DEFINITIONS

Lecture Term Definition 24 Imperiled Critically endangered, mostly fish, and angiosperms

Passenger pigeon High abundance to extinct

Conservation biology Integreative discipline applies principle of ecology to conservation of biodiversity and affects maintenance, loss and restoration of biodiversity. For ex: stabilization of red-cockaded woodpecker required cont. from several disciplines (law, polisci, and socio)

ESA (eco soc. of Am) 1915: disagreement about mission: ecologists or conservers? 1917: a wing within ESA was Com of preserv of natural cond. 1946: renamed to ecologists union and took direct action to save threatened natural areas 1950: renamed to nature conservancy

Objectivity Collection and interpretation of data without bias based on scientific method

Alwyn Gentry Identified, classified and mapped immense diversity in Central and South America and witnessed species extinction and deforestation

Threats to biodiversity Habitat degradation, invasive species and overexploitation

Habitat degradation reduce quality of habitat for many, but not all species

Habitat fragmentation Breaking up of continuous habitat into habitat patches in a human dominated landscape

Habitat loss Conversion of ecosystem to another use

Invasive species Non-native, introduced species that sustain growing pop and have larger effects on communities

Order of chaos Habitat fragmentation habitat degradation more vulnerable to invasive species

Bycatch Species of conservation concern: marine mammals, birds and turtles

U.S. endangered species act

Indentifies and protects ciritical habitat

Ex situ Endangered species and moving them to an off-site conservation to a wild area or within care of humans. Very expensive and had limited success in restoring wild populations (SMALL POP)

Fine filter Genes/populations/ species

Coarse filter Landscape/ecosystem/habitat : protects many species at once

Core natural areas Conservation of biod and ecological intregity. Uncut by roads and trails, not all areas qualify

23 80% endemic

Buffer zone Large areas with less stringent controls on land use but are partially compatible with species’ resource requirmnts

Reserve conf Largest pop, habitat for species, largest area

Surrogate species Protecting one species result in protection of another w/ overlapping habitat req: red-cockaded woodpecker

Flagship species Charismatic organism people give protection ; giant panda

Umbrella species Assume protection of habitat will protect other species with similar habitat req. have large ranges : grizzly bear, specialized habitats (red- woodpecker) , easy to count (butterflies)

Biogeography Species comp and diversity across geo locations

South NZ Dominated by birch trees and small leaves , branch of divaricating

understory shrubs have a zigzag (20 species)

North NZ Dominated by emergent conifers, flowering trees, has kauris one of largest species , and ancient ferns fiddleheads

Regional species pool All the species in a region (gamma diversity)

Global biogeography Controlled by geographic area & isolation, evolutionary history (tropical regions have longer history being temporally stable) global climate(higher lat, severe climactic conditions such as ice ages increase extinction rate and hinder speciation) and productivity (species div higher in tropics->higher produc->larger pop sizes-> lower extinct rates)

Alfred russel Wallace Study of species distribution across large spatial scales/ in 1862, he went to the Malay archipelago, singapore and collected beetles. Noticed mammamls of philipines were more similar to Africa (5,500 km away) than those of new guinea (750 km).

Wallace’s line Separation between two faunas. Noticed: earth’s mass can be divided into 6 geographic regions based on terrestrial animals, gradient of species diversity with latitude ( diversity greatest in tropics and decreases towards poles)

Great biotic interchange NA part of laurentia SA part of gondwana. Came together 3-6 ma. Movement of species from one continent to another

Vicariance Evolutionary separation of species due to barrier – c.d.

Ratites Large flightless birds whose ancestor came from gondwana

Species richness controlled by

Migration, speciation and extinction. increases with area, decreases with distance , balance between immigration and extinction

Cradle(birth of species) Tropics have higher rates of speciation than temp and polar

Museum (preservation of species)

Tropics have lower extinction rates than temp or polar regions

Species diversity in tropics

High species diversity + low extinction of tropics due to large area, high pop and stable temp

Regional biogeography Species diversity increases with area and decreases by distance due to balance b/w immigration and rates

Species-area relationship

Species richness increases with increasing larea sampled. Great Britain has the largest area therefore more species

Species-area curves S=zA + c Channel Islands (steeper slopes, higher z, greater variation in species richness) and French mainland

Equilibrium theory of island biogeography

Number of species on island depends on balance b/w immigration rates and extinction rates

Simberloff and Wilson (1969)

Worked with mangrove islands in florida: island closest to source recovered species richness within 140 days, island farthest from source didn’t recover after a year

Study the case study

22 Ecosystem function Physical, chemical, and biological processes that contribute to maintenance of ecosystem: carbon cycling, nutrient cycling, productivity, stability, decomp

Ecosystem services Benefits people gain from ecosystems like provisioning(water filtration), regulating(waste), cultural, supporting, pollution filtration, food production, wood, pollination, erosion control

biodiversity 1994: David Tilman and Stability, ability to maintain after disturbance. In Minnesota, plots w/

John Downing, Nature “Biodiversity

and stability in grasslands”

diff number of plant species. As number of species increased, their ability to resist disturbance was better. MORE SPECIES=BETTER BOUNCE BACK CAPABILITY

Ecosystem function

1994: Shahid Naeem Nature “Declining

Biodiversity can Alter the Performance of ecosystems”

Talks about productivity. Ability to provide living material. Has an ecotron where you control env. Conditions such as temp, humidity, light and grow diff mini ecosystems. Number of species determines how well ecosystem functions . Different heights of plants. Greater % change in % cover allowed for higher diversity

Michael Houston: hidden treatments in ecological experiments

Selection effect When building a fake ecosystem, you pick any of the species and put them in there. As you increase number of species in your fake ecosystem, you have a large chance of selecting a keystone species= higher ecosystem productivity

Complimentary effects All plants are growing at same height, competing for same sunray, same root depth, competes for same soil (monoculture)k. When you mix different species, there are tall species that use top light and species growing to diff. root depths partition resources

Functional trait Feature of organism relates to its function. Determines organisms’ response to pressures, and/or its effects on ecosystem processes . ex, leaf C:N ratio

Functional diversity Different functional roles in an ecosystem, combining multiple traits together into single diversity

Phylogenetic diversity Evolutionary relatedness of species present in area

Genetic diversity Heritable variation in populations which is created, enhanced, or maintained by evolutionary forces

21 Range size Extent of occurrence and area of occupancy. Many species occupy small ranges

EOO ( extent of occurance)

Stuff inside polygon

AOO (area of occupance)

Sum of occupied grid squares

Establishing species distributions

Range wide occurences Maxent modelling for predicting distribution of species, habitat data such as climate and elevation Maxent modelling provides habitat data such as climate and elevation

Marginal occurences

EOO (extent of occurrence) : area within convex polygon AOO ( area of occurrence) : sum of occupied grid squares

Habitat distributions From bathymetrical data to habitat map developed

Why care about range size?

Many species occupy small ranges - Rarity: low abundance for small range sizes, risk of extinction,

Why the range margin? Environmental factor : abiotic ( climate) Biotic ( competition or hebivory)

Variation in individual or population fitness : Edge populations may suffer from:

- reduced fitness (not always) - decreased abundance (not always) . “abundant center

hypothesis” range margin is often undersampled and doesn’t always correspond to poor env.

Mating system and range size

Selfers may have smaller or larger ranges than outcrossers

20 Trait Well defined, measurable property of organisms at ind level

Functional groups Groups of species withj similar functional traits. For ex, plants in the Fabaceae family host symbiotic bact that convert atmospheric nitrogen into nitrate, which is usable by plants. These plants belong to the Nitrogen fixer functional group. Some animals have sharp teeth some dull

Functional richness Number of functional groups in a community

Coefficient of variation Examines how variable a trait is, ex height. CV= standard dev/mean

Trait evenness (TE) 1/(standard devTS + 1) by van der Plas, where standard devTS is the space between traits

Branches Has meaningful lengths

root Common ancestor to all species in phylogeny

nodes Common ancestor to descending species

Terminal branch Called a tip

Estimation of phylogenies

Scientists used morphological traits to group species together. They needed to figure out which traits were similar among close relatives. The longer two species evolved independently, greater their phenotypic and ecological diff

Phylogenetic diversity (PD)

Total amount or distribution of phylogenetic branches at the community level

Taxonomic distinctiveness (TD)

Node counting (many nodes in its ancestry has many relatives, species with few has few rel), when branch lengths are uncertain

Faith’s phylogenetic diversity (PDfaith)

When branches have lengths which sums the branch lengths connecting species

19 Equilibrium theory Ecological and evolutionary comprises lead to resource partitioning. Carrying capacity is reached as resources are limiting. Ecologists argue this is unrealistic b/c species’ populations fluctuate in space and time

Nonequilibrium theory Fluctuating conditions such as disturbance, stress, predation keep dominant species from controlling resources. This mediates resource availability and affects species interaction and coexistence. When dominant competitor is unable to reach its own carrying capacity, co-existence will be maintained

Neutral theory Species don’t differ and diversity patterns are a product of dispersal, speciation and demographic stochasticity

Neutral theory order 1. Individual dies at random 2. Area colonized by any other species in community 3. If new species aren’t introduced, all but one will go extinct

New species thru immigration and speciation

Neutral theory predicts Diversity patterns even when all species are competitively equivalent an use the same resources

Landscape ecology Examines spatial patterns and their relationships to ecological

processes and changes. Sub-discipline of ecology that emphasizes the causes and consequences of spatial variation

Landscape ecologist Looks at spatial arrangement of different landscape elements across earth’s surface and how those patterns affect and are affected by ecological processes

Elements of landscape ecology

Biotic (plants, animals) abiotic (rain, soil, water, topography)

landscape An area in which at least one element is spatially heterogeneous

heterogeneous Displaying a varied composition or a mixture of elements. Many differences across space and/time

homogeneous Consisting of elements which are similar or identitical. Few to no differences across space/time

mosaic Composite of heterogeneous elements

Remote sensing Provides images of Earth of large scale ecological patterns

GIS Standard for landscape planning, conservation and urban development. Collects, stores, analysis, and displays geologically explicit data thru aerial photographs, satellite image and ground based field studies

GAP analysis in USGS Identifies species of concern that aren’t adequately represented on existing conservation lands

scale Spatial or temporal dimension of object or process, characterized by grain and extent

grain Size of smallest homogenous unit of study (pixel in digital image) determines resolution

extent Boundary of the area or time period of study

What does grain affect? Quantity of data that must be manipulated. Large grained may be good for regional to continental scales

How is extent defined? Can change the composition of landscape being described

Landscape composition 4. The kinds of elements or patches and how much of each kind is present. These elements are defined by the source of the data used and investigator. For ex, Yellowstone national park researchers designated five different age classes of lodgepole pine forest using fieldwork, aerial photographs, and GIS.

How can the composition of a landscape by quantified?

By counting the kinds of elements in the mapped area, y calculating the proportion of the mapped area covered by each element, or by measuring the dominance of diff landscape elements such as of a specie using Shannon index

Landscape structure Physical configuration of landscape elements

What is landscape structure characterized by?

Size of patches, whether patches are aggregated or dispersed, complexity of patch shape, degree of fragmentation

What causes landscape heterogeinty?

Disturbance. In 1988, forest fires burned nearly 1/3 of Yellowstone. A complex mosaic of patches that burned at different intensities resulted. This dictates landscape composition for decades to centuries

Landscape legacies Agriculture, logging, and other disturbances that affect current biodiversity and ecosystem processes even when people have left

Examples of landscape In central France, effects of Roman farming settlements were evident

legacies after 1600 years: Soil ,PH, phosphorus and plant species richness increased near the Roman ruins which resulted from lime mortar used in Roman buildings and agriculture

What does habitat loss and fragmentation do?

Decreases habitat area, isolations populations and alters conditions at habitat edges

Example of habitat loss and fragmentation

In 1986, a massive hydroelectric project in Venezula created islands of tropical forest surrounded by water in what was an intact forest. Small and medium sized islands lacked top predators found on mainland (cats, raptors, snakes). Herbivores, seed eaters and predators of invertebrates were 10-100 times more abundant on islands. The increase in herbivores had a dramatic effect on vegetation as treat recruitment decreased and tree mortality increased.

What do human activities do?

Convert large blocks of landscapes by flooding, clearing, urbanization, roads etc

What are the consequences of human activities?

Reduction of habitat available for other species(results in decline of thousands of species), fragmentation(increases edge effects and results in spatial isolation of populations making them vulnerable to the problems of small populations: harder to find mates, pollinators, food, more prone to genetic drift, demographic stochasticity

Why do species locally go extinct due to fragmentation?

Inadequate food resources, disruption for mutualism, shelter, or nesting sites so animals need to forage beyond their site

What was an example of habitat loss and fragmentation

Beginning of 1620, vast regions of old growth forest (ancient/virgin forest) in U.S. were cut down to provide lumber and to make room for agriculture, housing An intact eucalyptus forest in Western Aus have been cleared for grazing, further fragmented and only a few remnants of the forest remain (GRADUAL process of habitat loss and fragmentation)

What are some animals that benefited from habitat fragmentation?

In the Hudson river valley, forest fragments contain high pop of white-footed mice and there are no predators and few competitors. The mice are the reservoirs for lyme disease bacterium and ticks are the vector. Ticks in small fragments(<2 ha) are more prone to carry the bacterium = increased risk of human disease

What is the main effect of fragmentation?

Habitat loss

Edges Total length of habitat boundary that increase as fragmentation increases

Edge effects Biotic and abiotic changes associated with the boundary. Physical environment changes over a certain distance into the fragment thus biological interactions and ecological processes change too

Amount of edge measurement

p/a = perimeter to area. A round habitat has the lowest p/a and irregular shaped patches p/a

What is an example of edge effects in the Amazon rainforest?

When an intact forest is first fragmented, abiotic conditions change near the edge of the patch of forest that remains, giving rise to biotic changes. After logging, air temperatures increased for 65 m into the

remaining patch of forest. The increased air temperature and other abiotic changes lead to tree mortality and the arrival of disturbance adapted plants

What were the biotic conclusions of Chen et al. edge effects in old-growth Douglas fir forest?

Higher rates of decomposition, more wind thrown trees and woody debris, and differential tree seedling survival. Pacific fir seedlings survived better in the edges than Douglas fir and western hemlock

What were the conclusions of Johnson and temple’s 5 species of ground-nesting birds in tallgrass prairies?

Proximity to a wooden edge increased the probability of nest predation and nest parasitism by cowbirds lowering reproductive success

18 What are some solutions to the paradox of the plankton?

Heterogeneity, disturbances/ fluctuations and grazing/enemies

How does species richness differ among communities?

Variation in regional species pool and dispersal or immigration(species supply), abiotic conditions, and species interactions

What does the regional species pool do?

Provides an upper limit on the number and types of species present in a community. Importance of dispersal is seen in non-native species invasions

What is a vector for invasive species?

Humans

What is an example of invasive species in water of USA?

Zebra mussel destructive invader of inland waterways of US was carried there from Europe in ballast water

How many a specie be excluded from a community?

By competition, predation, parasitism and disease

Species interaction For species that depend on other species for growth, reproduction, or survival, those species must be present

Paradox of the plankton High species diversity despite extreme resource limitation? Conditions in lake changed seasonally, which kept one species from outcompeting the others

Resource partitioning Competing species likely to coexist when they use resources in different ways. This reduces competition and increases species richness

What does bird species diversity have in common with?

Higher foliage diversity (number of vegetation layers), indication of habitat complexity

Resource ratio hypothesis

Theory by Tilman suggested species coexist by using resources in diff proportions. For example, two tiatom species were grown in media w/ diff SiO2:PO4 concs. Cyclotella dominated when ratio was low, Asterionella dominated when ratio was high

What was Robert Paine’s competitive exclusion study on

Control and experimental. Removed starfish (top predator) and diversity in experimental plot declined from 15 to 8 (7 lost species). Starfish was a keystone and when it was removed, other species came

rocky intertidal zone? and hogged space

Immediate disturbance hypothesis

Species diversity should be highest at intermediate levels of disturbance by Connell

Competitive displacement

Growth rate of strongest competitors in community, dependent on productivity of community

Dynamic equilibrium model

Disturbance frequency and rate of competitive displacement combine to determine species diversity. Levels of disturbance and competitive displacement = same

Lottery model Resources are captured at random by recruits from a larger pool of potential colonists. Species have similar interaction strengths and population growth rates, and ability to disperse quickly to disturbances free up resources

17 Metapopulation structure

Sets of spatially isolated populations of the same species are linked by dispersal of individuals

What are metapopulations characterized by?

Repeated extinction and colonization

Why are patches prone to extinction?

Demographic stochasticitiy (small populations more likely to go extinct) and environmental stochasticity (environmental conditions change in rapid and unpredictable manner)

Levin’s model cp(1-p)-ep where c=patch colonization rate, e= patch extinction rate, and p =proportion of habitat patches that are occupied at time t

What are the four assumptions made by the levin’s model?

1. There is an infinite number of identical habitat patches 2. All patches have an equal chance of receiving colonists

(distance) 3. All patches have an equal chance of extinction (size)

Once patch is colonized, its population increases to carrying capacity more rapidly than rates of colonization and extintion

What is the significance of the Northern spotted owl in old-growth forests in Pacific NW?

Populations in metapopulation might go extinct while suitable habitat remains. Lande estimated entire metapopulation would collapse if logging reduced fraction of suitable patches less than 25%

What did research on the skipper butterfly in UK conclude?

Isolation by distance(colonization) and the effect of patch area or population size(small patches have small pop sizes and lead to extinction). Patches that had the largest area and closest to occupied patches were most likely to be colonized

Rescue effect High rates of immigration to protect a population from extinction

Ikka Hanski’s rescue effect

cp (1-p)- ep(1-p) where c=colonization rate, p= proportion of patches occupied, e= extinction rate . does not have an equilibrium. C>e, the p goes to 1. And if c<e, then p goes to 0

Metacommunity ecology

Examining species interaction in patches. Dispersal among patches is important for co-existence explained by 4 points:

1. Neural perspective: species are identical, equal competitors, patches identical, no specie superior over another, limited dispersal which limits competitive exclusion by keeping species separate in space, and by speciation which replaces species that are lost due to competition.

2. Patch dynamic: species compete, one specie has a risk of

going extinct and thus wants more dispersal. Patches identical=homogeneous. Tradeoff is required between competition and colonization abilities, limited dispersal

3. Species sorting perspective: species compete, patches differ, low dispersal and competitive exclusion is fast relative to dispersal. Species sorting assumes I is too small to affect outcome

Mass effects: Species compete, patches differ, higher dispersal . I can be large enough to move dn/dt<1 to dn/dt>1. Heterogeneity

Which paradigm doesn’t predict co-existence at larger scales?

Neutral perspective, even though a single species may exclude all others within a patch

Scale dependent diversity

ɏ= B + a. y= total number of species n all communities B= average number of species NOT in local community a= average number of species found in local community

What did mouquet & Loreau (2003) model mass effects in meta: community

Each species was the best competitor in a single community. As dispersal rate increased, alpha increases to a point where it starts to decrease. Beta goes down b/c patches are similar. Gamma stays the same to a point where it goes down

16 Tropic interactions What links organisms together (what they eat and what eats them)

Tropic level Describes feeding positions of groups of organisms in ecosystems based on number of feeding steps it’s separated from autotrophs

Which organisms don’t fit into the tropic levels?

Omnivores that feed at multiple tropic levels. Coyotes are opportunistic feeders and eat vegetation, other carnivores, mice and old leather boot

NPP 50% NPP ends up as detritus (dead organic matter). More strong for terrestrial than aquatic b/c it contains more trees

Allochthonous External energy inputs (large proportion of input of detritus into stream, lake derived from terrestrial organic matter, considered external to aquatic system

Autochthonous Energy and nutrients produced within ecosystem by autotrophs. Happens in low energy envs such as swamps (phytoplankton and zooplankton)

What does the amount of energy transfer from one tropic level to the next depend on?

Food quality, consumer abundance and physiology

What is the biomass-energy relationship in aquatic systems?

Biomass pyramid may be inverted because the primary phytoplankton with short life spans have high turnovers and growth rate. Greatest where productivity is lowest, sich as nutrient poor regions of open oceans

Which system consumes a lower proportion of autotroph biomass?

4. Terrestrial. In aquatic systems, 35% of NPP is consumed.

Why don’t terrestrial herbivores consume more of the available biomass?

1. Predation: herbivores constrained by predators and don’t reach carrying capacity

2. Secondary compounds and structural defenses of autotrophs prevent herbivory

Terrestrial plants have nutrient poor structural materials like wood, stems which aren’t present in aquatic autotrophs. Phytoplankton is more nutritious

Tropic efficiency Amount of energy at one tropic level divided by amount of energy at tropic level below it

Consumption efficiency Proportion of available energy that’s consumed

Assimilation efficiency Proportion of ingested food that’s assimilated

Production efficiency 4. Proportion of assimilated food that goes into new consumer biomass

What is assimilation efficiency dependent on?

Quality of the food and physiology of consumer. Food quality of plants and detritus is lower than animals b/c of compounds like cellulose, humic acids that aren’t easily digested and contain low conc of nutrients like N and P

What is production efficiency dependent on?

Thermal physiology and size of consumer

Why do eating animals provide better assimilation?

They have carbon:nutrient ratios similar to animal consuming them, thus assimilate more easily. Assimilation efficiencies of herbivores and detrivores vary b/w 20-50%, carnivores about 80%.

What factors provide higher assimilation?

- Endotherms (animals that generate heat internally) digest food more completely than ectotherm ( animals that rely on heat exchange with environment for thermoregulation). But since endotherms allocate more energy to heat production, they have less energy for growth and reprod than ectotherms. -Some herbivores have mutualistic symbionts that help them digest cellulose giving ruminants (cattle, deer camels) higher assimilaton than nonruminant herbivores

What determines consumer population sizes?

Changes in food quantity and quality and the resulting tropic efficiency. Steller sea lion pop in Alaska declined by 80% over last 25 years. Smaller body size and decreased birth rates suggested food quality may be a problem. Before, they ate herring (rich in fats). Due to increase in pollock, they started eating it. Pollock and cod have half the fat and energy as herring.

Amount of production in an ecosystem is controlled by:

Bottom up control Resources that limit NPP determine energy flow thru ecosystem

Top down control Energy that flows is governed by rates of consumption by predators at highest tropic level

Tropic cascade Series of tropic interactions that result in change in energy and species composition. Omnivory in food webs may buffer effects of trophic

cascades. When predator relieves pressure on tropic levels below the prey.

Dyer and Letourneau studied tropic cascade

Presence of Tarsobaunus resulted in greater consumption of Pheidole ants-> higher rates of herbivory on Piper trees-> lower leaf area per tree decreasing primary production. Example of top down

What determines number of tropic levels in ecosystem?

1. Dispersal may constrain ability of top predator to enter ecosystem

2. The amount of energy entering ecosystem thru primary production. The more energy entering system, the more is available to support viable populations of higher level predators

Frequency of disturbances or other agents of change determine whether populations of top predators can be sustained

How does disturbance affect number of tropic levels?

The recovery of higher trophic levels following a disturbance is delayed until lower tropic levels containing prey species needed to sustain predators can become established. If disturbances occur frequently, predators at higher tropic levels may never become established.

Food web Diagram showing connections between organisms and food they consume. They’re static descriptions of energy flow and trophic interactions. Some organisms change feeding patterns overtime. For ex, frogs shift from omnivorous aquatic tadpoles to carnivorous adults

Interaction strength 3. Measure of effect of one species’ population on size of another species’ population. Helps ecologists focus on links that are most important for basic research and conservation

Not done !!

15 Killer alga Unsual alga (Caulerpa) was found in the Mediterranean Sea. It was native of warm carribean waters. Never in colder waters, nor in such densities. Rate of spread 1 ha in 5 years

Sucession Change in species composition overtime by biotic and abiotic factors -> results in community change. For example, an ecosystem engineer (beaver)creates wetland that leads to species replacements

Abiotic agents

Disturbance Event that injures individuals and creates opportunities for other individuals

Stress Reduces growth/reprod of individuals (temp increase)

Climax stage a stable end point that experiences little change. Successions progress thru various stages

Primary succession involves the colonization of habitats devoid of life (I.e. volcanic rock)

Secondary succession involves reestablishment of a community in which some, but not all, organisms have been destroyed

Henry Cowles (1899) – Study of Succession

Space for time substitution Shore in diagram is growing – the sand is being deposited on the shore more walking from left to right is moving backwards in time. Example of succession arranged spatially. Assumed plant farther from lake edge= oldest, near lake=youngest

Space for time Allowed Cowles to predict how community would change overtime

substituton without waiting for pattern to unfold

Frederick Clements “superorganisms”

Groups of species working together towards some deterministic end. Community had a predictable life history. If left undisturbed, it would reach a stable point “climax community”

Henry Gleason “random product”

Communities were random product of fluctuating environmental conditions acting on ind. Species. They were not predictable and repeatable result of coordinated interactions among species

Charles Elton Both organisms and environment interact to shape direction of succession

Connell and Slatyer (1977) proposed three models for succession:

3. Facilitation model: early species modify the environment in ways that benefit later species. The sequence of species facilitations leads to a climax community

How does disturbance affect number of tropic levels?

Tolerance model – also assumes the earliest species modify the environment but in neutral ways that neither benefit nor inhibit later species

Food web Inhibition model – assumes early species modify conditions in negative ways that hinder later successional species

William Cooper Student of cowels, began studying in Glacier bay in 1915, “space for time”. Established permanent plots still being used today. Saw increase in plant species composition and distance from melting ice front

Mechanisms of Succession

Late succession: bigger, long-lived species, competition is imp Mid succession: mixture of positive and negative interactions Early succession: facilitation is imp

Resilience Length of time for recovery to occur

Resistance Measure of deviation from normal range. Ecosystem is “stable” if it returns to initial conditions

Alternative stable states Different communities develop in same area under similar env conditions

Hysteresis Inability to shift back to original community type, even when original conditions are restored

14 Communities Groups of interacting species that occur together @ same place, same time. Interactions among multiple species give communities their character and function Based on biological and physical guidelines

Taxonimic affinity Study of a community limited to all bird, insect or plant species within that community

Guild Group of species that use the same resources even though they might be taxonomially diff

Functional group Species that function in similar ways, but don’t necessarily feed on the same resources. For example mosquitoes and aphids both have stylet mouth parts but one feeds on mammal blood and the other feeds on plant phloem

Trophic levels Groups of species that have similar ways of obtaining energy (primary

producers, primary consumers)

Shannon index - Sum of number of individuals in species times ln(pi)

Evenness measure

(equitability) How evenly distributed individuals are among species

Where Hmax = lnS (number of species)

Biodiversity Diversity of important ecological entities that span multiple spatial scales, from gene to gene to communities. Implicit is the interconnectedness of all components of diversity

E. O. Wilson

Includes genetic and morphological variation within species, variation in the number of species and diff types of ecosystems

Rank abundance curves Plots proportional abundance of each species (pi) relative to others.

Species accumulation curves

Species richness is plotted as a function of the total number of individuals that have been counted with each sample. Invertebrates have greater species richness than fish or amphibians. Tropical soil bacteria has the highest # of species , temperate forests have the least

Species composition Identity of species present in the community. Two communities could have identical species diversity values, but different species

Direct interactions Between two species (competition, predation, faciliaton)

Indirect interactions:

When interaction between two species is mediated by third (or more) species. Occurs between two tropic levels

Tropic cascade: carnivore feeds on an herbivore and has an indirect positive effect on primary producer eaten by hierbivore Tropic facilitation: Consumer is indirectly facilitated by positive interaction between its prey and another species AT SAME TROPIC LEVEL.

Per capita interaction strength

⁄

E = # of target individuals with ineractor absent C = # of target individuals with interactor present I = number of interactor individuals

Dominant species (foundation species) can have a large effect on other species and species diversity by virtue of high abundance or biomass. May also be ecosystem engineers

Keystone species Have a strong effect because of their roles in the community - Effect is large in proportion to their biomass or abundance - Usually influence community structure indirectly, via trophic

means, as in the case of sea otters - (i.e. beavers – a few individuals can have a large impact by

building dams)

13 Ant-fungi relationship? Ant carry leaf segments to their colony where they will be fed to

Coral-algae relationship?

the fungi the ants cultivate for food. In return, the fungi produce specialized structures called gongylidia which ants feed on Coral provides alga with a home, nutrients (nitrogen and

phosphorus), and access to sunlight Alga provides the coral with carbohydrates produced by photosynthesis

Symbiosis Relationship in which two species live in close physiological contact w/ each other like corals and algae

May be paratisism, commensialism, and mutualism

Mycorrhizae 2 types:

Symbiotic associations between plant roots and various types of fungi. Fungi benefit the plants by increasing the surface are over which the plants can extract soil nutrients and plants benefit the fungi by supplying them with carbs

Ectomycorrhizae: the fungus grows between root cells and forms a mantle around the exterior of the root

Arbuscular mycorrhizae: the fungus grows into the soil, extending some distance away from the root; and also penetrates into some of the plant root cells. Same benefits as ectomycor except plants lose some cells

A gut mutualist wood eating cockroach would starve if gut mutualists such as protist shown here(hypermastigote) didn’t help it digest wood. The hypermastiote can break down cellulose, major structural unit of wood that cockroach can’t digest on its own

Obligate Not optional for either species. For example, leaf cutter ants and fungi can’t survive without each other and their interaction has led to both evolving unique features that benefit other specie

Facultative Not obligate, many mutualists and commensalisms show few signs of coevolut

Nurse plant Adult plants providing cooler, moister conditions in deserts. Seed of many plants can only germinate in this shade.

P. Bursaria Contains photosynthetic algae that provide it extra energy. The algae are protected in a constant env. Downside is the cost to alga giving up some carbs is it could use it for itself When grown in the dark, P. burasaria loses algae, but survives with minimal impact. If P. Bursaria dies, algae live freely in water but quickly recognizes empty P. bursaria

Wetland plant Typha aerates soil in cold temps, but not in high temps. In high temps, typha acted as competitor and decreased growth of myositis

Trophic mutualisms a mutualist receives energy or nutrients from its partner

Habitat mutualisms one partner provides the other with shelter, a place to live, or favorable habitat

Service mutualism One partner performs ecological service for another like pollination, dispersal, defense against herbivores, predators or parasites

Cheaters Individuals that increase offspring production by overexploiting their mutualistic partner. If this happens, interaction probably wont persist. Penalties may be given like the yucca moth by Pellmyr and Huth. Over exploitation causes yucca flower to abort moth seeds

How does mutualism affect demographic factors?

- By pseudomyrmex ants and acacia tree. Acacias grow to be shrubs or small trees, and they have unsually large thorns which house colonies of ants. The throns have a tough woody covering but a soft interior that’s easy for the ants to excavate. The queen ant establishes a new colony on abbullhorn acia by burrowing into a green thorn, removing some of its pithy interior and laying eggs inside the thorn.

12 Hairworm Induces cricket to commit suicide by altering its perception of thirst.

Fungi enslaves Sprays insects with seeds , so spores can be dispersed more easily