Life History Flashcards
Life History
Life history patterns vary among species and within a species
Life History events are an adaptation
David Sinclair
Discovered the cause of death in yeast
Believes that aging is a disease and that he can cure it
Allocation
the relative amounts of energy or resources that an organism devotes to different functions
Can be divided between growth, survival, and reproduction
Which varies among organisms
Frogs Life History
Is divided between an aquatic stage and a terrestrial one
Aquatic Stage: Egg stage, tadpole stage
Terrestrial Stage: juvenile stage, adult stage
Resulting in a several evolutionary decisions
Life history events are heritable and show variation among species and within
Duration of tadpole
Timing of metamorphosis
Genetic and Environmental Differences
Some frogs lay eggs in freezing cold water temperatures
Tropical frog breeds within a fluid and keeps its eggs outside of the pond altogether
Phenotypic Plasticity
May result in a continuous range of sizes, or discrete types called morphs
Ex. Spadefoot toad is an example of both
Phenotypic plasticity in timing of metamorphosis
Tadpoles are the same genotype
Adult phenotypes differ in side from accelerated
Corals are animals look like plants and can photosynthesize
Life cycle of a coral
Sexual Stage: meiosis and fertilization
Juvenile Stage: Larva and Polyp
Asexual Stage: The rest
Meiosis
Fertalization
Larva
Polyp (asexual)
There are trade-offs between life history traits.
There are trade-offs between the number and size of offspring
Trade-offs in organisms’ parental care
Trade-offs between reproduction and survival
Allocate limited energy or resources to one function at the expense of another
Reproductive Sexual Maturity is reached:
Energy can be divided between growth or reproduction
Growth can then stop or continue
Allocation Energy is fixed and can be divided between growth, survival, reproduction, and offspring quality
Off-spring quality ( many or few)
Parental Care:
Invest time and energy to feed and protect offspring
In the tropics, there are higher levels of competition in some areas, if you leave offspring alone, they can be consumed by predators
Ex. fish, frogs, etc.
Vivid paring: gives life, and seeds develop into embryos on the plant
Trade-offs between copulating and survival
Organisms face different selection pressures at different life cycle stages
What are the benefits and costs associated with small size in early life cycle stages?
How do adaptations at specific stages in a complex life cycle may benefit the species?
Coral: Many eggs and sperm: they are sexual
Origin of life: ocean
Diversity is very high
Crabs: have direct development
Most adult crabs are in the Benthic stage
Life Stages
Planktonic
* Has success!!!!
Non Planktonic/ benthic
* Do not live over evolutionary time as long as the planktonic ones!!!!
Iteroparous
reproduces multiple times
Semelparous
reproduces only once
Ex. pacific salmon, mayfly
R-Selected:
live fast, die young
Short life spans
Rapid development
Early maturation
Low parental investment
High reproductive rate
Ex. insects, small vertebrates such as mice, weedy plant species
K - Selected
Populations that are at or near the carrying capacity for a population (K)
An advantage in crowded conditions
Long-lived
Develop slowly
Late maturation
Invest heavily in each offspring
Low reproduction rates
Ex. rhinos, tortoises, etc
