animal ecology chapter 2. ecology ernst haeckel introduced the term ecology defined as the relation...

Animal Ecology

Chapter 2

Ecology

• Ernst Haeckel introduced the term ECOLOGY defined as the relation of animal to its organic as well as inorganic environment.

The Hierarchy of Ecology

• Organism

• Population

• Community

• Ecosystem

• Biosphere


• Organism: Is the base of the ecological hierarchy.

• Population: a group of animals coexist with others of the same species.

• Community: Populations of different species co-occur in more complex associations.

Communities

• The complexity of a community is measured as species diversity.

• Species diversity: is the number of different species that coexist to form the community.– Predation, competition, parasitism, and

mutualism.


• Ecosystem: An ecosystem consists of all populations in a community together with their physical environments.

• Biosphere: The largest ecosystem.

Environment and Niche


• Environment: includes the abiotic (nonliving) factors, and biotic (living) factors.


• Environment: includes the abiotic (nonliving) factors, and biotic (living) factors.

• Niche: a multi dimensional relationship of species with its environment.– Fundamental niche: is the potential niche

– Realized niche: the subset of potentially suitable environments that an animal actually experiences.

Figure 2.2 p 37

Populations

• Population: a reproductively interactive group of animals of a single species– A species may be a single, cohesive population

or may contain many geographically disjunct populations, often called demes.

– Members of a deme interbreed, and therefore share a common gene pool.

Metapopulation

• Refers to a population subdivision into multiple genetically interacting demes. – Gene flow can be symmetrical or asymmetrical– In asymmetrical demes you can have source

and sink demes

Population Demography

• Age structure: cohort and survivorship

• Sex ratio: sexual reproduction, cloning, unitary, parthenogenesis

• Growth Rate

Survivorship

• Cohort: individuals born at the same time.

• Survivorship: measures the survival of individuals in a population from birth to death of the last member of a cohort.– There are three principle types of survivorship

curves, they are referred to as I, II, and III.

Figure 2.4 p 39

Birds

Inverts,

fish, frogs

Figure 2.4 p 39

Birds

Inverts,

fish, frogs

Humans

Figure 2.4 p 39

Population Age Structure

• Some animals such as insects and many invertebrates reproduce only once before they die.

• Other animals such as mammals and many vertebrates survive long enough to reproduce multiple times.– These groups of animals exhibit age structure.

Figure 2.5 p 39

Population Growth and Intrinsic Regulation

• Population growth = birth rate – death rate.

• All populations have an inherent ability to grow exponentially, this is the intrinsic rate of increase (r).

Population Growth and Intrinsic Regulation

• Although all populations have an inherent ability to grow exponentially, there are limited resources in the environment.

• These limited resources in the environment create a carrying capacity (K) on populations of animals.

Figure 2.6 p 40

Carrying Capacity

• In reality populations of animals fluctuate around the carrying capacity, these are known as oscillations.

Figure 2.7 p 41

Why do populations Oscillate around the K?

Why do populations oscillate around the K?

1) The carrying capacity of an environment can change over time.



2) Animals always experience a lag between the time that a resource becomes limiting and the time that the population responds by reducing its rate of growth.



2) Animals always experience a lag between the time that a resource becomes limiting and the time that the population responds by reducing its rate of growth.

3) Extrinsic factors (other biotic and abiotic factors).

Figure 2.7 p 41

Extrinsic Limits of Population Growth

• Two Types of Extrinsic Factors



– Density-independent: these are abiotic limiting factors (frost kills all the mosquitoes)



– Density-independent: these are abiotic limiting factors (frost kills all the mosquitoes)

– Density-dependent: These are biotic limiting factors (competition, predators and parasites)

Community Ecology

• Populations of animals that form a community interact in three ways.– Detrimental (-)– Beneficial (+)– Neutral (0)

Types of interactions

• Predator/prey and parasite/host (+,-), coyote/rabbit; tapeworm/coyote.

• Commensalism (0,+), pilot fishes and remoras with sharks.

• Mutualism (+,+) termites and gut protozoa.

Competition

• Sometimes competition between species reduces fitness of both species, (-,-).

• Sometimes the effect on one species in a competitive relationship is negligible, (0,-) amensalism or asymmetric competition. (eg. Barnacles)

Competition

• Usually in nature competition is more complex when more than two species are competing for resources.

Competition and character displacement

• Competition only occurs when two or more species share a LIMITING resources not just sharing resources.


• Niche overlap: the portion of resources shared by the niches of two or more species.



• Competitive exclusion: strongly competing species cannot coexist indefinitely.



• Competitive exclusion: strongly competing species cannot coexist indefinitely.

• In order to coexist in the same habitat, species must specialize by partitioning a shared resource, this is known as character displacement.

Figure 2.10 p 44

The ghost of competition past

• The absence of competition today.

Guilds

• When several species share the same general resource by partitioning resources they are known as a guild.

Robert MacArthur

• Studied five species of warblers in spruce woods of the northeastern U.S.

• The five species of birds look vary similar in size and appearance.

Robert MacArthur

• Studied five species of warblers in spruce woods of the northeastern U.S.

• The five species of birds look vary similar in size and appearance.

• How can they coexist?

Figure 2.11 p 45

Predators and Parasites

• Predators and prey and parasites and hosts to some degree cause coevolution.

• Predators get better at catching prey and prey get better at escaping predators.

Predators and Parasites

• Most predators feed on more than a single species.

• However, when a predator relies primarily on a single prey species, both populations tend to fluctuate cyclically.

Figure 2.12 p 45

Predator Prey InteractionsDefenses by potential prey

• Distasteful prey and warning coloration.

Defenses by potential prey

• When palatable prey adopt warning coloration this is an advantage for the prey and deceit for the predator.

Defenses by potential prey

• Batesian mimicry: Palatable prey can deceive potential predators by mimicking distasteful prey.

• Müllerian mimicry: Two or more toxic species resemble each other.

Figure 2.13 p 46

Keystone Species

• An influential species on other species that if it is absent it drastically changes an entire community.

Figure 2.14 p 47

Ecosystems

• Transfer of energy and materials among organisms within ecosystems is the ultimate level of organization in nature.

• Productivity: incorporation of material and energy into biological systems.

Trophic Levels and Food Webs

• Primary Producers: fix and store energy from outside the ecosystem (photosynthetic organisms).

• Consumers: herbivores eat plants directly; decomposers bacteria and fungi.

• Carnivores: eat other animals.

Figure 2.15 p 49

Food chains in terms of Pyramids

• Ecological pyramids or Eltonian pyramids: depict numbers of organisms transferred between each trophic level. Units can be numbers, biomass or energy.

Fig. 2.16 p 51

Nutrient Cycles

• All elements essential for life are derived from environmental air, soil, rocks, and water (nutrients).

• These nutrients are released and returned to the environment when the organism dies.

• Therefore nutrients flow in a perpetual cycle between biotic and abiotic components of an ecosystem, this is called a biogeochemical cycle.

Nutrients recycled, energy flow is one way!

Figure 2.17 p 52

The Big Picture

• Ecology is the study of living organisms and their interactions with the environment and other living organisms.

• Ecology has a hierarchy of organization.

• Different types of interactions occur at the population, community or ecosystem level.

animal ecology chapter 2. ecology ernst haeckel introduced the term ecology defined as the relation...

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