Lecture 7 + 8 Flashcards
Which of factor is most responsible for creating new variation for natural selection to work with?
Mutations – they create new variation for selection to act on. Even if a trait is fixed, a mutation could create a new variant.
Biodiversity is great at deep sea hot vents. One type of organism you would expect to see at these vents is:
A chemo-autotroph
In upwelling systems….
- Nutrient rich deep open waters move upward
- Warm water from the deep ocean always moves upward to mix with cold surface water
- Water moves faster to the north than to the south
- Deep water volcanos essentially boil water causing bubbles to rise upward from the deep ocean to the surface
Nutrient rich deep open waters move upward
Which of the following statements concerning estuaries is true?
- Estuaries have a higher salt concentration than fresh water systems
- Estuaries have a lower salt concentration than fresh water systems
- Estuaries and the open ocean have equal salt concentrations
- Estuaries have a higher salt concentration than the open ocean
Estuaries have a higher salt concentration than fresh water systems
True of false: Light penetration is higher in the open ocean than in coastal waters
True
What percent of Earth is covered by oceans?
71% and is 97% of water on earth
- streams, rivers, ponds, lakes, and wetlands cover 0.25% of surface area of Earth and is 0.007% of water on Earth
Some of the major ocean biomes
- DEEP ocean
- subtropical gyres
- upwelling areas
- northern latitudes
- continental shelves
- estuaries
Below ___m, too little light anywhere in the oceans to support photosynthesis
200m. There is more light penetration in the open ocean than coastal waters because there is more algae, other organisms in coastal waters that block light.
What is the average depth of oceans? What is the deepest part?
Average depth of 4.3km. Deepest part is 10.9km.
- 96% of the volume of the ocean is in this “deep ocean” in the dark at depths greater than 200m
- oceans are temperature stratified
- deep ocean waters are very cold (4-5ºC everywhere)
What is the biodiversity of the deep ocean?
The deep ocean has extraordinary biological diversity, including worms, crustaceans, mollusks, and fish found nowhere else.
Many of the invertebrate animals are tiny, have very low metabolic rates, and possess a lifespan that may last for decades.
With no photosynthesis (primary production), what supports animal and bacterial life in the deep oceans?
Mostly supported from organic material sinking from surface oceans (“rain of detritus”)
Hydrothermal vents put out chemical energy, which is harvested by “autotrophic” bacteria that can fix CO2 and produce organic matter.
- Fascinating discovery (in 1970s), and locally important. But not all that important at scale of entire deep ocean
What does the temperature in the deep ocean do to organisms’ metabolisms?
Slows metabolism of bacteria and cold-blooded animals
Which best describes a consequence of the cold
temperatures in 96% of the volume of the oceans?
A) low rates of bacterial decomposition, so large quantities of organic matter preserved
B) slow bacterial decomposition, but animals consume organic matter, so little organic matter preserved
C) low activity by both bacteria and animals, leading to massive preservation of organic matter
D) low activity by both bacteria and animals, but the input of organic matter from surface waters is so low that little organic matter is conserved
B) slow bacterial decomposition, but animals consume organic matter, so little organic matter preserved
Why do bacteria not seem very important in decomposing organic matter in deep oceans?
Probably because of pressure in addition to cold. Also, because little organic matter survives in deep ocean long enough for bacterial populations to grow up and use it. Animals consume most of the sinking organic matter first.
How much organic matter is stored in the deep oceans?
Very little, much less than in terrestrial ecosystems, although some stored in shallow ocean systems.
Oceans are very important in taking up and storing some of the carbon dioxide released by humans, but the storage is as dissolved inorganic carbon in the deep Oceans.
How are surface ocean waters and deep ocean waters separated?
They are separated by strong temperature stratification.
In very shallow waters near land, photosynthesis is often ____. Who are the primary producers?
High. Primary producers include phytoplankton (micro-algae and cyanobacteria), but also larger algae attached to bottom, seagrasses (vascular plants), symbiotic algae in corals.
Seagrasses, corals, and macro-algae attached to the bottom can only live where ____.
Light penetrates to the bottom
- in most of the ocean, phytoplankton are dominant primary producers (including photosynthetic cyanobacteria as well as algae)
Terrestrial biomes are structured by gradients of
Temperature and moisture
Ocean biomes are structure by gradients of
Light and nutrients
- subtropical gyres: low nutrients, deep light penetration
- continental shelf waters and upwelling regions: low-ish nutrient inputs, shallow-ish light penetration
- productive estuaries: big range of nutrients, shallow light penetration
Subtropical oceanic gyres
Large water parcels isolated from the rest of oceans by circular currents (“gyres”) for surface oceans and temperature stratification for the deep ocean
Subtropical oceanic gyres characteristics
- after deep ocean, largest biome on Earth (by far!)
- cover half the surface area of the oceans (35% of the entire surface of the planet!)
- very high diversity
- very low rates of photosynthesis (lowest on planet for aquatic ecosystems, comparable to least productive deserts)
Subtropical oceanic gyres have the clearest water on Earth and the deepest light penetration. So why is primary production so low?
Nutrients are extremely low (comparable to distilled water)
- although high nutrients nearby (!!) in deep ocean waters
- stratification keeps the high nutrients of the deep ocean away from surface waters
-> but photosynthesis only occurs in surface waters, due to light
Low nutrient levels:
a) have little influence on size of phytoplankton
b) lead to small phytoplankton
c) lead to large phytoplankton
Lead to small phytoplankton
- high surface to volume ratio (lot of sites for enzymes to take up nutrients relative ot mass of chlorophyll)
-> long food chains –inefficient, so less production of top predator fish per unit of primary production
Sargasso Sea
In addition to phytoplankton, a floating Sargassum weed (macro-algae) in the Sargasso Sea (but not other gyres)
Upwelling
Result of interaction of prevailing winds interact with coastlines
- brings cold, deep-ocean waters to the surface
-> also nutrient rich
Light penetration of continental shelf waters and upwelling regions
Relatively low (due to scatter and absorption by phytoplankton)
- but the upward flux of water keeps phytoplankton buoyed in the light
- high rates of photosynthesis northwest of South America and middlewest of Africa, northeast of China, northeast of USA, western Europe
-> high photosynthesis also supported by mixing of nutrient-rich ocean bottom waters onto shallow continental shelves
Upwelling ecosystems
- high productivity
- relatively small area of the oceans (5%)
- relatively low diversity
- large phytoplankton
- short food webs
- very productive fisheries (25% of total ocean catch)
What is the size of phytoplankton in areas with high levels of nutrients?
Large phytoplankton –have low surface to volume ratio (less need for enzymes to take up nutrients)
- short food chains
-> efficient, so high production of fish per unit of primary production
Estuaries and coastal shelves characteristics
- often very high nutrients from land (and some from deep ocean)
- low light penetration (suspended sediment, plus phytoplankton absorption)
- often shallow, so sufficient light (even with low penetration)
- high productivity
- relatively low diversity (as in upwelling)
- large phytoplankton (as in upwelling)
- short food webs (as in upwelling)
- very productive fisheries (as in upwelling)
High latitude waters
Away from shore and quite productive
Photosynthesis is moderately high in the high-latitude ocean waters because
The waters are stratified, but more weakly than in the subtropical gyres (allowing a balance of some nutrients from below yet sufficient light)
Nutrients (nitrogen and phosphorous) come from
- river inputs from land
- deep ocean (where nutrients are very high, due to slow decomposition of organic matter than sinks there)
- only in the very surface of the ocean is there enough light for photosynthesis
Photosynthesis is controlled by mixing of the surface ocean waters (in turn controlled by climate):
- if no mixing, no nutrients from bottom waters
- if too much mixing, phytoplankton are mixed too deeply and get too little light
- more wind and less heating in the higher latitude waters than in subtropical gyres, so more mixing and less stratification
- but not too much mixing, so good balance between light and nutrients
Photosynthesis is high only when
Both nutrients and light are high
Comparing all the Earth (land and oceans):
A) most photosynthesis is on land, but the biomass in the oceans is greater
B) most photosynthesis is in the oceans, but biomass on land is greater
C) photosynthesis is roughly equal on land and in the oceans, but biomass in the oceans is greater
D) Photosynthesis is greater on land, but biomass is roughly equal on land and in the oceans
E) Photosynthesis is roughly equal on land and in the oceans, but biomass is greater on land
Photosynthesis is roughly equal on land and in the oceans, but biomass is greater on land
- remember that the area of the oceans is 2-fold greater
- biomass of primary producers turns over much more rapidly in oceans than in forests (or even grasslands)
-> days rather than decades
Large masses of semi-isolated surface water surrounded by a circular current of water moving clockwise would…
Gyres in the northern hemisphere
What is one possible explanation of why biodiversity is very high in subtropical gyres?
The low-nutrient status within a gyre has led to specialized adaptations
Which of the following statements are accurate? (Choose one or more answers)
- The rate of primary production is similar in the ocean and on land
- Total primary production is similar in the ocean and on land
- Terrestrial biomass is less than marine
- Marine biomass is less than terrestrial
- Total biomass is comparable on land and in the ocean
Total primary production is similar in the ocean and on land
Marine biomass is less than terrestrial
Which 2 properties have the greatest impact on structuring ocean biomes?
Light and nutrients
You are eating dinner (an impossible burger) on the deck of a boating trip while passing through a subtropical gyre. Your ship starts to take on water. Everybody is rescued but you did not finish your food. your ship and dinner sink to the bottom of the ocean. What will be the fate of your impossible burger after 2 months?
- The cold and pressure will preserve the burger
- The burger will be gone because it is consumed by bacteria
- The burger will be gone because it is consumed by deep sea animals
- The burger will be gone because it is consumed by phytoplankton
- Impossible burgers float, so it will be consumed by seagulls
The burger will be gone because it is consumed by deep sea animals
Which of the following ocean biomes has the lowest primary productivity?
- Estuaries
- Subtropical gyres
- Continental shelfs and upwelling regions
- Deep ocean
Deep ocean. Subtropical gyres have high light penetration, but low nutrients, however there is still some productivity. No light reaches the deep ocean so there is no productivity.
Which ocean biome has the lowest fisheries production?
Subtropical gyres
What term describes a group of individuals of one species?
Population
Which organism completes its entire life cycle in a single year?
- An annual
- A biennial
- A perennial
- An iteroparous perennial
An annual
Which of the following choices best describes an iteroparous organism?
- An iteroparous species breeds only once and invests all of its energy into reproduction.
- An iteroparous species breeds many times in its life and invests all of its energy into reproduction.
- An iteroparous species breeds many times and invests its energy into reproduction, growth and development.
- An iteroparous species breeds only once but invests all of its energy into growth and development.
An iteroparous species breeds many times and invests its energy into reproduction, growth and development.
What term describes individuals of a population that are all born within a particular period?
Cohort
Guild
Any group of species that exploit the same resources, or that exploit different resources in related ways
Based on the survivorship curves, which depicts circumstances where risk of mortality is greatest at older ages?
Type I (humans and large mammals)
Which terms describe generalized ecological spatial patterns that may be exhibited by organisms?
- Aggregated
- Random
- Regular
- Segregated
Aggregated
Random
Regular
When an individual male leaves a pack in search of its own territory, this is referred to as _________?
Dispersal
What is a population?
Biological population – number of individuals of a given species in a given area (at a given time)
Why is understanding populations important?
- understanding how and why populations change size gives insight into the ecological world
- we need to know population sizes/changes/distributions/etc. in order to make important decisions regarding conservation and management
How do we measure populations?
- complete or total counts
- impractical - incomplete counts
- sample part of the area and extrapolate - mark-recapture
- not very practical for deer - indirect counts
- often used for relative comparisons
-> hunter success per effort is one of the most common
What are the 4 most basic factors that result in changes in population size?
- reproduction
- deaths
- immigration
- emigration
Deterministic population modelling
Generalize important factors
- ignore “random” factors
- real populations have random factors that cause fluctuations
Demographic processes
Nt+1 = Nt + B - D + I - E
New population = population now + births - deaths + immigrants - emigrants
-> sometimes we only consider closed populations and ignore the immigrants and emigrants part
Birth rate
Number of offspring produced per individual in the population
ex. if N = 100 and 200 newborns, the birth rate = 2
Death rate
Proportion of individuals in the population that die
ex. if N = 100 and 75 die, death rate = 0.75
Geometric population growth
Population growth rate = Lambda =
Lambda = 1 + (birth rate – death rate)
Lambda = 1 + (b-d)
New population at next generation =
Starting population * population growth rate
Nt+1 = Nt * lambda
When lambda = 1
Population has constant size
Birth rate = death rate
- on average, each individual replaces itself
ex. lambda = 1 + (0.5 – 0.5) = 1
When lambda >1
Population is growing
Birth rate > death rate
ex. lambda = 1 + (0.5 – 0.1) = 1.4
When lambda < 1
Population is shrinking
Birth rate < death rate
ex. lambda = 1 + (0.1 – 0.5) = 0.6
What is wrong with arithmetic growth?
The size of the population in the next time step = the current pop * a growth rate
It would be odd if a population added the same number of individuals each time step regardless of its population size
Geometric growth formula
Nt = No*lambda ^t
Population size at time t = initial population size * geometric rate of increase ^ t
Geometric and exponential growth can look similar
- closed system (no immigration or emigration)
- geometric growth –discrete reproduction
-> population size at time t can be modelled as Nt = No*lambda^t - exponential growth –continuous reproduction
-> population size at time t can be modelled as Nt = Noe^rt
Difference between geometric and exponential growth
Geometric – discrete reproduction
Exponential –continuous reproduction
Both lambda and r are used to describe how fast a population is growing
What is r?
r is the per capita intrinsic rate of increase (also called exponential population growth rate)
r = b – d
If r > 0 then b > d and the population size grows
If r = 0 then b = d and population size stays the same
If r < 0 then b < d and the population size decreases
When growth is exponential, r is at maximum rate (rm)
How long would it take algae – growing exponentially –
to reach the mass of the known universe?
Months
We are growing from 1 cell to 4 × 10^67 cells -> 75 days
What is unrealistic about exponential growth?
There are limits to population growth -> carrying capacity
Logistic growth makes more sense
Can a population be over carrying capacity?
Yes but not for long
Where is the reproductive output per individual the highest?
At the beginning where there are few individuals, almost = 1, r is not being reduced much, almost at max
Less competition, ample resources, less competition
Population growth is highest at
middle part of logistic growth (steepest slope)
Population size v. population growth rate
Looks like a dome
- the population growth rate (dN/dt) increases until reaching the value of K/2, and then declines
Life history
The adaptations of an organism that influence its survival, growth, and reproduction
Some life history questions
How fast to grow and develop?
When to metamorphose?
How fast to grow?
How large to grow?
When to begin reproducing?
How many offspring and of what size?
Whether to care for offspring?
How often to breed?
How long to live?
Do species have simple or complex life cycles?
Complex life cycles are common in insects, marine invertebrates, amphibians, and some fishes
Many vertebrates have simple life cycles without abrupt transitions (Dall sheep, humans)
Semelparity
Breed once and die (salmon)
Iteroparity
Reproduce repeatedly during lifetime (humans, deer, tigers, etc.)
Principle of allocation
The principle that if an organism invests energy to one function (e.g., growth), it reduces the amount of energy available for another function (e.g., reproduction)
Trade offs
Trade-offs between size and number of offspring
- the larger the investment in each individual offspring, the fewer offspring can be produced
- investments: energy, resources, time
- parental care, larger egg or seed
Survivorship Curve – Type I
Low juvenile mortality and high mortality later in life
e.g., large mammals with parental care, some plants, some invertebrates
number of survivors: parallel before curving out and downward
risk of mortality: exponential growth
Survivorship Curve – Type II
Constant rates of mortality
e.g., small mammals, many birds, lizards
number of survivors: linear slope down
risk of mortality: parallel line
Survivorship Curve – Type III
High juvenile mortality and low adult mortality
e.g., marine fishes, some plants, some invertebrates
number of survivors: slide down curve
risk of mortality: slide down curve
r selection
abundant resources
unpredictable environment
density-independent mortality
K selection
limited resources
predictable environment
density-dependent mortality
r vs K: competitive ability
r: low
K: high
r vs K: body size
r: small
K: large
r vs K: development
r: rapid
K: slow
r vs K: reproduction
r: early
K: late
r vs K: offspring (number of)
r: many
K: few
r vs K: offspring (size)
r: small
K: large
r vs K: lifespan
r: short
K: long
r vs K: survivorship curve
r: Type III
K: Type I
Metapopulations: biological population
Number of individuals of a given species in a given area (at a given time)
However, it can be more complicated than this
Metapopulation
A set of spatially isolated populations linked to one another by dispersal
ex. Imagine a situation with 2 islands
If there is lots of dispersal - would function like one population
If there is little or no dispersal – would function like different populations
At low to moderate rates of dispersal – could function like a metapopulation
Metapopulation dynamics
At any one time – there is at least one patch where conditions are good and that allows a population to persist
True or false: Complete or total counts of populations are easy to collect and typically used for management of wildlife.
False because it is often very difficult to get complete counts of populations. So, managers typically use sub-sampling or indirect counts to make population estimates.
What is necessary for determining average density of a population?
The total number of individuals
The total size of a habitat
In a mark and recapture study you initially collect 50 frogs. You mark and release those 50 and plan to collect again in another week. The following week you collect 50 frogs and 10 of them are from your previous mark and recapture. How large would you estimate the population to be?
The population is estimated to contain approximately 250 individuals
Neurospora crassa (a bread mold) reproduces by making a pod (called an ascus) that always contains 8 spores, each of which can go on to form new individuals (each of which can then make a pod of its own). If the mold population grows geometrically from a starting size of 100 individuals, which of these equations would you use to calculate the population size of the mold after 7 generations?
N7 = 100 * 8^7
Consider one individual. One individual at time zero will produce 8 spores. So at time 1 the population size is 8, Those 8 descendants will each produce 8 spores so in the second generation we have 8*8=64. and so on
8888888 = 87 = 2097152
We then need to consider that we started with 100 individuals so 2097152 * 100 = 209715200
This is all represented by the equation N7 = 87 × 100
True or false: The size of a population can exceed carrying capacity.
True because populations can be above K for a short time, but limited resources will eventually cause the population to decline.
If birth and death rates are density dependent, then the density of a population will cycle near ______________.
The carrying capacity
You are doing a research project to determine the age of maple trees in a series of 100 square meter plots. Your data are interesting because many of the trees that are the same age are not the same size, even though they are within a few kilometres of one another. Why might this be?
Trees are long-lived and modular organisms. As a result, some individuals may have experience competition and herbivory that has affected growth and development.
A perennial plant (Sparaxus grandiflora) must invest resources differently when it starts to enter a reproductive stage. Which of the following choices explains how a perennial plant may deal with this?
- The plant does nothing different since it is a perennial
- The plant experiences trade-offs no matter if it is a perennial or annual. Therefore, it will likely have to reduce root growth and leaf development to compensate for the resources used for reproduction
- The plant will not experience any trade-offs since it has evolved to reproduce and grow simultaneously
- None of the above
The plant experiences trade-offs no matter if it is a perennial or annual. Therefore, it will likely have to reduce root growth and leaf development to compensate for the resources used for reproduction
How does probability of reproduction change as a function of increasing leaf area?
Probability of reproduction increases
A Type II survivorship curve:
- Shows that mortality is constant
- Shows that younger individuals have a higher death rate than older individuals
- Is typical of human populations
- Shows that the risk of mortality is the same regardless of age
Shows that mortality is constant
Shows that the risk of mortality is the same regardless of age
You have been researching species of bacteria found in the rocky intertidal zone. These bacteria are likely __________ because they live in a disturbed habitat, reproduce quickly, and invest little energy in growth or development.
r species
Which survivorship curve is an elephant?
Type I
Which survivorship curve is a cardinal?
Type II
Which survivorship curve is an oak tree?
Type III
Which survivorship curve is a salmon?
Type III
Which survivorship curve is a sea turtle?
Type III
Which survivorship curve is a polar bear?
Type I
True or false: A metapopulation is a set of spatially isolated populations linked to on another by dispersal
True
Which of the following are examples of dispersal?
- The passive transport of seeds on a duck to another lake
- A honey badger leaving its mothers care and going to a new area
- A dandelion seed gets carried a great distance on the wind when a child blows on the seed head
- A young male mountain lion seeking out its own territory
The passive transport of seeds on a duck to another lake
A honey badger leaving its mothers care and going to a new area
A dandelion seed gets carried a great distance on the wind when a child blows on the seed head
A young male mountain lion seeking out its own territory
