question

finite

answer

The amount of energy available to an organism over the course of its life is

question

life histories

answer

Trade-offs influence organisms'

question

keep itself going at the expense of reproduction

answer

Life span (i.e. senescence) , for example, is influenced by an organism's ability to

question

-the pattern of development and growth -the life span -the timing and quantity of reproduction

answer

Life history comprises :

question

-be mature at birth -continuously produce lots of high quality offspring -live forever

answer

selection's perfect organism would

question

-mature before it hatches, mates with brother -BUT, it dies after 4 days when its offspring hatch out

answer

Female Thirps egg mite mature at birth

question

-chick almost independent in a week -BUT takes two months for two eggs, males watch them for 3 months

answer

Brown kiwiw

question

-how selection balances trade-offs in different environments leads to different *life histories*

answer

Biology and physics impose limits, fitness *trade-offs*

question

finite

answer

Reproduction is a ________ resource

question

-what is the optimal number of offspring to have? -what is the optimal parental investment for each offspring?

answer

Trade-offs during any single reproductive period :

question

natural selection to maximize parental fitness

answer

life history traits are optimized by

question

the life history traits evolve in response to ecological conditions

answer

Adaptive life history strategy evolves as

question

isolation -are linked via energy trade-offs

answer

Life history traits do not evolve in

question

benefit and a coast to the organism

answer

Investment in each life history trait has a

question

investment into a certain life history trait

answer

For each life stage, there is an optimal

question

fitness by limiting energy available for other important functions

answer

Investment beyond that optimum reduces

question

idea that purpose exists in evolution in the same sense that it does for human intention

answer

Teleology :

question

avoided when discussing evolution

answer

Teleological language and explanations must by

question

predesigned or intentional goal

answer

Evolution has no

question

a conscious choice by that organism

answer

"strategy" does not imply

question

the description of complicated evolutionary processes

answer

"Strategy" is a shortcut for

question

-like all adaptations, life history strategy is subject to constraints and needs only to be good enough -optimal life history strategy means the best of those existing in certain population under certain environmental conditions

answer

Adaptive strategy does not mean the best possible

question

-a single life history trait that determines fitness

answer

Trade-offs means that is is the overall strategy rather than

question

as an integrated unit

answer

The components of the life history strategy evolve

question

expected reproductive contribution of an individual of age x to the next generation

answer

Reproductive value (Vx) of an organism is the

question

organism's fitness

answer

The reproductive value is closely tied to the

question

life span

answer

The reproductive value changes over the course of the _____ ______

question

the interaction of lx and bx columns

answer

Reproductive value is determined by

question

age to a maximum just as the organism enters the reproductive years

answer

Vx often increases with

question

declines

answer

As the birth rate and survivorship decline with age, Vx ______

question

-at A because there is essentially no fitness -fitness is the area under the curve

answer

Where on this graph would selection against lethality be most intense?

question

the life history consists of a suite of adaptations

answer

A life history strategy refers to the fact that

question

evolution

answer

Life history strategy is the product of

question

-devote to life functions such as development, maintenance, and reproduction -therefore,it must allocate that energy in ways that maximize fitness

answer

Each organism has a finite amount of energy to

question

expected contribution of an individual age x to the next generation

answer

The reproductive value measures the

question

genetic mechanisms and phenotypic plasticity

answer

Life history is affected by both

question

-the process by which an embryo becomes an adult -the presence of dormant stages during development -the development and constancy of the organism's sex

answer

The life cycle comprises three key developmental features:

question

-Juveniles develop from the fertilized egg, grow into adults whose gender is determined genetically, live out their lives as active adults, and eventually die -ex: humans

answer

A simple life cycle:

question

-changes in the body plan, including resting stages and change in the individual's gender -ex: amphibians, insects

answer

A complex life cycle includes

question

-the adult develops directly from the fertilized egg without a larval stage

answer

Direct development:

question

a larval stage that is often radically different form the adult individual

answer

Metamorphic development entails

question

-Gametophyte (G) - haploid (n) -Sporophyte (S)- diploid (2n) -Gametes fuse to produce a sporophyte -a sporophyte produces spores which give rise to a gametophyte -a full cycle (G to G or S to S) represents sexual reproduction in plants

answer

Plants and some algae- the life cycle represents alternation of generations

question

-significant energy expenditure -vulnerability to predation at certain stages

answer

Metamorphosis costs:

question

-Specialization on different functions of different life stages -exploitation of different ecological niches -reduced competition among larvae and adults

answer

Metamorphosis advantages:

question

-sexual larval forms that no longer metamorphose into adults -seems to be more common in extreme environments -the selective forces leading to neotony are not fully understood

answer

Neotony is the development of

question

-a developmental stage in which the organism is dormant, inactive and often resistant to harsh environmental conditions -ex. seeds, spores,cysts

answer

Resting stages :

question

-allows the organism to exploit important resources

answer

One advantage of metamorphism is

question

-sex is determined early in development and remains constant throughout life

answer

Sex changes // simple life cycle

question

-sex changes during the life span -Protandrous ; an individual is first male and then female -Protogynous ; an individual is first female and then male

answer

Sex changes // Sequential Hermaphroditism

question

-requires energy and complex genetic regulation -allow the organism to exploit resource-rich environments and organize the body plan for specific functions

answer

Metamorphosis has both costs and benefits

question

harsh physical conditions

answer

Resting stages allow the organism to avoid

question

change sex during the life span

answer

If male and female success varies with age, size, resources, or the social system, it may be adaptive to

question

-species -from hours to thousands of years -ex; creosate bush: an individual plant may be >10,000 years old

answer

Life span varies greatly among

question

late life decline in fertility and probability of survival -variation across taxa

answer

Senescence :

question

-not enough energy -other tradeoffs

answer

If there is a decrease in fitness with age, then why doesn't selection act against it?

question

-gist: bodies wear out -eventually accumulation of damage: errors in DNA replication and translation, build-up of poisonous metabolites -organisms adapted to resist as long as possible -but there isn't the variation to extend life further

answer

Rate-of-Living theory

question

-aging rate should be correlated w/metabolic rate -should not be able to select for longer life spans -BUT both predictions do not hold general

answer

Rate-of-Living theory makes two predictions

question

metabolic rate

answer

Life span is not correlated with

question

-bats have higher metabolic rates than other groups, but tend to have longer lives -marsupials have lower metabolic rates, but also have shorter life spans

answer

Austad & Fischer : wide variation in lifetime expenditure of energy

question

CAN

answer

Longer life can or cannot be selected for?

question

-4 lab populations. 2 selected for early reproduction, 2 longer life -collected eggs from youngest and oldest individuals -couldn't shorten lifespan much -could almost double lifespan in 13 generations

answer

Luckinbill et al.: artificial selection on Drosophila for longer life

question

"the result of intrinsic physiological limits on cells and tissues"

answer

think of rate-of-living as

question

-at ends of chromosomes repeated sequences (teleomeres) -a bit of teleomeres lost with each division -some cells have lots of telomerase, such as germ line and cancer cells

answer

Normal cells have limits on the number of times that they can divide

question

-e.g. dyskeratosis congenita

answer

is senescence simply the result of losing our teleomeres?

question

-lived longer -BUT lots of other studies show that the relationship is not that simple

answer

Jueng et al. made C. elegans over-express a Teleomere binding-protein

question

-Limiting resources devoted to reproduction result in decreased somatic maintenance -mutation that diverts energy toward reproduction early diverts energy away from maintenance and repair

answer

Why do Organisms age? Hypothesis 1 Limiting soma theory:

question

-The intensity of natural selection declines with age -Genes whose main effects occur after the peak in Vx are not subject to the same intensity of selection as those that occur when Vx is high or increasing -Deleterious mutations then accumulate and cause senescence

answer

Why do Organisms age? Hypothesis 2

question

-deleterious mutations with effects that begin late in life are harder to remove from the population

answer

Evolutionary Theory of Aging

question

-ecological selection

answer

Island opossums have fewer predators than mainland opossums thus less

question

-have longer natural lifespans -higher reproductive success later in life -slowed rate of physiological aging

answer

Predicts that island opossums should

question

-Pleiotropic effects of genes : the action of a single gene that affects several phenotypic traits -Genes that benefit younger individuals whose reproductive value is high will be selected for even if they have deleterious pleiotropic effects that occur in old age

answer

Why Organisms Age? Hypothesis 3

question

ex: called flycatcher -some individuals breed year 1, others year 2 -early breeders have smaller broods throughout life -add extra egg, broods get smaller -thus, there is a trade-off between reproducing early and late

answer

Trade-offs : Antagonistic Pleiotropy

question

-women have steep decline in reproductive potential late in life but well before death

answer

What about menopause?

question

-women live longer then they used to -menopause not adaptive because early humans didn't live long enough -females of some captive mammals present same pattern

answer

To main hypotheses : nonadaptive effect of modern lifestyle

question

-as women age, benefit/cost of children changes -divert effort from direct fitness to indirect fitness -true in elephants too

answer

Grandmother Hypothesis

question

the individual

answer

Natural selection operates primarily on

question

if it benefits an individual

answer

Mutations can only spread through a group by selection if

question

-idea that traits are selected for the good of the group over the individual -not an evolutionary stable strategy (ESS) because selfish mutation can invade, and altruistic mutation cannot invade -How then can altruism invade?

answer

Group selection :

question

-evolved organization of cells -act to increase indirect fitness

answer

Altruism can invade by

question

-interacts with pleiotropic effects

answer

The evolution of the life span

question

trade-offs in life history characters

answer

Finite energy available to an organism leads to

question

true in biological systems

answer

Generally speaking "live fast die young" isnt

question

the combination of external and internal factors that increase mortality as a function of age

answer

Senescence results from

question

-increase the life span

answer

Life span has a genetic component, selection can

question

-late-effect deleterious mutations -trade-offs between reproduction & maintenance -antagonistic pleiotropy

answer

Three mechanisms contribute to the evolution of senescence :

question

reproductive effort

answer

Selection optimizes

question

-cost that must be budgeted

answer

reproductive effort :

question

other functions

answer

Energy spent on reproduction can't be spent on

question

shorten

answer

Early reproduction can _______ lifespan

question

-How many offspring? -How much should be invested in each one?

answer

How much effort to put into reproduction in a given season?

question

maximized -to get the most offspring into future generations

answer

If trade-offs optimized, reproduction should be

question

increase

answer

High reproduction does not always ________ fitness

question

-enlarged clutches of pled avocet led to poorer quality of the occupied territories and higher chick mortality, decreasing their net reproductive success -removal of an egg from the female, anole lizards, leads to a higher survival to the next reproductive event due to the increase in the females stamina, sprint speed, and growth

answer

Examples of high reproduction not increasing fitness

question

iteroparous

answer

organisms that reproduce multiple times :

question

semelparous

answer

organisms that reproduce just once are :

question

variation

answer

Usually very little _______ in offspring size in most species

question

There is a trade-off between size and number of offspring

answer

Optimal compromise between size and number of offspring Assumption 1:

question

Above a minimum size, the probability that any individual offspring will survive is an increasing function of its size

answer

Optimal compromise between size and number of offspring Assumption 2:

question

The parental fitness gained from a single clutch of offspring of a given size is the number of offspring in the clutch multiplied by the probability that any individual offspring will survive

answer

Optimal compromise between size and number of offspring Analysis:

question

selection

answer

Where there is variation, _________ can act

question

variation

answer

Usually very little ________ in offspring size in most species

question

-Adult salmon return to hatchery, are spawned, fry released to natural rivers -individual females with bigger eggs made fewer -as eggs get bigger, a larger proportion survive -hatchery gives fry a boost; increases survivorship at smaller sizes -leads to selection for smaller eggs -this has conservation implication since hatchery fish are used to stock wild population, influences egg size

answer

hatchery chinook salmon in Canada study between offspring number and quality : SELECTION example

question

-selection reduces genetic variation of a trait -life history (i.e. reproductive) traits are so closely related to fitness -then, shouldn't life history traits have especially low heritability?

answer

Why is there variation in life history traits? Given that:

question

different genotypes/phenotypes have different fitnesses at different times

answer

What are the evolutionary forces that maintain genetic variation?

question

-compete with another sea squirt (B. leach) late in season -semelparous form puts all its energy into one reproduction, then succumbs to competition -iteroparous reserves some energy to out-compete B.leachi

answer

Sea squirt, semelparous and interoparous example:

question

-big showy flowers -offer no nectar -flowers are self-fertile

answer

selection optimizes life histories to explain the various patterns, except when it doesn't -Pink Lady Slipper

question

NO

answer

is the pink lady slipper orchid using an evolutionary stable strategy (ESS)?

question

-number -probability -and their future reproduction

answer

Trade-off between _______ of offspring and the __________ of their survival

question

-quality -number

answer

trade-off between offspring ______ and offspring ______

question

vacuum

answer

these relationships don't exist in a

question

experience low stress and low disturbance and are more limited by competition between individuals than external factors

answer

Competitive plants; life strategies

question

inhabit physically demanding habitats where stress is high and disturbance is low

answer

Stress tolerant plants; life strategies

question

inhabit environments with low stress and high disturbance

answer

Ruderal plans; life strategies

question

-Ruderal

answer

Plants in which corner of Grime's triangle would be favored in a recently clear-cut forest?

question

-Stress tolerant

answer

Plants in which corner of Grime's triangle would be favored in a barren desert?

question

-effect on the population growth rate

answer

Heppel: a method to determine which life history trait has the greatest

question

a measure of the effect that a change in trait has on population growth rate

answer

Elasticity:

question

-Stable environment: high competition and high and stable density -iteroperity, parental care, late age in maturity, small clutches, large offspring

answer

K selection= Quality

question

-Fluctuating environment: low competition, density fluctuates (often low) -semelparity, large clutches, early age at maturity, small offspring

answer

r selection= Quantity

question

it depends

answer

Evolutionary which is better, quality or quantity?

question

-in unpredictable environments, there is great potential for catastrophic loss of an entire reproductive effort -The bet-hedging strategy reduces the magnitude of each reproductive event, thus spreading the risk over multiple events

answer

Bet-Hedging theory

question

-Desert annuals produce extremely long-lived seeds -subsets of seeds germinate in different years -the proportion of seeds that germinate in any year is negatively correlated with variation in reproductive success

answer

Bet-hedging in plants

question

Two populations of the black-browned albatross: -a highly variable environment of south Georgia islands -a more stable environment of the Kerguelen islands --> on South Georgia, annual reproduction is lower, but interannual survival and life span is greater

answer

Bet-hedging in animals

question

- r-selection and bet-hedging

answer

A very unpredictably variable environment tends to encourage:

question

physiologically maximum possible

answer

The optimal reproductive output is not necessarily the

question

reproduction has a mortality cost, and the reproductive pattern is a response to the mortality schedule

answer

The age-specific reproductive rate (bx) and the age-specific survival rate (lx) are reciprocally connected:

question

-unique ecology

answer

The reproductive life history is a response to the species

question

the key ecological forces acting on reproduction

answer

A number of conceptual frameworks such as r/K fvgcfcfcfcselection, Grime's triangle, and the bet-hedging theory, organize these interactions according to

question

-quantity -quality -mean -variation

answer

Important selective forces imposed by ecology are ______ vs ______ offspring and the ______ reproductive output vs. the ________ in reproductive output.

Ch.10 Life History Strategies – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards