Species Interactions

Predation

• (+/-)

• Predators gain nutrients and energy

• Prey are killed or injured

Prey adaptations

• Spikes/thrones

• Chemicals (Aposomatic coloration) 

• Camoflage

• Social/physical (staying in groups)

Aposematic coloration

• Warning coloration

• Used by venomous/poisons/toxic animals

Batesian mimics

• Two species look similar but only one is toxic

• The mimic benefits more

  • monarch butterflies and viceroy butterflies

Mullerian

• Two species look similar and both are toxic

• Both the model and mimic benefit

  • Heliconus erato and melpamene

Non-native predators

• Pray lack any defenses against non-native predators

  • Lake trout vs non-native sea lampreys

Herbivory

• (+/-)

• Herbivores gain nutrients and energy

• Plants are killed or injured

Parasitism

• (+/-)

• Parasites gain nutrients and energy

• Hosts are injured or killed

• Parasites don’t want to kill them

Three categories of parasites

• Direct transmission'

• Vector-borne

• Complex

Direct Transmission

• Parasites that move through

  • Physical touch (lice and mites)

  • Fecal-oral route (fungi, nematodes, and protozoans)

  • Contaminated food and water (nematodes)

Vector-borne

• Parasites that move through vectors

  • Blood sucking insects

Complex

• Parasites that move through multiple hosts to complete their life cycle

Competition

• (-/-)

• Both competing populations lose access to some resources

Commensalism

• (+/0)

• One population benifits

• The other population is unaffected

Types of competition

• Intraspecific (Between the same species)

• Interspecific (Between different animals)

Exploitative Competition

• An indirect form of competition

• Each individual consumes resources an reduces the availability for others

Interference competition

• A direct form of competition

• physical fights for resources

• Paramecium Gause 

Paramecium Gause Experiment

• Separate they grew a lot

• Together they grew a little

Competative exclusion principle

• Two species can’t co-exist if they compete for identical resources (occupy the same niche)

Ecological niche

• the role a species plays in the environments

• They types of food it eats, where it lives, where it reproduces, and its relationship to other species.

Fundamental niche

The locations where a species could live and reproduce, in the absence of the predators and interspecific competitors

Realized niche

The location where a species actually lives and reproduces, in the presence of predators and interspecific competitors

Barnacles and inter-tidal habitat

• Chthamalus fundamental niche in larger than its realized niche (TOP)

• Balanus fundamental niche and realized niche are equal (BOTTOM

Inter-tidal

• High and low tide areas

Resource partitioning

• Animals that live in different microhabitiats or niches within the same area

  • ex) different species of birds looking for insects in different parts of the tree to reduce interspecific competition

Sympatric Species

Population or species that share the same geographic region

Allopatric Species

Populations that become geographically isolated so they evolve differently

Charles Darwin

• Hypothesized interspecific competition for food among sympatric species caused evolution

Mutualism

• (+/+)

• Both population benefit

Mutualism Examples

• Ants and Acacia (co-evolution)

• Fungus and alga = Lichens

  • Fungus provides protection, water, and minerals for the photosynthetic partner

  • The alga provides sugars through photosynthesis

• Coral and Algae

  • Coral provide shelter and CO₂

  • Algae provide sugars and O₂ through photosynthesis

• Roots and fungi

  • Fungi give plants water and minerals

  • plants provide fungi with sugars from photosythesis

• Human gut

  • Microbial help digest food and prevent dangerous microbes

  • humans provide shelter