Quiz 2 Flashcards
Ro
- net reproductive rate
- the mean number of offspring a typical female in the pop will produce over her lifetime
How is Ro calculated
- per capita birth rate in a give year b(x) times the survivorship probability for that year l(x) summed over the fishes life
- sum of (l(x) x b(x))
G
- average generation time of a population
- average age of the parents of all offspring from a single cohort
r
- intrinsic rate of population increase
- also population growth rate parameter
- units are time^-1
Px
- probability that an individual survives from one age class to the next
- (l(x)/l(x-1))
Birth-pulse model
- assumes all the births occur in a single pulse
- projects how the population will change over time
- need Px and Fx
Fx
- age specific fertilities
- b(x) times Px
What gives us vital information on whether or not a population is growing
Ro and G
Semelparity
spawn once then die
Iteroparity
-spawn multiple times during lifetime
What are constraints that can shape life history
-natural selection, reproduction, energy budget, physiology, environment
How is reproduction a variable of life history
- age at first reproduciton
- size at first reproduction
- mating behavior
How do we tell territorial and sneaker apart
- territorial males: High investment in seminal vesicles
- Sneaker males: high investment in sperm
Protandry
- begins life as a male and then changes to female
- may be driven by energetic costs
Protogyny
- begins life as a female and changes to male
- may be driven by competition
Euryohaline vs stenohaline
- Euryo: broad tolerance to salt
- Steno: narrow tolerance to salt
What fish displays latitudianl variation in life history
American shad
-had a higher growth rate in higher latitudes
Why were there latitudinal differences in American shad growth rates
-differences in temperature, higher productivity in higher latitudes, differences in seasons
Anadromy
-begins life in FW, grows in SW, reproduces in FW
Catadromy
-Begins life in SW, grows in FW, reproduces in SW
Amphidromy
-growth occurs in both SW and FW
Ovivipary
-offspring in eggs
Vivipary
-live birth
Anguillids
- freshwater eels
- 1 genus
life stages of eels
- larvae (leptochephali)
- transform in estuaries into glass eels
- develop yellow brown pigementation (elvers)
- bootlace eels -> yellow phase -> silver
Who was the first eel biologist
Aristotle
Johannes Schmidt
- scientist that studied the life cycle of eels
- found that they most likely reproduce in the Sargasso Sea
How can eels swim up vertically
Capilary action
Yellow eels (growth form)
- varied diets
- variable growth rates
- accumulate fat for migration back to the Sargasso
- can live in wide variety of habitats
Sex determination in eels
- geographically and density dependant
- females require less density
- males are found in lower parts of the estuary
What changes about eels as they get ready to migrate back to Sargasso
- they become silvery and their eyes enlarge
- typically stop feeding
