PPT 16: Ecology

The Red Queen Hypothesis

(related to evolutionary arms race) - ex. toxic newts - ex. ants and fungi They both evolved together

Daphnia cyclomorphosis

- Abundance of predators induces metamorphosis to pointier, more robust (and less digestible) morphology - However, this response can be induced by any one of 3 or 4 predators, or by turbidity - No evidence that predators are reciprocally selected—they may have other food sources

community ecology

- All of these processes help shape communities, but it's important to remember that communities change over time - We will now examine how communities change over time, which is ____

cost of depressaria to parsnip plant

- In a controlled environment, more seeds made and set compared to the wild. - Making furanocoumarins costs the plant in terms of energy and resource allocation

cospeciation

- In general, the more closely related the host, the more closely related the parasites - Not a one-to one mapping—patterns differ in some places - Some hosts have multiple parasites, some parasites live on multiple hosts

example of mimicry

- Mexican Milk Snake looks just like texas coral snake but isn't poisonous - monarch vs. viceroy butterfly; viceroy is the bad tasting one

Anti-herbivore defenses of plants

- Plants in the carrot family (Apiaceae) contain many noxious compounds that have been shown to deter herbivorous insects -

energy

Every trophic level wastes ____ (10% rule) - eventually, all stored energy is lost as heat

succession

a gradual change in species composition in a community over time - primary succession - secondary succession

How does coevolution happen?

a. Mutualism b. Escalating "arms race" - Predator/prey interactions c. Co-speciation - Host/parasite interactions

Some expectations about arms races

a. We expect predators to increase as prey increases initially b. However, a boom in predators will decrease # of prey c. As prey becomes scarcer, predators die of starvation d. As predators become scarcer, prey populations rebound e. Cycle through this until stable (equilibrium) densities are reached

ecosystems

all living organisms, as well as non-living elements, that interact in a particular area

A. (for these Q's, look for a strong one to one relationship)

answer to slide 29

two types of mimicry

batesian - sheep in wolf's clothing; the mimic isn't poisonous or dangerous mullerian - Two or more species have warning coloration that is similar

symbiosis

close interactions between species - parasitism - mutualism - Commensalism - Predator-prey

co-evolutionary

Each participant in the _________ relationship undergoes natural selection, with the *highest fitness associated with genotypes that address the partnership.* Other selective forces such as food availability, sexual reproduction, etc still apply, but are of lower importance and so don't determine the direction and mode of selection the way the partnership does

population dynamics

What regulates population size? births and deaths Age structure determines whether or not a population is growing

parasitism

ex. bird leaving one of their eggs in another species nest so they don't have to waste energy raising their own offspring?? (European Cuckoo)

populations

groups of individual organisms that interbreed with each other

individuals

individual organisms

commensalism

interaction in which one species benefits and the other neither benefits nor is harmed - ex. cattle egrets (birds that stand on cattles heads) example of a community interaction

secondary succession

occurs when a community has been damaged, but soil remains - like primary succession but with a head start; begins with a disturbance that opens up part of a community to development and growth of species previously outcompeted by other species in the area. ex. fire occurs 1. pioneer species annual plants grow in 1-2 years grasses and perennials: 2-3 years 2. intermediate species grasses, shrubs, pines, young oak and hickory: 5-150 years 3. climax community mature oak and hickory forest: 150+ years

exponential growth

occurs when each individual produces more than the single offspring necessary to replace itself. According to realistic (and moderate) estimates of birth and death rates, a population of just 500 elk would grow to more than a billion individuals within 80 years and eventually cover the earth

B.

answer to slide 28

cospeciation in pocket gophers and lice

- Pocket gophers live in burrows throughout the plains and western states - Play a critical role in soil ecology through tunneling and enriching - Ectoparasitic chewing lice specific to gophers live on their body and eat debris and dead skin

The predator-prey arms race

- Prey are under strong selection to avoid predation - Predators are under strong selection to find sufficient food (so to be successful at prey capture) - If a predator specializes upon a single kind of prey, or a prey item has only one significant predator, this interaction may be the strongest selective force facing the organism ----> Having multiple prey/predators diffuses the effect any one interaction has on overall fitness

correlation related to Depressaria

- The most toxic genotypes co-occur with the most metabolically capable Depressaria - The detoxifying ability of the moth is selecting for the toxicity of the plant? - The toxicity of the plant is selecting for the detoxifying abilities of the moth?

colonizing community

- first step of primary succession - the first arrivals to a lifeless and soil-less area; they are good dispersers, but poor competitors, so they are gradually replaced

coevolution

- interactions between species are strong; - selection and evolution across species boundaries - selection driven by interaction between species - species are engaged in a "reciprocal adaptive response"

climax community

- longer living, larger species outcompete the initial colonizers and persist as a stable and self-sustaining community - taller, faster-growing trees outcompete the smaller trees

primary succession

- no soil exists - begins after a disturbance leaves an area barren of soil and with no life

intermediate communites

- part of secondary succession - a variety of species is present, including both colonizers and competitors a. mosses begins to grow and trap moisture, allowing the seeds of other plants to germinate b. small herbs arrive and shrubs grow, shading out the mosses and herbs c. small trees grow and outcompete the shrubs

logistic growth

- this accounts for environmental resistance - describes population growth that is gradually reduced as the population nears the environments's carrying capacity (sliide 68 chart)

ecosystem ecology

1. All ecosystems rely on a constant source of energy - ultimate source of energy is sunlight - energy flows in one direction only 2. Nutrient cycles recycle the atoms that make up every object in an ecosystem - chemicals are cycled through the ecosystem

energy flow within an ecosystem

1. primary producers - plants convert light energy from the sun into food through photosynthesis 2. primary consumers - herbivores are animals that eat plants 3. secondary consumers - carnivores are animals that eat herbivores 4. tertiary consumers - top carnivores are animals that eat other carnivores

Depressaria

= insects that spend most of its life on a single plant; preferentially eats reproductive tissues (flowers and seeds)

mutualistic relationships

A form of symbiosis Both partners derive some benefit from the interaction Typically fairly specific - Otherwise, force of selective pressure may not be sufficient

Malthus' "Struggle for existence"

At the point where population size outstrips resource production, there are only two alternatives: find the means to expand the resource pool, or DIE.

1.

Choose the answer most correct: In a series of isolated populations of garter snakes what would you expect about their resistance to newts' toxins if you know that in some locations newts are either present or not and that their toxicity varies: 1. Resistance would be variable but will show a geographic pattern 2. Resistance would be equal in populations with and without the newts because the snakes are the same species 3. Resistance would be randomly variable 4. 1 or 2 5. 2 or 3

Phylogenetic coevolutionary hyotheses

Cospeciation: Host and parasite lineages diverge in tandem ("classic coevolution") - slide 50 tree

Cost to Depressaria--Detoxifying plant tissue

Depressaria detoxifies plants metabolically The ability to detoxify furanocoumarins has a genetic basis several genes encode elements of the metabolic pathways The metabolic processes are expensive in terms of energy

population growth

Exponential Growth occurs under ideal conditions - growth rate = births - deaths - population grows at a rate proportional to its size

populatin growth

Exponential growth is met by environmental resistance - limited resources, accumulation of wastes, increased competition or predation Carrying capacity: max # of individuals the habitat can support indefinitely - growth slows then stops when approaches carrying capacity

B.??

How can we best explain why a king snake looks like a coral snake? A. The coral snake mimics the king snake B. The king snake takes advantage of predators associating coral snake coloration with being venomous C. Bright colors advertise that the king snake is venomous D. The king snake looks completely different from the coral snake E. Both A and B are true

coevolution

_____ is different than everything we have talked about before because we are talking about interactions between species, not interactions within or between populations of the same species

selective regime

_____ is not set by the physical components of the environment, but by the biological interactions occurring within the ecosystem

community ecology

Populations interact to form communities

ecology

The study of the interactions of organisms with their environment - Individual - Population - Community - Ecosystem ---- biotic ---- abiotic

Depressaria and variation

There is variation among Depressaria in terms of the ability to detoxify the furanocoumarins There is variation among parsnips in terms of the amount of furanocoumarins

must show specificity!

To be co-evolution, the predator-prey relationship must be the primary selective force, and there must be reciprocity in the response aka ____

communities

populations of different species that interact with each other within a locale

trophic level

position in the food chain, relative to energy source

2. arms race

slide 52 graphs provide evidence for what type of relationship: 1. Mutualistic 2. Arms race 3. Co-speciation 4. None of these

energy

study slide 60

predation

when one organism feeds on another -> exerts strong selective pressure on prey - camouflage - warning coloration - mimicry - mechanical defense - chemical defense - behavioral defense