BIOL1500 Intro to Organismal & Evolutionary Biology Midterm 1: Chapter 51-56 (26-27)

ecology and biosphere, population ecology, species interactions, community ecology, ecosystems, biodiversity and conservation biology, animal behavior

Ecology

the scientific study of the interaction between organisms and their environment (where species live in numbers

Biosphere

abiotic variable across the planet, determines where species can exist`

adiabatic cooling

(caused by the presence of mountains) warmer air expands, loses pressure and rises -→ gets cooler, releasing energy, fewer interactions between molecules that would create heat!

• explains why rain falls on windward side of mountain range: air must over mountain for this process, water will be released (cool air holds less water)

main biomes of continental usa

temperate seasonal forest, temperate grassland, cold desert, subtropical desert

climate diagrams

allow us to view precipitation and temperature over the year

subtropical desert characteristics

low density, scattered vegetation

desert plan adaptations include reduced leaf surface area physical defenses, and tolerance to desiccation (losing all moisture)

temperate seasonal forest characteristics

distinct vertical layers (closed canopy, understory trees, shrubs, herbs)

deciduous trees dominant (lose their leaves)

temperate grassland (great plans)

very dry winters

very low productivity during winter

many animals graze

salinity

(characterizes aquatic habitats)

primary production

the amount of light energy converted to chemical energy by autotrophs

autotrophs

(ex. plants, phytoplankton, macroalgae): organisms that perform photosynthesis

nutrient upwelling

winds push warmer surface water away, pulls colder nutrient-rich matter in

streams and rivers characteristics

flowing, fresh water

ponds and lakes characteristics

nonflowing fresh water

freshwater wetlands characteristics

nonflowing fresh water, shallow enough to have emergent vegetation throughout (swamps have emergent trees, bogs have acidic adapted plants)

salt marshes and mangrove swamps characteristics

are characterized by intertidal, estuarine waters with emergent vegetation

estuaries characterized

coastal regions where seawater mixes with fresh water (lower salinity)

rocjy intertidal zone characteristics

intertidal, marine waters on a steep rocky coastline

coral reef, seagrass beds, and kelp forest characteristics

found in neritic zone → shallow region of ocean overlying continental shelf

benthic zone characteristics

the bottom surface of an aquatic environment, contains larger/microorganism q/ a food source of mainly detritus

geographic range

the area a population occupies

population size

the number of individuals in a population at a specific area

density of a population

the # of individuals in a certain area or volume

• populations near the center of a species range will be more abundant than the edges

• larger species tend to have lower densities

  • require more resources to survive

dispersion

the pattern of spacing among individuals within the boundaries of the population (NOT the same as dispersal)

clumped dispersion

Individuals are aggregated → why? Social groups, low dispersal, mating behavior, spotty resources, predation/defense

uniform distribution

example - territoriality → the defense of a bounded physical space against erncroachment by other individuals

random distribution

high, passive dispersal (wind-pollination), constant environmental resources cross space

demography

the statistical study of the processes that change a population’s size and density over time

life histories

the schedule of an individual’s life

• there are trade-offs in life history traits

K-selected populations

long life/low # of offpsring: high parental investment, ex. whales

r-slected populations

short life/high # of offspring: low parental investment, ex. rabbits

survivorship curves

the probability of surviving changes with age/stage (when are individuals more likely to die)

• y-axis represents the proportion of the initial cohort surviving over time

age structure/pyramids

can tell us if a population is growing, shrinking or static

exponential growth

population has unlimited growth, assumes infinite food/space/mates → reality has constraints, leads to carrying capacity (K) = max population sustainable, will transition to logistiv growth

• general: ∆N/∆t = B-D

• per capita rates: dN/dt = rN

  • r: per capita growth rate

  • r > 0: population grows, r < 0: population declines

  • ideal conditions r = r_max = intrinsic rate of increase

• graph: J shaped curve

logistic growth model

dN/dt = r_maxN(K-N)/K

• incorporates resource limitation

• produces s-shaped (sigmoidal) curve

  • growth fastest n = k/2

low density in logistic growth model

slow growth (few breeders)

intermediate density in logistic growth model

fastest growth - many breeders, enough resources

• populations fluctuate around K

density dependent factors (factors that limit populaiton growth)

resource limitation, parasitism (disease), predation

• incorporated into logistic population growth model

density independent factors (factors that limit populaiton growth)

generally climate and abiotic factors

interspecific interactions betwen two species

occurs between 2 species that live in the same area (community) → usually fighting for access to resources

• classified by how they affect the fitness of the 2 species

types of interspecific interactions

+/+: mutualism

±: exploitation

+/0: commensalism

-/-: competition

-/0: amensalism

explotation ±

low lethality and host specificity: grazers

high lethality and host specificity: parasitoids

low lethality and high host specificity: parasite

high lethality and low host specificity: predators

predators

predators limit prey abundances via consumption → there are numerical effects of predators or prey

• predation is a density-dependent population control factor

  • same goes for herbivores and parasites

anti-predator adaptation

prey have evolved diverse strategies to defend themselves from predators

• active/passive camouflage, behavorial modifications, structural/chemical defenses

Lotka-Voltera Model

(predator prey cycling in nature) → predator population will slightly lag behind prey

• ex. oscillations of snakes were caused by lynx predation (density-dependent factors rather than by overshooting carrying capacity)

predators can evolve counter adaptations

parasite

organism that feeds on cell contents/tissues/body fluids of another species (the host) while in or on the host organism

• usually harm but do not kill their host

direct transmission of parasites

directly between host with no intermediary (cold/flu)

• can complete life cycle between one host

vector transmissionof parasites

where (generally) an insect carries pathogen (generally bloodborne) and transmits it, may not get sick → just a carrier

• ex. malaria

vertical transmission of parasites

parent to offspring disease transmission

complex life cycle of parasites (horizontal transmission through life stages)

require 2-3 hosts in a specific order to complete life cycle

trophic transmissionL secondary hosts are usually eaten by final host for parasites to complete life cycle

exploitative competition

species compete over limiting resources, deplete its resources, and the resource limits their growth

• nonrenewable vs. renewable

• no physical interaction required

interference competition

direct competitive interactions between organisms

• territoriality, chemical warfare

competitive exclusion principle

2 species cannot coexist indefinitely if they are limited by same resource

• one species will inevitability be more successful

fundamental niche

conditions where a species could exist

realized niche

the conditions a species does exist (smaller due to competition)

types of mutualism

generalists, specialists, obligate mutualists, facultative mutualists

generalists

one species interacts with many species

specialists

one species interacts with one other species or only a small # of closely related species

obligate mutualists

species that provide benefits to each and need that interaction to persist

facultative mutualists

species that provide benefits to each other that do not need interaction to persist

• most organisms are mircobes (bacteria, fungi, protists) in their gut to help digest dood

  • mutualism for protection and defense

  • mutualism can aid reproduction and dispersal (bee pollen)

community

assmeblage of populations of different species in a particular area or habitat

species richness

number of species in a sample/size/community

species evenness

distribution of relative abundances for species in a sample/site/community

• 5 species each represented by 2 individuals EACH

species diversity

metric incorporating rich/evenness

shannon-weiner’s diversity index H’

a mathematical measure that quantifies biodiversity by balancing both species richness (the total number of different species) and species evenness (how evenly individuals are distributed among those species) (diversity metrics)

species interactions between many species in a community

(created by compounded 2-species interactions) species eating another, food chains with trophic levels

• producer → primary consumer → secondary consumer

  • there is also possibility for negative predation (ex primary consumer eats secondary consumer)

indirect effects in species interactions

involving an intermediate species between 2

initiated by predators: trophic cascade (primary consumers excluded bc they eat plants)

direct effects in species interactions

2 species interaction w/o involving another species (parasitism)

• can be positive or negative (arrows in trophic diagram can show effects or flow of energy)

keystone species

a species that has a disproportionate effect (though not necessarily on the community)

• test by removing species and seeing what happens to population

  • ex. some apex predators (though some keystone species may still have predators)

ecological sucession

predictable change in species composition over time (easily observable after natural disaster (ex. volcanic eruption)

• seral stage: each stage of community change in succession

primary sucession

developmental of communities in habitats that are initially devoid of plants and organic soils

• mountain slopes, ex. volcano → ZERO LIFE

secondary succession

development of communities that contain no plants but do have organic soil

• treefall gaps → some level of organic material

  • terrestial: pioneer species (grasses/weeds) → climax community

pioneer species characteristics

1. Good dispersers at new/disturbed sites: rapid growth/ reproduction, tolerant of harsh, abiotic conditions

   1. poor competitors, shade intolerant (for plants)

climax community characteristics

bad dispersers, slow growing (below-ground biomass), intolerant harsh abiotic conditions, large size as adults, shade tolerant for plants

theory of island biogeography

explains how island species richness results from a balance between immigration and extinction, shaped by island (patch) size and isolation

• demographic and environment stochasticity

demographic stochasticity

random variation in birth and death rates due to differences between individuals

environmental stochasticity

random variation in birth and death rates due to changes in environmental conditions

• drought/flood

gross primary prodcution

all the solar/chemical energy that is captured and converted into chemical bonds by photosynthesis

• after producers use energy for their own cellular respiration, what is left is net primary productivity

chemiosynthesis (chemoautotrophs)

an organism’s energy that doesn’t ultimately come from the sun, using the energy derived from the oxidation of inorganic chemical compounds rather than sunlight to convert carbon molecules and nutrients into organic matter (food)

carbon cycle

photosynthesis (conversion to glucose) and respiration (atp)

net primary production

the amount of energy that matters ecologically, can be transferred to next trophic levels (energy is lost at each trophic step)

• NPP = GPP - producer respiration (plant)

gross secondary production

the total amount of energy consumed by herbivores in a given area that is used for respiration, gorwith and reproduction (analogous to GPP for consumers)

net secondary production

the total of energy consumed by herbivores in a given area that is used for growth and reprodcution(nalogous to NPP for consumers)

• GPP → (- respiration for plants) NPP → ( - detritus) GSP → ( - respiration for mammals) NSP

ecological (Food Chain) Efficiency % net production from one trophic level to the next lower trophic level

net production energy (J)/ net production energy of the next lower trophic level (J)

• typically range from 5%-20%

  • being purely carnivorous is a relatively inefficient way to get energy from photosynthetic production

limits to trophic levels

there isn’t enough energy in the system to support more than 4/5 trophic levels

• longest chain will probably be marine

nutrient cycling

described by compartment models - the 4 compartments where nutrients accumulate

• nutrients are recycled through the ecosystem

4 compartments in nutrient cycling

available organic (consumers, dead organic matter), unavailable organic (coal, oil), available inorganic (soil, water, sediments), unavailable inorganic (rocks, minerals)

• nutrients circulate in biogeochemical cycles between living organisms and nonliving reservoirs (atmosphere/sedimentary

biogeochemical cycles

nutrients recycled between abiotic and biotic components of ecosystems

greenhouse gases

CO₂ acts like a window pane in a greenhouse trapping energy in the lower atmosphere, creating a warm earth

• downstream effect is ocean acidification (decreasing pH in ocean, ruining integrity and durability of marine life, altering availability of key ions, affecting physiological processes, like reproduction or respiration)

phosphorus cycle

Animals cannot directly use inorganic phosphorus (ex. in rocks)

• no phosphorus in the atmosphere

  • Comes from soil and plants (fixed by plants) eaten by animals or wind/rain erodes phosphate-rich rocks; runoff goes to the ocean

nitrogen cycle

neither animals or plants can fix inorganic nitrogen → only bacteria can fix nitrogen that come from the atmosphere

instrumental value

the value biodiversity has because of the benefits it provides to humans: 4 categories

• cultural, provisional, regulation, and supporting values

intrinsic value

the value biodiversity has in itself, regardless of human user or benefit

ecosystem services (biodiversity can increase ecosystem services)

a function performed by an ecosystem that directly or indirectly benefits humans

• pollinations services, water filtration, storm mitigation, prevention of invasive species, erosion mitigation

  • helped a lot by dunes

provisioning services

material things used (almost directly) for our own use

• ex: lumber fur, meat, crops, fiber, cotton

  • many of these plants have been artificially selected for human benefit

  • pharmaceutical chemicals, aspirin (willow bark), taxol (pacific yew bark), quinine

regulating and supporting services

allows an ecosystem to exist w/o suffering too many fluctuations

• regulating: biodiversity benefits regulation processes that reduce environmental fluctuations

  • supporting: benefits of biodiversity that allow ecosystems to exist, such as primary production, soil formation, nutrient cycling

cultural services

aesthetic, spiritual, cultural value; ecotourism

principle sof regenerative agriculture (how a healthy ecosystem sustainsn itself)

1. diversity is key

2. incorporate livestock

3. keep it organic

leveraging ecosystem services

biodiversity loss

extinction has been happening for a long time → historical mass extinction

main causes of biodiversity loss today

overharvesting, introduced species, pollution, global climate change, habitat loss ≠ fragmentation (Mass extinction event: extinction value is 1000x higher than extinction of 75% in a 2 million year period)