University:
Amherst College
Course:
BIOL 220 | Developmental Biology
Academic year:

2011
Views:

243

Pages:

13
Author:

stebazeillefth

Parental investment Parental investment Behavior that increases fitness of offspring at cost to parent Nutrition in egg Pre-hatching (nest site, protecting eggs) lowland gorilla Post-hatching (provisioning, protecting young) Parental investment Post-hatching investment is rare Patterns of parental investment mallee fowl • Female-only care predominates • Male, biparental care is rare How do we account for the general female bias in parental care? golden-lion tamarin Patterns of parental investment = Richard Dawkins Logic suffers from “sunk cost” or “Concorde” fallacy What about the abrupt termination of investment in polyandrous species? Patterns of parental investment Explained by order of gamete release? Mode of fertilization Provider sex Internal External guppy Male Few Many Female Many Few How to explain the predominance of male care in frogs where males deposit sperm first? piranha -1 .0 0.9 1 -0 .90 -0 .80 0.8 1 -0 .70 0.7 1 -0 .60 0.6 1 -0 .50 0.5 1 -0 .40 0.4 1 0.3 1 -0 .30 0.2 1 0.1 1 0.0 tree swallow -0 .20 9 8 7 6 5 4 3 2 1 0 -0 .10 Number of broods Importance of paternity Proportion of extra-pair young (EPY) Extra-pair paternity may select for decreased male care If costs to male and female to rear young are the same, but only 3 of 4 chicks are his… dark-eyed junco He should reduce his level of investment Recognition of unrelated young? No apparent discrimination against EPY male female Male yellow warblers do not adjust feeding rate in response to cuckoldry Male tree swallows show no feeding bias to own chicks, feed those closest or most in need Recognition of unrelated young? Alpha, beta male dunnocks care for young in proportion to time spent with female Females may use mating solicitations to manipulate male parental investment Control = male bluegill on nest Experimental = male bluegill on nest with “sneaker” in a jar Tested defensive responses to nest predator Recognition of unrelated young? Why the difference between care of eggs and care of fry? Sex differences in costs of investment Male care persists where costs to females exceed costs to males? St. Peter’s fish Male care depends on costs/benefits to male ~11 days ~7 days Sex differences in costs of investment giant water bug Large eggs require high level of care

Mating Systems and Parental Investment Part 5

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