Ecology Exam 1

Ecology

The scientific study of interactions between organisms and their environment

Interconnectedness

Events in the natural world are interconnected

Amphibian Sensitivity

Due to permeable skin, shell-less eggs, and exposure to both aquatic and terrestrial pollutants

Immune-Suppression Hypothesis

Pesticides suppress frog immune systems, increasing susceptibility to parasite infections

Ecology vs. Environmental Science

Ecology is pure science; environmental science addresses human impacts and environmental problems

Levels of Ecological Organization

Population, community, ecosystem, landscape, and biosphere

Population

A group of individuals of a single species living and interacting in a particular area

Community

An association of populations of different species in the same area

Ecosystem

A community of organisms plus their physical environment

Net Primary Productivity (NPP)

Energy captured by producers minus heat lost in cellular respiration

Natural Selection

Differential survival and reproduction of individuals with advantageous adaptations

Experimental Design Principles

Replication, random assignment of treatments, and statistical analysis

Autotrophs

Organisms that assimilate energy from sunlight or inorganic compounds

Heterotrophs

Organisms that obtain energy by consuming organic compounds from others

Rubisco

Abundant enzyme catalyzing CO2 uptake in the Calvin cycle

C4 Photosynthesis

Pathway with spatial separation of light and dark reactions

CAM Photosynthesis

Pathway separating CO2 uptake and Calvin cycle temporall

Endotherms

Organisms that rely primarily on internal heat generation

Ectotherms

Organisms regulating body temperature through external energy exchange

Thermoneutral zone

Temperature range where a constant basal metabolic rate is maintained

Guild

A group of species that use the same resources

Functional Group

Species that function in similar ways within a community

Species Richness

The number of species in a community

Species Evenness

The relative abundances of species compared with one another

Shannon Index

A commonly used index to measure species diversity combining richness and evenness

Trophic Cascade

A change in consumption rate at one trophic level causing abundance changes at lower levels

Ecosystem Engineers

Species that create, modify, or maintain physical habitat for themselves and others

Keystone Species

Species with strong community effects large in proportion to their low abundance or biomass

Community Membership Filters

The three factors determining community membership: regional species pools and dispersal, environmental conditions, and species interactions

Resource Partitioning

The theorized mechanism where competing species use different resources, reducing competition and increasing species diversity

Niche Variation Hypothesis

Populations occupying wider niches exhibit greater individual variation, which confers an adaptive advantag

Intermediate Disturbance Hypothesis

The hypothesis that species diversity will be greatest at intermediate levels of disturbance

Paradox of the Plankton

The coexistence of many species on few resources, occurring when the time for competitive exclusion equals environmental variation time (tc = te)

Complementarity Hypothesis

Proposes that as species richness increases, there is a linear increase in community function

Redundancy Hypothesis

Proposes that the functional contribution of additional species in a community reaches a threshold

Idiosyncratic Hypothesis

Proposes that the strength of ecological function varies greatly, with some species having large effects and others minimal

Mountain Forest Succession

A process driven by species interactions like competition and facilitation between trees

Early Successional Stage (Aspen-Stage)

An initial phase in mountain forests often dominated by aspen trees

Late Successional Stage (Fir-Stage)

A later phase in mountain forests often dominated by fir trees

Tree Thinning Experiments

An experimental method measuring tree mortality to understand successional mechanisms

Successional Mortality Factors

Mechanisms controlled by species interactions and conditions affecting tree survival