Biol 104 Final

First Ideas of Ecology from the early Greeks

Balance of Nature, maintained by the gods with human aid

Herodotus

Early historian who wrote about natural phenomena and the environment. looked for evidence for biological eveidence for the balence of nature

Oikology

from greek word oikos meaning home, study ofr our howm

Ernest heckle

coined term ecology in 1869

Ecolgoy

The scentific stuyd of the relathionship between organsims and their enviroments

Carey institute defintion of ecolgoy

scientific study of the processes that influence the distribution and abundance of organisms,the interactions among organisms, and the interactions between organisms, and the transformation and flux of energy and organic matter.

Population ecology

strongly linked to the study of demography

Population

a group of indivisuals of one species in an area, depends on the strength of interactions among indivisuals

Community ecolgoy

how species assemblages from and how species interact with htoes assemblages

community

a group or interacting populations of different species

authur tansley

British ecologist who coined the term "ecosystem" to describe the interactions between organisms and their physical environment.

ecosystme ecology

the study of the transfer and accumlation of matter energy, nutrients

Stoichometric contratint

energy comes from some where

Ecosystem delimitation

ecosystem ecology focuses on the conservation of matter and energy, researchers must clearly define the system’s boundaries to track energy and material flow in and out of the system.

Ecology conserned with processes that

Maintatin diversity and ow and why diverity affects other processes of intrest, forcus on a place not a taxon

Speceis richness

the way ecologist most basically count biodiveristy and refer to the number of different species in a given area.

Relative abundance

refers to the proportion of different species within a community, indicating how common or rare each species is relative to others.

Eveness

a measure of how evenly individuals are distributed across the different species in a community, helping to understand community structure and diversity.

Shannon Wiener index

used to quantify the diversity of a community by incorporating both species richness and evenness. Formula:
H' = –∑ (pi × ln pi)
where pi is the proportion of individuals belonging to the i-th species.
Higher H' = greater diversity.

Alpha diversity

Evenness equation

Evenness (J’) = H' / ln(S),
where H' is the Shannon-Weiner Index and S is species richness.
E ranges from 0 (uneven) to 1 (perfectly even).

alpha diveristy

Alpha Diveristy

the overall diversity within a particular area or ecosystem, measured by the number of species (richness) and their relative abundance. Local

Beta Diversity

describes the change in species composition from site to site or from time to time also some times called species turnover Beta diversity measures the variation in species composition across different environments, reflecting how unique each site's flora or fauna is. gets higher the more different species

Gamma Diveristy

the total diversity of a region, encompassing alpha and beta diversity, often measured across multiple ecosystems or geographical areas. combined or regional diveristy

Jaccard similarity

J = A / (A + B + C),
where A = shared species, B & C = unique species in each community.
It measures beta diversity — the similarity between two communities.

Soresen similarity

S = 2A / (2A + B + C),
where A = shared species, B & C = unique species in each community.
It measures beta diversity — the similarity between two communities, giving more weight to shared species than Jaccard.

turnover

Turnover refers to the replacement of some species by others between different sites or over time. It's a way to describe how community composition changes across space or time.

• High turnover = very different species between communities

• Low turnover = communities share most species

heterogenity

Heterogeneity refers to the degree of variation or diversity in environmental conditions or species composition within a given area.

• Spatial heterogeneity: variation across different parts of a landscape (e.g., forest + wetland)

• Leads to more niches → greater biodiversity

Associated with:

• Alpha diversity (locally) and Beta diversity (regionally)

• Often drives species richness due to diverse habitats

latitudinal biodiversity gradient

The latitudinal biodiversity gradient is the observed pattern where species richness typically increases closer to the equator and decreases towards the poles.

Why are the tropics more biodiverse

-inhabitable for many years
- climate stablity

-lots of biomass/ more habitats

Draw island size versus number of spaces

x axis is log scaled 10^x, larger the island the more speces

Species area curves

The species-area curves illustrate the relationship between the size of an area and the number of species it can support, showing that larger areas typically contain more species. This concept is vital in understanding biodiversity patterns and conservation efforts.

specialist

only use a couple of habitats

generalist

a species that can thrive in a wide variety of habitats and utilize a broad range of resources.

lager areas support

larger populations leading to less extinction risk and greater biodiversity in ecosystems.

What does a species–area curve look like on linear axes, and why?

On linear axes it is a concave‑down “saturating” curve: richness rises quickly at small areas then slows as the finite regional species pool is exhausted and each new area adds fewer new species.

Species distance relation ship

Species distance relationship refers to how individuals disperse relatively close to their original location, affecting local population dynamics and genetic structure.

Big Biodiveristy Experiment

To test how plant species richness affects ecosystem functions like plant productivity, nutrient use, and drought resistance.

Findings:

• Higher species richness → greater plant cover (more biomass)

• Higher species richness → lower soil nitrate levels, indicating more efficient nutrient uptake

• Species-rich plots were more drought-resistant, with smaller biomass losses during droughts

Ecosystem functioning relationships

Biotic and Abiotic processes within an ecosystem That contribut to ecosystem servcies

Ecosystem services

Ecosystem functions that are useful to humans, including provisioning, regulating, supporting, and cultural benefits.

leguemes ecostystem fuctions

Plant species that enhance soil fertility and provide food.

Ecosystem function categories

provisioning, regulating, supporting, and cultural functions.

Provisoning

the function of ecosystems that provides resources like food, water, and raw materials to humans. Ex. agriculture, fishing, and forestry.

regulating

the ecosystem function that manages natural processes and maintains balance within the environment, including climate regulation and water purification. Ex. carbon sequestration and disease control.

supporting

the ecosystem function that underpins the production of all other ecosystem services by maintaining essential processes such as nutrient cycling and soil formation. Ex. microbial activity and plant growth.

cultureal

the ecosystem function that encompasses the non-material benefits people obtain from nature, including recreational, aesthetic, and spiritual enrichment. Ex. nature walks, photography, and cultural traditions.

Functional Reduncacy

the concept that multiple species can fulfill similar roles within an ecosystem, ensuring stability and resilience in the face of changes or disturbances.

West Nile virus and bird diversity

Higher bird diversity is associated with fewer West Nile virus cases in humans because the virus circulates in birds and spreads less effectively in diverse bird communities.

What does the equation dN/dt = rN describe?

The rate of population change is proportional to the current size, modeling continuous exponential growth.

What do the variables in dN/dt = rN stand for?

N = population size, r = intrinsic growth rate, dN/dt = rate of population change.

What does N(t) = N0 * e^(rt) calculate?

The size of a population at time t, given exponential growth.

What are the variables in N(t) = N0 * e^(rt)?

N0 = initial population, r = growth rate, t = time, e = Euler’s number (≈ 2.718).

Exploitive Competition

A form of competition where one species uses resources more efficiently than another species, leading to a decrease in the population of the less efficient species.

population level birth and or death rates change with density why

Because of density-dependent factors that influence reproduction and survival, such as resource availability and competition.

Carrying Capacity

The maximum population size that an environment can sustainably support, influenced by resource availability and environmental conditions.

What does the equation dN/dt = rN(1 - N/K) represent?

The logistic growth model, where population grows rapidly at first but slows as it approaches a carrying capacity K.

What do the variables in dN/dt = rN(1 - N/K) represent?

N = population size, r = intrinsic growth rate, K = carrying capacity, dN/dt = rate of population change.

Relationship between N and K

as N approaches K, growth slows due to resource limitations.

Thomas Malthus

An economist known for his theory on population growth, which posits that population growth will always outpace food supply, leading to inevitable resource limitations.

Competition

Negative for both groups leadiing to decreased fitness, for reporoduction growth and survival due to limited resources. This often occurs when two or more species or individuals vie for the same resources in an ecosystem.

Intraspecific Compettions

Competition within a species for limited resources, such as food, territory, or mates, that can affect individual growth, reproduction, and survival.

Interspecific Competition

Competition between different species for limited resources, which can influence population dynamics and community structure in an ecosystem.

Amensalism

one specides is negitivly effect and the other is not effected at all , trampling grass

Comensalism

A symbiotic relationship where one species benefits while the other is neither helped nor harmed, such as barnacles adhering to a whale.

Muturalism

A symbiotic relationship where both species benefit from the interaction, such as bees pollinating flowers while obtaining nectar.

Facilitation

A type of ecological interaction in which one species benefits and the other is unaffected, often enhancing the environment for other species, like . haydraulic liftis when plants absorb water and nutrients from deep soil layers and redistribute them to the surface for other plants to use.

Turing patterns and facilliation

you can see where activation happens from facilliation in these patterns

Predation

A biological interaction where one organism (the predator) kills and eats another organism (the prey), influencing population dynamics and community structure.

Herbivory

A type of consumption where herbivores feed on plants, impacting plant population dynamics and community composition.

Parasitism

A biological interaction where one organism (the parasite) benefits at the expense of another organism (the host), often causing harm to the host.

Food Chain

A series of linked organisms where energy is transferred as one organism consumes another, illustrating the flow of energy and nutrients in an ecosystem.

Food web

many food chains, shows consumer can be consumed

Trophic

Realting to food of nutrition

Trophic dynamics

is the study of how energy and nutrients move through different trophic levels in an ecosystem, highlighting the interactions between organisms.

Tophic levels

different hierarchical levels in a food chain, defined by the organism's role in energy transfer, such as producers, consumers, and decomposers.

Autotroph

An organism that produces its own food through photosynthesis or chemosynthesis, serving as a primary producer in an ecosystem.

Heterotrophs

Organisms that cannot produce their own food and rely on consuming other organisms for energy and nutrients, such as animals and fungi.

How do ecologists quantify interactions in a food web?

Ecologists assign numbers to different trophic levels (e.g., primary producers as level 0 or 1) and quantify the strength of interactions between species. By averaging these interaction strengths, they can better understand the dynamics of the food web. doesn’t usually go past 6

high trophic level consumers

that occupy higher trophic levels, often including apex predators that have few or no natural enemies.

How does herbivory affect plant biomass, abundance, species richness, and evenness?

• Biomass & abundance: Herbivory reduces total plant biomass and abundance.

• Species richness: Little to no effect on the number of species present.

• Evenness: Can slightly increase evenness by suppressing dominant species and allowing subordinate species to persist.

Consumers can limit lower trophic levels

by reducing the abundance of primary producers and influencing species interactions, thereby altering community dynamics.

Why is the world green

• plants fight back

• environmental variability could limit herbivore populations

sea otters effects on sea uchins

Sea otters are a key predator of sea urchins, which helps to maintain kelp forest ecosystems by controlling urchin populations. This increase in kelp availability also supports a diverse range of marine life

trophic cascade

is an ecological phenomenon where changes at one trophic level can influence multiple levels below it, often leading to significant shifts in community structure.

Knock off effect

refers to secondary effects in ecosystems that occur as a result of changes in one population or species, often impacting others in unexpected ways.

Heterospecific infection

refers to the transmission of a pathogen from one species to another,

Parasitic disease

Abnormal condition that impairs the normal functioning of a host organism due to a parasite.

Infectious disease

any disease caused by pathogenic microorganisms that can be transmitted between hosts, often leading to illness.

Waterborne disease

a disease caused by pathogens transmitted through contaminated water sources, often linked to inadequate sanitation.

John Snow

A pioneering epidemiologist known for his work in tracing the source of cholera outbreaks in 19th century London.

Food borne Disease

A disease caused by pathogens transmitted through contaminated food, often resulting in gastrointestinal illness.

Wildlife Hunting disease

A disease transmitted from animals to humans, often through hunting or handling wildlife. Examples include zoonotic infections like rabies and hantavirus.

How does initial human to animal trassmission occur

Initial human-to-animal transmission occurs when humans come into contact with wild animals or their bodily fluids, potentially exposing them to zoonotic pathogens.

What are the three compartments in the basic disease (SIR) model?

• S = Susceptible: Individuals who can catch the disease.

• I = Infected: Individuals who have the disease and can spread it.

• R = Recovered: Individuals who have recovered and may (or may not) become susceptible again.

What are the key equations and parameters in the SIR disease model?

• Transmission rate:
  dS/dt = -βSI

• Infection rate:
  dI/dt = βSI - νI

  Recovery rate:
  dR/dt = νI
  Where:

• β = transmission coefficient (chance of infection per contact)

• ν = recovery rate

formula for basic reproductive number of infections in population where all are susceptible

R₀ = N × (β / ν)

If R₀ is greater than 1

the infection will spread through the population.

Trade off between transmission and virulence

refers to the balance that pathogens strike between spreading easily and causing severe disease. Higher virulence may lead to fewer opportunities for transmission as hosts become sicker.

Wildland urban interface

the zone of transition between wildland and urban areas, where human development and natural ecosystems meet.

Ecosystem Ecology

is the study of the interactions among organisms and their environment, emphasizing the flow of energy and matter through ecosystems.

Mira lake Hubbard Brook

foucused on how carbon cycles and influences ecosystem processes within the Hubbard Brook Experimental Forest in New Hampshire.