Ecology test 3

What Is Biodiversity?

The variety of all living organisms on Earth.

what does biodiversity include

includes all forms of life, visible and microscopic, and the complex web of interactions between them and their environments.

3 types of bio diversity

Genetic diversity

Species diversity

Ecosystem diversity

Genetic diversity

Genetic differences within a species

Species diversity

Diversity among species within an ecosystem.

Ecosystem diversity

Variety of ecosystems, such as forests and wetlands.

Species richness

the number of different species in an area.

formal species descriptions

Scientists identify, classify, and officially describe species.

Undiscovered species

Many species exist that scientists have not formally described.

Estimated global species richness

Scientists estimate how many species exist worldwide, including species not yet discovered.

DNA identification

DNA can reveal that organisms that look very similar actually belong to different species.

Species abundance

How many individuals of each species are present.

Species evenness

How evenly individuals are distributed among the species.

species-area relationship

Larger areas generally contain more species.

Alpha diversity

diversity of species in a single habitat

Beta diversity

difference in species composition between two or more habitats

Gamma diversity

Total species diversity across a large region

Species Rank Curves

A steeper curve indicates greater differences in abundance from the most common to the least common species.

A longer line indicates higher species richness.

Seven Forms of Rarity-Geographic range

How large or small an area the species occupies.

Seven Forms of Rarity-Habitat specificity

Whether it can live in many habitats or only a narrow range of habitats.

Seven Forms of Rarity-Local population size

How many individuals are present locally.

Widespread, Common rarity

geographic range - large

habitat specificity - Broad

local population size - large

Widespread, Rare

geographic range - large

habitat specificity - narrow

local population size - small

Restricted, Common

geographic range - small

habitat specificity - broad

local population size - large

Restricted, Rare

geographic range - small

habitat specificity - narrow

local population size - small

Frequent Type Rarity

Geographic range - large

Habitat specificity - narrow

Local population size- sparse

Endemic, Common

geographic range - very small

habitat specificity - broad

local population size - large

Endemic, Rare

geographic range - very small

habitat specificity - narrow

local population size - small

Functional Diversity Dendrograms

Maps the differences between

functional traits among species.

• Usually feeding niche

Sum total of branch lengths is a

measure of community functional

diversity

Functional Diversity

Larger circles = larger FD

Warmer colors = greater FD loss

Phylogenetic Diversity

A phylogeny of all known lemur taxa (blue branches)

The phylogeny can identify species that are unique.

Global geographical patterns in biodiversity

Tropical regions generally have the highest species richness.

intertidal zone

Transitional coastal regions

Alternately exposed and submerged by tides

High diversity

Zonation

is a vertical banding of the

organisms living on the rocky coastline.

Spray or Splash Zone

uppermost area exposed mainly to sea spray

high tide zone

area covered by water mainly during high tides and exposed to air for much of day

middle tide zone

area alternately exposed and submerged as tides change

low tide zone

area submerged most of the time, exposed mainly during high tides

Biotic factors affecting organisms living in the intertidal zone:

living influences such as competition, predation, and reproduction

Abiotic factors affecting organisms living in the intertidal zone:

nonliving influences such as temperature, salinity, waves, and dissolved oxygen

stress-waveshock

Adaptation, Example

1. Adherent threads: Mussels

2. Stick tightly: Chiton limpets

3. Conical shape: Barnacles, limpets

4. Flexible stalks: Kelp, Gooseneck Barnacle

5. Motility & hide in cracks: Crabs, Periwinkles

stress-dehydration

Adaptation Example

1. Motility; Sea stars, Periwinkles

2. Operculum; Periwinkles, Turban snails

3. stick tightly; chiton, limpets

4. Seal openings; Barnacles, mussels

stress-temperature extremes

Motility: Crabs

Evaporative cooling: Mussels

Tolerance: Barnacles

Nocturnal behavior: Rock Lice

stress-Salinity extremes

Tolerance, Periwinkles

Motility, Crabs

stress-Feeding

Suspension feeding: Mussels, barnacles

Grazing: Chiton, limpets, sea urchins

Detritus feeding: Crabs, sea hares, some snails

Predation: Octopus, sea stars, some snails and nudibranchs

Absorption of DOM: Sea urchins

stress-Competition

Aggression: Octopus, crabs

Rapid growth: Barnacles

Opportunistic larval establishment: Mussels, barnacles

Large number of offspring: Sea urchins, barnacles

Good dispersal: Species with planktonic larvae

stress-predation

Hard Shells: Barnacles, mussels

Motility: crabs

Toxins: Nudibranchs, kelps

Protective Coloration: Sculpins

Antipredation behaviors: Limpets

The Keystone Species of the Intertidal Zone

Pisaster (Sea Star) defends the rocky intertidal zone from being taken over by mussels, barnacles.

Primary Producers of the Intertidal Zone

Devil’s Bath Towel – Gigartina sp.

1. A type of red seaweed

2. Uses sunlight to make food through photosynthesis and provide habitat for other organisms.

Aplysia californica

releases a purple fluid that can blind predators. The fluid is synthesized from red algae they graze on

What is competition?

The interaction between organisms or species that compete for limited resources, such as food, water, or space, which can negatively affect their fitness.

Interspecific competition

competition between different species

Intraspecific competition

competition within species of same type

An ecological niche

is the role and position a species has in its environment, including how it meets the needs for food, shelter, and reproduction, as well as its interactions with other species.

what does ecological niche encompass

It encompasses all biotic and abiotic factors necessary

for survival and reproduction.

Competitive Exclusion Principle

No two species can occupy the same niche at the same time in the same environment.

If two species overlap substantially…

• One will be outcompeted and driven to extinction.

• Natural selection will favor individuals of both species that avoid

competition

resource partitioning

Reduced competition among coexisting species as a result of differing niches

Resource partitioning may include

feeding, nest sites, and other aspects of a species’ ecological niche

the fundamental niche

The potential niche of a species. Various factors, such as competition, may exclude a species from its fundamental niche

The realized niche.

The lifestyle a species actually pursues and the resources it actually uses

Character Displacement

The divergence in traits in two similar species living in the same area

The Lotka-Volterra Model

1.Used to estimate the populations of predator-prey systems

2. Used to estimate populations of competitors

carrying capacity (K)

is the maximum population density an environment can sustain.

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Stable coexistence

both species persist; their populations return toward a stable equilibrium.

Unstable coexistence

the winner depends on initial population densities; the system moves away from the equilibrium.

Zero Net Growth Isoclines and R

The amount of two

resources of interest

to a species are on

each axis.

Rx*

is the threshold level of resource X at which births and deaths are balanced….Hence Zero Net Growth. B = D

The resource supply point (S)

represents the natural availability of the resources in the environment.

The green resource vectors

always point toward the RSP. Consumption vectors point in the opposite direction.

Rx*, Ry*

the point where B = D; the critical resource levels

Exploitation

the consuming of one species by another, is a common and important force in nature. A simple model of exploitation is a (+, -) interaction

There are three main types of interaction

• Predator – Prey

• Parasite – Host

• Herbivore – Plant

Exploiter

(predator) gets a fitness benefit from consuming prey.

Prey

experience fitness loss because they have been eaten or partially consumed.

Detritivory

consuming dead prey is NOT predation

Possible Outcomes of Exploitation

1. Extinction of the prey, followed by extinction of the

predator

2. Extinction of predator, followed by increases in the prey

3. Cyclical population dynamics for the exploiter and prey

4. Stable coexistence between exploiter and prey

The Prey Equation

Prey capture rates vary widely

A whale shark might eat million of planktonic organisms

A python might eat a large meal 2-3 times per year

The Exploiter Equation

A predator consuming a prey organism does not translate directly to reproductive output. It takes many prey and several months for a fox to produce a litter of kits.

equilibrium

a condition where population growth is zero, so the population remains constant

zero-growth isocline

line on graph showing combinations of population densities where one population has zero net growth

Density dependence

population growth is affected by population density; prey self-regulation is added through carrying capacity

functional response

how an exploiters rate of prey consumption changes with prey density

allee effect

a population does worse at a low density; a lone buffalo may be more vulnerable to predators than a herd

coevolution

evolutionary changes in one interacting species influence selection on the other species

crypsis

camouflage that makes an organism harder to detect

aposematic coloration

warning coloration that signals a defensive or harmful trait

Batesian Mimicry

A harmless species evolves to mimic a dangerous species

mullerian mimicry

multiple harmful or defended species share similar warning signals

Invasive Species

Non-native and causes ecological harm.

functional response type I

1. consumption increases roughly linearly with prey density

2. the slides associate it with neutral stability and cycles

functional response type II

• Consumption increases but levels off as the predator becomes limited in how much it can consume.

• The slides say it decreases stability, potentially causing extinction.

functional response type III

An S-shaped curve: consumption rises slowly at first, then faster, and eventually levels off.

An efficient exploiter can produce greater stability and damped oscillations.

Evolutionary defenses-predator crypsis

predator camouflage

Evolutionary defenses-Prey crypsis

Zebra stripes providing camouflage in certain surroundings

Evolutionary defenses-Eyespots

Moth caterpillar or moth wings that startle or deter predators