BIO 331 Exam 2
Behavioral defense - answer Young animals are often small, naive, unskilled, and less
mobile - classic targets of a predator. As a means of offsetting this, parents often will
physically/spatially attend to their eggs or hatched/born young in order to defend them
from a variety of biotic threats, such as predators and parasites.
Among the most common forms of parental care; examples can be found in fish and
primates who clean their young of pathogens/parasites to reptiles or amphibians who sit
next to their eggs/nest to guard them/it. This form of parenting becomes more difficult in
more mobile species, or as young mature and become more mobile.
Nutrient provisions – answer Parents can invest in young by providing them with
nourishment either before hatch/birth (e.g. egg yolk, placenta) or after hatch/birth (e.g.
delivering food to them, or mammary milk).
This is the most common form of parental care. Even parents who never interact with
their offspring after egg-laying or birth typically endow their direct descendants with a
nutritional jumpstart (typically egg yolk) - this is true in everything from insects to jellyfish
to egg-laying vertebrates.
Because live-bearing is less common in the animal kingdom than egg-laying, internal
nutrient delivery is less common than external nutrient provisioning.
Behavioral transport - answerSome young are hatched or born in locations that are not
the same as those optimal for their full development, so some parents have evolved to
transport their immature, relatively immobile young from one site to another.
This form of parental care is most common in oviparous and altricial (meaning very
immature young species, i.e. naked, blind, helpless) and less common in viviparous
(meaning live-bearing) and precocial (meaning very mature young, i.e. mobile, active)
species; this is because animals hatching from eggs or as very undeveloped young
require more assistance with movement.
Chemical defense - answerAs an added means of defending young from predators (in
addition to behavioral defense), parents may endow their offspring with noxious
chemicals that leave them distasteful and unpalatable to potential predators.
This requires either a specialized storage or chemoprotective physiological mechanism,
so that the chemicals are not toxic to the offspring. This is a common form of very-early-
life parental investment in insects (e.g. butterfly/moth caterpillars).
Environmental regulation - answerThis is a broad class of parental efforts aimed largely
at controlling the abiotic (and occasionally biotic) conditions of development. Examples
, include site selection, ensuring adequate oxygen concentrations and ambient
temperatures, and shielding from weather.
Animals requiring very particular environmental conditions for development, or
inhabiting environments that have unique high-risk circumstances (e.g. bad-weather
threat, low oxygen conditions), commonly will show this form of parental care. Examples
span nearly all animal taxa, from oviposition site selection in insects, to egg fanning in
some fish, to incubation behavior in birds.
Teaching - answerA more complex form of behavioral investment in young, in which
parents interact repeatedly with offspring to introduce them to proper food sources
(search images), habitat, or other behaviors (e.g. song, nest building).
Natural selection favors parental instruction when offspring co-exist with parents for a
long period of time (i.e. numerous/extended opportunities for learning/reinforcement).
This form is also more common among cognitively competent (often vertebrate)
species.
Recognizing your offspring - answerHeterospecific - Right species?
Conspecific - Mine?
Inter-individual - Which one?
Evolution of offspring-recognition
signals - answera) vocal (crying, begging)
b) visual (patterns)
c) olfactory (mammals)
d) spatial location
What are the main factors that drive the evolution of intricate offspring recognition
mechanisms? - answer(1) raising young around other species
(2) raising young in large groups
(3) when some young are more valuable than others
(4) when you might mistakenly care for the wrong offspring
Playing favorites with offspring - answer• Different offspring carry different costs
(energy)
Different offspring carry different benefits
- survival, relatedness, breeding prospects
SELECTION TYPICALLY FAVORS
PARENTAL FAVORITISM
Hypotheses explaining
parental favoritism - answer1. The silver-spoon hypothesis (i.e. most valued)
a. Oldest and/or phenotypically best (based on quality signals)
Behavioral defense - answer Young animals are often small, naive, unskilled, and less
mobile - classic targets of a predator. As a means of offsetting this, parents often will
physically/spatially attend to their eggs or hatched/born young in order to defend them
from a variety of biotic threats, such as predators and parasites.
Among the most common forms of parental care; examples can be found in fish and
primates who clean their young of pathogens/parasites to reptiles or amphibians who sit
next to their eggs/nest to guard them/it. This form of parenting becomes more difficult in
more mobile species, or as young mature and become more mobile.
Nutrient provisions – answer Parents can invest in young by providing them with
nourishment either before hatch/birth (e.g. egg yolk, placenta) or after hatch/birth (e.g.
delivering food to them, or mammary milk).
This is the most common form of parental care. Even parents who never interact with
their offspring after egg-laying or birth typically endow their direct descendants with a
nutritional jumpstart (typically egg yolk) - this is true in everything from insects to jellyfish
to egg-laying vertebrates.
Because live-bearing is less common in the animal kingdom than egg-laying, internal
nutrient delivery is less common than external nutrient provisioning.
Behavioral transport - answerSome young are hatched or born in locations that are not
the same as those optimal for their full development, so some parents have evolved to
transport their immature, relatively immobile young from one site to another.
This form of parental care is most common in oviparous and altricial (meaning very
immature young species, i.e. naked, blind, helpless) and less common in viviparous
(meaning live-bearing) and precocial (meaning very mature young, i.e. mobile, active)
species; this is because animals hatching from eggs or as very undeveloped young
require more assistance with movement.
Chemical defense - answerAs an added means of defending young from predators (in
addition to behavioral defense), parents may endow their offspring with noxious
chemicals that leave them distasteful and unpalatable to potential predators.
This requires either a specialized storage or chemoprotective physiological mechanism,
so that the chemicals are not toxic to the offspring. This is a common form of very-early-
life parental investment in insects (e.g. butterfly/moth caterpillars).
Environmental regulation - answerThis is a broad class of parental efforts aimed largely
at controlling the abiotic (and occasionally biotic) conditions of development. Examples
, include site selection, ensuring adequate oxygen concentrations and ambient
temperatures, and shielding from weather.
Animals requiring very particular environmental conditions for development, or
inhabiting environments that have unique high-risk circumstances (e.g. bad-weather
threat, low oxygen conditions), commonly will show this form of parental care. Examples
span nearly all animal taxa, from oviposition site selection in insects, to egg fanning in
some fish, to incubation behavior in birds.
Teaching - answerA more complex form of behavioral investment in young, in which
parents interact repeatedly with offspring to introduce them to proper food sources
(search images), habitat, or other behaviors (e.g. song, nest building).
Natural selection favors parental instruction when offspring co-exist with parents for a
long period of time (i.e. numerous/extended opportunities for learning/reinforcement).
This form is also more common among cognitively competent (often vertebrate)
species.
Recognizing your offspring - answerHeterospecific - Right species?
Conspecific - Mine?
Inter-individual - Which one?
Evolution of offspring-recognition
signals - answera) vocal (crying, begging)
b) visual (patterns)
c) olfactory (mammals)
d) spatial location
What are the main factors that drive the evolution of intricate offspring recognition
mechanisms? - answer(1) raising young around other species
(2) raising young in large groups
(3) when some young are more valuable than others
(4) when you might mistakenly care for the wrong offspring
Playing favorites with offspring - answer• Different offspring carry different costs
(energy)
Different offspring carry different benefits
- survival, relatedness, breeding prospects
SELECTION TYPICALLY FAVORS
PARENTAL FAVORITISM
Hypotheses explaining
parental favoritism - answer1. The silver-spoon hypothesis (i.e. most valued)
a. Oldest and/or phenotypically best (based on quality signals)
