final exam

Overview of Ecology-

  • Ecology: is the scientific study of the interactions between organisms, the environment, and one another 

  • Several, interconnected levels

  • Population ecology 

  • Community ecology 

  • Ecosystem ecology 

  • Biome 

  • Biosphere 

Ecology and Environmentalism-

  • Environmentalism involves understanding ecology and applying these concepts 

  • Concerns that arise, especially from the human impact on the ecosystem 

Levels of ecology-

  • Individual 

  • Populations

  • Community

  • Ecosystem

  • biosphere 

Populations-

  • A group of the same species, in the same place, at the same time–can interbreed

  • Population size, density, and growth

  • Life history traits 

  • Gene pool: alleles present 

  • Subject to natural selectionevolution 

  • Species are made up of many populations 

  • As long as they are connected: metapopulation

  • Emigration 

  • Immigration 

Community-

  • All populations ( species) in the same area, at the same time 

  • Abundance and diversity of populations 

  • Complex interactions 

-benefits: symbiosis; mutualism

- Harms: predators and prey; parasites 

  • Food Webs

  • Limit to complexity based on energy constraints 

Ecosystem- 

  • The entire community with the environmental factors ( abiotic factors)

-defining niche

-many habitats 

                          -microhabitats 

Biome-

  • All the ecosystems in a large area subject to the same climate 

  • Wind

  • solar energy/sunlight

  • water/precipitation patterns 

  • Terrestrial Biomes 

  • Defined by climate and dominant plants 

  • Aquatic biomes 

  • Defined by salinity 

Abiotic Factors- 

  • Generally, two types of factors affect organisms throughout the levels of ecology 

  • Abiotic factors: arise from physical, chemical, and climate factors

  • Oxygen availability in aquatic environments 

  • Nutrients in the soil

  • Frequency of fire or storms 

  • Biotic Factors: arise from other organisms 

-symbiosis, prey availability, disease prevalence

Energy source-

  • The ultimate energy source for Earth is the sun 

  • The variation of the striking the earth’s surface and warming it produces two key factors for biotic and abiotic factors 

  • The amount of sunlight available to plants and others photosynthesizes 

  • Temperature and weather patterns in different areas of the earth (defined climate of regions)

Deep Sea Vents:

  • Do not depend on the sea directly 

  • Deep sea vents

  • Heat rises from deep-sea vents 

  • Use of H2s rather than h2o

  • Chemical source of energy rather than sunlight 

  • But living organisms from above may die and bring nutrients into this sea

Sunlight Variation in different areas-

  • The angle that the sun strikes the earth

  • Less energy at the poles and more at the equator 

  • Within ecosystem and habitat variation

  • Shadows

  • Thick vegetation

  • Water areas 

Temperature-

  • Matters most to animals 

  • Proteins are optimal in their function for life- especially enzymes regulating all physiology(life processes)






Water- 

  • Water viability is critical to all life 

  • Defining characteristics for ecosystems and biomes 

  • Organisms have many adaptations for this, including for living in very arid environments such as deserts 

  • Organisms may have a problem with too much water, such as standing water of leaves after a rain which could allow mold to develop

Factors-

  • Abiotic: nonliving

  • Water sources 

  • Nutrients 

  • Habitat structure 

  • Landforms

  • Climate and weather

  • Sunlight 

  • Biotic: living organisms

Evolutionary adaptations of organisms-

  • Changes in genes (alleles) that support a population to survive in different habitats \

  • Organisms in the same habitat may have different adaptations that allow them to use the same habitat in different ways facilitates their sharing of the same habitat

  • Sometimes called Niche/resource partitioning 

  • Niche: the role of an organism in its habitat- includes all the attributes 

Adjusting to Environmental Variability:

  • Ability to adapt 

-physiologic response 

   - acclimation

  • Anatomical (morphological) response 

  • Behavioral response - Migration 

Physiological responses-

  • Ability to adapt to changes in physiology 

  • Often a response to daily or seasonal climate change 

  • The longer-term: as climate changes significantly in a region, organisms there may be able to adapt to these changes

Limitations in adaptation:

  • Lizard species are less abundant in more northern climates due to their ectothermy which limits their ability to adapt to cold and ice 

Anatomical adaptation-

  • Seasonal: color of coat changes for camouflage 

Behavioral responses 

  • Changes in activity based on seasonal changes 

  • Some desert ants shift to foraging at night based on the increase in daytime temperatures- the soil becomes too hot for the ants to walk on during the day 

  • Organisms have some ability to adjust to daily and seasonal changes in their environments 

  • Warmer weather to cooler weather 

  • Drier weather to warmer weather 

  • This may include migration 

Biomes-

  • Large life zones 

  • Specified by climate and plants 

  • Water and precipitation

  • Sunlight

  • Wind

  • Plant cover 

  • Aquatic biomes 

  • How climate affects terrestrial biome distribution 

  • The water cycle 

  • Human impacts on biomes 

Aquatic biomes- 

  • A major Aquatic life zone, characterized by the physical environment 

  • 75% of the earth's surface 

  • Characterized by salinity 

  • Special adaptation for water 

  • Water surrounds organisms: predators from all directions

  • Water supports organisms 

  • Animal sensory structures are adapted to water 

Freshwater Biomes- 

  • Freshwater:1% salt

  • >1% of the earth 

  • est.6% of described species 

  • Source of water

  • Ponds and lakes: standing water

  • Streams and rivers: Moving water 

  • Wetlands 

Ponds and lakes- 

  • Organisms distributed according to depth

  • Photic zone: light

  • Aphotic zone: depth or murky-no light

  • Benthic zone: at the bottom

  • Phytoplankton: microscopic organisms 

Streams and rivers- 

  • Flowing water

  • Changes from source to mouth 

  • O2 levels vary 

  • Human alterations 

  • Reservoirs 

  • Dams for power, flood control, water traffic 

  • Pollution 



Wetlands- 

  • Transition between aquatic and terrestrial biomes 

  • Swamps, bogs,marshes 

  • Water storage areas, reduce flooding

  • Improve water quality 

  • Very productive areas 

Carnivorous plants- 

  • Often live in wetlands 

  • Standing water leeches the nitrogen from these wet soils. 

  • Nitrogen is necessary for proteins 

  • Carnivorous plants trap insects to get their needed nitrogen 

  • Venus flytrap, sundews, and pitcher plants 

Marine Biomes -

  • Marine: 3% salt 

  • Zooplankton 

  • Intertidal zone

  • Benthic realm 

  • Pelagic realm 

  • Coral reef

  • Estuary 

Coral Reef 

  • Photic zone of tropical waters 

  • Built from the generation of coral (cnidaria) 

  • Symbiosis with algae 

  • Diversity of invertebrates and fish 

Intertidal zone- 

  • Interface between the ocean and land

  • Periodic inundation with ocean water: tides





Estuary-

  • The transition between a river and the ocean

  • Tides being in salt water: changes in salinity

  • Very productive areas 

Climate and terrestrial biome distribution-

  • Climate primarily determines terrestrial biomes. 

  • Input of solar energy 

  • Produces various climates -air currents and moisture 

  • Effects of elevation

  • Mountain effects and rain shadows 

Solar energy- 

  • Powers the earth 

  • Warms the land, water, and atmosphere 

  • Drives air moments 

  • The curvature of the earth's crust affects the angle at the sunlight strikes the earths 



Elevation Effects-

  • Temperature changes 

  • Rainfall changes 

  • moisture/humidity changes 

Biomes 

  • Aquatic Biomes 

  • How climate affects terrestrial Biome distribution

  • Terrestrial Biomes 

  • The water cycle 

  • Human impact on Biomes 

Aquatic Biomes

  • A major aquatic life zone, characterized by the physical environment 

  • 75% of earth’s surface 

  • Characterized by salinity 

  • Special adaptations for water 

  • Water surrounds organisms:predators from all directions

  • Water supports organisms 

  • Animal sensory structure are adapted to water 

How the sun defines terrestrial Biomes

  • Differential heating on the earth’s surface 

  • Air movement 

  • Influences moisture content of air-adds weight to clouds

  • Precipitation-drier air 

  • Play off between heat and moisture 

Terrestrial Biomes

  • A major terrestrial life zone, characterized by a vegetation type and climate 

  • Tropical forest

  • Savana

  • Desert

  • Chaparral

  • Temperate grassland

  • Temperate broadleaf forest

  • Coniferous forest

  • Tundra 

  • Polar ice 

Tropical Forest

  • Equatorial areas: warm year around

  • Vegetation determined by rainfall 

  • Rain forest:200-400 cm/yr (6.6-13ft) rainfall

  • Dry forest: lowland areas with prolonged dry seasons 

  • Complex structure 

  • Layering 

  • Creates microhabitats-great diversity 



Forest Structure 

  • Emergent trees- rising above the established canopy 

  • Canopy- tallest trees, first to access light

  • Subcanopy- trees which can tolerate less light or are waiting for a chance to shoot up 

  • Understory and shrubs: tolerate less light 

  • Forest Floor: herbaceous plants, leaf litter

  • None in tropical rainforest 

  • Throughout 

  • Lianas–vines

  • Epiphytes– orchids, moss 

  • Light decreases from the canopy to the forest floor, which may be quite dark with little light for photosynthesis 

  • Plants underneath the canopy must be tolerant of low levels of light and may be slow growing 

  • Treefall or light gaps provide opportunity for saplings to shoot up and for herbaceous plants to establish 

Savana 

  • Poorer soil and limited rainfall

  • Rainfall:30-50 cm/yr ( 12-20 inches); may have a dry season 

  • Grasses and scattered trees

  • Large fast predators and fleet grazers 

  • Large and small herbivores: elephants and termites 

  • Water hole story on Nova- link in canvas 

  • Fire may be an important abiotic factor 

  • Clears the way for new growth 

  • Some seeds depend on fore exposure to germinate 

  • Grasses and some gymnosperms are well adapted to fire 





Termites and ants in savana 

  • Large mounds: very tough 

  • South africa 

  • Major herbivores 

Desert 

  • Low and unpredicted rainfall 

  • <30 cm/yr (12 in) 

  • Hot or cold

  • Large fluctuations in temp

  • Death valley, CA: 15-134 degrees F

  • Low temperatures- 22 degrees F- gobi desert ( china/ mongolia) 

  • Plant and animals adaptations 

  • Plants: store water, reduced leaves, slow growing 

  • Animals: estivation; active at night 

Spadefoot toads

  • Estivate most of the year, only emerging when it rains to mate and lay eggs 

  • Estivate vs Hibernate 

  • Estivate in the summer or hot climate 

  • Hibernate in the winter or cold climate 

Chaparral (mediterranean)

  • Cool mild winters( near coast) with hot dry summers 

  • California and mediterranean region

  • Evergreen shrubs dominate 

  • Fire Maintained 

  • Plants adapted for quick regeneration 

  • Seeds may need fire exposure to germinate 






Temperate Grassland 

  • Prairie, similar to savannas 

  • Most endangered biome

  • Rainfall: 25-75 cm/yr (10-30 in)

  • Deep and rich soil- converted to agriculture 

  • Dominated by grasses 

  • Adapted to reduce rain and grazing 

  • Trees limited to streams 

  • Fire and grazing of large herbivores prevent tree establishment 

Grass roots 

  • Native grass roots are well adapted for:

  • Holding soil- preventing erosion 

  • Obtaining water from deep in the earth 

  • They grow from tissues throughout the stem-so, they regenerate quickly after being grazed

Temperate Broadleaf forest 

  • Rain: 75-150 cm/yr ( 30-60in) 

  • Sufficient rain to support trees 

  • Even occurrence throughout the year 

  • Seasonality- varies 

  • Cold winters-hot summers

  • Deciduous trees: drop their leaves in preparation for winter (avoid freeing)

  • Leaf litter accumulation: lack of intense activity throughout the year( unlike tropical rain forests)

  • Hibernation 







Coniferous Forest 

  • Dominated by gymnosperms-cone-bearing trees 

  • Taiga: northern coniferous forest 

  • Largest terrestrial Biome 

  • Stretching across northern parts of northern america, europe, and asia 

  • Also occurs at high elevations- rocky mountains 

  • Snowy winters; short summers 

  • Accumulation of needles make soil acidic 

  • Slow growth 

  • Adaptations: conical shape of trees reduces snow stress 

Temperate rain forests

  • Coniferous forests- dominated by gymnosperms 

  • Spruce, fir

  • Often near coast 

  • Pacific northwest in alaska, oregon, washington 

  • Appalachian mountains in north carolina, tennessee, and va 

  • Rain is dropped here due to the mountains 

  • Remnants from the last ice age 

Tundra 

  • Colder and less moisture available- frozen much of the time

  • Permafrost: frozen land for 2 or more years 

  • Climate change is melting permafrost 

  • Causing many changes and difficulties 

Plant adaptations to Tundra 

  • Early flowering

  • Low growing

  • Small, waxy leaves 

  • Hairs to hold in warmth 

  • Cup-shaped flowers to focus sun-light on center of flower-heating up 

    • Warm insects pollinators 

Polar Ice 

  • Arctic Regions, Antarctica 

  • Very cold and low precipitation year round 

  • Mostly land is snow bound 

  • Plants: moss and lichens 

  • Animals: feed on these plants or from the surrounding sea

  • Invertebrate, migrating birds, seals, penguins 

Variety of animals 

  • No ants 

  • Global climate change is rapidly reducing the ice cover 

  • Exposed more ground to sunlight which absorbs the light and heats up more- make a “snowballing” effect for more climate change 

  • Animals adapted to the snow cover- with the loss of snow and ice, these animals are at high risk of extinction 

Human Impact of the water cycle 

  • Run-off from agricultural and other lands-adds pollutants to soil and waterways 

  • Dams 

  • Increased erosion-loss of trees and grasses that hold soil 

  • Removal of dense vegetation-tropical rain forest conversion- and intense irrigation 

  • Loss of moisture on the air

  • Increase evaporation- decrease groundwater 









Human impact on biomes

  • Land use and land changes 

  • Conversion of land for human purposes 

  • Change from one land use to another 

  • Access-roadways-to these lands

  • Impact of construction processes 

  • Fragmentation of land- creating smaller, often disconnected lands which are difficult for many species 

  • Forests 

  • Fresh water 

Forest Clearing

  • About ¾ of earth is altered due to human use 

  • Most for agricultural 

  • Due to unsustainable practices-land is worn out 

Urban development 

  • Run-off and other pollution 

  • Overuse of water resources 

  • Depletion of underground aquifers to grow grass in deserts and arid lands 

  • Too many people with increasing water demands 

Why population Ecology matters 

  • Conservation- maintaining ecosystem function and services 

  • Agriculture 

  • Shifts in food availability such as fish 

  • Spread of infectious disease, vectors of disease, and pests 

Ecosystem services 

  • Interconnections of populations and communities provide benefits 

  • Humans rely on these services,  often without being aware of it





Invasive species 

  • Species introduced into another area 

  • Easily reproduce and survive

  • Outcompete local species 

  • Become a monoculture or dominant 

  • Drastically change ecosystem relationships 

  • May cause species extinctions and ecosystem collapse 

  • Lion fish- from south pacific and indian ocean 

  • Privet- several spp. From china and japan 

Population Ecology 

  • Population: all the members of the same species living in the same area at the same time 

  • Potential to interbreed 

  • Share the same gene pool

  • Subject to the same selective pressures-natural selection 

  • Populations are the units upon which natural selection acts-thus, populations evolve 

  • Population ecology studies population size and factors that affect and regulate them 

Population characteristics 

  • Important measures for determining how populations are interacting, what role they play in their community and ecosystem, and for assessing their health

  • Population dynamics 

  • Population density 

  • Population age structure 

  • Life tables and survivorship 

  • Life history traits 





Population dynamics 

  • Factors that affect population size 

  • Abiotic 

  • Climate change 

  • Weather patterns- sudden storms

  • Water and minerals 

  • Sunlight 

  • Biotic Factors 

  • Members of the same population 

  • Other organisms 

  • Prey 

  • Predators 

  • Beneficial relationships– symbiosis 

Population density 

  • Snapshot view of a population 

  • How many individuals per unit area 

  • Can’t always get an exact number

  • Estimates 

  • Sampling techniques 

  • Mark-recapture for animals 

  • Survey plots or transects for plants 

Population age structure 

  • Age categories can give an idea of how a population will be growing, reproducing, and changing over the short and long-term 

  • Age structure: shows how many individuals are in a particular age range 

  • How many are sexually mature 

  • How many may be nurtured by parents 

  • How many are old enough that they are likely to die 

  • When the structure changes or varies a geat deal

  • Ages of male cactus finches in 1987

Life Table and survivorship 

  • Life tables are used in insurance for humans 

  • Often only applied to animals 

  • Different species have different strategies for survival in terms of populations and in response to natural selection

  • Survivorship curves

  • 1 Long-lived, and often larger organisms, few offspring, lots of parental care 

  • Humans elephants, whales 

  • 2 intermediate 

  • Squirrels, invertebrates, and lizards 

  • 3 short lived, usually smaller organisms, lots of offspring, no or little parental care 

  • Insects, annual plants, trees 

Life history traits 

  • Attributes of an organism over its life

  • Age at sexual maturation 

  • Number of offspring produced 

  • How many clutches or batches of eggs/seeds

  • Lifespan

  • Parental investment-in eggs/sperm, in pollen, in offspring, in family 

  • Over time, these have arisen as response to natural selection 

  • These traits and their timing tend to enhance reproduction and survival 








Life history traits as adaptations 

  • To establish the general life history pattern, the population has responded genetically many times to selective pressures.

  • This results in particular life strategies

  • Consideration of limited resources 

  • Two patterns 

  • Opportunistic 

  • Rapid reproduction with many offspring 

  • Usually quick dispersal 

  • Colonizers 

  • Type iii survivorship 

  • Equalibrial 

  • Limited reproduction, more parental care 

  • Type i survivorship 

Population growth 

  • Life history traits influence how a population grows 

  • Populations grow by 

  • Reproduction- new offspring born

  • Immigration- members moving into the population

  • Population reduced by 

  • Death

  • emigration- individuals leaving the population 

Models of population Growth 

  • Exponential 

  • No limitations in resource or space 

  • Population doubles with each reproductive cycle 

  • Unrealistic over the long-term 

  • May describe some populations early on 

  • Microbes— bacteria 

  • Logistic 

-limitations: carrying capacity (k) - environmental capacity 

Population cycles 

  • Boom and bust cycles 

-extremes in population growth and decline 

  • Factors involved 

  • Life history traits of species involved 

  • Food resources

  • Weather cycles 

Regulation of population Growth 

  • Logistic growth: what keeps populations from exceeding the carrying capacity 

  • Many factors may regulate or affect population growth, generally characterized as 

  • Density dependent factors 

  • Density independent factors 

  • Population cycles- species interactions 

Summary of density dependent and independent factors 

  • Limiting Factors 

  • Food resources 

  • Suitable habitat 

  • Mates 

  • Populations are influenced by both 

  • Complex connections 











Communities and ecosystems 

Community ecology 

  • All the living organisms living in the same area at the same time 

  • Interactions among the species/populations 

  • May be- 

  • positive / helpful+ 

  • negative/harmful - 

  • Neutral 0 

  • Interactions may help define the niche ( realized niche) of a species/ population 

  • Their role in the ecosystem 

Interspecific Interactions

  • Between different species in the same community 

  • Competition

  • Mutualism 

  • Symbiosis 

  • Commensalism 

  • Predation 

  • Exploitation 

  • Parasites 

Trophic structure 

  • Simple consideration of trophic roles 

  • Linear 

  • Food Chain 

Trophic refers to feeding

Trophic structure- how a community is organized 

Levels- 

Producers- autotrophs, self-feeders, base of the food chain 

Primary consumers- consumer the producers 

Secondary consumers 

Tertiary consumers  next quaternary consumers 

Trophic Pyramid 

Takes into account energy and nutrients 

  • Energy passes through the levels 

  • One-way 

  • Lose most energy at each level-used by that organism

  • When one organism is consumed, only 1/10 of its energy is passed on to the next level

-energy lost as heat ( metabolism)

  • This loss limits how many levels there can be 

  • Apex predators are the end of the levels 

  • Nutrients pass through the levels 

  • Cycle 

  • The nutrition in an organism can always be consumed by another organism 

  • Ultimately, by fungi and bacteria, the decomposer 

Food webs 

  • Made from individual food chains

  • Describes all the trophic terms

  • Herbivore 

  • Omnivore 

  • Carnivore 

  • Detritivore 

Biomagnification 

  • A consequence of how trophic relationships work

  • Toxins are magnified as they travel up a food chain 

  • Because each higher level has to consumer more than lower levels for energy 

  • Accumulate in tissues 

  • Higher level = higher toxins

  • That accumulation can be so high it can kill 

  • Example- Polychlorinated Biphenyls (pcb’s)

Species Diversity 

  • Several measures of species or diversity 

  • Species richness: a count of species in a community or area 

  • Species abundance: how many of each species in a community 

  • Species evenness: combination 

  • Communities with

  • High species richness and evenly distributed are usually more healthy and resilient to change -including severe weather 

Species and community structure 

  • Ecosystem engineers 

  • Greatly alter the physical environment-which benefits other species 

  • Beaver 

  • Keystone species 

  • A species with an impact on its community larger than its biomass or abundance- in terms of impact on organismal relationships within the community 

  • Sea stars 

Succession

  • First establishment of life in an area 

  • After a volcano eruption or other even that lacks soil

  • As organisms come in they affect the abiotic and biotic factors for other organisms which organisms respond to 

  • Life history traits and species interactions 

  • Stages to a climax community

  • Colonizers: first organisms( pioneer species)

  • Make soil

  • Bacterial moss lichens 

  • Small pores, easily dispersed 

Primary succession for different biomes

  • Hardwood forest

  • Desert and pond to forest 

Secondary succession 

  • Ecosystem can also respond to devastating changes

  • Fire or severe storm

  • Rarely destroys everything 

  • Seeds,spores,plant roots in soil

  • Burrowing animals

  • immigration

Mount saint helens

  • Washington state 

  • Active volcano-blew up in 1980

  • Quickly began to restore ecosystem 

Biomes maintes by fire 

  • Maintained by disturbance 

Examples: chaparral , savana, grassland 

  • Reduces presence of trees 

  • Humans subject most ecosystems to disturbance-to which these other ecosystems cannot respond 

  • At the same time, humans prevent fire in these other systems 

  • Causing a build up of fire materials 

  • Leading up to high levels of destructive fire 

  • Difficult to contain, causing extensive damage 

Ecosystem Ecology 

Primary production

Sunlight: source of terrestrial and much aquatic biome energy 

-most of this energy does not matter 

- warms the earth 

-1% enters the ecosphere 

Biomass: mass of living organism 

Primary Production: rate at which producers convert sunlight to biomass

  • Gross primary production

  • Net primary production       R= respiration      example- caterpillars

Comparison of biome GPP

-limitations

   -terrestrial systems

  • Sunlight 

  • Water

  • Nutrient 

Aquatic systems

  • Sunlight nutrients 

Nutrient cycles 

  • Within through organisms 

  • Carbon cycle 

  • Phosphorus cycle

  • Nitrogen cycle 

  • Nutrient pollution 

Biogeochemical Cycles 

  • Follows trophic groups 

  • Unlike energy, no loss at each level

  • Abiotic reservoirs 

- outside of living organisms

-water and air