parental behavior Flashcards
parental investment theory
amount of assistance a parent provides reflects an optimal evolutionary strategy for maximizing fitness
- extent to which parents compromise their ability to produce more offspring in order to assist current offspring
- can lead to conflict b/w the parent and child
- consider gamete size/number of offspring produced
parental behavior
behaviors performed in relation to the offspring that contribute to the survival of fertilized eggs/ova
altricial young
immature, helpless young
- female may or may not display maternal care (may depend on the number of offspring produced)
ex: fish, rats, mice
precocial young
young are born well-developed, may be able to survive without parental care
- ex: hoofed animals, whales, guinea pigs
- more investment during development, less parental investment needed postpartum
semi-precocial young
need a substantial amount of care, but can thermoregulate and cling to the mother
ex: humans, puppies
mammalian parental behaviors
nest building, food, shelter, protection, play with older siblings, pup retrieval, warmth, cleanliness, aggression
bird parental behaviors
nest building, incubation, brooding, care until independence
birds: 4 patterns of parental care
- nest parasite (ex: cowbirds, cuckoos)
- solely maternal care (ex: chickens)
- solely paternal care (ex: mallee fowl, jacana)
- biparental care (most common)
Evolutionary perspective on biparental care in birds
most young birds are helpless and require constant food and warmth to survive, if the male did not assist the female with parenting, the young would most likely die and the males own reproductive fitness would decrease
brood pouch
- formation induced by increased prolactin concentrations
- place on chest that loses its feathers and becomes increasingly vascularized to allow for a more efficient heat transfer from the parent to the chick
crop milk
- formation induced by increasing prolactin concentrations
- produced in the crop sac (an endocrine gland); resembles small curd cottage cheese; contents of crop sac change as the bird matures and gets older (milk–> predominately insects and seeds; changing contents dependent on decreasing prolactin levels)
endocrine correlates of bird behavior: sex steroids
sex steroid hormones increase with the onset of courtship behavior (estrogens), peak at egg laying= oviposition; and decrease to baseline prior to incubation (this is when we see a peak in prolactin levels)
-progesterone also induces incubation and inhibits courtship behaviors
endocrine correlates of bird behavior: prolactin
prolactin concentrations increase at egg laying, peak at incubation, and gradually decrease post-hatching DEPENDENT ON DEVELOPMENTAL STATE OF CHICK
- altricial young: prolactin levels remain elevated (crop milk, brooding, brood pouch)
- precocial young: supervision generally needed, but not extensive parental care
broodiness and prolactin
incubation of the eggs for warm, protecting, covering, and warming the young under the wing
**elevated levels of prolactin in every female bird species during incubation
Daniel Lehrman: ring necked doves
conducted research on ring necked doves that studied the hormonal influences on courtship and parental behaviors
- extended the idea that hormones affect behaviors; hormones can affect behaviors, and behaviors can feed back to affect hormone secretion
- bi-directional relationship between hormones and behavior
categorizations of mammals
- marsupials
- monotremes
a. no pouch
b. pouch - eutherian
a. altricial
b. precocial
c. semi-precocial
marsupials
produce highly altricial young that resemble embryos more than offspring
- pouch: contains mammary glands and serves as a receptacle for the young
- pouch adaptation: allows the mom to remain mobile, forage for food, and escape from predators all the while carrying her infant
- short gestation: more favorable in harsh climates
- ex: wallaby, kangaroo, koala, opossum
monotremes
produce very altricial young that are born as EGGS but nursed with milk when born
- pattern 1: no pouch, animal will build a nest, incubate the eggs, nurse at birth: ex-platypus
- pattern 2: pouch, animal will carry the egg in their pouch where the infant will live when it hatches and nurses- ex: spiny anteater= echidna