Ecology Midterm #2

Life Cycle

Stages in individuals development

Life History

Timing and nature of major events related to growth, deveopment, survival and reproduction

Tradeoff

More of one beneficial thing means less of another, physical or biochemical constraints and allocation of limited resources

Semelparous

one reproductive bout

When is semelporous favored

when going all out is only way to suceed or likelihood of survival after reproducing is low annual

Examples of semelporous

salmon, annual plants

iteroparous

multiple number of reproductive bouts

when is iteroparous favored

when reproducing sucess doesn’t require all out efort and likelihood surviving to reproduce again is high

Examples of iteroparous

most vertebrae and most peretial plats

Example of life history being heritable

in Poa annu, an annual grass, the sibling have similar age at first reproduction, growth rate and number of flowers

plasiticity

ability of individauls to change phenotype in response to environment

How life hsitory traits are plastic

acclimatization, development and changes in behavior (innate or learned)

Example of plastic life history traits

Plants - earlier or later maturity depending on day length

birds - may lay fewer eggs or abandon nest if conditions are unfavorable

K characteristics

competitive, good at capturing resources and using those resources efficiently, long lived, mature late, few offspring, invest a lot in each offspring

R characteristics

rapid population growth, quickly take over disturbed area, short life span, small, mature early, many offspring, invest little in each

Disturbed

existing community removed

Where do you most likely see annual plants

Just favored conditions occur unpredicatbly after disturbance wipe out existing vgetation

Potential basis for behavior

genetic basis

Example in where behavior shows genetic basis

oldfield mouse (enterance nest and escape tunnel) and deer mouse (entrance and nest) and found after mating them that the crossing pattern showed that behavior was genetic

Optimaility Theory

assumes natural selection favors traits that maximize benefits and minimize costs

Optimal

best possible tradeoff that exist

Questions regarding foraging behavior

when/where does an animal gather food

how much food does it gather a time

what type of food does it gather

how much of each prey item does it eat

Optimal foraging theory

proposals animals maximize energy aquired per unit of feeding time

Why do bears waste food

some parts are more valuble than others, time allocation, cant catch and dismantle at same time. When there is more food avalible, it makes sense to eat the more valuable parts

How fear affect elk’s foraging decisions

Grassland has more food and less cover, the conifer forest has more cover less food. Elk go to different areas depending when the wolves are out

High number of offspring and little investment in each

no parental care, mating system is broadcast, spawning, indiscriminate, both sexes has multiple mates

Low number of offspring and high investment in each

harsh environment, very difficult to get enough food to raise a chick, parental care is biparental, mating system monogamous, sexual dimorphism is slight

Sexual dimorphism

male and female differ in size, color, weappon or ornaments

sexual seleciton

selection on differences in mating sucess among individuals of one sex

What if female has low number offspring and high investment in each, but male show opposite pattern

The aprental care is female only, mating system is polygymy mate choice is some (for female) fighting, sexual selectiona d sexual dimorphism

Male has low number of offspring high investment in each, female opposite

parental care is male only, mating system polyendrous, mate choice probably, fighting, sexual selection ad dimorphism

What species biparental care is common in

birdds, crocodillians, primates

What species Female Only care is common in

mammals, crocodillians

What species Male only care is common in

Fish Shorebirds

What no parental care is common in

Fish, amphibian, lizard, snake, insect, mollusk, corals

Population

A group of indivieuals of the same species that live in teh same area at the same time and interact with eachother

Abundance

number of individuals of a species or population

Population size

number of individuals total

Population density

number of indiviedual per unit area

What population size tells us

conservation, extinction risk, genetic diversity

What population density tells us

What is population growth rate, if too high starvation and disease risk and too low risk of can’t find mates

Distribution

where a species is found

Dynamics

Variation in abundance over time

endemic species

only found in a small geographic area

cosmopolitan species

found across the world

Factors that affect geographic range

abiotic conditions, biotic conditions, disturbances, evolutionary and geographic history, dispersal

Example of abiotic conditions that affect geographic range

temp moisture soil type soil pH salinity

Example of biotic conditions that affect geographic range

competition parasitism and disease

Example of disturbances that affect geographic range

prarie fire

Example of evolutionary and geographic history that affect geographic range

ancient supercontinet and glacial history, earthworms not native to MN

Example of dispersal that affect geographic range

movement of individuals, different plant and animal species in North American vs Eurasia

Example, what environmental factor dtermine range limit for black spruce in MN

temp and precipitation

What expect happen black spruce range if MN climate was warmer and wetter

pushed more to the NE

How do populations fluctuate

All populations fluctuate in size

example of small size going extinct

channel island vary in land area and number of breeding pairs of specific bird

The extinction vortex

Why small populations have high extinction rate

extinction vortex chain of events

Human cause event or natural event → Small population size

Small population size → things cause loss of genetic diversity (inbreeding depression, drift, demographic and environemtal stochasity)

Loss genetic diversity → Reduction in individaul fitness and population adaptibility

Reduction in individual fitness and population adaptibility → lower reproduction and higher mortality

lower reproduction and higher mortality → smaller effective population size

smaller effective population size → Extinction

Metapopulation

group of geographically isolated population linked by disersal

What affect extinction

size of patch, ability of indvidual other matches to move in

What affect rate of colonization

how hard it is to travel through matrix, population density, distance between pathces

When will metapopulation persist over time

colonization rate greater than the extinction rate

Population growth

change in number of individuals in a population over time

Population Growth Equation

N_t+1=N_t+B-D+I-E

Exponential Growth

population growth rate doesn’t change, the number of individuals giving birth changes. The result is when number of indviduals is slow, population size changes slowly, when number of individuals is high, population size changes fast

R

intrinsic rate of increase (B-D)

instantaneous rate of change in population size

(dN/dt)=rN

r>0

dN/dt >0 positive slope and population is growing

r=0

dN/dt = 00, steady rate

r<0

dn/dt <0, negative slope population declining

Density independent factors affect what

population size or intrinsic rate of increase

Desnity Indepdent factors

not related to number of indviduals

Example of density independent factor

weather predicts thrip population size, mouse population fluctuates due to weather and plant growth

Density dependent factors

high population size, scarcity of food, space easier disease spread, can affect survival and reproduction

Negative density depdendence

large populations grow slower per capita

Positve density depdendece

Larger populations growt fast per capita

logistic growth

population size often stabilizees after a period fo growth due to negative density dependent factor

Logistic growth equation

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

K

carrying capacity, max population an area can support indefintely, population fluctuate around their carrying capacity.