Ecology Lecture No. 1: Introduction To Ecology
Tuesday September 11 , 2012
-The scientific study of interactions between organisms and their environment; the scientific study of
interactions that determine the distribution (geographic location) and abundance of organisms.
General Misconceptions In Ecology:
-The notion that there is a balance of nature and return to an original preferred state after disturbance
is a common misconception as many random factors contribute to complete changes in ecosystems that
are not necessarily reversible.
-The notion that each species has a role to play in maintaining the balance of a given ecosystem is a
common misconception as ecological communities exhibit a lot of redundancy in the sense that many
different species carry extremely similar ecological roles and the environment will continue regardless of
the fact that a particular species has gone extinct. There are however, a handful of keystone species that
the ecosystem relies upon to stay abundant.
-I) Organisms interact and are interconnected – though the connectedness may sometimes be vague, it
is nevertheless present.
-II) Everything goes somewhere – despite the negative consequences faced by an ecosystem, life
continues and organisms are immediately influenced.
-III) No population can increase in size forever – as in human populations and bacteria in a beaker, there
are certain limits that imposed upon population growth in every ecosystem.
-IV) Finite energy and resources result in trade-offs – organisms always develop vulnerabilities to their
ecosystem despite their numerous strengths.
-V) Organisms evolve – the abiotic and biotic factors of a given ecosystem will allow organisms selected
against the opportunity to evolve.
-VI) Communities and ecosystems change over time – ecological spaces housing numerous organisms are
never static; they are the products of change.
-VII) Spatial scale matters – There are important distinctions surrounding an organism, a population, a
community, an ecosystem, and the biosphere.
The Ecological Hierarchy:
-Organism – any contiguous biological system; part of a population. -Population - Group of individuals of a species that are living and interacting in a particular area.
-Community - Association of populations of different species in the same area.
-Ecological studies often include both the biotic (living components), and abiotic (physical components)
of natural systems. An ecosystem is a community of organisms plus the physical environment (abiotic).
-Landscapes - Areas with substantial differences, typically including multiple ecosystems.
-Biosphere - All living organisms on Earth plus the environments in which they live; all the world’s
Connections In Nature:
-Adaptation - A characteristic that improves survival or reproduction. If the adaptation is heritable, the
frequency of the characteristic may increase in a population over time.
-Natural Selection - Individuals with certain adaptations tend to survive and reproduce at a higher rate
than other individuals. E.g. antibiotic-resistant bacteria.
-Producers - Capture energy from an external source (e.g. the sun) and use it to produce food.
-Net Primary Productivity (NPP) - Energy captured by producers, minus the amount lost as heat in
cellular respiration; the actual energy available for consumers.
-Consumers - get energy by eating other organisms or their remains.
How Ecosystems Work:
-Energy moves through ecosystems in a single direction only—it cannot be recycled. But nutrients are
continuously recycled from the physical environment to organisms and back again—this is the nutrient
cycle. Energy is eventually lost as heat