Transcript Animals and their resources

Animals and their resources
• Autotrophs
– - green plants
• Heterotrophs
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Decomposers / detrivores
Parasites
(true) Predators
Grazers
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All life forms are both consumers and
victims of consumers.
• There are many consumer-resource
interactions:
– Predator-prey
– Herbivore-plant
– Parasite-host
• Producers
• Consumers
– Predator; Parasite; Parasitoid: Herbivore;
Detritivore
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You tell me
• (other) Examples of predator-prey
relationship?
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Some Definitions
• Predators catch individuals and consume them, removing
them from the prey population.
• Parasites consume parts of a living prey organism, or host:
– parasites may be external or internal
– a parasite may negatively affect the host but does not directly remove it
from the population
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More Definitions
• Parasitoids consume the living tissues of their
hosts, eventually killing them:
– parasitoids combine traits of parasites and predators
• Herbivores eat whole plants or parts of
plants:
– may act as predators (eating whole plants) or as parasites
(eating parts of plants):
• grazers eat grasses and herbaceous vegetation
• browsers eat woody vegetation
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An example of a parasitoid wasp.
• This was is laying its egg in
the caterpillar.
– The egg will develop into
larvae.
– The larvae will consume the
caterpillar as it grows.
• A combination of predation,
and parasitism.
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Detritivores occupy a special niche.
• Detritivores consume dead organic material, the wastes of
other species:
– have no direct affect on populations that produce these resources:
• do not affect the abundance of their food supplies
• do not influence the evolution of their resources
– are important in the recycling of nutrients within ecosystems
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Distinguishing between animal
consumers
• Polyphagous/ generalists: -- eat variety of prey species
though they often have clear preferences and thus have a
rank order
• Specialists (Monophagous): - may specialize on particular
parts of their prey but range over a number of species
– Most common among herbivores; why? - Different plants of plants are
quite different in their composition
– May specialize on a single species or a narrow range of closely related
species; caterpillars of the cinnabar moth which eat the leaves, flower
buds and very young stems of a species of ragwort
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Nutritionally speaking
• Meat is meat is meat is meat
• A plant is not a plant is not a plant
– Various parts of a plant have very different
compositions  thus have different resources
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• Diversity of different food resources offered by
plants – matched by the diversity of
specialized mouthparts and digestive tracts
that have evolved to consume them
• Eg: mouthparts of insects
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Specialized mouthparts in herbivorous insects: (a) honeybee with long ‘tongue’; (b)
hawkmoth with a long sucking proboscis; C) grasshopper with plate-like chewing mandibles; (d)
acorn weevil with chewing mouthparts at end of rostrum; (e) rose aphid with piercing stylet
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Vegetarians, omnivores/carnivores
• Plant body vs animal body
– Plant cells: bounded by walls of cellulose, lignin, and other structural
carbohydrates that give plants their high fiber content and high ratio
of carbon to other elements; potentially rich sources of energy.
– Problem: majority of animal species lack enzymes to digest these
compounds
– Chewing by grazing mammals; cooking by humans; grinding in bird
gizzards
– Developed mutualistic association with cellulolytic bacteria and
protozoa in their guts that do have the appropriate enzymes
• ..
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Digestive tracts of consumers are adapted to their diets. Digestive
organs of herbivores > carnivores
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Vegetarians, omnivores/carnivores
• Plant body vs animal body
• Animal body
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No structural carbohydrate or fiber component
Rich in fat and protein
C:N ratio of plant tissues – 40:1 and 10:1 in animals
Herbivores: burn off carbon  therefore their waste products (need a
new name; not waste) are carbon rich (carbon dioxide and fiber)
– Carnivores: excretion high in nitrogen
– So: want a caterpillar or a cod or a chicken or an earthworm? Much
the same in terms of protein, carbohydrate, fat, water and minerals.
– Carnivores: no problem digesting. Problem is in finding, catching, and
overcoming defenses of prey.
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Form and Function Match Diet
• Form and function of predators are closely tied to diet:
– vertebrate teeth are adapted to dietary items:
• horses have upper and lower incisors used for cutting fibrous stems of
grasses, flat-surfaced molars for grinding
• deer lack upper incisors, simply grasping and tearing vegetation, but
also grinding it
• carnivores have well-developed canines and knifelike premolars to
secure and cut prey
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A predator’s form and function are closely tied to its diet. (a)
upper incisors are used to cut plant material; (b) flat-surfaced
molars for grinding plant material; (c) knifelike premolars secure
prey and tear flesh
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More Predator Adaptations
• The variety of predator adaptations is remarkable:
– consider grasping and tearing functions:
• forelegs for many vertebrates
• feet and hooked bills in birds
• distensible jaws in snakes
– digestive systems also reflect diet:
• plant eaters feature elongated digestive tracts with fermentation
chambers to digest long, fibrous molecules comprising plant structural
elements
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with the skull from the quadrate bone to the
supratemporal
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Burmese python (3.9m) vs alligator (1.8m) in
Everglades National Park (Florida)
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defenses
• “the value of a resource to a consumer is
determined not only by what it contains but
by how well its contents are defended.”
explain
• Physical, chemical, morphological and
behavioral defenses
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A mite trapped in the protective ‘hairs’ on the surface of a leaf
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defenses
• Any feature of an organism that increases the
energy spent by a consumer in discovering of
handling it is a defense if – then - the
consumer eats less of it
– Eg: thick shell of a nut; cellulose; husks and shells
around shells
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• Resources can be protected
• Or defended
• Secondary chemicals
• Eg: white clover contain some individuals that release
hydrogen cyanide when their tissues are attacked
– Noxious plant chemicals: either quantitative
(effective at high [ ] and make tissues indigestible; or
constitutive / qualitative (produced even in absence
of herbivore attack; toxic even in small [ ])
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Induced and Constitutive Defenses
• Constitutive chemical defenses are maintained
at high levels in the plant at all times.
• Induced chemical defenses increase
dramatically following an attack:
– suggests that some chemicals are too expensive to
maintain under light grazing pressure
– plant responses to herbivory can reduce subsequent
herbivory
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• plants differ in chemical defenses
– Short-lived plants are protected from consumers by
their unpredictability of appearance in space and
time; thus invest less in defense
– Predictable, long-lived species (forest trees) make
investment in constitutive chemicals (typically) – and
protect the more important parts of the plant
• Wild radish. Flower petals v imp. (why?) [ ] of toxins twice
as high in petals as in undamaged leaves
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Prey have adaptations to avoid being
consumed.
– Chemical defenses
• Some animals store the chemical plant toxins and use them in their
own defense (monarch butterfly – caterpillar feeds on milkweeds;
caterpillar stores poison; bluejay vomiting butterfly after eating it. So?
.. Monarchs that eat cabbage are edible for birds)
– Hiding
• If a predator can’t see you, it can’t eat you.
• Evolution of cryptic coloration.
– Escaping
• If you can outrun your predator, it can’t eat you.
• Evolution of speed or maneuverability.
– Active defense mechanisms
• Animals with poison glands.
4/11/2016 • Plants with thorns, toxic substances.
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Chemical defenses.
• The production of
chemicals which repel
potential predators.
• Toxin + boiling temp =>
• Notice the colors of this
bombardier beetle.
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Prey have adaptations to avoid being
consumed.
– Hiding / behavior
• If a predator can’t see you, it can’t eat you.
– Living in holes (moles)
– Playing dead (african ground squirrel)
• Evolution of cryptic coloration.
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Crypsis and Warning Coloration
• Through crypsis, animals blend with their
backgrounds; such animals:
– are typically palatable or edible
– match color, texture of bark, twigs, or leaves
– are not concealed, but mistaken for inedible objects by
would-be predators
• Behaviors of cryptic organisms must correspond to
their appearances.
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Cryptic appearances (a) mantid; (b) stick insect; (c)
lantern fly
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For more…See slideshow – posted
on the ecology site
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Warning Coloration: aposematism
• Why should a prey item evolve bright colors?
– It definitely brings attention to you.
– Black and yellow are the most common colors.
• Unpalatable animals may acquire noxious chemicals from food or
manufacture these chemicals themselves:
– such animals often warn potential predators with warning coloration or :
• certain aposematic colorations occur so widely that predators may have
evolved innate aversions
• If an animal eats a brightly colored prey item:
– It may get sick.
– It may die.
– If it lives, it will remember.
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Unpalatable
organisms
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Why aren’t all prey unpalatable?
• Chemical defenses are expensive, requiring large investments
of energy and nutrients.
• Some noxious animals rely on host plants for their noxious
defensive chemicals:
– not all food plants contain such chemicals
– animals using such chemicals must have their own means to avoid toxic
effects
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Batesian Mimicry
• Certain palatable species mimic unpalatable species
(models), benefiting from learning experiences of
predators with the models.
• This relationship has been named Batesian mimicry
in honor of discoverer Henry Bates.
• Experimental studies have demonstrated benefits
to the mimic:
– predators quickly learn to recognize color patterns of
unpalatable prey
– mimics are avoided by such predators
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Harmless mantid (b) and moth (c) evolved to resemble a
wasp (a)
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Müllerian Mimicry
• Müllerian mimicry occurs among
unpalatable species that come to
resemble one another:
– many species may be involved
– each species is both model and mimic
– process is efficient because learning by predator with
any model benefits all other members of the mimicry
complex
– certain aposematic colors/patterns may be widespread
within a particular region
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Costa Rican butterflies and moths
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Effects of intraspecific
competition for resources
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Competing for resources
• Intraspecific competition: competition between individuals of
the same species
– Exploitation: competitors depleting each other’s resources [just eating
the same food]
– Direct interference: individuals of a species may fight for ownership of
a ‘territory’ [eg: vultures; tigers]
• Ultimate effects: survival, growth and reproduction (vital
rates) of competitors impacted
• Thus – competition typically leads to reduced rates of
resource intake per individual  decreased rates of individual
growth or development, increased rates of predation..
• Density-dependent. What does that mean?
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Conditions, resources, and ecological
niche
• Habitat vs niche?
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Habitat and Niche
• The habitat is a place or physical setting in
which an organism lives. Examples include:
– forests
– deserts
– coral reefs
• The habitat is characterized by:
– conspicuous physical features
– dominant plant (or animal) life
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Tropical rain forest…
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Tropical seasonal forest habitats
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Tropical grasslands
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Antarctic ice cap…
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Classifying habitats is useful but difficult!
• The habitat concept is useful; it emphasizes
conditions experienced by organisms.
• Classification systems are varied and typically
hierarchical:
– aquatic habitats (vs. terrestrial)
• marine habitats (vs. freshwater)
– oceanic habitats (vs. estuarine)
» benthic habitats (vs. pelagic)
• Finer subdivisions overlap rather broadly!
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Niche
• The niche of an organism encompasses:
– ranges of conditions tolerated
– role in ecological systems
• No two species have the same niche:
– each has distinctive form and function
• No organism can live under all conditions:
– each has unique habitat requirements
– each has a unique niche
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Peruvian rhinoceros katydid: specialized in
chewing leaves
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These Aphids: suck juices from stems
and leaves of milkweed plants
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Lchnuemonid wasps: lay eggs in the larvae of
beetles within wood
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niche
• To clarify: where an organism lives is not a
niche; it is a habitat
• A niche is not a place; it is an idea – a
summary of the organism’s tolerances and
requirements
• Niche of an organism describes how, rather
than just where, an organism lives
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Niche and dimensions
• Temperature: one dimension of an organism’s
ecological niche
• Tolerance of various other conditions (relative
humidity; pH; wind speed; waterflow; etc) + various
resources
• Multi-dimensional
– 3-D – temperature, pH, availability of a particular food
– Niche = n-dimensional hypervolume
• N = number of dimensions
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