Ecology Exam 3

Behavioral Ecology

The study of behavior; all the ways organisms interact with other organisms and the physical environment

Tinbergen’s 4 Questions

1. Mechanism of behavior
2. Development/Ontogeny of behavior
3. Function/Adaptive value of behavior
4. Evolution/Phylogeny of behavior

Proximate Explanation

“how”

Ultimate Explanation

“why”

Innate Behavior

Comes from an animals’ heredity

Learned Behavior

Comes from watching other organisms and life experiences

Spacial Learning

the process by which an organism acquires a mental representation of its environment.

Associative Learning

the process through which organisms acquire information about relationships between events or entities in their environment

Social Learning

learned by observing and imitating the behavior of others

Insight Learning

a sudden realization of a solution to a problem

Foraging

food acquisition

Communication

information exchange between organisms

social

interactions between members of the same species

Benefits of group living

1. reduced predation risk/decreases individual vigilance

2. access to mates

3. resource sharing

4. information center

Drawbacks of group living

1. Increased visibility to predators

2. disease transmission

3. increased competition

What are the four social interaction categories

1. cooperation - positive-positive

2. selfishness - positive-negative

3. altruism - negative-positive

4. spitefulness - negative-negative

Cooperation

positive-positive, benefits donor, favored by selection

Selfishness

positive-negative, benefits donor, favored by selection

Altruism

negative-positive, can indirectly benefit donor, can be favored by selection

Spitefulness

negative-negative, benefits no one, not favored by selection

reciprocal altruism

donor benefits when recipient reciprocates in future

Altruism can be favored through

1. kin selection

2. delayed direct fitness benefit

3. reciprocal altruism

Parent-offspring conflict

occurs when parents and their offspring differ in the optimal level of parental investment

Predation

organism kills and eats prey organism

What do predators limit?

prey abundance

Introduced (exotic) species

A species introduced to a region it has not historically existed

Invasive species

An introduced species that spreads rapidly and has negative effects on the ecosystem

Invasive vs. Invasive

Sometimes a newly introduced invasive species can mitigate or completely eliminate the effects of another invasive in the ecosystem (cactus moth vs. prickly pear)

What do herbivores limit?

Plant biomass

Biodiversity is maintained by

predation

Complex environments allow for

coexistence

Defenses to predation

1. Behavioral - limits detection, pursuing, catching

2. Crypsis - limits detection, camouflage

3. Structural - mechanical or body shape

4. Chemical - poison or venom, can spur mimicry

Two types of mimicry

1. Batesian

2. Mullerian

Batesian mimicry

when a species mimics the warning signals of another species without having the characteristics that make it undesirable to their shared predator, nonvenomous mimics venomous

Mullerian mimicry

two or more noxious animals develop similar appearances as a shared protective device, the theory being that if a predator learns to avoid one of the noxious species, it will avoid the mimic species as well

Parasites and _____ have a lot in common

predators

What makes parasites different from predators?

They typically don’t kill their host. Those that do kill their host do it slowly

Ectoparasites

live on the outside of the host organism ex. ticks

Endoparasites

live inside of the host organism, often microscopic ex. tapeworm

Mesoparasite

partially embedded in the host’s body

Obligate parasite

requires host to complete its life cycle

Facultative parasite

does not require host

Parasitic castrators

Destroy host’s ability to reproduce, redirects energy to parasite

Direct transmission

vector is not required ex. lice

Aggregated distribution

Most hosts not infected, others have heavy parasite loads, typically seen in direct transmission parasites

Trophic transmission

transmission via consumption by host

Vector transmission

third party required for transmission between hosts

Are vectors infected with parasites?

No, vectors carry parasite, but do not become infected

Brood parasitism

Laying eggs in other species’s nests, siblings are outcompeted

Sexual parasitism

Males are reduced in size, dependent on females, typically permanently attached

Mycoheterotrophy

1. Plants obtain carbon from photosynthesis
2. Fungi on roots trade nutrient absorption for carbon
3. Chlorophyll-less plants take carbon from fungi

Pathogens

are typically small endoparasites

What makes bats a common reservoir of zoonotic disease?

1. exposed to a wide variety of viruses

2. Hyperactive immune system, can fight off invaders

3. Less virulent invaders may be ignored and incubated

What drives zoonotic diseases?

Human impacts

Competition

an interaction between organisms or species in which both require the same limited resource

What does competition influence?

1. population dynamics

2. community structure

3. diversity

4. selection

Intraspecific competition

occurs when two or more species must share a limited resource

Interspecific competition

between multiple species

Liebig’s law of the minimum

A population increases until the supply of the most limiting resource prevents it from increasing further

Predictions of Liebig’s law

1. the more efficient species is likely to be the winner of a competitive interaction

2. competition is asymmetrical

3. the limiting resource is environment- dependent

What happens if two species are limited by the same resource?

They cannot coexist indefinitely

Competitive exclusion

species competing for the same resource cannot coexist

Resource partitioning

differences in resource acquisition prevent competitive exclusion

Temporal niche partitioning

differentiation of competitive ability in time

Competitive outcomes are affected by

1. abiotic conditions

2. disturbance

3. interspecies interactions

Character displacement

A special case of directional selection caused buy long periods of intense competition

Exploitation competition

Individuals consume a resource and drive down the abundance of a
resource to the point that other individuals cannot persist, favors species that access resource first

Interference competition

Antagonistic interactions that result in resource
exclusion for the subordinate competitor, favors large, strong adults

Apparent competition

Two species have a negative effect on each other through a common enemy including a predator, parasite, or herbivore, Species A increases = more predators = Species B declines

Mutualism

symbiosis that is beneficial to both organisms involved

Benefits of mutualism

1. Food

2. Shelter

3. Reproduction

4. Dispersal

5. Protection

Resource-resource mutualism

two individuals share/exchange resources

Service-resource mutualism

one individual provides a service (cleaning, seed dispersal, etc) in exchange for a resource (food, shelter, etc.) from the other individual

Service-service mutualism

two individuals provide a service for one another; very rare

Obligate mutualisms

required for the survival of the species

Facultative mutualisms

beneficial but are not required for survival

Cheating

organism receives benefit at cost to partner

Commensalisms

one species benefits, another
does not, but neither are harmed

Phoresy (commensalism)

attachment to another species for travel

Inquilinism (commensalism)

living in the burrow, nest, other living structure of other species

Facilitation (commensalism)

one species has a positive effect on another

What drives biotic change

abiotic gradients

Communities

Groups of species interacting in the same place at the same time,
can be delineated geographically at large scales

Ecotones

Sharp changes in environmental conditions and species composition over a relatively short distance

Communities can be delineated biologically by

1. taxon

2. guild (use the same type of resources in similar ways)

3. functional group (share similar characteristics)

Interdependent

species depend on each other to exist, Clementsian community
concept

Independent

species do not depend on each other to exist, Gleasonian community concept

Rank abundance curves

graphically display richness and evenness

Absolute abundance

number of individuals of a species

Relative abundance (pi)

proportion of the total community made up by each species

Shannon’s index

tells you how diverse the species in a given community are, rises with the number of species and the evenness of their abundance, Ranges from 0 to ln(S

Evenness

proportions of species or functional groups present on a site, more equal species in proportion to each other the greater the evenness of the site, site with low evenness indicates that a few species dominate the site, Ranges from 0 to 1

Alpha diversity

within the site

Beta diversity

between sites

Gamma diversity

across landscape, determined by diversity within sites and
differentiation between sites

What determines diversity in communities?

1. Resources

2. Habitat diversity

3. Keystone species

4. Disturbance

Trophic cascades

a series of indirect effects that “cascade”
through a community, top-down control

Alternative stable states

Other positions where a community is stabilized, communities don’t have just one “optimal” composition

Succession

a directional and predictable change in the [plant] community over time

Primary succession

initiates life