Date post: | 14-Feb-2017 |
Category: |
Education |
Upload: | stephanie-beck |
View: | 625 times |
Download: | 1 times |
Biodiversity, Species Interactions, and Population
ControlCh. 5
Miller & Spoolman, 16th ed.
Your Goal for this lecture
To be able to explain how interactions between organisms help drive natural selection
Big Idea # 1
Species interactions affect the resource use and sizes of other populations in an area
Species Interactions
There are 3 main types of species interactions:CompetitionPredationSymbiosis
Importance of Species Interactionshave a significant impact on each population
involvedare agents of natural selection - they
influence who survives and is able to reproduce
CompetitionCompetition for
resources2 types:
Interspecific - 2 different species compete for the resource
Intraspecific - members of the same species compete for the resource
WhiteboardsFor the species pictured, list some
resources they might compete for and identify if it is inter or intraspecific competition
Intraspecific - fighting often involved to “win” the resourceCan be very intense
Interspecific - usually no fighting, just better at getting it Less intense since species have slightly
different niches
Competitive Exclusion PrincipleNo two species can
occupy exactly the same niche because competition for resources would be too intense
The less competitive species must leave, adapt, or die
Examine the three graphs and determine what species is the better competitor and what evidence you have for that answer
Solving the Problem
Resource PartitioningTwo species evolve
adaptations that allow them to use the same resource in different ways, at different times, or in different places in order to minimize competition
How about humans? Are humans subject to the Principle of
Competitive Exclusion? Defend your answer Yes! Our use of resources directly competes with other
organisms, and forces them to leave the area or go extinct in that area (adaptation not possible since we change environment so quickly)
Predation
All consumers feed on other organisms
Herbivores feed on live plants
Carnivores feed on animals
Omnivores feed on both
Predator-Prey RelationshipsChanges in 1 population leads to changes in
other populations
How do changes in population size affect ecosystems?
A change in the size of one population will affect the size of other populations
J-curveExponential Pattern of Growth
Intrinsic Pattern of GrowthS-curve
Carrying capacity - the maximum population size of a species that the environment can sustain indefinitely, given the food, habitat, water, and other necessities available in the environment.
Could the carrying capacity of an ecosystem change? If yes,
how?
• The size of the predator population affects the prey population and vice versa
• Who is controlling the rises and falls of these 2 populations? The Hare or the Lynx?
What is an What is an adaptation or adaptation or strategy that would strategy that would be helpful to a be helpful to a predator?predator?
What is an What is an adaptation or adaptation or strategy that would strategy that would be helpful to a prey be helpful to a prey organism?organism?
Structural advantages Natural Weapons - Fangs, claws Flexible bodies Larger Size
Predator Strategies
Predator StrategiesAmbush-
Stalk a victim • VenomGape & Suck (fish)Keen
eyesight
Predator StrategiesSPEED & CUNNING
• More intelligent than prey
• Run faster than prey• Hunt in packs
Predator StrategiesCamouflage
Sit in plain site
Predator Strategies
Chemical warfarevenom
Prey StrategiesDefense Techniques
InflateFleeFight BackStabPoison
Prey StrategiesStructural advantages
Hard Body Coverings Thorns or SpinesBreak away body partsNatural Weapons
Chemical WarfareBlinding inkPoisonOffensive
Smells and Tastes
Prey Strategies
Camouflage Color ChangeCounter-shadingDisruptive PatternsMimicry
Prey Strategies
Mimicry• Mostly a prey technique
Optical and sonic illusions LOOKS like a predator:
• School of fish; false eyes; frilled neck and inflation
Batesian mimicry- a harmless animal mimics a harmful or unpalatable one
Mullerian mimicy-two or more unpalatable species resemble each other
2 rules about coloration
Small + beautiful = poisonousBeautiful + easy to catch = deadly
Whiteboard
Think of a local speciesWhat adaptations does it have
to catch prey or avoid being eaten?
Predator Prey relationships
Predator benefitsPrey does not…or does it?Predators
strengthen the population in the long term by preying on the weaker individuals
CoevolutionWhen two species have lived together and
adapted to each other for a long time such that changes in the gene pool of one species leads to changes in the gene pool of the other species
Symbiosis
Symbiosis – when different organism live in close, physical contact with one anotherParasitismMutualismCommensalism
Parasitism
A form of symbiosis in which one organism benefits and the other is hurtLeeches, fleas,
ticks, tapeworms, etc
ParasitismSimple parasites - fleas,
ticks, leechesMove from host to hostOr have only one host their
whole lifeComplex parasites -
plasmodium (malaria), toxoplasmosisMultiple hostsMultiple life stages
Parasitism and CoevolutionExample: malariaParasite infects red blood cellsRBCs are swept into the spleen every few days
and destroyedParasite evolved to latch onto blood vessel with
a sticky proteinBody recognizes protein as foreign and will
attack itParasite evolves to have many different types of
proteins, so body can never catch up
MutualismA form of
symbiosis in which both organisms benefit
Commensalism
A form of symbiosis in which one organism benefits and the other is not harmed or helped
Example: sharks and remoras
Exit TicketSummarize
How do population interactions act as a driving force for natural selection?