Ecology and Evolution Midterm 3

Ecology

The study of the relationships between organisms and their eviroment

• selective pressures on organisms

Ernst Haeckel

the investigation of the total relations of the animal both to its inorganic and to its organic enviorment

Suitable habitat

a variety of enviromental factors must be in the range of tolerance for individauls to live there

Geographical range

the measure of the total area covered by a population

what is a niche? what does it’s graph loo like?

is a n-dimensional hypervolume measumrent of the range of conditions that an organism can tolerate in which an organism can persist indefinitely.

• the range of antibiotic and biotic conditions that an organisms can tolerate

what is n-dimensional hypervolume

total range of environmental conditions and resources in which a species can survive, grow, and reproduce.

habitat

the place, or physical setting, in which an organism lives

what determines the distrobution and abundacne of a species

Biotic and abiotic factors limit distrobution and abundance

Why are some species endemic and other speces are cosmopolitan?

Dispersal limitation: the absense of a populartion from a suitable habitat because of the barriers to dispersal

Endemic species

speciess that live in a single often isolated, location

Cosmipolitan

species iwth very large geographical ranges that can span several continents

How does human activity affect population distrobutions?

1. spead of invasice species

2. climate change

3. habitat fragmentation: breaking up arger habitats into a number of small habitats

Metapopulation

population of populations connected by migration

habitat Corridor

a strip of favorable habitat located between two larger patches of habitat that fasciliates dispersal

How do scientists study ecology

Manipulative experiments: tested by altering a factor hypothesized to cause a phenomenon

Natural Enviroment: testing that relies on natural variation in the enviroment

Mathematical model: a system with a set of equations that correspond to hypothesized relationships amon the systems components

Ecological systems

1. indivdiaul

2. population

3. community

4. ecosystems

5. landscapes

6. biosphere

Indivdidual

• A living being

• an indivduals morphology, physicologym and behvaior enable it to survive in its enviroment

Population

• individuals of same species living in a particular area

• variation over time and space in the number, the desnity, and the composition of individuals

Community

• all populations of psecies living togther in a particualr area

• the divserity and relative abundance of different kinds of ogranisms living togther in the same place

Ecosystem

one or more communities of living organisms interacting with their nonliving physical and chemical enviroments

• the storage and transfer of energy and matter inclduing the various chemical elements essential to life

Landscapes

multiple ecosystems thata re connected by the movement of individuals, populations, matter, energy

• the movement of energy, matterm and individuals between different ecosystems

Biosphere

all ecosystems earth

• the movements of air and water and the energy and chemical elements

Weather

Population size and population growth rate

number of individuals = N

the change in size over time = dN/dt

Exponential population growth

population can grow rapidly under ideal conditions

dN/dt = rN

r= (b-d) = per capita population growth rate

dN/dt: change in N over time

Exponential growth model how can we make it better?

1. essential resources are unlimited (space, food…)

2. the enviroment constant

As density of population increases

• decrease in fecundity

• increase in mortality

logistical model of populatopn growth

dN/dt= (rN(K-N))/K or dN/dt= rN(1-N/K)

K= carrying capacity

• when N is low compared to K, population growth is exponential

• when N apporaches K, the term (1-N/K) approaches 0, slowing pop growth

carrying capacity

the maximum population size that can be supported by the enviroment

Density independent

factors limiting population size regardless of the population’s density

Weather

specific short term atmospheric conditions of tempature, precipitation, sunlight, and wind over periods of hours and days

Climate

the typical atomspheric conditions that occur throughout the year, measured over many years

How does productivity relate to biomes?

Productivity of world biomes depends on climate

tempature patterns refelct energy inpur from the sun

Overal rules of circulation patters

1. hot air rises

2. cold air holds less water

3. earth turns west to east

the circulation of air in hadley cells

1, the sun heats the most tropical air causing it to rise

2. the air rising cools, causes water vapor, then rain

3. the cool dry air goes back to earth

4. the cool air warms and dries and flows towards the equator

label the ferrel and hadley cells and how they circulate

What happens when solor radiation falls directly on tropic of cancer or tropic of capricorn?

increases the input and day length in

• tropic of cancer - northern hemisphere

• tropic of capricorn - sourther hemisphere

InterTropical convergence zone

where two hadley cells converge and cause large amounts of precipitation

• shifts cause seasonality preciciptation: rainy seasons and dry seasons

How does ITCZ shift seasonally

• due to uneven heating (tilt/rotation)

• leads to seasonality of precipitation in many places (wet and dry season)

• two rainy seasons near equato

Tundra and boral forests

plant productivity is energy limited (light and tempature)

Tundra: show saturated herbaceous plants, shrubs

Boreal: evergreen and deciduous forest, regularely burns

tropical rainforest and savanna

rainforests: highly productive, very high biodiveristy

savanna: seasonally dry

Coriolis effect

the defelction of an objects path due to the rotation of the earth

Ocean circulation

1. driven by atomspheric cireculation and the coriolis effect causing ocean currents to be clockwise in north and counterclockwise in south

2. ocean currents in part, are due to surface winds

3. gyre: large scale water circulation pattern between continents

Thermophaline ciculation

a global pattern of surface- and deep- water currents that flow as a result of variations in temperature and salinity that change the density of water

What are the effects of climate change on the water cycle?

• rising temps change when, where, and how much precipitationa nd evaporation

• some areas have increase soil moisture in the frtue, but others will have drier soil - dryers with reduce primary production and increase risk of rife

• precicpation is more variable

Causes of global warming

The balance between incoming (sun) and outgoing energy (greenhouse gases)

Input: no change in solar energy reachoing earth

• solar activity

• earth- sun geometry

• land- use ( how much light is reflected)

Output: less thermal radtion emitted by earth to space

• greenhouse gasses

• volcanic acitivity

green house gasses

1. water vapor

2. methane

3. nitrous oxide

4. carbon dioxide

H2O - water vapor

natural - part of hydrologic cycle, including plant transpiration

• capped! – cannot increase beyond saturation (rain

CO2

natural – produced by respiration, fire, consumed by photosynthesis

• anthropogenic – created by burning fossil fuels

Evidence: air bubbles trapped in ice cores can be used to determine CO2 levels as well as tempature back thousands of years

CH4

natural - produced and consumed by microbes

• anthropogenic - natural gas extraction, agricultural wetland crops (such as rice)

N2O

natural - part of the microbial nitrogen cycle

• anthropogenic – N cycle greatly changed by human agriculture (fertilizer use), also industrial uses

CFCs - chlorofluorocarbons, halocarbons

anthropogenic - used for refrigerants, industrial uses

fluxnet

worldwide network of meterological towers measuring fluxes of CO2 and other gases

The global carbon cycle

1. burned fossil fuels moves carbon from inactive geological reservoir to forms of petroleum or coal active resevoir in atmosphere

2. burn gasoline releasing C atoms that have been inactive for hundreds of millions of years

3. intensive agrictuture and deforestation adds large amounts of CO2 in atmosphere

Climate Finger printing

satelite tempature data show the atmosphere tempature fingprint predicted

Costs and befifics of regulation

cost- energetically expensive

benefit: maintain a constant and optimal internal enviroment

optimized internal functions

increased activity and growth rate

extended range of enviromental conditions

Conformers benefits

1. less energectically costly

2. requires less food

3. wider thermal tolerance niche

Phenotypic plasticity

the ability of a single genotype to produce multiple phenotypes in different enviorments

How do organisms respond to a variable environment?

regulate

depends on scale of environmental variability over time and space relative to the organism’s or tissue’s lifetime

Types of repsonses to enviromental variation

1. Homeostasis

2. acclimation

3. developmental plasticity

4. resistance or avoicande of adverse enviorments

Homeostasis

• Quick, short term reversable responses

• maintnance of nearly ocnstant internal enviroment in the midst of a varying external enviroment

• behavorial: shade, sunlight

• physiological: sweating, shivering

• microhabitat

microhabitat

a specific location within a habitat that typically differs in enviromental conditiosn from other parts of the habitat

Acclimation

• long-term reversible repsonses

• reversible phenotpyic change in an individual organism in repsonse to chnaging evriomental conditions

• Seasonal changes

Developmental Plasticity

• slow and irreversible

• differences in a phenotypic traits for a given genotype under different enviromental conditions

Resistacne of avoidance of adverse enviroments

1. can be relativelu quick or slow, reversable or perminant

2. migration - seaosnal movement from one region to another

3. dormacy- organisms dramatically reduce metabolic processes storage

Torpor

a breif period of dormacy that cocurs in birds and mammals in which individauls reduce their activity and their body tempature

Behavior

action or repsonse to a stimulis

Behavioral ecology

behavorial adaptations that evolved in response to ecological selection pressures

Proximate

Cause: mechanisms - how does it work?

Development: Ontogeny: how does it develop

Ultimate

cause: adaptive significance: what is its function

development: phylogeny of trait: what is its evolutionary history

Optimality modeling

predicts that an animal should behave in a way that maximizes the difference between the benifit of a behavior and its cost

What are all organisms constrained by?

1. time

2. energy

3. risk of injury

Cost- benefit analysis

determines whether the cost of an activity is less than teh benefit that can be expected from the activity

Assumptions of optimality models

animals are well adapted to their enviorment

they have some advantage to them to behave inc ertain ways

natual selection has molded animals to their enviroment

Living in groups costs and benifits

benefits

• increased foraging efficiency

• reduced predation

• increased access to mates

• help from kin

costs:

• competition for food

• increased risk of disease or parasites

• attraction of predators

• loss of paternity

• brood parasitism

• loss of individaul repoduction

• increase competition

Dilution effect

the reduced or diluted probability of predation to a single animal when it is in a group

Overshoot

When a population grows beyond carrying capacity

Die-offs

a susbatntial decline in density that typically goes well below the carrying capacity

Interactions among species

consumption: +/-

competition: -/-

mutualism: +/+

commensalism: +/0

Mensalism: -/0

Neutralism: 0/0

Predation

+/-

• heterotopic organusms whcih consume tissue as a soruce of energy and carbon

• feed on living organisms

Intraspecific competition

comeptition among individuals of the same species

Interspecific competition

competition among individauls of different species

Renewable and nonrenewable resources

renewable: resources that are cinstantly regernated

nonrenewable resources: resources that are not regernated

Exploitative competition

competition is the result of indirect

interactions, individuals use

resources, reducing the amount

available for other individuals

Interfernece competition

competition is the result of

direct interactions, individuals

use resources, and prevent

other individuals from accessing

those resource

Competition model

species 1: dN(1)/dt=r(1)N(1)(1 - N()1/K(1))

Add species 2: dN(1)/dt=r(1)N(1) (1 - (N(1)+alphaN(2))/K(1))

species 1 is not reaching carrying capacity if species 2 is present

alpha: competition coefficent

Competition coefficents

variables that convert between the number of individauls of one species and the number of indivdiauls of the other species

Compeition zero-groth rate species 1

set equation = to 0

K(1)=N(1)+alphaN(2)

set N(2)=0, solve N(1)

set N(1)=0, solve (N2),

solve for carrying capacity

• on the lines species 1 population is not growing

• below line species one can grow

• above line specis one will decline

Comeptition growth rate Species 2

chnages alphaN2 to betaN1

K2=N(2)+betaN(1)

K(2)=N(2)

N1=K(2)/beta

• on line species 2 is not growing

• below line species 2 can grow

• above line species 2 will decline

a. species 1 wins

b. species 2 wins

c. coexistence

d. could go either way

Questions concerning the role of predation in ecology and evolution?

1. Do predators limit prey populations below their carrying capacity?

2. To what extent do predators stabalize or cause fluctuations in teh prey population size?

3. Do predators over-eat their prey?

4. Do rpedators influence the evolution of prey characteristcs and vice versa?

Lotka and Volterra prey? what does it’s stabe graph look like?

prey: dN/dt = rN-cNP

c: predators ability to capture prey

rN: preys births

cNP: the decrease in prey population due to predators (#eaten)

Lokta and Volterra model predator

dP/dt= a(cNP)-mP

a(cNP): predator births

mP: predator deaths

a: efficiency of catching and converting prey in predators

What is Lotka-Volterra equations when prey and predator populations are stable?

Set dN/dt and Dp/dt = 0

solve an get

prey: P=r/c

predator: N=m/ac

Zero growth isocline

the population size of one species that acauses the population of another species to be stable

descibe the predator prey graph and each quadrant?

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2: both prey and predator are decreasing

1: both predator and prey and increasing

4: predator pop. is increasing and prey pop. is decreasing

3. predator population is decreasing, prey population is increasing

Objections to lokta-volttera model

1. no tendency for populations to return to a stable equilibrium: extinction of populations more likely

2. there are no density-dependent restrictions to population growth

Rozenweigh and MacArthur graphs

Adds density dependence

1. at high prey densities, prey populations ahve limited resources, reaches carrying capacity (K), no predators necessary

2. at low prey densities, prey isocline will bend down because due to low prey productivity

Efficient predator

iscoline moves left

icreasing oscillations until extinction of predator and/or prey

Unstable

Inefficient preadtor

isocline moves right

decreasing oscillations converging on stable equilibrium

stable equilibirum