module 10 Flashcards
Intrinsic Rates of Increase
which size of animal has larger intrinsic rates of increase
On average, small organisms have higher rates of per capita increase and more variable populations than large organisms.
increase intrinsic rate of increase
increase organism size
small organisms live a shorter lifetime need to be replaced more
large organisms take up more resources
Life History
interplay between
based on
Organism’s lifetime pattern of growth, development, and reproduction
Interplay between:
- Fecundity – # of Offspring it produces
- Its Survival
- Size & Age at Reproductive Maturity
Based on Evolutionary Context
What is the best way to live life in order to maximize the number of offspring that eventually Breed?
Principle of Allocation
what has fixed energies
leads to
If organisms use energy for one function, the amount of energy available for other functions is reduced.
- Growth
- Maintenance————have fixed energy
- Reproduction
Leads to trade-offs between functions
Trade-offs of life history include
- Mode of reproduction
- Age at first reproduction
- Allocation to reproduction
- Number and Size of eggs, young, or seeds
- Timing of reproduction
-Trade-offs imposed by physiological, energetic, and environmental constraints
female size and eggs
-large # of eggs= ____ gene flow
female size increases
produce larger eggs- smaller amount of eggs produced
greater gene flow
larvae from larger eggs hatch
- Larvae from larger eggs hatch earlier
- Feed earlier-not a lot of competition a lot of resources available
- Grow faster
- Don’t drift as far
- Do not disperse great distances.
- Greater isolation ->rapid gene differentiation.
- other measures of reproductive output
- recruitment success definition
- larger seeds produce ______ seedlings
Fertility Rate -> Fecundity Rate -> Birth Rate ->
- Recruitment success. (best measure)
- -Addition of new, breeding individuals into population through reproduction
- -Seed size variation explains variation in Plants
- -Larger seeds produce larger seedlings
seed masses (seed size) increase, seedling height small seed equals \_\_\_\_\_seedling recruitment
seedling height increases
- Larger seeds produced taller seedlings.
- -Energy reserve boosts seedling growth.
- -Rapid growth helps seedling penetrate thick litter layer.
-low seedling recruitment
Westoby et.al. recognized four plant form -graminoids forbs woody plants climbers
who produces larger seeds?
Recognized four plant forms:
- Graminoids: Grass and grass-like plants.
- Forbs: Herbaceous, non-graminoids.
- Woody Plants: Woody thickening of tissues.
- Climbers: Climbing plants and vines.
-Woody plant and climbers
–Produced 10 x’s the mass of seeds of either graminoids or forbs.
Evolutionary Context?
Westoby et.al. Recognized six seed dispersal strategies: unassisted adhesion wind ant vertebrate scatter hoarded
- Unassisted: No specialized structures.
- Adhesion: Hooks, spines, or barbs.
- Wind: Wings, hair, (resistance structures).
- Ant: Oil surface coating (elaisome).
- Vertebrate: Fleshy coating (aril).
- Scatterhoarded: Gathered, stored in caches.
Dispersal mode might influence seed size.
which is the largest seed?
unassisted
wind dispersed-small seed
scatter hoarded-largest
vertebrae dispersed-large seeds
Particular Environmental Factors Key
plants must become _____ in an environment
small plants produce _____ # of seeds
who has advantage in areas of high disturbance
-seed size set to _____ number of established young
Particular Environmental Factors Key
- Role of Competition & Disturbance
- Plants must become Established in Environment
- -Small plants producing large # of small seeds
- Advantage in areas of high disturbance.
- -Plants producing large seeds
- Constrained to producing fewer seedlings
- More capable of surviving environmental hazards & Competition
- Trade off between # of seeds & Successful Seeds
- -Seed size set to maximize number of established young
Natural Selection
Reduces Variability
Sexual Reproduction -increases what is \_\_\_\_ to individuals each offspring contributes to \_\_\_\_ to fitness finding mates is
- Increases Variability
- Costly to Individual
- -Each Offspring contributes ½ to fitness
- -Finding Mates & Copulation is hard
Asexual Reproduction
- Mutation only Variability
- Offspring Contribute wholly to fitness of parent
What is male and female ?
females produce
males produce
female reproduction thought to be limited by
male reproduction thought to be limited by
- Females produce larger, more energetically costly gametes.
- Males produce smaller, less energetically costly gametes
- Female reproduction thought to be limited by resource access.
- Male reproduction limited by mate access.
Hermaphrodites
Exhibit both male and female function.
Conditions favoring hermaphroditic populations:
- Low mobility
- -Limiting male:male competition.
- Low overlap in resource demands
- -By male and female structures.
- Sharing of costs
- –For male and female function.
hermaphrodism-Simultaneous
Both Sexual organs present at all times
Snails, worms
hermaphrodism- sequential
- One sexual function occurs, followed by the second
- Mollusks, Echinoderms, Some Fishes
- change sex throughout time
Dioecious plants
Separate male and female individuals
Hermaphroditic Plants
individuals with _____flowers
Individuals with perfect flowers, male (stamens) and female (ovaries) reproductive organs in the same flower
Monoecious
hermaphroditic and monoecious plants may or may not be able to
- Individuals with imperfect flowers
- -Separate male and female flowers on the same plant
- Hermaphroditic and monoecious plants may or may not be able to self-fertilize
Probability of future survival can be reduced by
no reproduction = _____mortality
reproduction=__________mortality
- mate acquisition
- defense of a breeding territory
- feeding and protection of young
low mortality
high mortality
Allocation to reproduction _______ allocation to growth
reduces allocation to growth in many plant and animal species
Iteroparous
-include most ___ animals
- Organisms reproduce more than once
- include most vertebrate animals, shrubs, trees, and perennial plants
Semelparous
- initial energy investment to
- one large
- then the organism
- Organisms reproduce only once
- -initial energy investment to growth, development, and energy storage
- -one large reproductive effort
- -Then the organism dies, sacrificing all future reproduction
- Most insects, annual and biennial plants, some fish (salmon)
Semelparous
some are _____ and some are _____
- Short-lived
- -mainly small plants that live in disturbed or ephemeral habitats
- -Future reproduction is uncertain
- Some are long-lived
- -Many insects spend years as larvae
- -Periodical cicadas live underground up to 17 years
- -Some plants live for many years before a single reproductive event
- -Bamboo may not flower for over 100 years
Optimal reproductive effort
-maximizes what
-semelparity
what is optimal
iteroparity
what is optimal
-organism survives to
-Balance between current & future reproduction
Maximizes parental fitness
- Semelparity
- -One large reproductive event followed by death is optimal
- Iteroparity
- -Less than maximum effort is optimal on the first attempt
- -Organism survives to reproduce again
Vertebrate energy budgets
-different before and after _____
before-
after
individuals delaying reproduction will
-tradeoff is that reproductive lifespan will
- Different before and after sexual maturity.
- Before - maintenance or growth.
- After - maintenance, growth, or reproduction.
- Individuals delaying reproduction will:
- Grow faster and reach a larger size.
- -Increased reproduction rate (short term)
- -Possibly reduced reproductive lifespan
Energy allocated to reproduction involves trade-offs between:
benefit of and the cost of
of offspring produced decreases, offspring survival _____
- Current benefits from production of offspring
- Cost of potential reduction in future reproduction
-increases, less resources need to be shared
R0
-function of
increases with ____ at maturity
-reproductive lifespan _____ by delaying maturity
-life history should ______ r0
if organism can increase ro by delaying maturity,
-then _______ period should be ______
-Net Lifetime Reproduction
- Function of:
- Fecundity
- –Increases with body size at maturity
- Reproductive lifespan
- -Shortened by delaying maturity
- Life History should maximize R0
- If organism can increase R0 by delaying maturity,
- -then juvenile period should be extended.
Species with higher mortality show
low mortality rate =
higher relative reproductive rate.
less investment in reproduction
reproductive effort
-adult: juvenile ratio low-invest ___ amount in reproduction
Total energetic cost of reproduction per unit time
- Energetic costs of reproduction include:
- gonad development
- movement to breeding area
- competition for mates
- production of gametes
- nutrient demands
- nesting
- parental care
-invest in huge amount in reproduction
mating system
For sexually reproducing species, the mating system describes the pattern of mating between males and females in a population
- Strength & Duration of Pair bond Important
- Differing roles & selective pressure of sexes
Mating Systems -promiscuous -polygamy ---polygyny- ----polyandry- season/serial monogamy -monogamy
- Promiscuous- par bond weak, not exclusive, a lot
- polygamy-
- -polygyny- many females one male
- -polyandry–many males one female
- seasonal/serial monogamy- find another mate once breeding season ends
- monogamy-exclusive
When Should an individual be Polygynous?
-when better habitat is needed over shared parental care
Parental Investment
Act of parental care than enhances the survival of individual offspring or increases their numbers.
- Feeding of the young
- Thermoregulation of young
- Protection of young
- Teaching of young
Fish, Amphibians, & Reptiles
parental care
-rare exceptions
- Little post-fertilization parental care
- Rare exceptions, esp. toads
- -Young Develop on back or in mouth
Mammals
-most mammals are
- Females Primarily responsible
- Female “Carries” young for long period
- -Male cannot help
- Most mammals are relatively self-sufficient at birth
Parental Care in Birds
-leads to predominantly _____
usually both parents
demands of incubation and immobility of hatchling
leads to predominantly monogamous
some have equal partitions, but separate nests
-Female Inseminated once, lays eggs, & leaves
Male raises first nest, while –female lays additional nest & Raises it.
Emancipation of Males from Parental Care benefits for males and females
- Allows Males to increase Fitness through multiple matings
- allows females to choose between better males
Sexual Dimorphism
different morphologies in males and females
Reasons for Sexual Dimporphism
Different Sexual Roles
-Trade-off of Energy
–Females – Larger Gametes, Protection of Young
Sexual Selection
-Differences in reproductive rates among individuals as a result of differences in mating success.
Mate Choice Sexual Selection -intrasexual selection -what kind of sexual traits -intersexual selection -\_\_\_\_\_ exercise of choice -usually \_\_\_\_\_\_\_ choice
Sexual Selection
Differences in reproductive rates among individuals as a result of differences in mating success.
-Intrasexual Selection:
Individuals of one sex compete among themselves for mates.
Secondary Sexual Traits
Antlers, Horns, Tusks, etc.
-Intersexual Selection:
Individuals of one sex consistently choose mates among members of opposite sex based on a particular trait.
Direct exercise of choice
Usually Female choice
Male increase fitness through
Females Increase fitness through
# of Matings Quality of Mating-must choose best mate
Males Develop_______ to attract females
- may or may not be indicative of quality or increase _____
- values of advertisement
advertisement Traits
- May or may not be indicative of quality or increase survival
- Values of Advertisements
- -Are they Honest signals?
Runaway Sexual Selection
drive traits to
balanced by
- Females persistently choose the most extreme male phenotypes
- Drives Trait to Extremely elaborate traits
- -Balanced by decrease in fitness of males
Handicap Hypothesis
demonstrates ____ fitness of bearer
traits increase
only the __________ can survive
- Elaborate, sexually selected displays & adornments act as handicaps
- -Demonstrate high fitness of bearer
- -Traits increase:
- –Risk of predation
- –Harm
-Only the most fit can survive.
handicap hypothesis
Trait may also be Indicator of their ability to:
-large traits ____
-abilty to cope with ________
- Ability to grow trait (excess resources)
- -Large Traits Costly
- -Antlers in Cervids
- Ability to Cope With Environmental Stress
- -Symmetery in Bilateral Traits
- -Tail Lengths
- -Cervid Antlers
Parasite-Mediated Sexual Selection
-type of ____ hypothesis
Hamilton-Zuk Hypothesis
Type of Handicap Hypothesis
-Females choose individuals free of parasites
-Only parasite-free develop high quality traits
Extra-pair Copulations
-a single mate best for parental care
-mated individuals mate outside of pair
males _____ # of offspring with _______ in parental care
females
males with the best territory _______
A single mate best for Parental care
-May not be best for Fitness
Mated individuals Mate outside of pair
-no pair bond with EPC
males
Increase # of Offspring with little increase in parental care
Females
-Male with best Territory, may not have best Genetics
Extra-Pair Copulations & Female Mate Choice
females can effect paternity after copulations
-especially ____
through
-sperm expulsion
Females Can Effect Paternity after Copulations
- -Especially Birds
- Timing of Mating
- Sperm Competition
- -Most Viable sperm Fertilize egg
- Order of Mating
- –Last Mate Usually Achieve Fertilization
- Sperm Expulsion-can expel sperm from the body to decrease likelihood of fertilization
grimes
Proposed two most important variables exerting selective pressures in plants:
Intensity of disturbance:
and intensity of stress
what is also influenced by stress and disturbance?
intensity of disturbance
-Any process limiting plants by destroying biomass.
Intensity of stress:
-External constraints limiting rate of dry matter production.
Competition factors in as well
Influenced by stress & disturbance
Four Environmental Extremes:
- Low Disturbance : Low Stress
- Low Disturbance : High Stress
- High Disturbance : Low Stress
- High Disturbance : High Stress
Ruderals
Highly disturbed habitats
Grow rapidly and produce seeds quickly.
-grasses
Stress-Tolerant
High stress - no disturbance
Grow slowly - conserve resources.
-shrubs
Competitive
Low disturbance - low stress
Grow well, but eventually compete with others for resources.
-tress
r selection
k selection
r selection
(per capita rate of increase)
Characteristic high population growth rate.-grow at high rate
K selection
(carrying capacity)
Characteristic efficient resource use.-competitive species
most organisms are in between
which one is predictablee which one is not
Most organisms are in-between.
r selection: Unpredictable environments.
K selection: Predictable environments.
r and K: Fundamental Contrasts
intrinsic rate of increase
competitive ability
reproduction
r
k
- Intrinsic Rate of Increase:
- -Highest in r selected species.
- Competitive Ability:
- -Highest in K selected species.
- Reproduction:
- -r: Numerous individuals rapidly produced.
- -K: Fewer, larger individuals slowly produced.
Opportunistic
Equilibrium:
Periodic:
low lx - low bx - early α-r selected
high lx - low bx - late α-k selected
low lx - high bx - late α
a, lx, bx
Age of reproductive maturity (α)
Juvenile survivorship (lx)
Fecundity (bx).
