Midterm 2 Flashcards
1
Q
what is ecology
A
- study of biotic and abiotic interactions between organisms and their environment
- typically involves measuring distribution and abundance in various environments and what resources are available to organisms
2
Q
interactions between organisms
A
- +- Territoriality
- +- Predation
- Parasitism
- ++ Mutualism
- 0 Commensalism
3
Q
Teritoriality (– or +-)
A
- Maintenance of home range and defense against intruders
- Individuals maintain territories to:
– protect a feeding area
– breeding site
– a specific nest site
4
Q
Predation (+-)
A
- Mobile and non-mobile predators
- search for prey using chemical, mechanical and/or visual stimuli
5
Q
optimal foraging theory
A
- Diet breadth - rule: food scarce, increase breadth (or when food is plentiful - focus on nutritious items)
- 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
6
Q
predator avoidance
A
- Characteristics that increase resistance to predation are SELECTED for
- Examples of adaptation are:
– crypsis (camouflage)
– deceit
– escape responses - Mimicry
- Müllerian (not known in marine organisms) and Batesian
- mechanical defense
- inducible defense
- chemical defence
- Visual cues
7
Q
chemical defense
A
- Toxic compounds
- Conspicuous colour plus chemical defense
- Many very poisonous marine organisms are brightly coloured (aposematic colouration)
- These defenses (chemical and mechanical) vary with latitude, habitat and oceanic basin
- Organisms without such defences may hide or grow fast (e.g. sponges, seaweeds) to enhance survival
8
Q
Parasitism (+-)
A
- Parasites evolve to reduce damage to host
- Commonly involve complex life cycles with more than one host
- Parasites may invade specific tissues, such as the reproductive tissue of the host
9
Q
commensalism (0+)
A
- Commensal crab and fish live in this burrow of Urechis caupo
10
Q
Mutualism (++)
A
- Coral + zooxanthellae
- cleaner fish + predators
11
Q
Effects of disease
A
- 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 & pollution (? Sea star wasting disease)
12
Q
ecological processes
A
- Competition
- Predation
- Parasitism
- Disturbance
- Facilitation
- Larval dispersal (unique to ocean)
- Larval settlement
13
Q
populations level
A
- Group of individuals that are affected by the same overall environment and are unconnected with other populations of the same species.
- Changes in populations come from survival, birth, death, immigration and emigration
- Marine populations are
dynamic - Survival of adults is a major factor in populations
- Many marine species produce hundreds of thousands of eggs per
female - Reproduction is seasonal and corresponds to food and environmental factors
- Population size and extinction are closely related - low density of adult individuals can result in population extinction
- Many marine species spawn eggs & sperm in the water if density is low the likelihood of sperm fertilizing an egg is low
14
Q
modes of populations change
A
- exponential growth
- logistic growth
- random change
15
Q
allee effect
A
Correlation between population size, density & fitness
16
Q
community level
A
- Communities are organized around the habitat or around foundational species
- Species that determine structure -
foundation species, interacting species - Processes: Competition, predation,
disturbance, disease, parasitism, facilitation - Environmental influences: temperature, salinity, light, water energy, depth, nutrient regime
17
Q
foundation species
A
- These organisms play a role in facilitation which is a + + relationship. - E.g. retention of water by seaweeds at low tides for small organisms to remain moist
18
Q
larval access
A
- Many marine organisms have planktonic larvae that can disperse across large areas.
- Suitable substrate upon which these larvae can settle is a limiting factor in marine communities.
- There are many factors that can result in good and bad recruitment and this can result in affecting adult population sizes
19
Q
competition: limiting resources
A
- Renewable - e.g., copepods exploiting diatom population
- Non-renewable - space on a rock exploited by long-lived sessile species
20
Q
outcomes of competition
A
- Competitive exclusion - one species outcompetes another for a resource
- eg. extinction
- Coexistence - two species exploit different resources, some process allows two species to exploit same resource without displacement
- eg. “niche shift” - character displacement - evolution of shift in morphology or behaviour
21
Q
heterogeneity in habitat
A
- Niche structure - predictable partitioning by co-existing species of a habitat into subhabitats
- Extensive coexistence with apparent resource limitation
22
Q
evidence for interspecific competition
A
- Field experiments - remove hypothetical competitor (e.g., barnacles)
- Laboratory experiments - e.g., growth experiments with one and multispecies combinations -disadvantage is lack of field conditions
- Displacement in nature- e.g., invasive species, increase of resource exploitation in estuaries.
- Problem - other factors could be at work.
- Contiguity of resource use - e.g., “adjacent niches”
- could arise by evolutionary change
23
Q
predation and herbivory
A
- Predation or Herbivory can suppress the competitive success of superior species over inferior species, especially if predator prefers competitively superior prey
- E.g. Piaster ochraceus & Mytilus californianus or sea urchins, sea otters & seaweeds (keystone species), or removing urchins results in dominance of a fast growing seaweed
- Seasonal influx of predators can decimate some local communities
- E.g. Migratory seabirds in the intertidal zone
24
Q
disturbance
A
- Usually refers to physical change in environment that causes mortality or affects reproduction (storm, ice scour).
- Habitat wide (storms, ice, oil spill)
- Localized in patches (horseshoe crabs, logs)
- Suppresses effect of competition (Intermediate disturbance-predation effect)
25
Q
levels of disturbance or predation
A
- Low levels of disturbance or predation: Competitive dominant species takes over
- Intermediate levels: Promotes coexistence, more species present
- High levels: most individuals removed, reduces total number of species
26
Q
parasitism and disease
A
- Parasites can result in the reduction of growth and reproduction in the host. Recall the complex life histories of parasites - marine parasites often have several possible hosts
- Population declines have been attributed to disease that results in massive mortality (E.g. Pacific sea star wasting, Toxoplasma gondii & sea otters)
- Diseases are not well understood in the marine environment.
- All of these can affect the dynamics in a community
27
Q
facilitation
A
- Positive interaction between species where some species facilitate the other’s presence
- E.g. seaweeds retaining moisture or providing substratum
- Foundation species
28
Q
succession
A
- Predictable order of appearance and dominance of species, usually following a disturbance.
- Examples of disturbance and colonization:
- volcanism–> coral colonization; deep-sea invertebrate colonization
- Deposition of sand –> colonization by burrowers
29
Q
factors in succession
A
- Initial colonists - properties: not specialized, high reproductive rate, dispersal-oriented
- Later colonists - better competitors that displace earlier species?
- Prevention of invasion - good competitor? Good at resisting predation? Environment altered, which prevents further colonists from invading?
- Is there a climax community? Assemblage of competitively superior species? Resistant to predators? Evidence for such communities? Dominance?
30
Q
direct and indirect effects of ecological interactions
A
- Direct effects: Predator consumes prey, prey population decreases
- Indirect effects: Sea otter consumes urchins; as a consequence, seaweed prey of urchins increases in population size
- Density mediated indirect effect: Density at one feeding level increases, which reduces prey of another species, and, in turn results in an increase of the prey of the second species
- Trait-mediated indirect effect: Presence of a predator, causes prey to be active less and feed less on their own prey, so prey of second species increase in abundance, even though the second species did not decline (their feeding activity declined).
31
Q
ecosystem level
A
- Ecosystem: group of interdependent biological communities and abiotic factors in a single geographic area that are strongly interactive.
- Nearly all ecosystems have primary producers (mainly photosynthetic), secondary producers (herbivores), and carnivores. Material escaping this cycle is material to be decomposed in the saprophytic cycle.
- Food webs may be controlled by top-down processes where top predators have strong effects or bottom-up processes where changes in primary production drive changes in food web.
- Strong top-down linkages or bottom-up linkages generate a tropic cascade through the food web
32
Q
productivity
A
- Biomass (standing crop) – mass of organisms in a defined area or volume
- Primary productivity – amount of living material produced in photosynthesis per unit area per unit time
- Secondary productivity – primary consumers per unit area per unit time
- Tertiary productivity – consumers of herbivores.
- Example: energy transfer to an adult herring
- However, marine communities do not exist as simple food chains
33
Q
keystone species
A
- Some organisms have strong effects on competitive interactions and on entire ecosystems
- Examples, otters & killer whales on urchins, seastars and mussels.
- These are top-down effects
- Bottom-up effects, e.g. phytoplankton can affect the number of apex preditors (e.g. algae, sea ice, krill, fish, whales)
34
Q
marine biogeography
A
- No marine species occurs worldwide
- Two factors limit distribution:
– habitat-physiology limitations
– barriers to dispersal - The marine assemblages are known as provinces
- Currents and temperature changes affect differences
- Present distribution due to evolutionary history - vicariance and dispersal
35
Q
how do organisms respond to changes in the marine environment
A
- Seasonal and daily changes - cyclic
- Rapid environmental changes (flooding, rain)
- Organisms must have receptors to sense the change in order to respond
– Receptors-antennae, tentacles, protein systems
– Transfer systems - nervous connections to muscle systems, endocrine systems - Responses can be adaptive (e.g. organisms in a tide pool) and maximize fitness
36
Q
types of responses
A
- Behavioural
- Physiological (cellular changes at large systemic level)
- Biochemical (changes of concentrations of enzymes, ions within specific cell types)
- Gene regulation
- Metabolic rate (total rate of energy used by an organism, usually oxygen consumption) is typically used to get an overall impression of a response to a change in the environment
37
Q
what is acclimation
A
response followed by new equilibrium
38
Q
what is regulation
A
maintenance of constancy despite environmental change
39
Q
what is conformance
A
internal state changes to match external environmental change
40
Q
scope for growth
A
- The difference between energy assimilated and the cost of metabolism
- Measure of energy reserves: Scope for growth minus excess energy beyond that needed for maintenance
- Surplus energy may be divided between somatic growth & reproduction
- More food, scope of growth will increase
41
Q
measure of physiological condition
A
- Can be measured by scope that the organism has for activities e.g. swimming
- Organisms need to have reserves and oxygen systems for quick muscular responses
- Mortality rate can also measure effect of changes in the environment (e.g. temperature)
- LD50 - where 50% of the population dies (24h)
42
Q
temperature
A
- Temperature variation is common in marine environment:
– Latitudinal temperature gradient, regional differences
– Seasonal temperature change
– Short term changes (e.g., weather changes, tidal changes) - Temperature regulation:
- Homeotherms - regulate body temperature, usually higher than ambient
- Poikilotherms - do not regulate body temperature
- Species evolve differences in temperature tolerance
- Populations living along a latitudinal gradient might evolve local physiological races, with different temperature responses
- Freezing - winter & high latitudes
- Some fish have glycoproteins and glycopeptides, which function as antifreeze and bind to incipient ice crystals to prevent further growth
43
Q
poikilotherms
A
- Have the advantage of no cost of keeping temperature constant and high, but at the price of metabolic efficiency
- Heat gain - problem for poikilotherms in intertidal zone at low tide or tidal pools on a hot day
– Circulation of body fluids - brings heat to surface of body so it can be dissipated
– Evaporation - also allows heat loss to avoid overheating - can compensate for temperatures by means of acclimation; can stabilize metabolic rate over a wide range of intermediate temperature
44
Q
homeotherms
A
- Homeotherms - advantage of constancy of cellular chemical reactions, disadvantage of heat loss
- 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
- Marine mammals typically have a higher metabolic rate compared to terrestrial mammals of similar size
45
Q
heat
A
- Heat Shock - has effects on physiological integration of biochemical reactions in cells, can denature proteins that cannot function at high temperature
– heat shock proteins - are formed during heat stress, which forestall unfolding of protein 3D structure
– ubiquitin - low molecular weight protein
46
Q
seasonal changes in temperature
A
- Seasonal extremes of temperature affect both activity and reproduction
- Effects are different at northern and southern limits of geographic range
- Seasonal changes in timing and amount of egg and sperm production and release are highly correlated to temperature
47
Q
salinity
A
- Variation of salinity: estuaries, tide pools, intertidal zone
- Many marine groups intolerant of salinity change (low salinity)
- Populations in open ocean often less tolerant of salinity change: e.g., pelagic planktonic organisms
- Regulation of vertebrates of ionic
concentrations to very narrow variation, other groups show more variation and response to external change
48
Q
diffusion and osmosis
A
- Diffusion - problem of regulation of ion concentration
- Osmosis - problem of regulation of
cell volume - Osmosis - movement of pure water across a membrane permeable to water, owing to difference in total dissolved material on either side of membrane
- 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
- 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
- Most marine organisms have ionic concentrations of cell constituents similar to seawater
49
Q
ion regulation
A
- Done by many species, but best by crustacea (e.g., crabs), vertebrates
- Accomplished when isolation of body possible (e.g., crab carapace) so exchange and regulation localized
- Poorly accomplished by species with poor isolation (e.g., echinoderms, sea anemones)
50
Q
cell volume regulation
A
- Osmolytes: organic substitute for inorganic ions - allows regulation of cell volume and maintenance of inorganic ion concentrations
- Free amino acids used by many invertebrates, bacteria, hagfishes. Use uncharged amino acids that have little effect on protein function (e.g.,
glycine, alanine, taurine) - Urea used by sharks, coelocanths
- Glycerol, mannitol, sucrose used by seaweeds, unicellular algae
51
Q
oxygen
A
- Oxygen - synthesis of ATP; energy source in cells
- Some habitats are low on oxygen
- Low tide for many intertidal animals
- Within sediment: often anoxic water
- Oxygen minimum layers in water column: where organic matter accumulates at some depths
- Seasonal oxygen changes: hypoxic zones, “dead zones”
- Oxygen consumption increases with increasing body mass, but weight specific oxygen consumption rate declines with increasing total
body mass - Oxygen consumption increases with activity
- Nearly all animals are obligate aerobes, but many animals have a mix of metabolic pathways with and without use of oxygen
- Anaerobic pathways:
- Vertebrates and some invertebrates use glycolysis - breakdown product is lactic acid, which accumulates in muscle tissue
- Many invertebrates have alanine and succinic acid as anaerobic breakdown products
- Oxygen uptake mechanisms:
- diffusion
- feathery gills
- Larger animals have circulatory systems and oxygen-carrying blood
pigments
52
Q
blood binding pigments
A
- Blood pigments: substances that greatly increase blood capacity for transporting oxygen
- Haemocyanin - copper-containing protein, found in molluscs, arthropods
- Haemoerythrin - iron-containing protein, always in cells, found in sipunculids, some polychaetes, priapulids, brachiopods
- Chlorocruorin - iron-containing protein, found in some polychaetes
- Haemoglobin - protein unit (globin) and iron-bearing unit (heme), found in many phyla (Myoglobin is part of this family of proteins)
- Blood pigments can serve as reservoirs for animals living in low oxygen environments
53
Q
oxygen association- dissassociation
A
- Bohr effect: Hb ability to hold oxygen decreases with decreasing pH
- pH is less near capillaries that are starved for oxygen, owing to presence of CO2 released from cells (respiring); Hb releases oxygen, which
diffuses into cells
54
Q
low oxygen environments
A
- Low tide (not immersed in seawater)
- Oxygen minimum layer
- Climate change:
–Thermal stratification
–Loss of movement of layers of water to depth
–Hypoxic zones
–Decrease in O2 over 50 years (solubility decreases as temperature increases)
55
Q
light
A
- Many animals detect light with aid of a simple layer of sensory cells, but many species have complex eyes with focusing mechanisms (and can see colour)
- Allows detection of prey, predators
- Aids in navigation
- Behaviour (including mating)
- Photosynthetic organisms can also sense light and have phototropic responses - some have eye spots that sense light as well as the direction of light
56
Q
Vision
A
- Relies on pigments that absorb light
- Rhodopsins
- Vertebrates have rods & cones
- Retina focuses the light
- Colour vision is widespread among
vertebrates and invertebrates in the marine environment
57
Q
Bioluminescence
A
- Bioluminescence - light manufactured by organisms, using specialized light organs, sometimes with the aid of symbiotic bioluminescent bacteria
- Functions to confuse predators
- Perhaps other as yet undiscovered
functions
58
Q
life in sea water
A
- Life in seawater is a selective force on marine organisms
- Primary effects - direct results of properties of seawater
- Secondary effects - secondary impacts of properties of seawater
59
Q
properties of fluids
A
- The properties of water are different from air
- Density (greek letter rho - ρ)
–seawater is more dense than freshwater - Dynamic viscosity (greek letter mu - μ)
–molecular “stickiness” between layers of a fluid
–the more “sticky” the more energy that is required to move within - Kinematic viscosity (greek letter nu - ν)
–“gooeyness” under gravity (how it falls) - Two forces compete in fluids: viscous forces and inertial forces - Reynolds number (Re) is an estimate of the relative importance of each of these
60
Q
reynolds number
A
- When Re is less than 1000 then viscous forces are dominant
- If Re is much greater than 1000 then inertial forces predominate
- Objects exist under very different conditions in the same seawater, depending on their size and velocity
- Re=Vlρ/μ
- Low temperature: viscosity dominates
- High temperature: inertia dominates
– Temperature range of 5-15°C - kinematic viscosity decreases 45%! - Energetically less costly to swim at higher temperature
61
Q
movement of water
A
- If Re is high = flow is turbulent
- If Re is low = flow is laminar
- Shear can result in microturbulence
62
Q
principle of continuity
A
- Assume fluid is incompressible and moving through a pipe
- What comes in must go out!
- Velocity of fluid through pipe is inversely proportional to cross section of pipe
- Allows organisms to regulate water flow
63
Q
sponge pumping
A
- Sponges consist of networks of chambers, lined with cells called choanocytes
- Velocity of exit current can be 1-2 cm/s (10,000- 20,000 μm per sec)
- But, velocity generated by choanocytes is 50 μm per sec. How do they generate such a high exit
velocity? - Cross-section of flagellated chambers adds up to several thousands of times the cross sectional area of the exit canal
64
Q
water movement and organisms
A
- Bernoulli’s principle: pressure varies inversely with fluid velocity (if total energy is constant)
- If diameter of a pipe decreases then velocity will increase but pressure will decrease
- Can provide lift or create a current
65
Q
pressure current
A
Water moving past an object
creates drag
- At high Reynolds number, the pressure difference up- and downstream explains the pressure drag. Streamlining and placing the long axis of a structure parallel to the flow will both reduce pressure drag
- At low Reynolds number, the interaction of the surface with the flow creates skin friction
- Fast and continually swimming fish (e.g. sharks) are very streamlined to reduce drag, many also have adaptations such as arrangement of scales to reduce minor irregularities as well as having slime on their skin
66
Q
sessile forms- how to reduce drag
A
- Problem: You are attached to the bottom and sticking into the current
- Drag tends to push you down stream - you might snap!
- Examples : Seaweeds, corals
- Solutions:
–Flexibility - bend over in current
–Grow into current
–Strengthen body
67
Q
reproduction
A
the replication of individuals
68
Q
dispersal
A
the spread of offspring from one area to another
69
Q
migration
A
directed movement between areas and populations
70
Q
sex
A
- Sex is complex
- Sex is inefficient
- Sex is costly
- Is sex necessary?
–Sex means genetic recombination - Crossing over & segregation
- Matings between non-related individuals
- Genetic recombination is believed to be why sexual reproduction is so successful
- Sex produces genetically diverse offspring
71
Q
trends in reproduction
A
- Many organisms can reproduce asexually & sexually
- Rarely is sex wholly absent
- Exclusively sexual reproduction is also rare (mammals)
- Asexual predominates in small organisms
- Sexual predominates in large organisms
- Sexual selection can result in traits that are useful in attracting a mate or competing for a mate
72
Q
sexual selection
A
- Selection for extreme forms that breed more successfully
- major claw of fiddler crabs,
- Can involve selection for display coloration, enhanced combat structures
- Female choice often involved; selection for fit males (good genes hypothesis)
- Intrasexual selection: within a sex
- Intersexual selection: between males & females
73
Q
sexuality
A
- Separate sexes: gonochoristic
- Hermaphroditism: individual can have male or female function, simultaneously or sequentially, during sexual maturity
