Chapter 7 - Life History Flashcards by Juan Piolo Miguel Senires

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

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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

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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

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This is the changing of sex throughout the life cycle and is hypothesized to be based on advantage of reproduction.

Sequential Hermaphroditism

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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

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Refers to the major events related to an organism’s growth, development, reproduction, and survival.

Life History

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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

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An organism’s lifetime pattern of growth, differentiation, storage, and reproduction

Traits that affect an organism’s schedule of reproduction and survival

Life history

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Life histories are influenced by (4)

Physical conditions
Food supply
Predators
Other environmental factors

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Life Histories are constrained by (2)

a. General body plan of organism
b. Lifestyle of individual

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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

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What are the three factors in energy division of an organism that shape its Life History Strategy

a. Growth
b. Reproduction
c. Survival

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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

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Life history variation within species results from this

Genetic Differences

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Emerging life histories are based on what?

based on which variation is more favored to survive and reproduce

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Present life histories are described as ______.
Why

They are optimal only to maximized fitness (selection towards them in their environment)

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Other term for constraint that shows life-histories as imperfect.

Trade-offs

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Give an example of trade-off

Beetle head size and eye size. Larger the horn, smaller the eyes

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Phenomenon where a single genotype produces different phenotypes

Phenotypic Plasticity

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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)

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Describes the relative amounts of energy or resources that an organism devotes to different functions

Allocation

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Results of Phenotypic Plasticity (2)

Variation in continuous range
Morphs

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T/F Phenotypic plasticity is always an adaptive response

False, it can also be a PHYSIOLOGICAL RESPONSE

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First organisms on Earth reproduce asexually by?

This results in clones

Binary fission

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Production of equal sized gametes

Isogamy

Production of two types of gametes with different sizes

Anisogamy

Disadvantages of sexual reproduction (3)

1. Meiosis only produces a haploid gamete (Organism can only transmit half of its genome) 2. recombination and the independent distribution can disrupt favorable gene combinations (Could reduce offspring fitness.) 3. Lower growth rate than asexual organisms

Advantages of sexual reproduction (2)

1. Recombination (Promotes genetic variation and evolution) 2. 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.

1. competitive (low stress-low disturbance) 2. ruderal (low stress-high disturbance) 3. 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

1. Juvenile survivorship (lx) 2. Fecundity/Fertility (mx) 3. Age of reproductive maturity (ɑ)

types of life histories based on Juvenile Survivorship (lx), Fertility (mx), and age of Reproductive maturity(ɑ)

1. Opportunistic - Low lx, Low mx, Early ɑ 2. Equilibrium - High lx, low mx, Late ɑ 3. 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