On October 23rd, 2014, we updated our
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the movement of materials and energy through living communities
the successional development of ecosystems
the abundance and distribution of biodiversity in context of the environment.
To structure the study of ecology into a manageable framework of understanding, the biological world is conceptually organized as a nested hierarchy of organization, ranging in scale from genes, to cells, to tissues, to organs, to organisms, to species and up to the level of the biosphere
Ecosystems are primarily researched at (but not restricted to) three key levels of organization, including organisms, populations, and communities . Ecologists study ecosystems by sampling a certain number of individuals that are representative of a population.
Ecosystems consist of communities interacting with each other and the environment. In ecology, communities are created by the interaction of the populations of different species in an area.
What is Biodiversity?
Describes all varieties of life from genes to ecosystems and spans every level of biological organization
Biodiversity includes species diversity,ecosystem diversity, genetic diversity and the complex processes operating at and among these respective levels.
What is Biodiversity?
Preventing or prioritizing species extinctions is one way to preserve biodiversity.
Conservation priorities and management techniques require different approaches and considerations to address the full ecological scope of biodiversity.
What is Biodiversity?
An understanding of biodiversity has practical application for ecosystem-based conservation planners as they make ecologically responsible decisions in management recommendations to consultant firms, governments and industry.
Review and Summary
The ecosystem is the interaction between living organisms (bacteria, animals and plants) and their physical environment (air, soil, water and climate).
Ecology is the study of the interactions between life and its physical environment
Biodiversity refers to the variety of life forms living in a specific habitat.
The ecological niche (function) is a central concept in the ecology of organisms.
The niche is the set of biotic and abiotic conditions in which a species is able to persist and maintain stable population sizes (Hutchinson,1957) . The ecological niche is divided into the fundamental and the realized niche.
The fundamental niche is the set of environmental conditions under which a species is able to survive. The realized niche is the set of environmental plus ecological conditions under which a species is able to survive.
Organisms have functional traits that are uniquely adapted to the ecological niche. A trait is a measurable property of an organism that strongly influences its performance.
For example, the uniquely adapted nature of each species to their ecological niche means that they are able to competitively exclude other similarly adapted species from having an overlapping geographic range. This is called the competitive exclusion principle .
Important to the concept of niche is habitat . The habitat describes the environment over which a species is known to occur and the type of community that is formed as a result. For example, habitat might refer to an aquatic or terrestrial environment that can be further categorized as montane or alpine ecosystems.
It consists of individuals of the same species that live, interact and migrate through the same niche and habitat. A primary law of population ecology is the Malthusian growth model which states that:
"...a population will grow (or decline) exponentially as long as the environment experienced by all individuals in the population remains constant."
An important concept in population ecology is r/K-selection theory . It was introduced in 1967 in a book entitled The Theory of Island Biogeography and was one of the first predictive models to explain life-history evolution . The premise behind this model is that forces of natural selection change according to the density of the population .
When an island is first colonized, the density of individuals is low and the population size increases with reduced levels of competition and an abundance of available resources. Under such circumstances a population experiences density independent forces of natural selection.
When the population becomes crowded, it reaches the island's carrying capacity, and individuals compete more heavily for limited resources. Under crowded conditions the population experiences density-dependent forces of natural selection.