New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Species Interactions I

by: Jesse McDonald

Species Interactions I Biology 286

Marketplace > Purdue University > Biology > Biology 286 > Species Interactions I
Jesse McDonald

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

These correspond with lecture 18 and the introduction of species interactions.
Introduction to Ecology and Evolution
Dr. Josh Springer
Class Notes
Biology, Ecology, natural selection, evolution, species
25 ?




Popular in Introduction to Ecology and Evolution

Popular in Biology

This 3 page Class Notes was uploaded by Jesse McDonald on Tuesday March 29, 2016. The Class Notes belongs to Biology 286 at Purdue University taught by Dr. Josh Springer in Spring 2016. Since its upload, it has received 10 views. For similar materials see Introduction to Ecology and Evolution in Biology at Purdue University.


Reviews for Species Interactions I


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 03/29/16
Species Interactions I   Individuals of the same species compete.     Species Interactions, Population Dynamics, and Natural Selection:  ● Species interact in a number of ways within a habitat:  ○ What are the resource requirements that different species of plants have in  common?  ○ What types of interactions exist between animal and plant species?  ○ What types of interactions exist among animals species?  ○ How can species interactions be categorized?  ● Competition for resources among different species can be intense.  ● Acquisition of resources by individuals of one species can reduce availability for other  species.  ● Heterotrophs have a broad range of potential species interactions:  ○ Feeding ­ predator and prey  ○ Competition for resources  ○ Using another organism as habitat  ■ A fungus (parasite) living on a host  ● Not all interactions among species are negative though.  ● Some can benefit both species: mutualism.   ● Species interactions affect the population dynamics for each species involved:  ○ Influence the processes of birth and death.  ○ Differentially influence survival and reproduction of individuals  ● These interactions can be agents of natural selection, playing an important role in  evolution.     Species Interactions can be classified:  ● Positive (+)  ● Negative (­)  ● Neutral  (0)         Response  Type of Interaction  Species A  Species B  Neutral  0  0  Mutualism  +  +  Commensalism  +  0  Competition  ­  ­  Ammensalism  ­  0  Predation  +  ­  Parasitism  +  ­  Parasitoidism  +  ­    Interactions can function as agents of natural selection:  ● A species of seed­eating birds feeds on the seeds of one species of plant.  ● Seed size (a heritable characteristic) in this plant is highly variable; some individual  plants produce large seeds and some produce small seeds, with a range of sizes in  between.  ● The larger a seed is,and the thicker its seed coat is, the more difficult it will be for a bird’s  bill to crush.  ○ If the seed coat is not broken, the seed will not be digested, providing no food  value to the bird.  ○ Bill size is variable in the bird population.  ○ Therefore the birds prefer to eat smaller seeds.  ● By selecting the small seeds, the birds are reducing the fitness of the plants that produce  small seeds.  ● Results in a shift in the phenotypes in the plant population to plants that produce larger,  harder seeds.  ● The bird population is the agent of selection, over time causing a genetic change in the  plant population → Heritable!  ● This change in the phenotypic distribution of the plant population will change the food  resources available for the birds.  ● There will be fewer smaller seeds, reducing the available food for birds with smaller bills  and reducing their fitness.  ● Over time, the phenotypes in the bird population will shift toward larger bills; the plant  population acting on the bird population by shifting to smaller seeds again.  ○ This is an ongoing circle of selective agents!  ● Coevolution​  is the process in which two species undergo reciprocal evolutionary  change through natural selection.  ○ Often seen in predator­prey relationships  ○ Often seen between flowering plants and their animal pollinators   ● Coevolution can lead to specialization:  ○ Changes in the phenotype can limit that ability of a species to engage in similar  interactions with other species.  ○ The increase in bill size for the hummingbird will limit its ability to fed on smaller  flowers.  ○ What happens if plant populations or hummingbirds have increasingly lower  densities?  ■ Allee effect?   ● Interactions that negatively affect both species involved can lead to the divergence of  phenotypic characteristics.  ○ Divergence reduces the intensity of the interaction  ○ Often seen in competitive interactions  ○ Over long time periods can lead to speciation     Species Interactions can be diffuse:  ● These diffuse interactions can be competitive:  ○ In most terrestrial communities there are many animals that feed on seeds ­  insects, birds, small mammals.  ● These diffuse interactions can be mutualistic:  ○ In plant­pollinator interactions, most plants are pollinated by multiple animal  species, and most pollinators pollinate multiple plant species.  ● Diffuse coevoluti ­ a network of species undergoes reciprocal evolutionary change.     Species interactions influence the species niche:  ● Fundamental niche ­ the environmental conditions under which a species can survive  and reproduce.  ○ Sometimes called the​hysiological niche  ○ The set of environmental conditions under which a species can persist.  ● Realized niche ­ the portion of the fundamental niche that a species actually uses as a  result of interactions with other species.  ● The presence of predators or a pathogen can also restrict the fundamental niche  (parasite).  ● Rhizobium are nitrogen­fixing bacteria that live within the root systems of some plants  and provide them with nitrogen, allowing them to live in soils with a low nitrogen content.  ○ Without ​hizobium​ the plants would be restricted to a narrower range of soils  with higher levels of nitrogen. 


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Janice Dongeun University of Washington

"I used the money I made selling my notes & study guides to pay for spring break in Olympia, Washington...which was Sweet!"

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.