introduction to ecology chapter 1 ecology: evolution, application, integration ecology: evolution,...

Introduction To Ecology

Chapter 1

Ecology: Evolution, Application, Integration

Ecology: Evolution, Application, Integration David T. Krohne Copyright © 2015 Oxford University Press

Concepts

1.1 What Is Ecology?

1.2 What Important Ideas Will Emerge in Your Study of Ecology?


Concept 1.1

Ecology is “The scientific discipline that is concerned with the relationships between organisms and their past, present and future environments, both living and non-living.” Official ESA Definition*

*August 2000 Annual Meeting of the Ecological Society of America

What is Ecology?

• Ecology is the scientific study of the interactions between an organism and its past, present and future environments both living and non-living.

• Understanding these relationships will explain the patterns of distribution and abundance we see in nature.

Key words used to define Ecology

Interactions - between everyone

and everything

Organisms - all taxa are

fair game

Environment - includes

ABIOTIC and BIOTIC

factors outside the organism

Abundance - population

sizes

Distribution - where we find

organisms

Environment

• Abiotic (physical) environment– Temperature, water availability, soil, salinity,

nutrients…

• Biotic (biological) environment– Predators, prey, parasites, pathogens, symbionts…

Hierarchy in Nature

A Case Study: Snowshoe Hare Ecology

• Observations:– Coat color of a snowshoe hare

changes in spring and fall– Color change is asynchronous

among individuals– Highest mortality is observed in

spring and fall (compared to winter and summer)

• What drives coat color change?• What makes this study an

ecological study?Ecology: Evolution, Application, Integration David T. Krohne Copyright © 2015 Oxford University Press


• Proximate causes– Ecological factors – Direct effects of external

stimuli; direct, immediate causes

– e.g., temperature and photoperiod

• Ultimate causes– Evolutionary factors that led to

appearance of certain traits– e.g., selective pressure from

predation

What determines a change in snowshoe hare coat color?



Interaction is key in ecologyCan you name abiotic and biotic factors affecting ecology of snowshoe hares?

Snowshoe Hare

Ecology: A Complex

Story

Ecological Studies Often Encompass Several Levels of Organization


Ecology Is Hierarchically Subdivided

• Organismal ecology: interactions between individuals and their environment– Physiological ecology– Behavioral ecology

• Population ecology: dynamics of a group of individuals of a single species– Population genetics, demography


Ecology Is Hierarchically Subdivided

• Community ecology: interactions among a group of coexisting species

• Ecosystem ecology: interactions between ecological communities and their abiotic environment

• Ecosphere or biosphere: sum of all Earth’s ecosystems


Ecology Connections

• Natural history – Observational study of plants and animals in their

natural environment– Popular in Victorian age for men and women of

wealth to spend time walking and pondering gardens, etc.

– Darwin was essentially a Natural Historian who was observant and brilliant enough to see the patterns in his observations


How do Ecologists, Naturalists and Environmentalists Differ?

Example: Consider the American Robin, Turdus migratorius

• Naturalist: Observes robins and paints/photographs/ writes/composes music about robins. Provides valuable “Natural History.”

• Ecologist: Asks, “What causes the robin’s singing behavior? Seeks to explain the Natural History.

• Environmentalist: Seeks action to preserve the habitat of the robin.

Ecology Connections

• Environmental science– The study of the impact of humans on the

environment– Environmental studies includes knowledge from

other fields such as history, political science, economics, philosophy

– Good Example: returning the wolves to Yellowstone National Park – keystone predator

• Lots of pros and cons; entrenched bias against predators• Decision based not just on ecological science, but other

issues such as reactions of cattle ranchers as well as public opinion were considered etc.

Ecology Connections

• Resource management sciences – Sciences devoted to managing and husbanding

resources important for human use– Wildlife management– Forestry– Range management– Fisheries biology


Take Home Points

• Ecology is the study of the interactions between an organism and its biological and physical environment.

• Ecologists study interactions at multiple levels of organization: the organism, the population, the community, and the ecosystem.

• Natural history observations raise ecological questions and frame hypotheses.

• Other applied fields, such as environmental science and the management sciences, apply ecological principles to resources important to humans.


What Important Ideas Will Emerge in Your Study of Ecology?

Fundamental ecological principles

Application of the scientific method to answer specific ecological questions


Ecology is a quantitative science

Fundamental Ecological Principles

• Ecology-evolution connection– Ecosystems are a product of evolution of species

• Ecological systems are often not in equilibrium– No “ecological homeostasis” or “balance of

nature”– Both equilibrium and nonequilibrium ecological

processes are important• Human impact on the environment and on

ecological processes

Fundamental Ecological Principals

• Ecology-evolution connection– Ecosystems are a product of evolution of species

–Change in hare coat color is an adaptation– Ecological theater and Evolutionary play

Subdisciplines of Ecology

• Physiological Ecology• Genetic Ecology• Evolutionary Ecology• Behavioral Ecology• Landscape Ecology• Paleoecology• Systems Ecology• Theoretical Ecology

• Insect Ecology• Bird Ecology• Microbial Ecology• Freshwater Ecology• Marine Ecology• Terrestrial Ecology• Many more

Fundamental Ecological Principles• Early ecological views:o There is a “balance of nature” in which natural

systems are stable and tend to return to an original state after disturbance.

o Each species has a distinct role to play in maintaining that balance.

Concept 1.2


• Ecologists now recognize that natural systems do not necessarily return to their original state after a disturbance, and seemingly random perturbations can play an important role.

• Evidence suggests that different species often respond in different ways to changing conditions.

Examples• Food webs in ecological communities• Flow of matter and energy through ecosystems• Succession – climax is not a “constant” stable state

to which communities return after disturbance.

Concept 1.2

Fundamental Ecological Principles• Scientists now recognize that ecological interactions

are more complex than previously thought.• One view that has stood the test of time: Events in

nature are inter-connected. • A change in one part of an ecological system can

alter other parts of that system.• Emergent properties of communities and ecosystems

o Can’t rely on 2 species interactionso Multiple species, multiple interactions – unexpected

outcomes


• Ecological systems are often not in equilibrium– No “ecological homeostasis” or “balance of

nature”– Both equilibrium and nonequilibrium ecological

processes are important• Human impact on the environment and on

ecological processes


Ecology is a Science

• Ecology uses the Scientific method– Uses tools such as

• Observation

• Experimentation

• Mathematical modelling

– Uses statistics to analyze data and arrive at• A conclusion that is unbiased, based on the data;

• A mathematically derived level of confidence in that conclusion

01_p010.jpgScience is all about testing hypotheses and rejecting the false ones.

Ecology Is a ScienceIt Uses Scientific Method


Support the hypothesis

Which System to Choose to Study Ecological Questions? The concept of model system

August Krogh Principle

“For many problems there will be some animal of choice or a few such

animals on which it can be most conveniently studied.”

A. Krogh, 1874–1949, Nobel Laureate 1920Ecology: Evolution, Application, Integration David T. Krohne Copyright © 2015 Oxford University Press

Which System to Study?

The concept of a model system

• Basic biology and natural history of a species well known

• Possess specific features that allow addressing a specific question

• Amenable to experimental manipulation


Sarracenia purpureaModel system

Experimental Design, Statistics

• A huge part of ecology is about asking a good question and designing a study with the right kind of observations, experiments and statistics to get a reliable answer.

Experimental Design, Statistics

• Data interpretation requires the use of statisticso Data sets are often very large and complex. o Statistics allows us to express a mathematically tested level

of confidence in the outcome of a study.

Ecology Is a Quantitative Science

• Statistical analysis of the data is required– Statistics allows us to express a mathematically

tested level of confidence in the outcome of a study.

• Traditionally accepted confidence level—95%, but can vary depending on the question

• Ecological modeling– Statistical, mathematical, and computer models


What’s the overall aim?

• To recognize patterns in nature

• To explain or understand these patterns

• To predict what will happen to these patterns if conditions change

• To control or exploit populations

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