Transcript mb3ech03-a - Chaparral Star Academy

3 Ecological and Evolutionary
Principles
Notes for Marine Biology:
Function, Biodiversity, Ecology
by Jeffrey S. Levinton
• Ecological hierarchy
• Population-level processes
• Individual interactions
The Ecological Hierarchy
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Biosphere
Ecosystem
Community
Population
Individual
Ecological Processes Population Level
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Competition
Predation
Parasitism
Disturbance
Facilitation
Larval dispersal (unique to ocean)
Interactions Between
Individuals
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+- Territoriality
+- Predation
+ - Parasitism
++ Mutualism
+ 0 Commensalism
Predation
POPULATION EFFECTS - prey population collapse, occasional
predator-prey cycles
Predation effects reduced when
(a) Prey population has rapid recovery rate
(b) Predators limited by other factors (e.g., octopus by den sites)
(c) Escapes from predation: (1) escape behavior, (2) cryptic color,
form, (3) chemical (warning coloration) or mechanical defense (fixed or
inducible), (4) refuge habitat, (5) refuge time (nocturnal, feeding at time
of low tide when predators are away)
Predation Example: Stationary Predator Anthopleura
xanthogrammica
Mobile predators
flatfish
Crypsis:
Decorator crab
Instructor: here is a recommended link to use for class
http://video.google.com/videosearchq=mimic+octopus&hl=en&e
mb=0&aq=f#
Thaumoctopus mimicus mimic octopus
Aposematic (warning
coloration)
Instructor: here is a recommended link to use for class
http://www.rzuser.uni-heidelberg.de/~bu6/flat0415.jpg
Pseudoceros bifurcus
(flatworm in
Phillipines) has
tetrodotoxin (blocks
Na channel)
Escape Behavior
Scallop Lima hians
Spisula escaping starfish
Inducible defenses
bryozoan spines nudibranch.
Why just a plastic response?
+predator - predator
Barnacle Chthamalus
anisopoma
Optimal Predator Models
• Diet breadth - rule: food scarce, increase
breadth
• Time spent in a patch - rule: greater the
distance between patches, spend more
time in a given patch
• Size selection - maximize energy intake,
usually leads to selection for intermediate
size
Energy reward
of a mussel as
function of size
Preference of
crab for
different
mussel sizes
Shore crab Carcinus
maenas feeding upon
the mussel Mytilus
edulis.
Optimal Prey Size:
Maximize intake Function of time
and prey size
Parasitism
• Parasites evolve to reduce damage to host
• Commonly involve complex life cycles
with more than one host
• Parasites may invade specific tissues,
such as reproductive tissue of the host
Complex life cycle found in a trematode parasite
living in several marine animal hosts
Invasion of the parasitic rhizocephalan
barnacle Sacculina into the body of a crab
Planktonic
larva of
parasitic
barnacle (attaches
to 1st antenna of crab
Mutualism: Cleaner wrasse removes ectoparasites from
a number of species of fish that visit localized “cleaning
stations” on a coral reef. Fish (b) is a mimic species that
actually attacks fish that would normally be a “client” of
the cleaner wrasse.
Commensalism
Commensal crab and fish live in this burrow of
Urechis caupo
Effects of Disease
• Destruction of important species, e.g.,
shellfish disease attacks
• Removal of ecologically important species
(example: removal of key grazer)
• Interaction with other factors such as
climate change
Construction of a Population
Model
dN/dT = f (N,M,R,I,E)
N = population size
M = mortality
R = reproduction
I = immigration
E = emigration
M is a function of physical environment, competition, predation, etc.
R function of physical environment, resources (e.g., food)
Example of Population Model
Barnacles: What parameters matter the most?
dN/dT = f (N, I, M)
I is larval settlement
M a function of larval-adult interactions, overgrowth, predation
Note R doesn't matter if planktonic larvae mainly go elsewhere
Mortality pattern expected for a species with a
planktonic larva. Note higher mortality rate of
larval stage.
Modes of Population Change
Exponential
Growth
Logistic growth
Random change
Small-scale Spatial Distribution of
Individuals
Random
Uniform
Aggregated…
Aggregations on larger scales….
Metapopulation
• Definition: A group of interconnected
subpopulations
• Sources and Sinks