Ecology Final Notes

Competitive Exclusion

Two species using a limiting resource similarly cannot coexist for extended periods.

Disturbance

Event disrupting a stable habitat, often increasing available resources.

Intermediate Disturbance Hypothesis

Species richness peaks at moderate disturbance frequencies.

Resource Partitioning

Division of resources among species to reduce competition.

Character Displacement

Evolutionary change leading to differences in species traits to reduce competition.

Ecological Release

Niche expansion due to reduced competition.

Predation

Introduced predators can impact native prey populations significantly.

Population Cycles

Factors like habitat complexity and prey switching can prevent predator-induced extinctions.

Evolution

Change in allele frequency in a population over time.

Mechanisms of Evolution

Includes non-adaptive mechanisms like mutation and genetic drift, and adaptive mechanisms like natural selection.

Proximate vs

Proximate mechanisms explain how traits work, while ultimate mechanisms focus on why traits evolved.

Migration/Gene Flow

Changes in allele frequency due to individuals joining or leaving a population.

Adaptive Mechanisms

Natural selection and sexual selection are conditions under which evolution occurs.

Evolutionary Ecology of Virulence

Study of how harmful a pathogen is to its host and the evolution of parasite traits.

Virulence

The harmfulness of a pathogen to its host, affecting the host's fitness.

R_0

Basic reproductive number, indicating the number of new hosts infected per original infection.

Adaptive trade-off hypothesis

The idea that virulence evolves to an optimal level based on a trade-off between costs and benefits.

Avirulence hypothesis

The concept that pathogens evolve towards zero virulence as virulence comes at the cost of transmission.

Central place foraging

Foraging behavior where animals leave and return to a central location, considering travel time and optimal food choices.

Marginal value theorem

Theory predicting how long an animal should exploit a resource patch before moving to another based on diminishing returns.

Fitness of Parasites

Depends on transmission, with parasites evolving to maximize their basic reproductive number (R_0).

Vectored Parasites

Parasites transmitted by vectors like fleas or mosquitoes, with lower costs for immobilizing hosts and potentially increasing transmission.

Waterborne Parasites

Parasites transmitted through water systems, with high replication benefits and low costs, like Cholera toxins increasing dissemination.

The Four F’s of Behavior

Foraging, Fighting, Fleeing, and Fornicating, key behaviors influenced by costs and benefits in maximizing energy intake and reproductive success.

Slope

The difference between time spent and not spending time.

Optimal choice

The best duration for staying in a given patch, depending on costs to reach the next patch.

Tangent line

The line that defines the optimal duration for staying, derived from the gain function and travel time.

Marginal Value Theorem

Considers travel time, richness of patches, and optimal time in a patch for foraging decisions.

Extrinsic Constraints

Factors in the environment affecting foraging behavior, like predator presence.

Intrinsic Constraints

Cognitive limitations influencing optimal foraging strategies.

Plasticity

Expression of traits in response to environmental changes, allowing for different phenotypes.

Quantity vs Quality

Trade-off between number and size of offspring, often seen in egg size and number trade-offs.

Semelparous

Organisms that reproduce once and then die, like salmon or mayflies.

Iteroparous

Organisms that reproduce repeatedly, such as bluegills or mosquitos.

r vs K selection

The ultimate (evolutionary) cause of r vs K strategies is the selection acting in a way that maximizes r in a population.

r-selection

Strategy where population is growing rapidly, resources are not limiting, and quantity (not quality) of offspring explains fitness differences among individuals.

K-selection

Strategy where the population is near carrying capacity (K), competitive ability of offspring explains fitness differences, and it occurs in persistent, stable habitats.

Altruistic behavior

Behavior that reduces an individual’s fitness but raises the fitness of another individual or group, leading to less conflict and potential outcompeting of selfish populations.

Kin selection

Altruistic behavior directed at other copies of the same gene, reducing gene fitness but benefiting related individuals.

Population Ecology

Study of characteristics, growth, and dynamics of populations, including properties like density, sex ratio, and age distribution.

Survivorship curves

Graphical representation of mortality rates in a population, categorized as Type 1 (high survival rate), Type 2 (constant survival rate), or Type 3 (high mortality rate at young age).

Logistic Growth

Population growth that levels off at carrying capacity (K), influenced by factors like resource availability and density-dependent mechanisms.

Community Ecology

Study of interactions among species in a shared environment, focusing on factors like species richness, evenness, and diversity at different scales.

Dispersal

Movement of organisms from one location to another, influencing species distribution and persistence in communities.

Biotic factors

Factors such as herbivores, predators, competitors, parasites, and pathogens that affect species distributions.

Abiotic factors

Non-living factors that can make individuals more sensitive to biotic factors and influence the survival of populations.

Allee effect

When rare species struggle to find mates, making it hard for the population to persist.

Source-sink

A situation where more deaths than births occur, but the species does not go extinct due to a favorable habitat.

Niche

The set of factors defining the space where an organism can survive and reproduce.

Fundamental Niche

The full range of environmental conditions where a species could exist.

Realized Niche

The narrower set of conditions where a species is actually found.

Species Interaction

The way species interact with each other, affecting distribution and population viability.

Commensalism

An interaction where one species benefits, and the other is unaffected.

Mutualism

An interaction where both species benefit, which can be obligate or facultative.

Coevolution

Evolutionary process where traits evolve in response to characteristics of interacting populations.

Trophic mutualism

Partners trade food/resources, like plants and mycorrhizal fungi exchanging nutrients.

Habitat mutualism

One partner provides a place to live in exchange for defense or food.

Service mutualism

Partners exchange services like cleaning, pollination, or seed dispersal.

Competitive Exclusion

Principle stating that two species using a limiting resource in the same way cannot coexist indefinitely.

Predation, parasitism, herbivory

Interactions where one species is harmed, and the other benefits.