Chapter 7 - Life History Flashcards
What happens to clownfish when the female dies? Why?
The largest male becomes the female as all clownfish are born male.
This is because they follow a strict size hierarchy.
Only the largest and 2nd largest (female and male) breed
Why is it that larger organisms are preferred for reproduction?
Larger organisms produce more offspring than smaller ones
ex. In clownfish egg number is proportional to body size
Explain the life history/cycle of clownfish (3 main steps)
- Breeding male breeds with female
- Hatchling Fish leaves anemone and live in open ocean
- Young eventually return to reef and develop to juveniles
This is the changing of sex throughout the life cycle and is hypothesized to be based on advantage of reproduction.
Sequential Hermaphroditism
How is size hierarchy in clownfish maintained?
If a fish grows too close in size to another in the same anemone they will fight causing the smaller fish to die or be expelled
Refers to the major events related to an organism’s growth, development, reproduction, and survival.
Life History
Traits that characterize the life history of an organism (3)
- Age and size at sexual maturity
- Amount and timing of reproduction
- Survival and mortality rates
An organism’s lifetime pattern of growth, differentiation, storage, and reproduction
Traits that affect an organism’s schedule of reproduction and survival
Life history
Life histories are influenced by (4)
- Physical conditions
- Food supply
- Predators
- Other environmental factors
Life Histories are constrained by (2)
a. General body plan of organism
b. Lifestyle of individual
The overall pattern in the timing and nature of life history events averaged across all the individuals in the species (population-level representation)
Life History Strategy
What are the three factors in energy division of an organism that shape its Life History Strategy
a. Growth
b. Reproduction
c. Survival
Is a product of environmental adaptation (natural selection)
Can vary per individual in a species as a result of either genetics or environmental conditions
Life History Traits
Life history variation within species results from this
Genetic Differences
Emerging life histories are based on what?
based on which variation is more favored to survive and reproduce
Present life histories are described as ______.
Why
They are optimal only to maximized fitness (selection towards them in their environment)
Other term for constraint that shows life-histories as imperfect.
Trade-offs
Give an example of trade-off
Beetle head size and eye size. Larger the horn, smaller the eyes
Phenomenon where a single genotype produces different phenotypes
Phenotypic Plasticity
Give an example of Phenotypic plasticity
Ponderosa pine
- allocates more biomass to leaf growth relative to sapwood in cool and moist climate
● In warmer desert, it allocates more to sapwood (for water transport)
Describes the relative amounts of energy or resources that an organism devotes to different functions
Allocation
Results of Phenotypic Plasticity (2)
- Variation in continuous range
- Morphs
T/F Phenotypic plasticity is always an adaptive response
False, it can also be a PHYSIOLOGICAL RESPONSE
First organisms on Earth reproduce asexually by?
This results in clones
Binary fission
Production of equal sized gametes
Isogamy
Production of two types of gametes with different sizes
Anisogamy
Disadvantages of sexual reproduction (3)
- Meiosis only produces a haploid gamete
(Organism can only transmit half of its genome) - recombination and the independent distribution can
disrupt favorable gene combinations
(Could reduce offspring fitness.) - Lower growth rate than asexual organisms
Advantages of sexual reproduction (2)
- Recombination
(Promotes genetic variation and evolution) - Beneficial in a challenging environment
(genetic variation is needed for environmental adaptation)
A life cycle in which there are at least two distinct stages that differ in their habitat, physiology, or morphology
Complex Life Cycle
Abrupt transition in form from larval to the juvenile stage
Metamorphosis
Complex Life Cycle and Metamorphosis are due to?
Different selection pressures for adult and offspring
Type of life cycle with two different stages/generations: multicellular gametophyte and multicellular sporophyte
Alternation of generations
Simple life cycle where fertilized egg to juvenile transition occurs within the egg prior to hatching (no free-living larval stage)
Direct Development
Semelparous vs Iteroparous
Flowers/fruits once vs flowers several times
Reproduce only once in a lifetime due to high energy investment, usually in annual plants
Semelparous
Can reproduce multiple times due to low energy investment,
Iteroparous
Refers to selection for high population growth rates.
Occurs where population density is low.
Characteristics: “live fast, die young”
r-Selection
“r” = intrinsic rate of population increase
Refers to selection for slower rates of increase
Occurs in populations that are at or approaching K or
carrying capacity
Low population Growth rates
Characteristics: “slow and steady”
K-Selection
“The success of a plant species in a given habitat is limited by two factors: stress and disturbance.” Developed by:
Phillip Grime
Any external abiotic factor that limits vegetative growth
Stress
Aby process that destroys plant biomass
Disturbance
4 habitat types based on high or low stress and disturbance
High high
Low high
Low low
High low
*Note: If we assume no life on High high, there are only 3 habitat types
Three main habitat types in Grime’s Triangular Method.
- competitive (low stress-low disturbance)
- ruderal (low stress-high disturbance)
- stress-tolerant (high stress-low disturbance)
They are superior in ability to acquire light,
minerals, water, and space
Have selective advantage when low stress and low
disturbance
Competitive Plants
Plants that adapted to high levels of disturbance and low stress
Often called “weedy” species
Ruderals
Dominant where stress is high, disturbance is low usually with slow growth, evergreen foliage, slow resource use, low palatability, and rapid response to temporarily favorable conditions
Stress-tolerant plants
Removed influence of size and time to allow comparison of life histories of very different organisms
Charnov’s Dimensionless Life History
3 Factors Considered in Population Dynamics Classification of Life-History by Winemiller and Rose
- Juvenile survivorship (lx)
- Fecundity/Fertility (mx)
- Age of reproductive maturity (ɑ)
types of life histories based on Juvenile Survivorship (lx), Fertility (mx), and age of Reproductive maturity(ɑ)
- Opportunistic
- Low lx, Low mx, Early ɑ - Equilibrium
- High lx, low mx, Late ɑ - Periodic
- Low lx, high mx, late ɑ
Summary of Life history and their specific use cases:
r-K -> relating life history characteristics to population
growth characteristics
Grime’s -> most appropriate for life history comparisons between groups of plants.
Charnov’s -> most helpful when comparing life histories across broad ranges of taxonomy or size.
trade-offs occur when
organisms allocate their limited energy or other resources to one structure or function at the expense of another
Investment in offspring includes:
○ Energy
○ Resources
○ Time
○ Loss of chance for other activities (e.g. foraging)
Trade-off in offspring:
Investment per each individual offspring vs
number of offspring
- For large investment per individual, there
is only small number produced
- For small investment individuals, there are
many offspring produced
True or False: Parental investment is proportional to offspring “quality”
True, Lower investment = higher offspring mortality
The maximum number of offspring that a parent can successfully raise to maturity
Described by David Lack
Lack Clutch Size
Number of eggs per reproductive bout
Clutch Size
Why is clutch size (CS) limited by the max number of young that a parent can raise simultaneously
If less than CS, less passed on genes
If more than CS, more likely to die or starve
Propagating mechanism via egg, spore, or seeds
Propagule
Organisms that do not give parental care reproduce via
Propagules
Ability to produce an abundance of offspring
Measured by # of offspring raised to maturity
Fecundity
Refers to the number of times of reproduction
Parity
Adult survival is high when
Age of reproduction is high
Reproduction effort is low
Di ko na nasama yung concept 7.4
