Ecology Unit 2

Life History

a schedule for an organisms life

Lack's clutch size hypothesis

opimal clutch size in birds will be a balance of the conflict between the number of eggs produced and the parents ability to fledge young

Unrealized fecundity

the extra fecundity the oragnism would have recieved if they had fledged more young

Relationshio between seed weight and seed set

Plants have a trade off in resource allocation. Can either have a few really big seeds or lots of very small seeds

When to have small seeds (bet hedging)

• Resourced are unpredictable

• Predation/competition risk is high
  -The enviorment is high disturbance

When to have big seeds

• Stable Enviorment

• Predation/competition risk is low

• The enviorment is low disturbance

Important variables in life histories

• Age of maturity

• Parity

• Fecundity

• Aging

Parity

Number of breeding events per lifetime

Competitor Plant Life History

• Large with fast potential growth rate

• Reproduces at young age
  -Small proportion of energy goes into seed production

Stress Tolerators Plant Life History (disturbances in abitoics factors)

• Slow potential growth rate

• Reproduces at a relatively late age

• Small proportion of engery goes into seed production

Ruderals Plant Life History (physical disturbances)

• High potential growth rate

• Live in high disurbance areas

• A lot of investment goes into seeds and not heir own growing. Persists though reproduction

• Ex. Plants intertidal zones

Allometry

Relative increase in one variable given an increase in another

Semelparity

organisms with only one reproductive event over a lifetime

Iteroparity

organisms with multiple reproductive events over a lifetime

Inclusive fitness

when those who share your gentics reproduces an organisms realized fecundity increases

Realized Fecundity

actual number of survivoring orgamisms with an organisms genetics (in both offspring of the individual and the individuals relatives)

Senscence

a gradual decline in fecundity and increase in mortality that somes with advanced age

Fundemental niche

range of abitoic and biotic conditions that a species can tolerate and actually reproduce

• Latitudinal is determined by temperature

• Longitudinal is determined by precipitation

Realized Niche

where a species actually lives (decided by biotic factors

Population

collection of indiviuals of the same species coexisting and interacting

Population Structure

the density and spacing of individuals as well as proportion of individuals within different age classes

Deme pattern

aggregated by an arbitrary social struture

Reason for clumped dispersion pattern

there is a reason for organisms to come together (food availability

Reason for random dispersion pattern

Random doesn't have a cause

Reason for regular dispersion pattern

reason for animals to be evenly spaces (territorial animals

Vulture decides to take commercial instead of flying south for the winter. He's heard about airline food

so he brings along a dead raccoon for a snack.
As he gets his ticket

Vagility

the ability and propensity (behaviorally) move

Metapopulation Landscape Model

-Occupancy

• 3 Types of habitats

  • Unsuiable

  • Suitable

Source Sink Landscape Model

• Quality

• Adds propensity

• Adds quality habitats individuals will want to go to

Source Habitat

High Qualiy. Birth rates are higher than death rates. Immigration exceeds emigration rates

Sink Habitat

Low Quality. Death rates higher than birth rates. Emigration exeeds immigration. Grows through movement

Landscape Model

• Permutability

• Adds connected habitats

• Higher permeability depends on the ability of the individuals

Ideal Free Distribution

shows how long it will take for a high quality patch to match the quality of a low quality patch

To to measure populatio sizes

Direct count

• Small populations with big offspring
• Sessile organisms

Sample and estimate total

Lincoln Petersen Index

Estimates population size using marked and recapture method

Lincoln Petersen Index Assumptions

• All indivduals have equal probability of capture

• No change in the size of the popualtion between sampling periods

Demography

study of predicting population growth

Exponential growth

young are added to population continuously

Exponential growth Equation

N(t) = N(o) * ert

N(o) = population at beginning of model
N(t) = Population at the end of the population model
e= base of the natural logarithm (2.81)
t= how long
r= difference between birth and death rate

dN/dt=rN

Rate indivduals added to the population

Problem with Expoential growth equations

Assumes once an organism is born they can reproduce. Doesn't work well for any organism with life stages

Geometric Population Growth

change in population at intervals (ex. between years)

Geometric Population Growth Equation

N(t) = N(0) * λt

N(o) = population at beginning of model
N(t) = Population at the end of the population model
λ = finite rate of increase, also calculated as er

Parameters in life tables

• Nx = number of individuals of class x

• lx = survivorship

• probability of an individual in class 0 surviving to class x

• mx = mortality rate for class x

• probability of dying before reaching next age

• sx = survival rate for age class x

Cohort Life Table

Follows a group of marked individuals born at the same time until they die

Static Life Table

Collects data on all indivduals in a single sample period. Collection of many ages (cohorts)

Ro

Number of female young a female individual reproduces. Net reproductive rate

Intraspecific interactions affecting growth rates

when resources affect ONE species (competition)

Interspecific interactions affecting population growth rates

Other species affecting resources. Predation

Immigration and Emigration affecting population growth rates

how the flow of individuals in a population affects the population

Carrying Capacity (K)

Number of individuals that would consume all of the resources. When populations exceed K death rates exceed birth rates

Density independent

limitation in N from factors that do NOT depend on population size (natural disasters)

Density Dependent

regulation of N by factors that become more powerful as N increases. ( more important in ecosystems with high species diversity

Self thinning curves

as the density of plants goes up the actual weigh of the plant goes down due to less resources availible per plant

Genet

Clone of indivdual
( or small carnivore. Not quite sure)

Ramet

Distinct individual