life history Flashcards
What defines a population?
A population is a group of individuals of the same species in a defined area, isolated to some degree from other populations. It consists of conspecific individuals living close enough to interbreed.
Why is defining marine populations challenging?
Defining marine populations is difficult because the ocean is continuous around the globe, and marine organisms often produce long-lived larvae, which can disperse over long distances.
What is a metapopulation?
A metapopulation consists of spatially separated populations occupying discrete habitat patches that interact by exchanging individuals. These populations are connected through individual movement.
What is population connectivity?
Population connectivity refers to the frequency and magnitude of individual movement between populations. It has important consequences for recovery and the effectiveness of management.
What are the key parameters in life history?
- Fecundity (reproductive output)
- Mortality (death rate)
- Settlement size (number of individuals reaching adulthood)
- Growth rate (rate of development and size increase).
What is a life cycle in marine organisms?
Marine organisms often have complex life histories with different life stages that vary greatly in size and ecology. Early life stages experience different conditions and needs than adults, and have different traits and roles in ecosystems.
How do life history strategies affect reproductive success?
Species with smaller eggs tend to have higher mortality rates in the plankton. Egg size and number are adjusted to maximize reproductive success under prevailing conditions. Different species have vastly different life spans and reproductive strategies.
What are otoliths, and how are they used in marine research?
Otoliths are calcium carbonate structures used for hearing. They can also be used for aging organisms by counting the number of growth rings.
How can otoliths help measure dispersal in marine organisms?
By exposing a clutch of eggs to tetracycline, which creates fluorescent rings in larval otoliths, researchers can track the movement of larvae. In one study, 60% of larvae returned to their natal habitat.
What are the key life history traits of coral reef fishes (CRFs)?
- Adult fish are typically <5 cm.
- They are visually or behaviorally cryptic.
- They live near or within the seabed.
- High mass-specific metabolic rate and high mortality rates.
- Low batch fecundity (few offspring per batch).
- High proportion of larval supply leads to fast population turnover.