Ecology and Evolution Quiz Three

what part of differential equation for logistic growth is the "brakes"

1 - N/K

Life table

A summary of how survival and reproductive rates vary with the age of organisms.

Life history traits

Age at first reproduction duration and schedule of reproduction Number of offspring Size of offspring Lifespan Maintenance

Why do all populations eventually reach a carrying capacity

Because Earth is a finite planet and cannot support ever-increasing numbers of any species. Something will eventually limit them.

Sequential hermaphroditism

Changes in sex during the course of the life cycle

David Lack experiment 1947

Clutch size (number eggs produced per reproductive cycle) limited by maximum number of young parents can raise at once. In clutches with fewer eggs, chances of survival better. When they attempt to rear too many, offspring will be more likely to starve. Larger clutches at higher latitudes bc longer daylight

Why do clownfish bother being nonbreeders under dominance of single breeding female and male

Depend on the protection of anemones for survival. More likely to survive under this system than try to find another anemone or just chill in the ocean

Density independent factors

Effects on birth and death rates independent of the number of individuals in population ex: temperature, predation, catastrophic events

T/F density independent factors are an important method to regulate population size

False - they do not regulate population size because they do not consistently increase population size when small and decrease when large

T/F survivorship curves are constant for each species

False. They can vary among populations of a species, between males and females, among cohorts.

Seahorse mating

Female transfers unfertilized eggs to male. male stores eggs and fertilizes them. Males are more likely to mate with larger females and eggs from larger females are more likely to be successfully transferred to males and develop into viable offspring. Female competition - bigger, fancier fins, brighter colors

What happens when operational sex ratio is female-biased, i.e. more females are ready to mate than males

Females compete over limited number of reproductively ready males. females become larger and more aggressive than males, and they possess territories that include male nests. they mate with all males in this territory and then the males take care of the chicks.

Effect of removing ovaries of lizards

Females without ovaries grew faster because they had free resources to invest in growth. Females with ovaries invested resources to grow eggs

Life-history trade-off in guppies

Guppy populations in areas of high predation have more, smaller offspring which reproduce earlier. populations in areas of low predation have fewer, larger offspring which reproduce later

How is miscarriage adaptive

If fertilized eggs carry harmful mutations spontaneous abortion often happens

Trade offs occur when

Individuals allocate their limited energy or other resources to one structure/function at the expense of another

Type II survivorship curve

Individuals have an approximately constant chance of surviving from one age to the next throughout their life. On log scale, straight negatively sloped line

What huge event made the human population start increasing super fast

Industrial revolution

Type III survivorship curve

Lots of young die but those that live are likely to stay living. On log scale, sharp drop and then slightly negative line.

Lack Clutch Size

Maximum number of offspring that a parent can successfully raise to maturity

What happens if larval habitat is extremely favorable for growth and survival

Metamorphosis is delayed or sometimes eliminated altogether (paedomorphism)

Western fence lizard shows size-number trade-off because

More eggs and smaller size in Washington, Less eggs and bigger size in california

Lack's hypothesis on clutch size

Most productive clutch size should be the clutch size most commonly observed in nature.

How to estimate survivors

Multiply number of individuals in each age class (Nx) by survival rate for the age class (Sx).

What is the quantity-quality trade-off expression? define variables

N = R/C N = number of offspring R = reproduction C = cost (size of offspring, essentially)

Exponential growth equation

N(t) = N(0)e^rt dN/dt = rN

Type I survivorship curve

Newborns, juveniles, and young adults have high survival rates and death rates do not begin to increase greatly until old age. Ex: US population. on log scale, it's straight for a long time then drops off

Geometric growth equation

Nt+1 = λNt

Nx

Number of individuals alive at age x

Number of young song sparrows at different densities graph (figure 10.15 CE)

Number of young per female that survived to independence declined with population density. Nesting pairs that were fed more reared more young to independence

Life history

Pattern of investment an organism makes in growth and reproduction

Explain a way age structure can influence whether population increases or decreases in size

Populations w members of around 20-30 years old will grow more rapidly than ones w members 50+ years old bc more individuals at reproductive age

What does dN / dt represent

Rate of change in population size at time T

When Sinervo raised fence lizard eggs and removed some yolk from some

Reduced eggs developed faster but produced smaller hatchlings

If λ is constant over time, what happens to the proportion of individuals in each age class?

Remains constant - "stable age distribution"

paedomorphism

Retention of juvenile features in the adult

Common propagule tradeoff

Size vs. number

When age-specific survival and fecundity / birth and death rates are constant over time, one should expect λ to do what?

Stay constant over time

Static life table

Survival and reproduction of individuals of different ages are recorded during a single time period.

Fecundity (Fx)

The average number of offspring produced by a female while she is of age x

How is size hierarchy maintained in clownfish

The largest fish in a reef is the female. The rest are "ranked" so each fish is smaller than the one ahead of it in rank. Largest male - breeding. If a fish grows to be too close in size to one of its anemone-mates a fight results which usually ends in smaller fish being killed or expelled

Selection favors the optimal strategy for reproduction. What does this mean?

The one that maximizes the number of offspring that survive to maturity

Age structure

The proportions of the population in each age class

How do male sand gobies regulate offspring number

They eat eggs if oxygen concentration is low because it raises the probability of surviving for the ones left

Why do Seychelles warbler manipulate sex ratio in direction opposite to expected

They produce males when they're in worse conditions so that the male birds can fly away and search for different territories. In better conditions, they produce more females so they can stay behind and help mother

Age-specific survival rate. (Sx)

This is the chance that an individual of age x will survive to the age x + 1.

Survivorship (Ix )

This is the proportion of individuals that survive from birth to age x.

Doubling time

Time it takes for N0 to become 2N0 td = ln(2)/r

T/F selection can shape how organisms invest in reproduction over their lifetimes

True

Compare US survivorship and Gambian survivorship

US survivorship does not drop greatly until old age. Gambians die earlier. Gambians born in hungry season die even faster.

Exponential growth

When a population changes in size by a constant proportion at each instant in time

Geometric growth

When a population changes in size by a constant proportion from one discrete time period to the next

Population regulation

When one or more density-dependent factors cause population size to increase when numbers are low and decrease when numbers are high

Mechanisms to help small, vulnerable stages of life

Yolk Energetically expensive egg capsules - endosperm. kernels, meat of coconut Physical protection

How do insects who can do haplodiploidy (unfertilized = male; fertilized = female) regulate sex ratio?

You only need a few males, so when clutch sizes are larger there is a smaller male:female ratio (aka there are more females)

How does an organism reduce risk of investing

adjust the family - adjust number of offspring; manipulate ratio of sons to daughters

As densities increase it is common for

birth rates to decrease death rates to increase dispersal from population to increase --> decreased pop size

Dispersal is beneficial because

can reduce competition between relatives can allow organisms to reach new areas to grow and reproduce can increase chance of escaping regions of high mortality - pathogens, predators

K

carrying capacity

When number of young maturing is equal to mortality rate, the population size is called the

carrying capacity

Density-dependent factors

cause birth rates, death rates, or dispersal rates to change as density of population increases.

differential equation for logistic growth

dN/dT = rN (1 - N/K)

Logistic equation

dN/dT = rN (1 - N/K) rN - gas (1 - N/K) is net effect of limiting factors - brake

Higher annual fecundity in 14 different bird species was associated with

decline in annual survival rate

What happens to population growth rates at high densities

decline. both λ and r

Why are differences in morphology and behavior adaptive at different life cycle stages?

differences in selection pressures over the course of the life cycle. this can pair particular functions with particular stages and reduce some of the trade-offs that result from simultaneously optimizing multiple functions.

Small size benefits and drawbacks

drawbacks - vulnerable to predation, poor competitors for food, susceptible to environmental perturbations benefits - can perform essential functions impossible for large adult stages. dispersal, dormancy

Which affects an organism's fitness more: mutation that is beneficial early in life or late in life

early in life

Which affects an organism's fitness more: mutation that is deleterious early in life or late in life

early in life

propagules

eggs or seeds

r

exponential growth rate / intrinsic rate of increase

Cohort life table

follows the fate of a group of individuals born during the same time period until death

Assuming females limit reproduction, if a female is in bad condition, it is in her best interest to

have more females. they will probably reproduce at least once whereas males in poor condition may not

Assuming females limit reproduction, if a female is in good condition, it is in her best interest to

have more sons in good conditions who can mate with many partners

Austad's mainland vs island opossums

island opossums live 25% longer and have springier tendons (age slower). Fewer offspring = tradeoff.

Allocating resources to current reproduction can

lead to a decrease in an individual's growth rate, survival rate, or potential for future reproduction

General hypothesis - sex changes are timed to take advantage of

maximum reproductive potential of different sexes at different sizes

What happens to the operational sex ratio when both females and males cooperate in care of young

more even. males and females equally "tied down"

Dispersal

movement of organisms or propagules from birthplace.

The size of seeds a species produces is ________ correlated with the number of seeds it produces

negatively

When a population that is growing exponentially is ploted on normal vs. log scale

normal - J log - straight line

When eggs artificially removed, females will have more eggs. This leads to drop in

nutritional quality of later-produced eggs - lower lipid content. survivorship

When λ < 1 or r < 0

population decreases size

When λ > 1 or r > 0

population increases exponentially in size

When λ = 1 or r = 0

population size does not change

what part of differential equation for logistic growth is the "gas"

rN

Why do island opossums differ in reproduction

since they live longer, a slower, yet still successful, reproductive strategy evolved

Niche shift

size- or age-specific changes in an organism's ecological function or habitat

Benefit of being small for dispersal

smaller propagules disperse more readily and can travel farther

Benefit of being small for dormancy

smaller seeds, eggs, and embryos are better suited to dormancy than large multicellular organisms because they do not have to expend as much metabolic energy to stay alive

Dormancy

state of suspended growth and development in which an organism can survive unfavorable conditions

How to estimate newborns in following year

sum of (Fx)*(Nx)

Larvae often spend all their time

taking in food and turning it into body mass, without forming many complex morphological structures

The fact that the thickness of annual growth rings declines in Douglas fir trees that produce many cones indicates

there is a reproduction vs. growth trade-off

Drosophila males kept with virgin females vs. previously mated females

they spend more time and energy courting unmated females, so they had shorter life span (independent of size - males w larger size tend to live longer anyway) *take-away -* there is cost of sexual activity

Quantity-Size tradeoff

trade-off between investment in each individual offspring and number of offspring produced. Large investment --> less offspring; small investment --> more offspring.

When might you expect a niche shift to occur

when the organism reaches a size at which conditions are more favorable for its survival or growth in the adult habitat than in the larval habitat

lambda (λ) symbolizes

year to year population growth rate λ = (Nt+1/Nt) ex: if population at time 0 is 100 and at time 1 is 138, λ is 1.38

Why does dN / dt approach zero when population size nears carrying capacity

you can't change a lot growth wise anymore

Relationship between λ and r

λ = e^r r = ln(λ)