Ecosystems

Part 1

Levels of organization

Levels of organization

What is a species?

Basic unit of biological classification

Organisms that resemble each other, that are similar in genetic makeup, chemistry, and behavior, and that are able to interbreed and produce fertile offspring

Is it a species?

Vocab

Intra = “within” Intraspecific interactions = ??

Inter = “Between” Interspecific interactions = ??

Population Dispersal patterns

Clumped – most individuals are together In environments with patchy resources Most common in nature

Random – little interaction between members of a species In environments with consistent resources

Uniform – found when distance between neighbors is maximized Arises from competition for a resource

Population dispersal patterns – the visual

Ecological Niches Definition: ??? Influenced by the physical environment Take into account:

Interactions with the biotic and abiotic environment

Available resources To describe:

Organisms adaptive traits Habitat Place in the food web

Generalist vs. specialist

Generalist: live in broad niches and withstand a wide range of environmental conditions (K-selected)

Specialist: live in narrow niches and sensitive to environmental change (r-selected)

Who has the advantage in the environment?

Law of Tolerance

The existence, abundance, and distribution of each species depends on the species tolerance to both the physical and chemical factors of the environment

Limiting factor: any factor in the environment that limits the growth of a population

Resource partitioning

Species “share” a resource and avoid direct competition with each other

Types: Temporal: use resource at different times Spatial: use the resource in different areas Morphological: evolves different

characteristics to use the resource

Ecosystem Community Characteristics

1. Physical appearance: relative size, stratification, distribution of the populations and species

2. Species diversity: number of different species

3. Species abundance: number of individuals of each species

4. Niche structure: number of ecological niches, how they resemble or differ from each other, species interactions

Biological Interactions amongst species

Interaction Description ExampleAmensalism One species suffers and

the other is not affected-due to scarce resource-usually occurs with when one organism engages in chemical warfare

Black walnut tree releases a chemical to kill neighboring plants

Commensalism One species benefits and the other is not affected1)Transportation2)Housing3)Use of something created

1) Shark and ramora

2) Epiphytic plants

3) Hermit crabs

Biological Interactions amongst species

Interaction Description Example

Competition 1) Interference – directly between individuals

2) Exploitation – indirect by depleting a common resource

3) Apparent – indirectly when sought by same predator

1) Elk and moose foraging

2) Grass and trees using water

3) Wolves hunting elk and moose

Mutualism Interaction where both species benefit

Trees and mycorrhizal fungi

Biological Interactions amongst species

Interaction Description Example

Parasitism One species benefits and the other is harmed

-Tapeworm-cuckoo bird

Predation Predator hunts and kills prey for food

-??

Saprotrophism Obtain nutrients from dead or decaying matter

-Fungi-vultures-dung beetles

Key Stone Species

A species whose presence contributes to the diversity of life and whose extinction would lead to extinction of other forms of life Dramatic shifts in the ecosystem can

occur when a keystone species is removed

Keystone species examplesSea Stars “Starfish” Sea stars prey on

muscles, urchins, and other shell fish

When removed muscle populations explode and out compete other organisms

Sea urchins rise to the point they destroy coral reefs

Sea Otter Prey on sea urchins Sea urchins eat

through kelp holdfasts, which anchor the kelp to the ground, causing entire kelp forests to float away

Wolves in Yellowstone

Homework: Download the article from my website Read and annotate

# paragraphs Highlight main ideas Write a one paragraph summary