Ecosystems Part 1
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 InteractionDescriptionExample AmensalismOne 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 affected 1) Transportation 2) Housing 3) Use of something created 1) Shark and ramora 2) Epiphytic plants 3) Hermit crabs
Biological Interactions amongst species Interaction DescriptionExample 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 MutualismInteraction where both species benefit Trees and mycorrhizal fungi
Biological Interactions amongst species InteractionDescriptionExample ParasitismOne species benefits and the other is harmed -Tapeworm -cuckoo bird PredationPredator hunts and kills prey for food -?? SaprotrophismObtain 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 examples Sea 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