Lecture 6 Flashcards
Over half the species on Earth obtain
energy by feeding on other organisms, in
a variety of types of interactions.
All are ______ —a relationship in
which one organism benefits by feeding
on, and thus directly harming, another.
exploitation
energy derived
from consumption of organic
compounds that were produced by other
organisms.
generated through
the consumption of organic matter by
heterotrophs.
Secondary production
eats tissue/internal fluids of living plants/algae
Herbivore
kills and eats other organisms, referred to as prey
Predator
lives in/on another organism (hots) feeding on parts of the host; usually don’t kill the host
• some (pathogens) cause disease
Parasite
Heterotrophs are classified according to type of food they eat
• Herbivores – plants and algae
• Carnivores – other living animals
Strictly carnivores → dentition – molars sharp
• Detritivores – consume dead organic matter (detritus)
• Omnivores – consume plants and animals
Two Main Differences bt Herbivores and Predators
- Herbivores - Exploit primary producers
- Carnivores - Exploit what eats primary producers
- i.e. carnivores have a broader range of diets; herbivores have narrow diets
- Herbivores - Exploit primary producers
- Carnivores - Exploit what eats primary producers
- i.e. carnivores have a broader range of diets; herbivores have narrow diets
Predation and Herbivory
Not all organisms fit neatly into these categories
• i.e. some predators such as wolves eat berries, nuts, and leaves
insects that lay an egg on /in another insect host; insect-insect interaction
- After hatching, larva remain in the host which they eat and usually kill
- Are they unusual parasites or unusual predators?
o Specialized egg depositors
• Provisioning hunting wasp stings caterpillars to paralyze them
o Provisions an underground cell with paralyzed caterpillars then lays an egg in the chamber and wasp larvae eat the prey alive
Parasitoids
an alternative method of determining an organism’s diet that involves the measuring of stable isotopes
concentrations of naturally occurring isotopes (C13, N15, and S34) differ among potential food items
isotopic composition of feeding organism and its potential food sources can help us identify the food sources (424-425)
Adaptations to avoid being eaten are everywhere
Plants have an array of _______
structural defenses (thorns and hairs)
Not all organisms fit neatly into these categories
• i.e. some predators such as wolves eat berries, nuts, and leaves
Adaptations: Compensation for herbivory
o Plants clipped (grew more plentiful), compensating response
o Plants unclipped, less flowers and vegetative structures
Adaptations: Chemical defenses (2 types)
Constant – unpalatable right from the beginning; relatively low levels of toxin at all times
Induced – wait for induction (prey, chewed) before release of toxic chemicals
Adaptations: Physical Defenses
large size, rapid or agile movement, body armor
Adaptations: Chemical Defenses
species that contained toxins; brightly colored, as a warning – “aposematic coloration”
Predators learn not to eat them
Adaptations: Mimicry
crypsis – prey is camouflaged or resembles its background
- Resembling other species that are fierce or toxic
are chemicals that
reduce herbivory.
Some are toxic to herbivores (e.g., spices), others attract predators or parasitoids that will attack the herbivores.
Secondary compounds
Adaptation: Behaviour
such as foraging less in the open; or keeping lookouts for predators
i.e. meercats on the lookout or forage less in the open
To understand different heterotrophs is to understand _____ and _____
COSTS and BENEFITS
To understand different heterotrophs is to understand COSTS and BENEFITS
Examples:
- Soil microbes: little energy used to find food; low quality food
- Cheetah uses much energy to capture and kill prey; high return
Multicellular organisms have evolved specialized tissues and organs for:
absorption, digestion,
transport, and excretion.
Food availability can vary significantly over time and space
If energy is in short supply, animals is “heterogenous” landscapes should invest their time obtaining the highest-quality food possible with is the shortest distance away
• Maximizing their strategy
o Carnivores switching their diet
• Switching to most abundant prey
Switching may occur because the predator forms a search image of the most common prey type and orients toward that prey. Or, learning enables it to become increasingly efficient at capturing the most common prey
proposes that
animals will maximize the amount of energy gained per unit time, energy, and risk involved in finding food
It assumes that evolution acts on the behavior of animals to maximize their energy gain.
Optimal foraging theory
How could a species take advantage
of larger prey?
- Evolve new structures (larger
beak) . - Behavioural changes. (teach and learning behaviour in a more advance, complex societal structure)
