Lecture 13 - Vertebrate Life History II Flashcards
What are the features of the Chinook Salmon life cycle?
life span 4-8 years
anadromous: adults live in ocean, breed in freshwater
mate & lay eggs
semelparous
What was the effect of the commercial hatchery on chinook salmon?
greater number of smaller eggs was favoured due to the protections of the hatchery making it easier for small eggs to survive.
What are the features of terrestrial ectotherms?
low metabolic rate (↓ energy needs)
behavioural control of body temperature
how do ectotherms life history traits differ from endothermic vertebrates?
smaller offspring size
larger litter sizes
lower growth rate
infrequent reproduction
Why is the ability to manipulate incubation temperature unique to reptiles?
endotherms have stable body temperatures (limited flexibility)
fish (stable environment), amphibians (hydric constraints)
What are the advantages of viviparity?
mother controls incubation/gestation conditions
favoured in cold or unpredictable climates
how many times have viviparity evolved?
100+ times
What does altricial mean?
naked, need warmth & food until leave nest
What does precocial mean?
well-developed, leave nest once dry
How much variation in life history is seen in birds?
massive amount
What are the possible explanations for life history diversity?
food limitation
developmental mode (altricial-precocial)
nest site & mortality patterns
Are there any semelparous birds?
no
What explains the variation in bird life history the best?
variation is the availability of safe nests
safe nests k-selected
open nests r-selected
