glysophate ("Round-Up") is most used herbicide in the world - cuts off amino acid synthesis in plants

GM crops are resistant to Round Up, but weeds aren't 

after a few years, glysophate is no longer as effective at killing Johnsongrass - those previously exopsed to glysophate were favored to those not -- RESISTANCE

1) populations produce many more offspring than survive

2) a population's biotic potential is rarely reached because of a lack of resources

3) members of a population differ from each other in many ways

1. All life EVOLVED from one relatively simple kind of organism

2. Every species arose from a species that preceded it in time.

3. Evolutionary changes occur over long periods of time
4. Each species originated in a single area.
5. Over long periods of time, more related groups arose by a continuation of the same evolutionary processes.

6. greater similarity = closer relationship and more recent common ancestry

7.Elimination of old kinds is due to competition with new kinds or environmental change.

NATURAL SELECTION 

1. Populations have the potential to increase rapidly in number from one generation to the next.

2. in the short run, populaton size remains fairly constant because the environment limits population growth.

3. Individuals within populations are distinct.

4. Struggle for survival = those with favorable variations survive to produce more offspring

5. Some variations are heritable

6. environments have been changing throughout geologic time

7. natural selection causes accumulation of favorable variations and elimination of unfavorable ones

1. Variation

2. Heritability

3. Differential fitness

plants from diverse populations responded differently when grown in the same environment

there is a genetic basis to variation in traits from region to region

characteristics pass from parent to offspring in packets called genes, which exist in alternate forms known as alleles and that some alleles prevent the expression of others

inheritance 

 In a population:

- mating at random

- in the absence of evolutionary forces

allele frequenceies remain constant.

1. Individuals within same species are variable

2. Some variations passed to offspring (heritable)

3. In every generation, more offspring are produced than survive (struggle for survival) to reproduce

4. the fittest survive to reproduce (survival of the fittest)

individuals

populations

natural selection

evolution

1. Stabilizing - selection favors individuals close to the mean

2. Directional - selection favors individuals in one direction over another

3. Disruptive - selection favors individuals in both extremes

urbanization is the movement of people to more condensed living, like in cities

it is currently increasing rapidly around the world

McDonnell and Pickett 

the urban-rural gradient concept

-based on the gradient paradigm in ecology (ordered environmental variation explains variation in ecological structure and function)

- argued for study of basic ecological patterns and processes, multi-scaled

- argued for inclusion of humans in ecological study

-long term observation

- experiments

- data discovery, synthesis, and modeling

- comparative ecosystem ecology

- large scale diversion

- channeling of streams

- disruption of connectivity

- increase in impervious surface cover

- in the desert, localized increases in pervious cover (green space)

floodplains

lakes and stream segments

the average number of secondary cases a typical infectious person will cause in a completely susceptible population

measures the intrinsic potential for an infectious agent to spread

1. the number of contacts made (c)

2. the probability of infection given contact (p)

3. duration of incfectiousness (L)

4. the proportion of contacts who are susceptible (S)

infection cannot invade a population 

implications: infection-control mechanisms unnecessary

on average, the pathogen will invade that population

implications: control measure necessary to prevent/ delay an epidemic

0 at initial invasion

1 at peak of epidemic

number of susceptibles decreases through recovery or death -- eventually insufficient to carry epidemic, dies out

f = fraction of the population that must be vaccinated

f > ____

-- external (p-independent factors)

-- self- regulation (p-dependent factors)

-- interactions with other species (p-dependent factors)

1. birth/death and density influences growth instantaneously

2. all individuals genetically the same

3. all equals equal in terms of birth and death - age doesn't matter

inexact

1. record age at death of individuals over a short time interval (estimation bias problems)

2. estimate survival using the proportion of individuals in each age class. survival estimates assume a stable population (not declining or growing)

often best

- identify individuals born at same time and keep records from birth. requires recording how long each individual lives (intensive)

survivorship and mortality

if population is increasing or decreasing or remaining the same

I - High overall survivorship

II - constant risk of mortality

III - low juvenile survivorship