Species Interactions & Communites

Question 1

Interspecific interactions

Answer 1

• predation (including herbivory)
• symbiosis (including parasitism, disease)
• competition
• inter = different species

Question 2

Predation

Answer 2

• positive/negative interaction

- forms = carnivory and herbivory

Question 3

Carnivory

Answer 3

Animal eats animal

Question 4

Herbivory

Answer 4

Animal eats plant

-plant does not always die

Question 5

Defenses against predators

Answer 5

• remarkable diversity of predator defense adaptations
• co-evolutionary arms race (predators depend closely on specific prey which causes prey to evolve their escape skills which then causes predators to become better hunters)

Question 6

Defenses against predators: (10 defenses)

Answer 6

• be difficult to see (camouflage)
• defend with chemicals (poison frog)
• mimic a defended species (batesian, müllerian)
• be hard to eat (spines, thorns, i.e. puffer fish)
• let someone else be eaten (live in large group)
• gang up on predator (mobbing)
• scare or confuse predator (octopus ink)
• be vigilant/alert
• fight back
• flee

Question 7

Batesian mimicry

Answer 7

A harmless species mimics a harmful one (i.e. hawkmoth larva mimics poisonous green parrot snake, monarch butterfly mimics poisonous viceroy butterfly)

Question 8

Müllerian mimicry

Answer 8

2 unpalatable (both toxic and harmful) species mimic each other (i.e. cuckoo bee and yellow jacket mimic each other)

Question 9

Symbiosis

Answer 9

An interaction between organisms of 2 different species that involves direct physical contact

Question 10

Parasitism

Answer 10

Parasite lives in or on a host

• often not lethal
• emit pathogens (disease causing organisms that are generally microscopic and can be lethal)

Question 11

Commensalism

Answer 11

One species benefits, the other is unaffected

• not very common
• usually not obligatory (both species can live without each other)

Question 12

Mutualism

Answer 12

Host and symbiont both benefit

• plants and pollinators
• plants and fruit-eating animals (animals use energy then spread seeds when they poop)
• plants and ants (ants receive food, plants receive protection)
• often obligatory (need each other to survive)
• can be extremely close (endosymbionts: live inside of host)

Question 13

Competition

Answer 13

Occurs when 2 or more species rely on the same limited resource
-negative/negative

Question 14

Niche

Answer 14

The sum total of an organism’s use of resources in its environment
-how an organism fits into the environment: habitat it uses, temperatures it prefers, food it eats, when it reproduces, etc.

Question 15

Competition exclusion principle

Answer 15

• 2 species that share the same limiting resource cannot coexist indefinitely
• 2 species that share the same niche cannot coexist indefinitely

Question 16

Avoiding niche overlap (avoiding competition)

Answer 16

Over time, natural selection should minimize competition

-resource partitioning (divide up resources by where you live, eat, and reproduce)

Question 17

Character displacement

Answer 17

Tendency for characteristics of sympatric populations to diverge more than allopatric populations
-there are greater differences in a trait when 2 species co-occur compared to when they are present alone

Question 18

Community

Answer 18

Group of populations of species in the same area or habitat

Question 19

Trophic structure

Answer 19

Who eats what/whom

Question 20

Food chain

Answer 20

Simple linear relationship of who eats whom

• plant -> grazer -> primary consumer -> secondary consumer
• food web is typically more accurate

Question 21

Types of symbiosis: (3 types)

Answer 21

1. parasitism (positive/negative)
2. mutualism (positive/positive)
3. commensalism (positive/no effects)