SPECIES INTERACTIONS - PowerPoint PPT Presentation

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SPECIES INTERACTIONS

ANNOUNCEMENTS

Final Exam is in ONE WEEK:

Tues. Dec 20th
8 – 10 am
Last name begins with letter A – L LH 5
Last name begins with letter M – N  LH 7

We will be checking IDs

Bring student ID, pencils & erasure
No calculators or hats

ANNOUNCEMENTS

Review sessions for Final Exam:

Open to all students irrespective of section

Wed Dec 14th by Will & Carlos

Begins at 3pm in LH2

Sunday Dec 18th by Will & Carlos

Begins at 7 pm in LH1

Mon Dec 19th by Jennie

11am – noon in BS 004
1 – 2 pm in BS 004

ANNOUNCEMENTS

Extended Office Hours

Monday Dec 19th
Noon – 4pm

Hints for Final Exam

Questions from previous exams will be modified
Look for overarching themes
As usual, apply what you know. Don’t memorize!
Material from last 2 lectures = 25 – 30% of Final Exam

ANNOUNCEMENTS

Exam 2
Exam 3

Distribution & Approximate Grade Cutoffs
Look for grades on Blackboard by tomorrow

Populations Do Not Exist in Isolation!

Populations are tightly linked to other populations that share the same habitat

Types of Interactions Between Species:

Neutral relationships (0 0)
Commensalisms (+ 0)
Mutualism (+ +)
Competition (- -)
Parasitism (+ -)
Predation (+ -)

SPECIES INTERACTIONS: COMMENSALISM

Commensalism:

Relationship directly helps one species without having effect on other species

Ex: Birds uses trees as roost site

Birds benefit from tree
Trees get nothing, but are not harmed

SPECIES INTERACTIONS: MUTALISM

Mutualism:

Beneficial interaction between two species

Co-exploitation (not altruism)

Obligatory Mutualism:

Species can’t grow/reproduce without the other

Yucca Plant and Yucca Moth:

Plant only pollinated by yucca moth
Moth larva can only grow in yucca plant

Mutualism between fish

SPECIES INTERACTIONS: COMPETITION

Interspecific Competition:

Competition across species

Occurs when niches overlap

Niche = a set of habitat requirements
Two species struggle for same resources

Negatively impacts both species
Two outcomes:

Coexistence
Competitive Exclusion

Intraspecific Competition:

Competition between members of the same species

Competitive Exclusion:

Occurs when niches overlap completely

Fierce competition for overlapping resources

One species drives another towards extinction

One Species Eats Seeds of One Size Range

Number consumed

Seed size

Complete Niche Overlap

Species 1: Strong competitor

Species 2: Weak competitor,

Driven to extinction

Number consumed

Seed size

Coexistence:

Occurs if niches do not overlap completely

May lead to suppressed growth and/or reproduction

Species partition/share available resources

Use same resource in diff ways or at diff times

Partial Niche Overlap: competition for seeds of intermediate size

Species 2

Species 1

Number consumed

Realized

Niche

Seed size

Competition occurs when organisms compete for the same resources.

These trees are competing for nitrogen and other nutrients.

Competition occurs when individuals occupy space and prevent access to resources by other individuals. The space preempted by these barnacles is unavailable to competitors.

Competition occurs when an organism grows over another, blocking access to resources. This large fern has overgrown other individuals and is shading them.

Competition occurs when one species produces toxins that negatively affect another. Note how few plants are growing under these Salvia shrubs.

Competition occurs when mobile organisms protect feeding or breeding territory. These red-winged blackbirds are displaying to each other at a territorial boundary.