In species where adults have lower survival rates,
individuals will allocate more energy
intro reproduction and begin to reproduce earlier
The “equilibrium” strategy is similar to K selected
species because they both have low
numbers of offspring; high juvenile survival; late reproductive maturity
The life study of adaptations that influence the
number of offspring of an organism produces is known as life history
Most species do not fit exactly into a specific life
history classification. TRUE
Organisms often face many selective pressures for
life histories. However, in plants, the two most important forces exerting
selective pressure on plants is the intensity
of disturbance; intensity of stress
Natural selection will favor allocating more
resources to reproduction when adult
survival is lower compared to juvenile survival
When comparing the relative size of offspring in
mammals, altricial birds, and lizards: lizards
had the smallest relative offspring size; each group differed in their relative
offspring size; birds had the largest relative offspring size
Populations that experience lower rates of mortality
would show lower relative reproductive
effort
A scientist studying the life history of a
particular species would ask which of the following questions? What the trade-offs for producing either
many small offspring or several large offspring?; what are the factors that
influence age at first reproduction?
Woody plants and vines produce larger seeds than graminoids
The three life history strategies for fish proposed
by Winemiller and Rose include: equilibrium,
periodic, opportunistic
The intensity of disturbance and stress
are considered the most important selective forces on plants
High levels of gene flow would most likely lead to genetically similar populations
Stress on plants can be caused by low nutrients, too little light, too little
water
A population that is under r selection would be maximizing population growth rates
Reproductive effort includes: the allocation of energy, the allocation of time
The life study of adaptations that influence the
number of offspring an organism produces is known as life history
If an organism produces many offspring, the offspring will be small because of
limited energy resources
Based on Shine and Charnov’s studies, the benefits
of delaying reproduction include: higher
reproductive rates, higher growth rates as juveniles
Early reproduction and smaller body size is
indicative of an r selective species
A plant found in a disturbed habitat: can grow and produce seeds rapidly
Environmental conditions that limit the growth of
plants is known as stress
Stress-tolerant plants correspond to K selection
One of the biggest trade-offs in reproduction for
many organisms is the number of
offspring versus the size of the offspring
A major factor in determining the age at first
reproduction in lizards and snakes is adult
mortality rates
The process during which seeds begin to grow is
known as germination
The number of eggs or seeds produced by an organism
is known as fecundity
Shine and Charnov in 1992 indicate that only adults
would allocate energy to reproduction
Plants that produce many seeds have seeds that are smaller
Organisms often face many selective pressures for
life histories. However, in plants, the two most important forces exerting
selective pressure on plants is the intensity
of stress, intensity of disturbance
A population that is maintained near its carrying
capacity is under K selection
Populations of darters with higher rates of gene
flow typically produce many smaller eggs
Stress-tolerant plants are characterized as: slow growing, typically evergreen
A population with high mortality would be expected to
have a high reproductive effort
Any process that removes biomass from an ecosystem
is known as a disturbance
What is the advantage to producing smaller seeds? A plant can produce greater number of seeds
If an organism is reproducing, then it may allocate less energy to growth and
maintenance
Typically Graminoids produce the smallest seeds
K selected populations maintain populations near the carrying capacity
Shine and Charnov point out that a juvenile will
allocate resources to growth and
maintenance only
Examples of disturbances would include: floods, fires, hurricanes
Populations with very similar allelic frequencies
would indicate that the populations are
genetically similar; high levels of gene flow between populations; little
population structure
A plant that can live high-stress conditions but low
disturbances are stress-tolerant
Plants that are ruderal correspond to r selection
Larger seeds may outperform smaller seeds in a
deciduous forest because: the larger
seeds provide more energy reserves for additional seedling growth; they can
penetrate a thick layer of litter on the forest floor; they can emerge early in
the spring to gain access to sunlight before other plants produce leaves
Removing size and time effects allows scientist to make comparisons of life history strategies
across different evolutionary phylogenies
Selwa’s and Kikuzawa’s studies on seed size
demonstrated that larger seeds produce
larger seedlings
What are the characteristics of darters that make
them an ideal study organism for studying gene flow? Darters are a taxonomically diverse group; darters vary greatly in
their life history characteristics; darters live in similar habitats and also
have similar anatomy
Which of the following are environmental extremes
that plants can experience? High
disturbance, low stress; low disturbance, low stress; low disturbance, high
stress
Based on the principle of allocation, an organism that puts energy into growth will have less
energy available to reproduction
An organism that are in predictable environments are
often under K selection
Jacobsson and Eriksson create control plots to
determine how many of the plants would
have germinated without being planted
Females are often used to study reproductive effort
because: males expend energy in nest
building and territory guarding; their effort is mostly limited to egg
production
Life history variation within a species is similar
to interspecific variation in that the
age at first reproduction is later where the adults experience lower mortality
Seeds that are cached by birds or mammals are
classified by Westoby, Leishman, and Lord as scatter hoarded
K selected species are likely to have: constant mortality rate regardless of age;
high survival in early and middle life followed by a rapid decline later in
life
Larger seed size may be important in environments where competition with plants already
present is high
Which of the following are factors that limit the
rate of energy intake for an organism? Food
availability; how fast the organism can process food
Populations that are found in high areas with high
levels of disturbance are most likely under r selection
The equation for the proportion of adult body mass
allocated to reproduction over a life span is C*E
Clutch size in fish can range from two to 600 million
A polymorphic locus has two or more alleles
The equation for the dimensionless variable for
relative offspring size is l/m
Bertschy and Fox estimated the ages of sunfish in
Canadian lakes by measuring the length
of the fish
Plants that are found in highly disturbed habitats
are referred to as ruderals
The sand spur, often found at sandy beaches, has
barbs that latch onto fur or skin. This plant’s mode of dispersal would best be
described as adhesion-adapted
When different alleles are found in a population
that synthesize different allozymes, this is known as a polymorphic locus
Jacobsson and Ericksson created control plots by not planting seeds in half of the plots
The proportion of adult body mass allocated to
reproduction over a lifespan can be determined by multiplying the body mass allocated to reproduction by the adult life
span
Populations that are r selected are most likely to
be found in environments with higher
rates of disturbance
Which group of animals shows the most variation in
life history traits? Fish
Seeds with an elalosome are most likely dispersed by
ants
A species whose population remains near the carrying
capacity would favor efficient
utilization of resources
Survival rate among adult sunfish in different
populations ranged from one adult in
five to two out of three
Plants classified as ruderal may depend on disturbance to reduce competition among other plants
The relative size of offspring can be determined by dividing the mass of the offspring once it
leaves the parent (l) by the mass of the adult at first reproduction (m)
A plant that may last for several years and has
thickening tissues that provide support would be classified as a woody plant
Determining mechanisms that select for seed size in
plants is difficult due to the varied
growth forms of plants
Plants that produce the largest seeds are most
likely scatter hoarded
A fish that combines low juvenile survival with high
numbers of offspring and late maturity would have what kind of life history
strategy? Periodic
Dividing the total number of recruits by the total
number of seeds would be calculating the recruitment
success
The largest seeds known are produced by coconut palms
The gonadosomatic index (GSI) is calculated by dividing the weight of the ovaries by the
body weight with an adjustment for number of batches per year
The main purpose of Bertschy and Fox’s study was to
explain how life history evolves
variations within a species
The trade-off between offspring size and number in
darters is darters that produce larger
eggs produce fewer eggs
The intrinsic rate of increase, rmax is
highest in species that are r selected
An organism that has a single reproductive event is semelparous
An organism with a type I surviroship curve that
reproduces many times throughout its life is iteroparous
Which of the following was the main mechanism
observed by Turner and Trexler for isolating populations? Larger egg size
Bertch and Fox (1997) studied pumpkinseed sunfish to
determine how adult survival influences
the evolution of the age at reproduction
When favorable conditions are infrequent, which strategy
may be the best to ensure reproductive success? Periodic
Plants that produced the smallest seeds most likely have unassisted dispersal
Development would be slowest in species maximizing competitive ability
A blue whale that reproduces every few years
throughout its life is iteroparous
Determining mechanisms that select for seed size in
plants is difficult due to the varied
growth forms of plants
The smallest seeds known are produced by orchids
A particular species of long-lived shark may only
reproduce once every 5 years. How would the gonadosomatic index be adjusted? The weight of the ovary would be divided by
5
The findings of Turner and Trexler found that larger
darters produce a larger number of eggs
Darters that lay larger eggs are more likely to have
isolated populations because the young are
larger when they hatch, begin to feed sooner, and spend less time in the
current
Comparing epiphytes to trees to determine the
mechanisms driving the evolution of seed size is difficult because of the various growth forms of plants
