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Lecture

BIOL 1902 Lecture Notes - Embryonic Diapause, Altricial, Skink


Department
Biology
Course Code
BIOL 1902
Professor
Michael Runtz

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of 2
Walking Stick eggs end up underground too
o Eggs guarded by ants
Northern Water and Garter Snakes internally hold eggs until they hatch
o OVOVIVIPARITY
o Do not guard their young
Five-lined skink guard their egs
Female Wolf Spiders carry eggs in an EGG SAC held by the SPINNERETTES
Female NURSERY WEB SPIDERS carry the EGG SAC in their chelicerae (jaws)
o Before hatch, they build a nursery web and guard the sac
Giant Water Bugs offer male-only parental care
All of these animals provide very little PARENTAL INVESTMENT internally
95% of mammals, females provide ALL of the PARENTAL CARE
Moose have 8-month gestation with a placental connection
Moose have PRECOCIAL young
PARENTAL CARE feeding and protecting
Wolves, Coyotes and Red Foxes exhibit BIPARENTAL CARE
Wolves are SOCIAL animals
Black Bear cubs are born highly ALTRICIAL
Opossum more altricial
o Born after 12-day gestation
Aplacental
Bears mate in June and give birth January
o Gestation is 2 months
DELAYED IMPLANTATION allows bears to mate and to give birth when the time is right!
Many Carnivores display delayed implantation
Bats mate in summer and give birth the next spring
o Gestation about 40 days
o Bats do not exhibit delayed implantation!
They store sperm
Social insects (bumblebees and paper wasps) also store sperm
> 90% of all birds provide BIPARENTAL CARE
Eggs are huge investment
o Ducks, grouse, sandpipers = large eggs, 40% yolk
o Songbirds = small eggs, 25% yolk
PRECOCIAL CHICKS leave the next after hatching
Longer development in the egg allows chicks to hatch mobile and largely self-sufficient.
INCUBATION is also an investment
Female ducks and grouse do all the incubation
Any species in which the males do all of the incubation?
o In Phalaropes (polyandrous species) males incubate!
PARENTAL CARE includes NEST SANITATION
Hawks add green conifer sprigs to nests
Nest defense
FEIGNED INJURY DISPLAYS = BROKEN WING ACTS
Duck and goose broods can be extremely large due to
o BROOD AMALGAMATION
Creching
Black-billed Cuckoos (and yellow-billed cuckoos) are also Facultative Brood Parasites
Opossum have about 50 babies in their hair (?)
BROOD REDUCTION occurs in eagles
o Two young hatch but only one survives
o The oldest eagle kills the youngest SIBLICIDE
Female Muskrats kill their neighbour’s young – INFANTICIDE
o Male Lions do this too
When a female Tree Swallow remates, the new make kills all of her young
BRUCE EFFECT voles abandon …
Young Veeries lay their eggs on other people’s nests
o Cowbirds are OBLIGATE BROOD PARASITES