Ecology Ch. 12

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, r_max 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