This document discusses different types of interactions between organisms including parasitism, mutualism, predation, and competition. Parasites feed on and harm their host, while mutualistic relationships involve two organisms that benefit each other. Predation involves one organism killing another for food. Competition occurs when organisms require the same limited resources. These interactions can drive coevolution between species over time as they adapt to each other.

1. “living together”

2.  one organism benefits by feeding on another
 prey = host
 host is harmed or weakened
 differentiate between predators and
parasites…
parasites are usually smaller and more numerous
than host
parasites usually have complex life cycles
 coevolution…examples include malaria and
sleeping sickness

3. LIVER FLUKE

4.  both organisms benefit
 examples…
lichens
bacteria living in the digestive tracts of cows and
termites
ants and acacia
mycorhizae and legumes
lichens

5. WHITEBARK PINE AND
CLARK’S NUTCRACKER

6.  one species benefits and the other is
relatively unharmed
 controversial – why???
examples – barnacles on a whale

7. GREAT WHITE SHARK
AND REMORA

8.  predators kill and eat other organisms
 some scientists include herbivores (plant-eaters)
in this category
 predators are usually larger and less
abundant than their prey
yes, it’s a predator!

9.  these interactions result in coevolution
 evolution of camouflage, skilled hunting
ability, poisons
 some examples
counteracting behaviors –bats and moths

10.  some examples (continued)
camouflage – colors,
patterns and shapes that
resemble surroundings,
these organisms do not flee –
cheetahs, frogfish
warning coloration – usually
bright, these organisms taste
bad or are poisonous

11.  some examples (continued)
mimicry – one species has evolved resemble
another
 Müllerian mimicry – occurs among different distasteful
species such as monarch butterfly (poisonous) and
viceroy butterfly (distasteful)

12.  some examples (continued)
mimicry
 Müllerian mimicry – results in faster learning by
predators such as the black and yellow color pattern
that is repeated in nature

13.  some examples (continued)
mimicry
 Batesian mimicry – harmless animals resemble
poisonous ones

14.  some examples (continued)
mimicry
 startle coloration – patterns of color that resemble
much larger/dangerous organisms

15.  some examples (continued)
mimicry
 aggressive mimicry – predators entice prey to come
close by resembling something attractive to them
the real deal…only about 10 cm long

16.  some examples (continued)
chemical warfare – both predators and prey use
toxic chemicals
 plant poisons
 venomous snakes and spiders
 ink emitted by certain mollusks

17.  some examples (continued)
plants and herbivores have also coevolved
 milkweed is toxic to all organisms except the monarch
butterfly…these butterflies store these chemicals and
use them as their chemical defense weapon
 change in teeth of grazing animals to be able to eat
grasses that have evolved to have a hard outer
covering (made of silicone)

18.  competition – occurs when
a resource is limited
 intraspecific vs.
interspecific competition
 classic studies of
competition
Paramecium caudatum and
Paramecium aurelia – showed
that 2 species with similar
requirements cannot coexist
(for an extended time period)

19.  classic studies of
competition (continued)
warbler study – each
species occupies its own
niche
 niche – all aspects of an
organism’s habitat, how
it “makes a living” and
its physical environment
no/minimal niche
overlap = no
competition

20.  classic studies of competition (continued)
barnacle study - by excluding each species it
was determined that they could both inhabit the
low tide areas

21.  fundamental niche - set of resources a
population is theoretically capable of using
under ideal conditions
 realized niche - the resources a population
actually uses

22.  competitive exclusion principle (Gause’s
Principle)
Two species competing for limited resources
cannot coexist in the same place at the same
time.
click this
box!

23.  organisms with high biotic potential that are
introduced (accidentally or purposely) into non-native
ecosystems where there is little
environmental resistance
biotic potential – maximum reproductive ability in
an optimal environment
 so what’s the big deal? they can effect…
natural resources
human health
click on this carp
guy
economy
 invasive species have no predators, diseases,
parasites, other organisms competing for the
same resources and limiting environmental
factors

24.  disrupt natural communities and ecological
processes
 cause harm to the native species in that
ecosystem by competing with them for the
same resources
 invasive species can outcompete native
species
 ecosystems often become less biodiverse
(more susceptible to further damage)