Species Interactions Lecture

(ecological niche)

• Species need an appropriate combination of biotic and abiotic factors in order to survive (match to their existing adaptations)

• Each species has their own conditions for them to be successful

• Why do you find a species in a particular space?

Functional niche

• Potential spectrum of resources and conditions across which a species can survive

• Actually not achievable (theoretical possible)

Realized niche

• Actual spectrum of resources and conditions across which a species survives

• What actually happens

• Nth dimensional hyper-volume

Nth dimensional hyper-volume

• you can add an infinite number of dimensions to that figure, but the end thing that we are left with is some kind of volume that is an abstract, theoretical thing 

Ideal free distribution

• All else equal, species should distribute themselves to match the available resources. But often they do not

• Helps you to understand why you find an organism where you do

• Basically, saying that organisms are going to pick the best spot 

How do organisms know the value of the patch they are choosing?

• although evidence from stickle back study shows that animals can adopt the correct distribution

What is one of the flaws in ideal free distribution

Dispersal Limitation

• Caused by factors that keep an organism from utilizing or colonizing a new place

• Idea that there are things in the physical environment that get in the way of organisms moving one place to another

• They are limited in their movement and cannot freely distribute

spatial factors

temporal factors (disturbance events)

What are the two factors in dispersal limitation?

spatial factors

Ex: habitat connectivity, oceans, mountains, other species, etc

temporal factors (disturbance events)

Ex: habitat connectivity, droughts, floods, heat waves, other species, etc.

Metapopulation model

• Population

• All members of a species

• All interacting sub-populations or patches

Models the interaction (individual or gene flow) between sub-populations

metapopulation model

source-sink metapopulation model

landscape metapopulation model

What are the three spatial population models?

metapopulation model

Describes potential emigration pathways

Source-Sink metapopulation model

Integrates ideal free distribution into model

Landscape Metapopulation Model

Integrates ideal free distribution and spatial factors

Consumer resource

competition

mutualism

commensalism

ammensalism

What are the 5 types of interactions?

Consumer resource

• Herbivores, predators, parasites, parasitoids (these are all the same thing; all consumer resource interactions)-> one thing is benefiting, while the other is paying the cost

• Reciprocal effects -> +/-

competition

-/-

mutualism

+/+

commensalism

+/0

ammensalism

-/0

diffusivity

• gets at the idea of how many species are involved in interacting with each other

intensity

______ is a combination of lethality, intimacy, and frequency of interaction

lethality

Anywhere there is a negative can be a ________

intimacy

_________ is how many species they are interacting with

predator

• low intimacy, high lethality

• Consumer kills resource species and is not specialized or any particular species

parasitoid

• high intimacy, high lethality

• Consumer kills resource species and is highly specialized for prey species

Parasite

• high intimacy, low lethality

• Consumer harms resource species, and highly specialized for prey species

Herbivore

•  low intimacy, low lethality

• Consumer harms resource species and is not specialized for any particular species

Decomposer/Detritivore

resource is dead

Parasitoids

highly constrained by natural selection and co-evolution, so few species

Need to very specialized, but not so effective that the host goes extinct

herbivores

lightly constrained by natural selection and co-evolution, so lots of species with this strategy

consequences

All species interactions have evolutionary __________

adaptations

___________ may arise from species interactions, not just in response to the abiotic environment

plants

• Secondary compounds (not needed for metabolism) ex: white clover has cyanide (but does not need it)

• These secondary compounds help them to deal with species interaction

constitutive defenses and induced defenses

constitutive defenses

• tannins-> always there

induced defenses

• terpenoids, phenolics-> produced after being induced (cyanide would fall in this category)

animals

• Defensive structures (anatomical)

• Defensive behavior (behavioral)

• Physiological adaptations (physiological)

evolutionary forces

adaptations to reduce competition

Adaptations to reduce predation

character displacement

• selection favors traits that do not overlap across species

• Ex: beak size in galapagos finches

(adaptation to reduce competition)

Adaptations to reduce predation

• Decrease likelihood of detection

• Avoid attack

• Passive (indirect) defense: “always on”

• Active (direct) defense: “turned on when needed”- choice by the organism

Passive (indirect) defense

• “always on”

active (direct) defense

• “turned on when needed”- choice by the organism

Schooling (behavioral)→ safety in numbers

confusion effect→ balls of schooling sardines can confuse the predator

camouflage from countershading on their bodies→ active and passive anatomical defense

Adaptation to reduce predation in sardines

interference or exclusion

exploitation

intraspecific vs interspecific

Types of competiton

interference or exclusion

• Direct aggression/combat/blocking

• “Interferes” with daily life

exploitation

Indirect; mediated through resource

intraspecific

within the same species

interspecific

within different species

Apparent competition

• Consumer resource interaction (not competition)

• Gives the appearance of competition

• Predator mediates through indirect effects

• Other consumer resource interactions can also medicare through indirect effects

Lotka-Volterra

what formula models competition?

1. Species 1  (carrying capacity )is always higher than species 2: Species one will always win

2. Species 2 is always higher than species 1: species 2 will always win

3. Species 1 can cross over species 2- unlikely to occur

4. Both species are co-existing at point A and are kept in check below their carrying capacity- normally occurs. Theoretically there is a point of balance in the middle but it only takes a small nudge to mess that up

What are the four outcomes using Lotka Volterra?

Obligate Mutualism

• INTERACTION IS REQUIRED

• Species involved are obligated to engage in it

• Corals are animals 

• Zooxanthellae are tiny unicellular photosynthetic dinoflagellates

• Corals provide zooxanthellae provide corals with energy

• This is a resource-defense mutualism

Facultative Mutualism

• Interaction is not required but is beneficial

• They can live their life without mutualistic interaction, but it is beneficial

• This is a resource-defense mutualism

• Not required

• Aphids sucking sap off trees (herbivory) , lady bugs are after the aphids. The ants chase the lady bugs away, so they don’t go for the aphids.

• Aphids secrete honey dew out of their butt and give it to the ants as a reward

Pollination and seed dispersal

• Examples of plant-animal mutualism

• These are resource-service mutualisms

Commensalism (+/0)

• Positive for one species and does not do anything for the other species

• Ex: Sharks with smaller fish (they get free protection from the shark)

• Ex: Bird on back of cow (bird is looking for prey on top of the cow)

Amensalism (-/0)

EX: Raccoons get hit by cars that humans drive

• Bad for the racoon but not really anything for you

Interference competition and interspecific

What type of species interaction is this?

Lions and Hyenas

Amensalism

• Bad for the fish, does not do anything to the bloom

What type of species interaction is this?

• Algae blooms and dead fish

• Resource service mutualism

• Wattled jacana is picking off the ticks from the capybara

What type of species interaction is this?

• Capybaras and wattled jacana

Predator prey interaction

What type of species interaction is this?

• Bear and fish