EEB 100 UCLA FINAL

Earthrise

A photograph of the earth taken by astronaut William Anders in 1968, said to be "the most influential environmental photograph ever taken"

Eco-

House, Household

-Logy

the study of

What is Ecology?

the scientific study of our home/environment

- the study of the relationship between organisms and their environment

human ecology

the study of how humans are affecting the planet

downward curve

summation that we are rapidly losing species, land, fresh water, and air.

population growth impact the environment

deline in resources (land, water, food, air, materials), biodiversity loss, climate change, pollution

Theoretical ecology

Knowledge for the sake of knowledge or interest

Applied ecology

Applying ecological knowledge to real world systems - sustainably manage resources, restore degraded ecosystems, conserve endangered species, save life on earth

Population

a group of individuals of the same species that inhabit a given area and are able to interbreed

structure of populations

density, spacing, age distribution

Unitary Organism

exist as individuals

- after fertilization , the zygote grows into a genetically unique organism through a series of predictable stages

- most animals are unitary organisms

Modular organism

produces more, similar modules

- most plants can be modular, develop by branching, producing repeated structural units

- roots show modular growth

- some animals are modular

Genet

genetic individual

Rament

individual module of a genet

Geographic Range

- encompasses all of the individuals of a species, usually many populations

- individuals are found in suitable habitats within that geographic range

geographic range limitations

abiotic factors, temperature, soil moisture, elevation, biotic factors, predation, competition, parasitism

Endemic Species

Have geographically restricted ranges, and specialized habitat requirements

Biodiversity hotspots

- high diversity, high threat

-2.3% of earths land surface, but support more than half of the world's plant species as endemics

Geographic barriers

reduce/prevent individuals colonizing new areas

-bodies of water, including rivers; mountains; large areas of unsuitable habitat such as deserts

Metapopulations

populations divided into subpopulations that live in suitable habitat patches surrounded by unsuitable habitat

- the environment is heterogenous

- spatially separated but connected by movement of individuals

What often function as metapopulations?

Human altered landscapes

What are the three types of distribution?

Random, uniform, clumped

Random Distribution

the position of one individual is independent of another

- E.G. plant seed scattering by wind

Uniform distribution

Organisms are found at a regular distance from another

- often a result of negative interactions among individuals such as competition

Clumped Distribution

Individuals are found in groups

- Most common spacial distribution and results from

- Suitable habitat or resources in patches, species form social groups, ramets formed by asexual reproduction

Why does distribution matter?

to understand patterns, habitat conservation, species conservation, quantifying population size

Abundance

# of individuals in the population

Population density

# of individual/area

Density of a cell

count how many individuals in a single cell

Why do we care about abundance/density?

Crowding - competition, resource decline, disease etc.

Too Sparse - reproduction effects, social breakdown, decline, etc..

How do you determine population size

Pop size = pop density x the area occupied

If an organism is sessile, how can you determine density?

using quadrants/sampling units

- area is divided into subunits

- # of individuals counted in a random sample of subunits

- mean density x total area = estimate of population size

Mark-recapture

the most commonly used technique to measure animal population size

- method is based on

-- capturing a number of individuals in a population

--marking them

--releasing of marked individuals back into the population

--after an appropriate period of time, recapture a sample of the population

How does CMR work? (ex)

1. 10 individuals marked on day 1

2. Of 10 individuals caught in day 2, 5 were marked

3. half the individuals in T2 were marked, so half of the population in total

4. Therefore, population is 20 individuals

N

Total Population

m

initially captured and marked individuals

s

captured animals on the second visit

r

the # of animals marked on the 2nd visit

N =

ms/r

Assumptions of Mark-recapture

1. No effect of marking on probability of recapture - tages should not be obvious or slow the individuals, or reduce fitness

2. mixing of marked and unmarked - mix into the entire population

3. Captured individuals are representative of the whole population, not a certain age group or one sex vs another, only weak individuals

4. Marks are not lost

Methods of Marking

Tags, leg bands, pit tags, pain, chopping off toes

Example of mark recapture problem: You capture and mark 80 snails by putting a small spot of white paint on their shells. When you return five months later, you capture 45 snails and 5 of them have the mark. Based on these data, the pop has how many individuals?

720

Signs of animals present

vocalizations, animal scat, animal tracks

What type of population has an age structure

one with overlapping generations

- reproduction is restricted to certain age classes

- mortality is more common in certain age classes

What age classes can be divided into three ecologically important age classes?

-pre-reproductive

-reproductive

-post-reproductive

Dendrochronology

counting annual growth rings to determine the age of a tree

- diameter can give an imperfect estimate

Dispersal

the movement of individuals in space

emigration

when individuals leave a subpopulation

immigration

when individuals enter a subpopulation

Why do we care about dispersal?

- maintains gene flow

-shows how movement is necessary for survival

- if it has been affected by habitat loss or change

how will this affect the population

Migration

movement of organisms that is round-trip

Zooplankton migration

move in the water column (lower depths at day, surface at night)

bats migration

leave caves at dusk, move to feeding areas, and return.

earthworms

move deep into the soil for winter to avoid freezing then move back up in the spring

earthworm migration

move deep into the soil for winter to avoid freezing then move back up in the spring

Gray whales

feed in the arctic during the summer, winter off the california coast where calves are born

Life History

theory of biological evolution that seeks to explain how aspects of organisms anatomy, behavior, reproductive development, and life span have been shaped by natural selection

What is life history?

An organism's lifetime pattern of growth, development, and reproduction

- at what age size do organisms mature?

- how do organisms reproduce?

- How long do they live?

- how many offspring do they produce?

- at what age do they stop reproducing?

ETC

Why study species life histories? (ex)

-learn how to conserve fish, turtles, and mammals etc...

What does the evolution of life history involve?

Trade-offs

- individuals have a limited a mount of resources that can be allocated to specific tasks

- an allocation to one aspect reduces the resources available for other aspects

Tradeoffs include what?

-mode of reproduction

-age at first reproduction

-allocation to reproduction

-number and size of eggs, young, or seeds

- timing of reproduction

What are trade offs imposed by?

genetic, physiological, energetic, and environmental constraints (biotic and abiotic)

What are two specific types of trade-offs?

Sexual and Asexual reproduction

Benefits of asexual reproduction

-offspring are geneticall identical to parents, so well adapted to the local environment

-All individuals are able to reproduce, potential for high population growth

Costs of asexual reproduction

No genetic recombination - less variation among offspring

- less ability to respond to changes in environmental conditions

Benefits of sexual reproduction

Recombination leads to variation in the population

-increase in the range of potential responses to environmental changes

Costs of sexual reproduction

-each offspring carries only half of a parents genes

-it requires specialized reproductive organs

-production of gametes and mating energetically expensive

What is the most familiar form of sexual reproduction?

Involves separate male and female individuals

Dioecious

Plants that have separate male and female individuals

-individuals with perfect flowers, male (stamens) and female (ovaries) reproductive organs in the same flower are hermaphroditic

Monoecious

individuals with imperfect flowers, separate male and female flowers on the same plant

Hermaphroditic animals

have both male and female reproductive organs

Simultaneous hermaphrodites

the male organ of one individual is mated to the female organ of another and vice versa at the same time

(earthworms)

Sequentrial hermaphrodites

an individual will be a male during one part of its life cycle and female during another

-may be triggered by size or by a change in the sex ratio of the population

(species of fish)

What are some activities involved in reproduction that could potentially decrease fitness of the individual?

-Mate acquisition

-defense of a breeding territory

-feeding and protection of young

What does allocation to reproduction often reduce?

allocation to growth

Examples of more reproduction less growth

-Douglas fir trees: the bigger they are the less cones they had

-Sardinella: the smaller they were the higher fecundity they had

Fecundity

number of offspring produced per unit of time

Delayed reproduction

a number of species show a positive correlation between body size and fecundity

-individuals that postpone reproduction for growth will have more offspring per reproductive period

Examples of delayed reproduction

-three crab species of the genus cancer: bigger they were the more eggs per brood they had

-european red squirrel: the bigger they are the bigger number of young weaned

How you can tell when reproduction should occur?

From life tables

Ix

Shows the probability of an individual surviving to age x (from birth)

Sx

Shows the probability of an individual at age x surviving to age x+1

Bx

average number of female offspring produced by an individual at age x

R0

sum of all IxXbx

What is age at maturity influenced by?

patterns of age specific mortality

Natural selection favors:

-earlier maturation when adult survival is low compared to juvenile survival

-delayed maturation when juvenile survival is low compared to adult survival

Benefit of delaying maturity

a larger body size at age of first reproduction

cost of delaying maturity

increased risk of death before reproducing

What is reproductive effort governed by?

trade-offs between fecundity and survival

Reproductive effort

the total energetic cost of reproduction per unit of time

Energy investment

Examples

the amount of energy invested in reproduction varies widely across organisms (as percent of annual energy budget)

-allegheny mountain salamander 48%

-some grain crops 35 to 40%

-wild annual plants 15 to 30%

-herbaceous perennials 15 to 20%

-common lizard 7 to 9%

Energetic costs of reproduction

-gonad development

-movement to breeding area

-competition for mates

-production of gametes

-nutrient demands

-nesting

-parental care`

Law of diminishing returns

-as the number of offspring produced per reproductive effort increases, there is a corresponding decline in their probability of survival

-the current reproductive success (number of offspring produced times their probability of survival) reaches a maximum value at intermediate vales of reproductive effort

When is parental fitness often at its maximum?

at intermediate values of reproductive allocation

many small vs fewer large

a lot of small species reproduce quickly while larger ones do not

Many small

Each individual receives a smaller investment

-for plants: little energy stored in seeds

-for animals: little energy in parental care

often live in unpredictable environments or areas where parental care is difficult, so the probability of survival is lower

large numbers increase the chance that a few will survive and reproduce

Fewer Large

Each individual receives a greater investment

-for plants: more energy stored in seeds

-for animals: more energy stored in parental care

Iteroparous organisms

reproduce more than once

- include most vertebrate animals, shrubs, trees, and perennial plants

semelparous organisms

reproduce only once

-initial energy investment to growth, development, and energy storage

-one large reproductive effort

-then the organism dies, sacrificing all future reproduction

- seen in most insects, annual and biennial plants, some fish (salmon)