Exam Three: Learning Objectives Flashcards
Define life history
schedule of an organism’s growth, development, reproduction, and survival
Life history traits include __ strategies and __ of key life events; as well as __ adaptations shaped by __
reproductive; timing
reproductive; selection
List eight life history traits
age at maturity
size at maturity
number of offspring
offspring size
parental care of young
life span
reproductive span
semel- v iteroparity
Define fecundity
number of gametes, seeds or propagules produced
Species with higher fecundity tend to lay __ eggs; describe the trade off
small
trade off: can lay many eggs or large eggs, but not many large eggs
Define the principle of allocation
given limited access to energy, if an organism allocates resources to one function (e.g., growth, maintenance), it reduces the amount of energy available to other functions (e.g., reproduction)
Describe the proportiaonality between female size and the number of eggs laid; and the number of eggs compared to the number of eggs
female size directly proportional with number of eggs - large female = more eggs
indirect relationship between number of eggs and egg diameter, smaller egg diameter = more eggs laid
Gene flow is inferred from __ __
allele frequency
Define a locus
position on a chromosome
What is a polymorphic locus?
site of a gene with many alleles
We can use allele frequency similarity between populations to make inferences about __ and _ __ among them
dispersal
gene flow
Describe the relationship between allele frequencies at a locus and dispersal between populations
if several populations of the same species have similar allele frequencies at a locus, then there is probably a lot of dispersal (gene flow) among the populations
Species producing larger seeds produce __ seeds
fewer
The mode of seed dispersal is dependent on __ __. This is important because dispersal is critical for a population to establish its __
seed size
range
Describe the tradeoff between seed size and number
allocating more energy per offspring means a parent organism will produce fewer offspring
in plants, to see the trade off between offspring size and number, you can compare vastly different taxa
You can also compare closely related species, and different populations of the same species
mass of seeds is inversely proportional to number of seeds
Discuss the evolutionary implications of life history in terms of allele frequency and darter populations
allele frequencies were similar among some species; gene flow among populations was thus probably high for these species
allele frequencies were different among populations of other species; gene flow among populations was probably low for these other species
Gene flow is more common among species with a smaller egg size - shows inverse linear relationship
Discuss the different life history strategies of grasses and herbs and trees
seedling growth was greater for species that produce larger seeds
in grasses, bigger seedlings had a greater chance of surviving past the seedling stage
for trees, larger seeds germinated earlier in the spring, before the overhead trees put out their leaves and shaded the new plants
European magpies tend to lay clutches with 7 eggs, which results in about 3-4 successfully fledged chicks, discuss what happens if eggs are experimentally removed or added
fewer eggs = fewer fledged chicks
more eggs = less well-nourished chicks = fewer fledglings
Why is clutch size a heritable trait?
clutch size of seven yields greatest fitness, and is heritable, then clutch size of 7 becomes common in the population
Describe the hypothesis: drought is an evolutionary force that selects for dry-adapted life history strategies
collect seeds from naturally wet and naturally dry sites before and after drought (4 populations), rear them and determine when they flower
seeds from dry site flowered around 41 days
seeds from a wet site flowered around 59 days with large phenotypic variability
in a post-drought population, the wet site population will look more like a dry site than a wet site, as the evolutionary conditions act as natural selection
Species with delayed reproduction generally have __ adult survival
higher
High allocation to reproduction is associated with high __
mortality
T/F: there can be no variation among populations in terms of evolutionary traits
false, many species exhibit different survival curves
As allocation to reproduction increases, relative rates of adult _ decline
survival
What is the plant CSR system?
classification system based on principles of allocation and trade-offs
Classification systems use population-level characterisitics such as:
growth rate (r), carrying capacity (K)
survival (lsubx), fecundity (msubx), and age at reproductive maturity (alpha)
Describe r-selected species
small and fast life style
weedy species good at moving into new, competitor-free environments after a disturbance
operate in the fast ‘exponential’ part of the growth curve, where r is high
Describe K-selected species
big and slow lifestyle
good competitors that eventually dominate in low-disturbance environments
operate in the high-density but slow ‘logistic’ part of the growth curve in the region of K
Relate the following attribute to r and K species:
intrinsic rate of increase (rmax)
competitive ability
development
reproduction
body size
reproduction
offspring
r: high, not strongly favored, rapid, early, small, single semelparity, many small
K: low, highly favored, slow, late, large, repeated iteroparity, few large
Classification for plants based on life histories adapted to _- and __
disturbance; stress
What are the three CSR life history strategies
C - competitive plants
S - stress-tolerant plants
R - ruderals
Describe stress-tolerant plants
allocate to maintence
efficient at using resources
adaptations for temperature and water regulation
high tolerance to stress, low intensity of competition
Describe ruderals
allocate to reproduction, weedy, move in quickly to competitor-free, available habitat
low intensity of stress and high intensity of disturbance
Describe competitive plants
allocate to growth
where disrubance and stress are low (where species interactions are key), these species are the best competitors
Discuss life history traits associated with response to climate change and fish
the larger the species, the less they shift
the longer the age at maturity, the less a species shifts
the larger the length at maturity, the less a species shifts
Define interference competition
takes the form of direct antagonistic interactiosn between individuals (e.g., direct combative contact)
Competition can occur among organisms of the same species (__ competition) or between organisms of different species (__ competiton)
intraspecific
interspecific
Define the effect on species one and two for competition
1 -
2 -
Define the effect on species one and two for exploitation
1 +
2 -
includes predation, parasitism, and herbivory
Define the effect on species one and two for mutualism
1 +
2 +
Define the effect on species one and two for commensalism
1 +
2 0
Define the effect on species one and two for amensalism
1 -
2 0
When does competition occur?
when multiple organisms use (or ‘share) a resource that is in scarce supply relative to demands (i.e., a limiting resource)
Poor growth at high density and low resource supply reveals __ competiton
intraspecific
When is a resource considered a limiting one?
if adding a resource increases growth, then that resource is limiting
Describe some evidence for intraspecific competition
the quality of plant food declines at high herbivore density, leading to poor herbivore survival and performance at high herbivore density
Discuss competition/ limiting resources of isopods
isopod survival was poor when their density was high
adding food to the high-density group did not increase survival
not competition, actually cannibalism
If nitrogen is a limiting resource, and the organisms in a population are competing for
nitrogen, describe how population density or organism size will respond to the addition of
more nitrogen.
adding nitrogen will increase the growth, giving a more exponential curve
logistic population growth is an outcome of __ competition
intraspecific
When density is high and resources are scarce, individuals must compete with members of their own population to obtain resources; at high population density, birth rates __ and death rates __, resulting in __ or __ net population growth
decline
increase
little; no
What is the equation for intraspecific competition only (i.e., logistic population growth)
dN/dt = rN ((K-N)/K),
dN/dt =0 when N=K
What’s the equation for intraspecific and interspecific competition
dN2/dt = r2N2 ((K2 - N2 - alpha2,1 * N1)/ K2)
dN2/dt=0 when N2 = K2 - alpha 2,1 * N1
Define a niche
set of environmental factors that influence the survival, growth, and reproduction of species, consisting of many factors (temperature), including factors that species may compete for (food, resources, space)
Define the two rules to competitive exclusion principle
two species with identical species cannot coexist indefinitely
species that do coexist must have different niches
Describe the competitive exclusion principle: two species with identical niches cannot coexist indefinitely
a shared resource (water, nitrogen, food, space) will eventually be depleted to a level that is too low for the less efficient species to persist
remember, efficiency = ability to continue growing on a small amount of resource)
Describe the competitive exclusion principle: species that do coexist must have different niches
two species that coexist by using different resources will have different adaptations
Relate the competitive exclusion principle to the galapagos finches
beaks are important in obtaining food, and beak properties (size) correspond with the type of food that finches (and many other birds) eat, the use of different food sources among co-existing finches should correspond with differences in beak properties
By using different resources (__ __), the finches don’t have the same feeding _- and they can ___
resource partitioning
niches
co-exist
Define the phenotypic variation that can occur with resource partitioning
birds with larger beaks ate harder seeds, birds with smaller beaks ate softer seeds
Link between __ trait and feeding __; drought resulted in few seeds, all hard - which birds survived?
adaptive
niche
only birds with the largest beaks survived - natural selection + environmental influence
Describe parasitoid resource partitioning
many wasps and flies are parasitoids
wasps developed on smaller caterpillars, flies developed on larger catepillars
Define character displacement
an evolutionary shift in a population’s traits to reduce niche overlap and competition
When two species occur apart (when they are __), they have similar beak sizes, with some degree of overlap in size
allopatric
When populations of the two different species live in the same place (when they are __) their beak sizes __ from each other; and beak sizes of each population is __ when compared with __ populations of their own species; this reflects selection for traits that __ competition because less __ equals greater __
sympatric
diverge
shifted
reduce
competition; fitness
Give some examples of competition that has evolutionary consequences
character displacement, resource partitioning, and co-existence
If two species with identical niches cannot co-exist, then will once species lead to the local extinction (extirpation) of the other species with similar niches?
yes, competitive exclusion principle
Define character displacement
an evolutionary shift in a population’s traits to reduce niche overlap and competition
Give an example of character displacement
two allopatric species of finches have similar beak depth, once they become sympatric, there is a differentiation or shift in beak size to reduce competition
A species that can persist well under certain conditions (within fundamental niche) can be driven to __ under those same conditions when forced to compete with other species (revealing narrow __ of realized niche)
exclusion
limits
T/F: A fundamental niche is the same as a realized niche
false; certain conditions might be within a population’s fundamental nice, but not within its realized niche when forced to compete with another species
Higher resource use efficiency is a cause of __ __
competitive exclusion
Intraspecific competition: at higher snail densities (and thus lower food supplies) snail growth rates __
decline
When does exploitation occur?
when one organisms obtains resources, nutrients, or energy by consuming all or part of another (not always lethally)
Exploitation interactions regulate __ __
population density
Does a parasitic infection of a predator species (foxes) allow its prey resource (hares) to increase in abundance?
foxes decrease in population due to mange outbreak, hares increase due to no fox regulation
How does herbivory affect plant populations?
intense rainfall increased mortality and reduced flowering of cactus
cacti were unable to produce seeds due to exploitation of flowers by finch, which reduced cactus population in later years
T/F: Most ecological phenomenon are outcome of one cause
false - most ecological phenomenon is the outcome of many causes
the challenge of ecologists is to identify the relative importance of the various causes
What are three examples of exploitation?
predation, parasitism, and herbivory
what is a top-down control of hare populations?
predators impact hare population
what is an example of a bottom-up approach?
food (plants) regulate hare density
What is a natural experiment and why is it helpful?
mother nature does the manipulation for you
broad scales are often too difficult to manipulate - can’t do a whole exclusion experiment at the scale of an entire country
What are three examples of exploitation?
excluding caddisflies allowed algae/bacteria populations to increase
excluding foxes allowed hare populations to increase
excluding insectivorous birds and bats allowed insect densities to increase
Define interaction between experimental factors
arises when the effect of one factor depends on whether the other factor is imposed
Is predation the number one important factor in regulating population density?
no - food supply is
Define a factorial experimental design
both treatment levels in one of the experimental factors were present within each treatment level of the other experimental factor
Give an example of a 2x2 factorial design
predators present v. predators excluded
supplemental food v. ambient food under each predators (present and excluded)
Interactive suggests __
non-additive
Discuss the life cycle of plagiorhynchus
adult plag. (parasitic worm) lay eggs in primary host (european starling)
parasite eggs released into environment in bird feces
secondary host (pill bugs) eat bird feces and become infected with plagiorhynchus, which matures within the pill bug
mature plag. infect the primary host (starlings) when starlings eat pill bugs
cycle repeats
What increases the chance of a pill bug being eaten?
infected pill bugs spent less time in sheltered areas and more time on light-colored substrates
these behavioral changes increase the chance a pill bug is seen and eaten by a bird, enhancing its own transmission to a primary host
T/F: exploitation can change the outcome of competition
true
Dynamics within a population are often?
cyclic
Describe the cyclic population density pattern in exploiter-resource interactions
incr predator densities causes prey to decline
depletion of food (prey) causes predator density to decline
declining predator population allows prey population to recover
abundant prey allows predator numbers to begin increasing
What are three types of refuge
places that are difficult for predators to find or access
high densities (predator confusion and satiation)
being big
Refuges allow the persistence of prey or hots in the face or __/__
predation/ parasitism
T/F: Even incomplete protection enables coexistence of predator and prey
true - refuge
Discuss the paradox of refuges
no refuge - both predator and prey go extinct
perfect refuge for prey - predator goes extinct
incomplete refuge - cyclic populations
Define mutalism
an interaction between species in which each receives a benefit (resources, habitat, protection) from the other
Define a commensal interaction
one species benefits, the other is neither benefitted or harmed
What is a facultative mutalist
organisms that can live without their mutualistic partner
What is an obligate mutualist?
organism that cannot live in the absence of the other partner
What is the endosymbiotic theory?
Eukarya arose from symbiotic relationships between primitive eukaryotes and bacteria (prokaryotes)
modern __ (which convert sugars to APT) and __ (which perform photosynthesis) arose from these bacterial partners
mitochondria; chloroplasts
How are mitochondria and chloroplasts similar to a free-living bacterial cell?
have double membranes
have their own genetic material
genomes have bacterial-type genes for ribosomes
What are three benefits to plants in a mutualist relationship?
nutrient and water acquisition
protection from herbivores
pollination and seed dispersal
Nitrogen is often a __ __ for plant growth
limiting resource
Describe the relationship between plants and N fixing bacteria
n-fixing bacteria pull atomospheric N into soil, fertilizing these plants
Most atmospheric N is present as an N _ bonded to N, which requires __ to break; this bond can be broken by bacteria, which fix N, bringing it ino a biologically usable form; in return, N-fixing bacteria get some of the __ (__ __) they need from the plant
triple
energy
energy (organic carbon)
What is the advantage to having mycorrhizal fungi?
acquire many resources that are already in the soil
Why do plants form partnerships with mycorrihizae fungi?
to increase plant access to soil resources by fungi increasing the root surface area and so enhance the ability of plants to take up nutrients and water; may also help protect plants from root predators
What do mycorrhizae fungi get in return from plants?
carbon
What kind of effect does mycorrhizae fungi have on leaf water potential?
infected plants (with fungi) maintained a higher water potential; removal showed reduced rates of transpiration
When a soil nutrient (phosphorus) is __, the maize plant strongly depends on mycorrhizae. When P is __, the plant does not need the mutualism as much. Plants give __ to fungi, which helps fungi explore soil and get P for plant to use, if plants can get P on their own, their is little value in giving away __ to fungi
scares
abundant
C
C
When would mutualists turn parasitic?
if plant is being stingy and not giving away enough C, the fungi will parasitize the plant
Benefit for plants is __ when paired with fungi that developed in unfertilized soil than when paired with fungi that developed in fertilized soil
greater
Fungi are less beneficial if they come from the __ where plants are stingy
environment
Describe the mutualistic relationship between swollen thron acacia and pseudomyrmex ants
ants give significant defensive response to any attack on home tree
trees give soft pith easily dug out by ants, provides shelter, water, sugar, fats and proteins
New sprouts of acadia tree with ants grew seven times __ than those without ants
faster - demonstrates mutualistic relationship
What is likely a reason that new acadia trees with ants had a better survival rate?
ants provided defense against herbivores
ants also prune away leaves from nearby plants, likely reducing competition
Discuss the mutualistic relationship between coral polyps and zooxanthelle (algae)
coral animals (polyps) catch and kill prey, supplying nutrients to the zooxanthellae
zooxanthellae photosynthesize, supplying organic compounds to the coral in return
How does coral control zooxanthellae?
coral uses signal compounds that alter the permeability of the algae’s cell membrane
Coral controls the population __ rate of zooxanthellae
growth
Zooxanthellae heavily use the _ provided by the coral polyp animal. so the __ stays inside the polyp/algae unit
N;N
Describe the obligate mutualist relationship between coral and crusaceans
crabs and shrimp protect coral from predators and receive food and shelter in return
lipid packaged into fat bodies that are fed to the crustaceans are only in the presence of crustaceans
The diversity of a community is an outcome of… (3)
the abiotic environment and fundamental niches of species
population dynamics: dispersal and extinction
interactions among species
Diversity is also (2)
a building-block of the structure of communities
a factor that affects how ecosystems function
Most species are __ or of modest __
rare; abundance
Very few species are present at __ population density
high
If you use a lognormal distribution, patterns of diversity are shaped like a __ distribution if you use a __ scale on the _ axis
normal
logarithmic
x
what does a rank abundance curve show?
abundance of each species, sorted by abundance rank
a community is more diverse when both the species __ and __ is higher
richness; eveness
What is a species eveness?
how even the most abundant species is across a community
What is species richness?
total number of species in an area
Species diversity is just one aspect of __
biodiversity
How do you measure biodiversity?
through genetic diversity among populations within a species and among members of a population
Define biodiversity
variety of living things and their functions
Define species diversity
number and eveness of species
define community diversity
variety of communites; across a broad area, there can be many distict types of species groupings
Define functional species
a. types of species (diversity of niches and tropic levels) or
b. things species do (diversity of processes, like nitrogen fixation)
Define species (biological)
a group of individuals that can interbreed and have offspring capable of reproduction
Define species (phylogenetic)
a group of individuals whose members are descended from a common ancestor and who all possess a combination of certain defining, or derived, traits
What are the two concepts for defining a bacterial species?
recombination
ecological species
Define the recombination concept
emphasizes the homogenizing mechanism of sharing genome fragments, somewhat akin to sexual recombination
Define the ecological species concept
emphasizes a microbial taxon’s ecological niche as a set of environmental conditions that maintains cohesive lineages
Bacteria and archea form coherent __ clusters that are chacterized by distinctive __ properties; clusters are created by __ and __
genomic; phenotypic
selection; recombination
__ __ is one factor regulating diversity
environmental complexity
High environmental complexity is often characterized by higher __ __
species richness
Even ecosystems that appear simple and homogeneous can actually be __ and __
complex; heterogeneous
abandoned agricultural field
Many fertilized soil had __ fungal diversity
lower
Why would fungal diversity decrease with fertilizer increase?
as the farm field became more fertilized over time, rank abundance curves became steeper (less evenness) and shorter (less richness)
What area has the highest plant diversity?
tropical rainforests - Ghana
Describe the biome in tropical Ghana
rainy areas; acidic soils; low nutrient concentration
List evolutionary reasons that show diversity declines as environment becomes enriched in nutrients
1 nutrients are typically in scarce supply, and the limiting nutrient is super scarce
2 natural selection has thus resulted in adaptations for acquiring nutrients from nutrient-poor environments
3 but when nutrients are made highly abundant (thru human activities) these adaptive traits are no longer an advantage
4 in fact, principles of allocation and evolutionary tradeoffs suggests these adaptations have become a burden
5 the small number of species that don’t invest in such traits can invest in fast growth when resources are abundant
6 these few species will competitively displace most others that cant convert resources directly to growth
List spatial reasons that show diversity declines as environment becomes enriched in nutrients
1 spatial heterogeneity in resource availability creates environmental complexity and supports high diversity
2 lots of patches with different levels of resource supply, and with differences in which particular resource is scarce = lots of distinct niches
3 high nutrient availability everywhere reduces spatial heterogeneity
4 where soil resources are high, light is the only limiting resource
5 life becomes a race for light, a few species that can get tall fast will prevail
Define disturbance
discrete event that disrupts ecosystems, communities, or population structure changes resources, substrate availability, or the physical environment
Disturbances result from both abiotic factors (__) and biotic factors (__ __)
volcano
disease outbreak
What is the intermediate disturbance hypothesis
low intensity of disturbance - competitive exclusion, keeps diversity low
high intensity of disturbance - community becomes limited to rapid colonizers and quick reproduces
only an intermediate level of disturbance shows highest species diversity
Environmental variation supports high __ diversity
biological
What is alpha diversity
amount of different species within a given area
What is gamma diversity?
total species diversity in a landscape - will only count new species in each alpha group
If the community were to change a lot from one mountain to the next, species turnover would be __
high
as you move from mountain to mountain, the communities are mostly made up of the same species suggesting __ species turnover
low
the diversity of a community is a balance between __ by new species and __ of species that are already present
colonization; extinction
Define insular
any area of habitat suitable for a specific ecosystem that is surrounded by an expanse of unsuitable habitat (mountaintop, island, nature preserve)
We should expect many species where colonization rates are high and extinction rates are low in (2 habitats)
1 habitats that are well connected to colonization sources
2 large habitats with a diversity of niches
We would expect few species where colonization rates are low and extinction rates are high in two habitats
isolated habitats that potential colonists have a hard time reaching
small habitats with a few niches
Larger islands support more __
species
T/F: Species richness is greater on smaller island
FALSE; more area probably represents a greater variety of habitats (more environmental complexity), yielding more niches and thus more species (extinction < colonization)
There is greater bird species richness observed on __-isolated islands
less
__ doesn’t reduce colonization, __ does
distance; isolation
Isolation results from the __ of __ corridors
absences; dispersal
species richness of mammals is greater on __ mountaintop areas
larger; more area = greater variety of habitats
As the number of species on an island increases, the extinction rate __, because with more species-an more exploitation and competition, its __ likely that some species will go extinct
increases;
more
Community diversity stabilizes at an equilibrum _ __ (S)
species richness
At some __ __, the rate of colonization by species equals the rate of extinction present on the island
species richness (S)
As species richness increases, the rate at which new species arrive will __
decline
Define species turnover
refers to a change in which species are present because of ongoing colonization and extinction; species richness doesn’t have to change
The equilibrium model of biogeography predicts __ __
species turnover
What is an equilibrium model of biogeography?
model that tracts the number of extinctions and immigrations (species turnover) in various areas over time
List three postulates that will hold true if a species supports the equilibrium model
as the islands aged, species richness on each island approached an equilibrium
on each island, there is an ongoing colonization and extinction despite little further change in species richness
larger islands eventually do accumulate more species than smaller islands do
Describe evidence for the equilibrium model in the florida keys
all insects experimentally removed (fumigated)
afterwards .. insect diversity recovered, but did not continue increasing without end, returned to about the pre-fumigation equilibrium species richness and then leveled off
richness was lower on the more isolated island
Size reduction of islands led to rapid __, with no compensating increase of __, leading to a __ final S
extinction; colonization
lower
T/F: the area-diversity pattern applies beyond small insular areas like lakes, mountaintops, and islands
true
greater species richness is observed on larger continents and regions, rather than smaller ones
Define the latitudinal richness gradient
species richness of many groups is highest near the equator (in the tropics) and declines with latitude (toward the poles)
What is one hypothesis for the latiudinal richness gradient?
there is way more land area in the tropics than in other climate zones
__ regulates __
area; richness
Species richness can be a __ of __
legacy
history
Describe species richness as a legacy of history
Mediterranean-type climate of the Cape used to be found in huge areas of central Africa (large source of species) so even though it is small today, it is representative of a once-large area where we would therefore expect high diversity
Diversity today may reflect __ episodes of speciation
past
Why are East Asia’s temperate forests 3-6 times more diverse?
center of temperate tree speciation, maybe explaining really high diversity in that region
history matters for diversity more so than the current size of a region does
__ and the orienation of __ ranges appear to influence diversity
glaciation; mountain
Why is species diversity so low in europe?
most european mountain ranges have an E-W orientation
What is an E-W orientation, and what does it mean for diversity?
orientation would have blocked southward retreat for tree species as glaciers advanced; this inference is backed up by estimates of plant extinction rates in three regions (the highest is in europe)
During periods of cooling and glacial advance, species in the northern hemisphere need to travel __ to remain in their __ zone
southward
climate
Bird diversity is highest where the foliage height diversity was the __ (in argentina)
lowest
Foliage high diversity in northern temperate forests shows bird specie diversity is highest when foliage height diversity is __
high
Why would the two birds and foliage height diversity show different patterns?
island biogeography effects were more important than the effects of environmental complexity in determining diversity
What factors may break the rules?
importance of area, isolation, and environmental heterogeneity for controlling diversity
