SPECIES INTERACTIONS Chapter 12 Notes

Species Interactions Can Be Classified © 2015 Pearson Education, Inc. What are the possible types of interactions among individuals of two different species? How can these interactions be classified? The effects of one species on another can be  positive (  )  detrimental (  )  neutral or no effect (0)

Categories of relationships © 2015 Pearson Education, Inc. Neutral  When neither species affects the other  The relationship is (0 0) – neutral for both Mutualism  When both species mutually benefit from the interaction  The relationship is (   ) – positive for both  Many examples from pollination biology

Categories of relationships © 2015 Pearson Education, Inc. Commensalism  When one species benefits and the other is unaffected  The relationship is (  0) – beneficial for one, neutral for the other  For example, an orchid growing on a tree limb  Shark & remora

Figure 12.1 © 2015 Pearson Education, Inc.

Categories of relationships © 2015 Pearson Education, Inc. Competition is detrimental to the populations of both species (   )  Both species compete for a resource or resources Amensalism is detrimental to one species while the other is unaffected (  0)  Considered by some ecologists to be a form of asymmetric competition, such as when a taller plant species shades a shorter plant species

Categories of relationships © 2015 Pearson Education, Inc. There are multiple types of relationships where one species benefits, but the other is harmed (   ) Predation  One species feeds on another, killing it (food webs) Parasitism  One species feeds on another, reducing its fitness but not killing it Parasitoidism  One species uses another for reproduction, and its larvae feed on it, eventually killing it

Categories of relationships © 2015 Pearson Education, Inc. Summary of interactions among species

Table 12.1 © 2015 Pearson Education, Inc.

Species Interactions & Population Dynamics © 2015 Pearson Education, Inc. Test yourself, classify these…  Cows & Grass  Mosquitos and humans  Squirrels and Oak Trees  Birds at a bird feeder

Species Interactions & Population Dynamics © 2015 Pearson Education, Inc. Most species interactions are interactions among individual organisms How do these interactions affect population dynamics?

Species Interactions & Population Dynamics © 2015 Pearson Education, Inc. Interactions with individuals of different species have effects on population growth of a species When a predator kills prey, the predator is an agent of mortality  As the number of predators (N predator ) increases, the number of prey captured and killed increases, increasing the death rate of the prey population (d prey ) Can be represented as a linear relationship

Figure 12.2a © 2015 Pearson Education, Inc. d 0 prey is the death rate of the prey population when the size of the predator population is zero The death rate of the prey population increases as the number of predators increase d 0 prey Predator population size (N predator ) 0 (a) Death rate of prey species (d prey )

Species Interactions & Population Dynamics © 2015 Pearson Education, Inc. In predator-prey interactions, the predator benefits as the prey provide a food resource There is a direct link between the availability of prey and the birthrate of the predator population

Figure 12.2b © 2015 Pearson Education, Inc. The birthrate of the predator population increases as the size of the prey population increases Prey population size (N prey ) 0 (b) Birthrate of predator species (b pred )

Density Dependence Describe the relationship between changes in prey population density (PPD) and changes in predator efficiency (Pred-eff) Hint: As prey density decreases, predator efficiency…

Quiz yourself… In the following diagram… 1) identify producers 2) identify omnivores 3) identify any possible secondary carnivores 4) identify all possible primary consumers

Food web a b g h f i c e d

Ecological Niche The Ecological Niche of a species is made up of… The range of conditions under which it persists The resources it uses It’s role in the community Lifestyle

Ecological Niche Niche related vocab: Aquatic (lives in water) or terrestrial (lives on land) Nocturnal (night active) or diurnal (daytime active) Crepuscular (active at dawn & dusk) Any words that end in “–ore” tell what they eat Arboreal – lives in trees Riparian – lives near rivers Marine – lives in salt water

Ecological Niche Example: Red Fox = mostly carnivore (small mammals, birds, fruit) nocturnal solitary (territory = 2 mi 2 ) active all year Breeds in fall, young in spring Uses underground dens Prefers edge habitat (field-forest)

Ecological Niche Interactions that a species experiences with other organisms affects its niche The range of conditions under which a species survives with no interactions = fundamental niche (like a zoo habitat) Due to competition, predation, disease, etc…species usually occupy only a part of the fundamental niche = realized niche

Ecological Niche

Cattail experiment: Typha latifolia (wide-leaf cattail) Typha angustifolia (narrow-leaf cattail)

Ecological Niche

At water depths <20cm: T. latifolia (wide-leaf cattail) dominates because it can out-compete T. angustifolia (narrow-leaf cattail) At water depths >20cm: T. angustifolia dominates because T. latifolia cannot survive at those depths

What about urban & suburban niches? Some species benefit from some urbanization: Cardinals in Columbus more numerous in suburbs than in surrounding farm land Why? What other species can benefit from some urbanization?