the fungi by excreting sugars from their roots

Eutrophication

occurs when excess nutrients are introduced into a body of water

• increases rate of supply of organic matter in an ecosystem and stimulates aquatic plant and microorganism growth

• occurs natural but anthropogenic activities (industrial waste, runoff of fertilizers rich in nitrogen and phosphorus) contribute to eutrophication events

results in production of dangerous toxins, dead zones (low oxygen or no oxygen), increase in treatment costs, harm to industries and communities that rely on the affected watershed

The Carbon Cycle

2 interconnected sub-cycle: rapid carbon exchange with living organisms, long-term cycling of carbon through geologic processes

• Photosynthesis converts carbon dioxide gas to organic carbon, and respiration cycles the organic carbon back into carbon dioxide gas

• Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized

Heterotrophs and autotrophs are partners in biological carbon exchange

plants play a major role

Heterotrophs and Autotrophs

Heterotrophs:

• acquire high-energy carbon compound from the autotrophs by consuming them

• need oxygen

Autotrophs:

• need carbon

constant exchange of oxygen and carbon dioxide between autotrophs and heterotrophs

Carbon reservoirs

Where carbon is stored

• atmosphere, bodies of water, ocean sediment, soil, land sediments (fossil fuels), earth’s interior

major reservoir in form of carbon dioxide in atmosphere

• influenced by reservoir in oceans

  • Carbon dioxide (CO₂) from the atmosphere dissolves in water and combines with water molecules to form carbonic acid, and then it ionizes to carbonate and bicarbonate ions

  • >90% of carbon is found in bicarbonate ions

Fossil fuels

• primary mechanism that releases carbon dioxide

Global Climate Change

• Global climate change refers to long-term changes in global weather patterns.

• Most noticeable change: increase in global temperatures.

• Caused largely by rising levels of atmospheric carbon dioxide (CO₂).

• Scientists have observed clear changes over the past ~60 years

Indirect evidence used to study past climate

correlations between temperature changes and possible climate drivers

• Ice cores

• Boreholes (narrow shafts drilled into the ground)

• Tree rings

• Glacier lengths

• Pollen remains

• Ocean sediments

Milankovitch Cycles

• Caused by small variations in Earth's orbit around the Sun.

• Affect how much solar energy reaches Earth.

• Cycle length ranges from 19,000 to 100,000 years

• Climate changes associated with these cycles occur very slowly.

• The current climate warming is much faster than changes caused by these cycles

Solar Luminosity (Solar Intensity)

• Refers to the amount of electromagnetic energy emitted by the Sun per unit time.

• Natural variations in solar intensity can influence Earth's temperature

• Higher solar intensity → higher Earth temperatures

• Lower solar intensity → lower Earth temperatures

• Solar intensity has not changed significantly in the past ~200 years, so it cannot explain recent climate warming

Volcanic Activity

influence climate through the release of gases and particles

• Volcanic eruptions usually cool the climate temporarily

Greenhouse Effect

greenhouse gases in the atmosphere trap heat

• gases absorb infrared radiation released from the Earth

  • gases: H₂O, CO₂, CH₄, O₃

• most significant drivers of the climate

• Human activities affecting greenhouse effect

  • burning fossil fuels

  • agriculture

  • deforestation and land clearing

Greenhouse Effect Process

1. Some solar radiation reaches Earth’s surface, while some is reflected back into space.

2. Land and oceans absorb energy, warming the planet.

3. Earth releases energy as infrared radiation (heat).

4. Greenhouse gases trap some of this heat, warming the atmosphere and surface.

Carbon Dioxide and Global Temperature

• Higher CO₂ → Higher global temperature

• Lower CO₂ → Lower global temperature

• Human Activities that release CO₂

  • Deforestation

  • Cement production

  • Animal agriculture

  • Land clearing

  • Burning forests

Methane

forms when bacteria break down organic material in anaerobic (low-oxygen) environments

Released by:

• Natural gas extraction

• Landfills

• Agriculture

• Animal digestion (livestock such as cattle)

• Decomposition of organic waste

Positive Feedback

A self-reinforcing cycle where an initial change causes additional changes that amplify the original effect

• Temperature increases → processes occur that cause even more warming

Artic Albedo Feedback

the percentage of sunlight a surface reflects

Process: arctic ice melts → more water in ocean, lower % then ice → less reflected, more heat absorbed → ocean warms more