Species Interactions

herbivores

remove leaf, bark, stems, roots, sap which influences a plant’s ability to grow, survive and reproduce. they prefer young tissues cuz they have low quantities of structural components that are hard to digest

plants response to herbivores

they produce more young tissues. redirect their energy and nutrients from reproduction and growth into building those new tissues

what do sessile plants do to avoid predation

they have adaptations that reduce selection by herbivores - onion, garlic

symbiosis

an intimate relationship between two organisms

parasitism

one partner benefits and one suffers from interaction

do parasites kill their hosts, why or why not

they tend to not kill their hosts because the host provides habitat and food. they have an obligatory relationship for parasite to survive and reproduce - the parasite can’t live w/o the host.

decreased b

1. reduced energy

2. reduced expression of secondary sexual traits - cannot attract mates

increased d

1. secondary infections

2. increased predation - decreased escape ability, conspicuous (abnormal) behaviour

ectoparasites

parasites live outside the host

endoparasites

parasite lives inside the host

indirect parasite transmission

host-host transmission involves intermediate host (vector, carrier)

direct parasite transmission

host-host transmission involves direct contact or dispersal (air, water, etc)

micro parasites

small - viruses, bacteria

• infection short relative to hosts’ lifespan

• direct transmission

macroparasites

large - worms, ticks

• infection long relative to hosts’ lifespan

• indirect transmission

parasites function as _________ regulators of host pops and can be described using _____

density dependent, LV models of predator prey

parasite N dependent on

pop dynamics, dispersal patterns and interactions of all host species

host N dependent on

pop dynamics of parasite

were the deer affected by brainworm

not adversely affected because they evolved defenses

were the moose and woodland caribou affected by brainworm

they were adversely affected, creating neurological disorders (paralysis of hind quarters), have not evolved defenses

when will host-parasite and predator prey relationships become beneficial to both species

during co-evolution

mutualism

relationship between 2 species where both species benefit

• inds of both species increase their survival, growth and reproduction

• reciprocal exploitation (exploiting each other and both benefit) vs cooperative effort

commensialism

relationship between 2 species where one species benefits without affecting the other

each species ____ influences each others pop growth rates

positively

aij=

coefficient of mutualism

• effect of an ind of species j on growth of species i

What type of relationship exists between coral polyps and Zooxanthellae?

Mutualism—coral polyps provide CO₂ and nutrients to the algae, while algae provide energy and oxygen through photosynthesis.

What percentage of energy do coral polyps get from carnivory?

Coral polyps obtain 10% of their daily energy from carnivory.

What percentage of energy do coral polyps get from Zooxanthellae?

Coral polyps obtain 90% of their energy from the photosynthetic algae, Zooxanthellae.

How do Zooxanthellae benefit from coral polyps?

They acquire CO₂ and nutrients from polyp feces.

Why are coral-algae interactions essential for survival?

Without this mutualism, corals could not survive in nutrient-poor environments.

Why are coral reefs ecologically important?

Coral reefs provide critical habitat for many species of invertebrates and fish.

What is an example of a reef-forming coral species?

Cauliflower coral (Pocillopora species).

commensialism

one species benefits, the other is unaffected

examples of commensialism

• barnacle and whale

  • barnacle benefits - space, transport/access to food

  • whale - no cost/benefit (but barnacles may reduce hydrodynamics - parasitism?)

• shark and remora

  • remora benefits - transport protection, access to leftover food fragments

  • shark - no cost/benefit (but remoras may remove bacteria/parasites - mutualism?)