what is apparent competition?

A situation in which two or more species negatively affect one another indirectly through their interaction with a common predator.

In agriculture, cultivation methods are designed to reduce competition. For example, a crop of wheat is sown at a density that minimizes competition within the same species. The plants are grown far enough apart to reduce competition between the roots of neighboring wheat plants for soil mineral nutrients. The spraying of the ground to kill weeds reduces competition between the wheat and weed plants. Some weeds would grow taller than the wheat and deprive it of light.

What is resource partitioning and how does this relate to the realized niche?

Resource partitioning is when two species partition [divide] a resource based on behavioral or morphological variation.  In this way, one species does not out-compete the other and coexistence is obtained through the differentiation of their realized ecological niches.

The divergence in the characteristics of two otherwise similar species where their ranges overlap caused by the selective effects of competition between the species in the area of overlap.

An example would be ground finches of the Galapagos Islands species.  The finches usually have beaks of different sizes, indicating the different ranges of preferred food size.  When the two species Geospiza fortis and G. fuliginosa occurred on large islands together, they could be distinguished unequivocally by beak size. When either one occurred by itself on a smaller island, however, the beak size was intermediate in size relative to when the two co-occurred.

Be able to interpret the Type III functional response and specifically describe what is happening at the low prey densities.

At lowest prey densities predators with type III consume very low #’s of prey; highest consumption is at intermediate prey densities.  Type III predator response is depressed at low prey density because of low hunting efficiency or absence of a search image. 

Several factors lead to decreased predator response at lower prey densities (1) a heterogenous habitat may afford limited number of hiding places which protect larger proportion of prey at lower densities (2) lack of reinforcement of learned searching behavior due to low rates of prey encounters (3) switching to alternative food sources when prey are scarce

What is meant by coupled oscillations?  Why do we often see oscillations of predator and prey populations out of sync? 

Coupled oscillations occur when predators and prey fluctuate in closely linked cycles.  Oscillations are often out of sync due to environmental or biological factors.  E.g. environmental variability, habitat disturbance 

Consider example of predator/prey, parasite/host, parasitoid/host, or herbivore/plant.  Describe co-evolutionary changes in both members of the interacting pair in terms of physiological, behavioral and morphological types of adaptations.  

E.g. Yucca moth and yucca flower

-Moth enters yucca flower and deposits 1-5 eggs in ovary, scrapes pollen off anthers in the flower and rolls it into small ball, flies to another plant, enters a flower and places pollen ball onto stigma of flower before laying another batch of eggs, eggs hatch, larvae burrow into ovary and feed on developing seeds. 

Moth larvae can grow nowhere else and yucca has no other pollinator.  Both have specialized traits in respect to each other:  yucca flower has sticky pollen that can easily be formed into ball for moth to carry, stigma is specially modified as receptacle to receive pollen; moths visit only one species of yucca, mate within flowers, lay eggs in ovary, exhibit restraint in number of eggs laid per flower, have modified mouthparts and behaviors to obtain and carry pollen.

Aposematic coloration

conspicuous patterns of colors adopted by noxious organisms to advertise their unpalatability or dangerousness to potential predators

Know the three types of mutualistic relationships, the general benefits to the involved species and specific examples.

Trophic mutualism: involves partners specialized in complimentary ways to obtain energy and nutrients from each other.  E.g. symbiotic associations of  Rhizobium bacteria and plant roots to form nitrogen-fixing nodules.  Each partner supplies a limited nutrient or energy that the other cannot obtain for itself.  Rhizobium  can assimilate molecular nitrogen from the soil, but requires carbohydrates supplied by a plant for energy to do this.

Defensive mutualism: invovlves species that receive food or shelter from their mutualistic partners in return for defending those partners against herbivores, predators or parasites. E.g. in marine systems specialized fishes and shrimps clean parasites from the skin and gills of other species of fish.  These cleaners benefit from food value.; fish are unburdened of some of their parasites. 

Dispersive Mutualism: involves animals that transport pollen between flowers in return for rewards such as nectar or that disperse seeds to suitable habitats as they eat the nutritional fruits that contain the seeds. E.g. cape region of South Africa foraging ants with plants (family Proteaceae).  Ants pick up seeds and transport them to underground nests where they eat the fleshy structures inside.  The seeds which ants cannot eat are discarded in underground chambers or refuse heaps.

Why do species cheat when it comes to receiving benefits?

The natural tension between partners in mutualism can lead to cheating in.  There is inherent conflict between participants that stems from dependency of the relationship.  In order for one of the participants to increase its fitness, it must do so at the expense of other participant

What is commensalism? Provide example and describe effects on the interacting species.

a relationship between two species where one species derives benefit from the relationship and the second species is unaffected by it.  (+/0 relationship)

E.g. the anemonefish lives among the tentacles of an anemone and is protected from potential predators not immune to the sting of the anemone.  The anemonefish is protected from the sting of the anemone tentacles by a susbstance contaioned in the mucous on its skin.  Anemone does not sting fish

What is ammensalism? Provide example and describe effects on the interacting species.

Ammensalism : occurs when one species hurts another, but does not benefit from this interaction. (-/0 relationship)

E.g. as wild pigs forage they often disturb the upper layer of soil and many organisms may be taken from their burrows and exposed to predation by the action of the pigs.  The harm that the burrowers suffer does not improve the pig’s situation at all

Be able to define the concept of community

An association of interacting populations usually defined by the nature of their interaction or by the place in which they live. E.g. Sagebrush community, pond community.  Community structure and function are manifestations of a complex array of interactions directly or indirectly tying all members of a community together into intricate web

Be able to label a curve and note the type of functional response and what that line is telling us. (Type I,II,III) 

See Fig 23-12.