Early life history Flashcards
What two traits set fish apart from other vertebrates?
Indeterminate growth
Continual increase in length and volume
Larval stage
Larval stage usually bears little resemblance to juvenile or adult
True or false: Fecundity decreases with egg size and/or increased parental care.
True
What is the Critical Period Hypothesis?
Starvation at a critical period is a strong determinant of year-class strength
What is the Match-Mismatch Hypothesis?
The timing of reproduction in many marine fishes was evolved to take place where and when food will be available
Name a way to measure reproductive effort and how it works.
GSI - gonadosomatic index = gonad weight/body weight
Give an example of how ontogeny can affect phylogeny.
Eg. Ontogeny was used to determine phylogenetic relationships between the leptocephalus larvae (eels) and Elopiformes (tarpon and ladyfishes).
Give examples of physical/behavioral changes in smoltification.
Turn from countershaded and barred to silvery
Become slimmer and more streamlined
Complexity of hemoglobins in the blood increases
Many changes are seen in gill function
Positive rheotaxis disappears
Imprint on odor of home stream
How do flatfishes transition from the larval stage?
Laterally flattened (compressed)
Individuals are either left-eyed (sinistral) or right-eyed (dextral)
Neurocranium, brain, and eye sockets will eventually rotate from one side to the other
Transition to the adult stage typically requires what?
Sex determination is usually decided during early ontogeny and can be genetically or environmentally determined
Differentiation - development of ovaries or testes
Maturation - production of viable gametes
What sets sex determination in fishes apart from other vertebrates?
Sex chromosomes are rare among fishes compared to other vertebrates, and in taxa in which ESD occurs sex chromosomes are rare.
Widespread environmental sex determination makes fishes vulnerable to environmental degradation.
Prematurational sex change occurs in many fishes
Seen in agnathans and teleosts as gonads develop from a single structure
Postmaturational sex changes can occur as well
Consider the growth-weight formula. Wt = aL^b if b = 3, what does this mean for the fish?
The animal stays the same shape as they grow.
Consider the growth-weight formula. Wt = aL^b if b > 3, what does this mean for the fish?
The animal gets rounder as they grow.
Consider the growth-weight formula. Wt = aL^b if b < 3, what does this mean for the fish?
The animal gets less round as they grow.
What is Fulton’s condition factor used for?
To assess the health of populations. In salmon, % water is correlated with % lipid and can be used to determine lipid concentration
