ECCB Exam 2

Resource

Anything an organism consumes or uses that causes increase in population growth rate when it becomes more available (and vice versa)

Competition is always for resources. Competition can be classified into

Direct or Indirect

Indirect competition

Resource Competition = Exploitative competiton

Direct competition

Interference Competition

Interspecific competition

Can occur between closely related and between distantly related species

The fundamental niche

is the complete set of conditions under which an organism could potentially survive and reproduce

Realized niche

Is the subset of the fundamental niche describing the conditions, under which an organism actually lives, given limitations created by interactions with other species.

Competitive interactions can also be altered by

Disturbances

Apparent competition

When a species has a negative effect on another species through an enemy - including a predator, parasites/pathogen, or herbivore

It looks like competition because as one species increases the other population size shrinks. It is NOT competition because it is not mediated through a resource

Density-dependent limitations

Factors that affect population size (specifically the per capita g rate) in relation to the population’s density

Negative density dependence:

when the per capita growth rate decreases as population density increases (what the logistic model captures with the use of K

Positive density dependence

When the per capita growth rate increases a spopulation density increases (also known as Allee effect)

Positive density dependence typically occurs

when population densities are low, which may make it hard to find mates, particularly when sex rations are uneven

Low densities can also lead to harmful effects of inbreeding and higher predation risk.

Age structure

The distribution of individuals among age classes (=age categories) within a population

Life history

The schedule of an organism’s growth development, reproduction, and survival; represents an allocation of limited time and resources to achieve maximum reproductice success

Fecundity

the number of offspring produced by an organism per reproductive episode

Parity

The number of reproductive episodes an organism experiences

Parental investment

the time and energy given to an offspring by its parents

Longevity (life expectancy)

the life span of an organism

Principle of allocation

the observation that when resources are devoted to one body structure, physiological function, or behavior, they cannot be allotted to another.

“slow’’ life history

Long time to sexual maturity

Long life spans

Low numbers of offspring

High parental investment

K-selected organisms

‘‘Fast’’ life history

Short time to sexual maturity

Short life spans

High numbers of offspring

Little parental investment

r-selected organisms

Consumer

predator, herbivore, parasite

Resources

prey, primary producer (plant, alga), host

Predator

Kills and consumes animals

Herbivore

Consumer of (living parts of ) plants ( or other primary producers, such as algae)

Defenses against consumers

Diversity of strategies against consumers have evolved (most likely as a result of natural selection)

Chemical Plant defense against herbivory

Producing chemicals that are noxious or poisonous to herbivores

Mechanical plant defense

Developing strucutures like thorns that make it harder for animals to eat them

Nutritional plant defense

Growing structures that are less nutritious for grazer (have less N and P)

Tolerance plant defenses

Adaptions to regrow quickly after being grazed

Chemical Animal defenses against predation

Producing chemicals that are noxious or poisonous to predators

Physical Animal defense

Developing physical barriers to predation (e.g., shells) Also: ability to run/fly/swim fast

Aposematism Anima defense

Warning colors, sounds, or other characteristics to alert predators that this prey will not be tasty

Crypsis Animal defense

Camouflaged colors, shapes, and other ways of hiding from predators

Mimicry Animal defense

Looking, sounding or in other ways mimicking a species that predators avoid

Behavioral Animak defense

Behaving in ways that minimize risk from predation

Warning coloration (aposetism)

A strategy where distastefulness evolves in association with very conspicuous colors and patterns. Some predators have innate aversions ro aposematic colors; others learn to avoid certain colors and marking through experience

Batesian mimicry

When palatable species evolve warning coloration that resembles unpalatable species (e.g., hover flies and hornet clearwings resemble the common wasp)

• Dishonest/Deceptive signal

Mullerian mimicry

Honest signal

e.g., Bees and wasps mimic each other

What causes time delays in predator-prey interactions?

• -Intervals between birth and sexual maturity in both populations

• - Influence of prey availability may not be felt strongly in predator - population, until young born that year are themselves reproductively mature

Lotka-Volterra Model

Prey population growth (change in number of prey over time = instantaneous rate of change)

Per capita growth rate prey (intrinsic growth rate)

Number of prey

Search efficiency of predator

Also known as “attack rate”

• - Constant attack (extremely high search efficiency) this would be 1

Number of predators

Lotka-Volterra Model for predator population growth

Predator population growth (change in number of predators over time = instantaneous rate of change)

Search efficiency of predator

Conversion rate (converts encounter rate to number of new predators produced)

Mortality rate of predator (independent of prey availability)

Deterministic models

The output of the model is fully determined by the parameter values and the initial conditions

-Lotka-Volterra model is deterministic

Stochastic models

Have some inherent randomness. The same set of parameter values and initial conditions will lead to an ensemble of different outputs

Lotka-Volterra Assumptions

Many of the assumptions are unrealistic

• Closed system (one predator, one prey, no immigration)

• No refuges for prey

• No handling time for predators

• Prey grow exponentially in the absence of predators

• Predators consume infinite amounts of prey (i.e. predators never become satiated

Coevolution

• Biotic interactions can lead to coevolution

• really mean coadaptation

• Species evolve by natural selection imposed by each other. Reciprocal adaptation.

• Coevolution can occur as a result of mutualistic interactions, it might be faster and more evident in antagonistic interactions, which can lead to an evolutionary arms race

cost of sexual reproduction

Sexual organs require considerable energy and resources

Mating behaviors require time and energy, and increase risk of herbivory, predations, and parasitism

Sexual reproduction, through recombination, breaks apart successful gene combinations

Benefits of sexual reproduction

Coping with environmental variation: offspring are likely to encounter different environmental conditions than their parents did

Offspring with genetic variation resulting from sexual reproduction have an increased probability of possessing gene combinations that will help them adapt to different conditions ( a “diverse portafolio” where at least some combination will survive). However, environment (abiotic) does not co-evolve with the organism

More benefits of sexual reproduction

Coping with parasites and pathogens: pathogens have much shorter generation time and larger population sixed than the host species they infect

Shorter generation times (DNA replicated more often) and large population sixes ( DNA is replicated in many more individuals) = Higher chance of DNA replication errors = more new mutations

With more mutations, there is higher chance that a small number of mutations will turn out beneficial to the pathogen and allow it to overcome the host’s defenses

Sexual reproduction of the hosts does not generate new mutations, but mixes up alleles from different genes and chromosomes, generating more variation among individuals ( ‘‘diverse portfolio” of defenses) compared to asexual (=clonal) reproduction.

Red Queen Hypothesis

Species that evolve fast enough to keep up with (or outpace) evolution in their enemies will generally persist

longer than those that evolve more slowly. Thus, like the Red Queen, a species and its enemies continually

evolve "to keep in the same place

Symbiosis can be:

Mutualism

Consumer resource (exploitation)

Commensalism

At least one partner obtains a positive benefit

Endosymbiosis

A symbiotic association where one organism lives inside the other

• The one that lives inside is known as endosymbiont

Vertical transmission

From parents to offspring = heritable

Hortizontal transmission

Anything different from vertical (from the environment, from other individuals; from other species)

Types of mutualisms according to type of benefit

1) Mutualisms can aid in defense agains enemies

2) Mutualisms can improve the acquisition of water, nutrients, and places to live

3) Mutualisms can facilitate:

• Pollination

• Seed dispersal

What do pollinators get from plants

Most pollinators receive food in the form of pollen of nectar

Seed dispersal

Large plants seeds are typically dispersed by animal mutualists if the animals receive a benefit in return

One of the most common benefits is food in the form of seeds

This benefit only works if plants produce large numbers of seeds and not all seeds that are carried away are consumed

Generalist

A species that interacts with many other species

Specialist

A species that interacts with many one other species of a few closely related species

Obligate mutualists

Two species that provide fitness benefits to each other and require each other to persist

Falcultative mutualist

Two species that provide fitness benefits to each other, but the interaction is not critical to the persistence of either species

Coral Bleaching is a disruption of a mutualismt

The biggest cause of bleaching today has been rising temperatures caused by global warming. Bleached corals do not die right away, but if temperatures are very hot or are too warm for a long time, corals either die from starvation or disease

Mycorrhizal fungi

Fungi that surround plant roots and help plants obtain water and minerals

Endomycorrhizal fungi

Fungi characterized by hyphal threads that extend far out into the soil and penetrate root cells between the cell wall and the cell membrane

Ectomycorrhizal fungi

fungi characterized by hyphae that surround plant roots and enter between root cells but rarely enter the cells

Acquisition of resources in plants

Many plants rely on mutualisms with fungi and bacteria to help them obtain nutrients

Fungal hyphae provide plants with soil minerals and water; plants provide the fungi with sugars from photosynthesis

Acquisition of resources in animals

Many protozoans form mutualistic relationships with animals

ex) protozoa in termite guts get nutrients from digesting wood particles; protozoa also get a home in the gut and termites receive waste products of protozoan digestions

Climate data are usually reported as anomalies

Difference between a measured value and its baseline or reference (many times a long-term average)

Atmosphere common indices of change

• Average surface air temperature

Biosphere common indices of change

• Phenology: seasonal timing of animal and plant life history events (reproduction, migration, hibernations, etc._

Cryosphere Common indices of change

All frozen water on Earth, including in frozen soild (permafrost)

• Sea ice Extent

Hydrosphere common indices of change

All surface and subsurface liquid water on Earth:

• Includes water vapor and clouds

• excludes frozen water (cryosphere)

• Sea level

lithosphere

Rock, dirt, minerals of Earth’s crust and uppermost mantle

Global mean sea level

Has risen about 8-9 inches (21-24 centimeters) since 1880. The rising water level is mostly due to a combination of melt water from ice on land (glaciers and ice sheets) and thermal expansion of seawater as it warms

In some ocean basins, sea level has risen as much as 6-8 inches since the start of the satellite record

Regional differences exist because of natural variability in the strength of winds and ocean currents, which influence how much and where the deeper layers of the ocean store heat

The 3 warmest years in NASA’s 146-years record

2025,2024, and 2023

What causes sea level rise?

1. Melting of ice on land

2. Thermal expansion

3. A third. much smaller contributor to sea level rise is a decline in the amount of liquid later on land - aquifers, laker and reservoirs, river, soil moisture. This shift fo liquid water from land to ocean is largely due to people depleting ground water

Evidence of warming come from proxies

Proxy record uses a local quantitative record (thickness of tree rings or variation in the isotopic signature found in ice cores) to estimate some climate variable. like temperature or rainfall.

Proxy data show

that during the last 30 years the Northern Hemisphere has been warmer than any other 30-year period in at least 800 years and probably 2000 years

Thickness of tree rings

Trees generally grow faster when is warm and moist. By measuring variation in tree ring width, climatologists can reconstruct how temperature and precipitation have varied over the life of a tree

Isotopic signature found in ice cores

• Ice sheets of Greenland and Antarctica laid down over millennia

• Tiny bubbles trapped in the ice provide long- term record of concentration of gases in atmosphere, volcanic dust, relative amount of Oxygen isotopes (16O and 18 O)

Honey stick

Comparison of temperature reconstructions spanning the Common Era including the original Mann et al honey stick reconstruction and its 95% uncertainty range

Infrared radiation is absorbed by atmosphere

CO2, H20, methane CH4, Nitrous Oxide (N2O)

Keeling Curve

Current values > 400 ppm (lastest reading 424)

Carbon dioxide concentration

Pre-industrial CO2 long-term mean value

278ppm

Biological consequences of climate change - Direct effects

from changes in temperatures, precipitations or other attributes of the physical environment