Transcript Chapter 3: Ecological and Evolutionary Principles

Chapter 3: Ecological and Evolutionary
Principles
Chapter 4: Form and Function:
The chemical and physical
environment
©Jeffrey S. Levinton 2001
The Ecological Hierarchy
• Biosphere: entire set of living organisms and nonliving on the Earth.
• Ecosystem:
includes many communities, both abiotic
and biotic factors
• Community: made of several populations all living in
the same place.
• Population: group of individuals made of same species.
• Individual: is an organism that is independent of other
individuals.
Ecological Terms
Habitat: place an organism lives (like an
address). Habitat is species specific.
Niche: function of organism in its habitat or
environment (the organism’s job)
How do organisms interact with each
other?
How do marine organisms interact with
their environment?
Interactions Between
Individuals
(Table 3.1)
•
•
•
•
•
•
+- Territoriality
+- Predation
+ - Parasitism
++ Mutualism
+ 0 Commensalism
+- or -- Competition
Territoriality in marine fishes:
Below: Clown fish protect and
defend anemones that are their
homes.
Above: damsel fish defend
territories of coral or algal mats
that they farm.
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
Invasion of the parasitic barnacle
Sacculina into the body of a crab
Definitive
host
predation
Encysted
metacercaria
Adult
worm
defecation
Egg
2nd
defecation intermediate
hosts
Miracidium
Sporocyst
1st intermediate
host
Cercaria
Redia
Complex life cycle found in a trematode parasite
living in several marine animal hosts
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.
(a)
(b)
Cleaning stations occur in shallow water
environments and many types of organisms use them.
Commensalism
Commensal crab and fish live in this burrow of
Urechis caupo (a worm species)
How do marine animals interact with their
environment? (abiotic factors)
•Temperature
•Salinity
•Oxygen
•Light
Measures of organism’s response include:
•Behavioral
•Physiological
•biochemical
Temperature
• Temperature variation is common in marine
environment:
Latitudinal temperature gradient can be very
pronounced (Jordon’s Rule)
Seasonal temperature change common
Short term changes (e.g. weather changes, tidal
changes)
• Tolerance to temperature is an important
factor in the distribution of marine organisms
• Temperature affects growth and reproduction
Temperature for homeotherms
• Heat loss - problem for homeotherms
who maintain high body temperatures
Insulation - used by many vertebrates
(blubber in whales, feathers in birds)
Countercurrent heat exchange circulating venous and arterial blood in
opposite directions while vessels are in
contact to reduce heat loss
Temperature
Countercurrent heat exchange -
Heating
Chamber
37°C
28 °C 30 °C 32 °C 34 °C 36 °C
27°C
29 °C 31 °C 33 °C 35 °C 37 °C
Example of countercurrent heat retention
Temperature
Countercurrent heat exchange in dolphin
limb - artery is surrounded by veinlets,
which return heat
veinlets
Temperature
Metabolic rate
Poikilotherms - can compensate for
temperatures by means of acclimation;
can stabilize metabolic rate over a wide
range of intermediate temperature
Stabilization of metabolism
over wide range of temperature
Temperature
Temperature
• Freezing - a problem in winter in some
environments and in high latitudes where
sea ice forms, can destroy cells
Some fish have glycoproteins, which function as
antifreeze
Example: Antarctic fish genus, Trematomus, live
in water temps close to –1.9 C throughtout the
year. These fish die if water temps exceed 6 C!
Antarctic Sea Urchin that produces chemicals to use
very little energy (extremely low metabolic rates)
Salinity 1
• Salinity change affects organisms because
of the processes of diffusion and osmosis
Salinity
• Example of osmosis problem - animal
with a certain cellular salt content is
placed in water with lower salinity: water
will enter animal if it is permeable - cell
volume will increase, creating stress
• (many marine inverts are permeable)
Salinity
% Body volume change
• Experiment - Place sipunculid worm
Golfingia gouldii in diluted seawater. At
first volume increases of worm, but then
worm excretes salts, regulating volume
back
5
0
1
2
Time (hours)
Salinity 7
• Diffusion - random movement of
dissolved substances across a permeable
membrane; tends to equalize
concentrations
• Problem - diffusion makes it difficult to
regulate concentration of physiologically
important ions such as calcium, sodium,
potassium
Salinity
• Most marine organisms have ionic
concentrations of cell constituents similar
to seawater (see table 4.1)
• Marine organisms such as the Atlantic eel
(Anguilla rostrata) can live in both
freshwater and saltwater, however most
have very narrow tolerance ranges of
salinity.
Salinity 11
• Bony fishes - have overall salt concentrations of
body fluids of 1/3 strength of regular seawater.
Creates continual osmotic problem of water
loss
Fish must drink continuously
Gills actively secrete salts
Sharks employ urea to maintain osmotic balance
Salinity 12
• Bony fishes - osmotic regulation
Water exchange
Drinking
Osmotic loss
through gills
Urine
Solute exchange
Drinking
(seawater
containing ions)
Na+,Cl(gill secretion)
Mg2+, SO42-
Oxygen 1
• Most marine organisms require oxygen for
manufacture of necessary reserves of ATP,
energy source in cells
• Some habitats are low on oxygen Low tide for many intertidal animals
Within sediment - often anoxic pore water
Oxygen minimum layers in water column where organic matter accumulates at some
depths
Oxygen
• Oxygen uptake mechanisms:
Animals only a few millimeters thick rely upon
diffusion for oxygen uptake
Larger animals use feathery gills with high
surface area to absorb oxygen; mammals have
lungs with enormous surface areas to take up
oxygen
Larger animals have circulatory systems that
circulate oxygen to needy tissues. Many have
oxygen-carrying blood pigments.
How do marine animals deal with low levels of
Oxygen??
1. Decrease activity and therefore O2 consumption
(intertidal crabs)
2. Switch to breathing air: examples include some crabs
and mussels (Mytilus californianus consumes O2 at the
same rate in air as water)
3. Use metabolic pathways that do not require O2
4. Alter blood pigments to carry more O2
5. Behavioral response to leave the environment.
This species of mussel opens when it is exposed
to air and breathes through its valve.
Light
• Many animals detect light with aid of a simple layer of sensory
cells, but many species have complex eyes with focusing
mechanisms
Allows detection of prey, predators
Aids in navigation (some animals may use land masses or stars to aid
in navigation of long migrations)
• Eyes of animals:
Pinhole camera
Nautilus
Light
Lens
Fish
Curved, reflective
Scallop
Scallops and oysters
have the ability to
detect light and even
see images with
reflective sensory
organs.
Light
• Bioluminescence - light manufactures by
organisms - using specialized light organs,
sometimes with the aid of symbiotic
bioluminescent bacteria
Functions to confuse predators or attract mates
Perhaps other as yet undiscovered functions