1-13 Ecosystems

APES 2024

Interactions o fliving organisms with each other and the physical environment determine the

Interactions o fliving organisms with each other and the physical environment determine the

Features of an ecosystem

Biotic

Living organisms, ex. plants, animals, microorganisms, fungi, and protists

Abiotic

Nonliving (physical): hydrosphere, atmosphere, geosphere, ex. nutrients, pH, salinity, dissolved oxygen (DO), wind speed, temperature, and depth

Biosphere

The region of our planet where life resides, the combination of all ecosystems on Earth

Ecosystem

Community of living and physical conditions in an area

Some ecosystems such as caves and lakes have

Very distinctive boundaries

In most ecosystems it is difficult to deteremine

Where one ecosystem stops and the next begins

Ecosystems interact with the surrounding environment through

The exchange of energy and matter

Competition

The struggle of individuals to obtain a shared limiting resource

Competitive exclusion principle

The principle stating that two species competing for the same limiting resource cannot coexist

When two species have the same realized niche, one species will

Perform better and drive the other to extinction

Resource partitioning

When two species divide a resource based on differences in their behavior or morphology

When two species overlap in their use of a limiting resource, selection favors

Those individuals of each species whose use of the resource overlaps the least with that of the other species

Over many generations, the two species can evolve to

Reduce their overlap and thereby partition their use of the limiting resource

Predation

An interaction in which one animal typically kills and consumes another animal

To avoid being eaten or harmed many prey species have

Evolved defenses

Parasitism

An interaction in which one organism lives on or in another organism

A single parasite

Rarely causes the death of it’s host

Pathogen

A parasite that causes disease in its host

Parasitoid

A specialized type of predator that lays eggs inside other organisms, referred to as it’s host

Herbivory

An interaction in which an animal consumes plants or algae

When herbivores become abundant they can have

Dramatic effects on producers

Many species of producers have

Evolved defenses against herbivores such as sharp spines and distasteful chemicals

Mutualism

An interaction between two species that increases the chances of survival for reproduction for both species

Mutualism examples

• Acaia trees and ants in Central America: trees supply food and shelter, ants protect from herbivores and competitors

• Coral reefs and algae: reefs provide home for algae, algae provides the coral with sugars through photosynthesis

• Lichens are made up of algae and fungi, fungi provides nutrients to the alga and the alga provides carbs to the fungi with photosynthesis

Commensalism

Where one species benefits and the other is neither harmed nor helped ex. trees provide a place for birds to perch, look for food, and build a nest but the tree is neither harmed nor helped

Native species

Species that live in their historical range, where they have lived for hundreds, thousands, or millions of years

Exotic (alien) species

Species that live outside of their historical range ex. honeybees were introduced to North America in the 1600s and Red foxes were introduced to Australia for fox hunting

Some nonnative species are

Introduced by accident

Rats on cargo ships ended up on

Oceanic islands

Fungi introduced to the US have

Killed al most all American Elm and Chestnut trees

Often exotic species fail since

They cannot survive the new region

Invasive species

An exotic species that does thrive and causes harm to other species

US invasive species examples

Rats, zebra mussels (Great Lakes), and kudzu