Behavior Flashcards
• Natural selection favors behaviors that help
individuals survive and reproduce
• Proximate causes of behavior
– How stimuli initiate behaviors
• Ultimate causes of behavior
– Why a behavior has evolved
Activity Rhythms
• Rhythmic, cyclic, or predictable activity patterns
– Nocturnal, diurnal, or crepuscular
– Migratory or seasonal movements
– Timing of reproduction
– Torpor and hibernation
• Circannual—cycles that occur year to year
• Circadian—cycles based on a 24-hour cycle
Circadian Rhythms
• Based on a 24-hour light-dark cycle • Universal in mammals • Endogenous control – Internal mechanism or “clock” • Cluster of neurons in the superchiasmatic nucleus (SCN) in the brain in mammals • Exogenous control (external stimuli) – Changes in day length or temperature
Circannual Rhythms
• Cycles lasting approximately one year – Typically in seasonal environments • Breeding • Migration • Hibernation – Controlled by environmental cues • Temperature and precipitation changes • Day length changes • Changes in food abundance
Foraging Behavior
• Optimal foraging – Natural selection should favor foraging behaviors that deliver the
highest payoff
• Each food has a unique: – Nutritional value
– Abundance in environment
– Pattern of availability in the habitat
– Set of risks related to capture and processing
Caching Behavior
• Used by some shrews, moles, rodents, carnivores, lagomorphs • Seeds are most commonly cached food – Concentrated energy source – Can remain dormant for long periods – Chipmunks bite off embryo • Kangaroo rats transport seeds for caching – “Manage” the cached seeds for degree of fungal growth, diet diversification, and to prevent germination
Caching Behavior
Hoarding
• Scatter hoarding
– Few food items stored at many locations throughout the territory
– Adaptive only if the cache remains intact and is not lost to conspecifics
or other thieves
• Larder hoarding
– Many food items stored at a central site
Fossorial Foraging
• Burrowing is energetically expensive
• Burrowing patterns cover maximum area
– Burrow forks and burrow lengths are uniform
• Burrowing behavior is constrained by
physiological, morphologic, and climatic
factors
Shelter-Building Behavior
• Shelter-building behaviors provide: – Protection from predators – More stable temperatures – Places to store food • Shelters can be: – Underground – In tree holes or under leaf “tents” – In ponds (beaver lodges)
• Communication signals are “behavioral,
physiological, or morphological characteristics
fashioned or maintained by natural selection
because they convey information to other
organisms” (Otte 1974)
• Can be visual, olfactory, auditory, tactile, or
any combination
Visual Signals
• Intraspecific communication – Submissive vs. aggressive postures • Interspecific communication – Alarm displays in lemurs • Types of visual signals: – Facial expressions – Body postures – Anatomical structures • Anatomical structures – Antlers and horns – Weapon automimicry – Aposematic coloring
Olfactory Signals
chemical
• Pheromone
– Chemical signal that elicits a response in a
conspecific receiver
• Allomone
– Chemical signal that elicits a response in an
allospecific receiver
• Specific chemicals may convey unique
messages
• Scents dispersed in air travel long distances
Olfactory Signals
scent and glands
• Scent marking
– The maturation and use of scent glands are
controlled by gonadal hormones produced at
sexual maturity
– Most scent marking is done by dominant males
– Scent marking is often associated with the
possession of a territory
• Urine and fecal signals
– Convey information about individual’s physical
condition
– Establish and maintain territorial boundaries
– Males recognize females in estrus
– May help establish reproductive synchrony among
herd/pack
• Scent Glands
– Source of
pheromones and
allomones
Olfactory Signals
organ
• Vomeronasal Organ – Important in receiving sexual pheromones – Flehmen behavior (ungulates and Carnivora)
Olfactory Signals
individual
• Self-anointing
– Smearing scent on the body
– Used for mother-young recognition
– Defensive behavior
• Hedgehogs use toxins from toads to self-anoint
• Rats may self-anoint with weasel scent to mask their
own scent
• Individual recognition
– Discriminate between individuals by scent
Acoustical Signals
• Sense of hearing in mammals is acute
• Auditory communication is of great importance
– E.g. Virtually continuous noises made by members of a
herd
• Vocal communication varies among species from short,
simple calls to a large and varied vocal repertoire
• Singing mouse
Alarm or Contact Calls
• Alarm calls may be predator-specific • Contact calls may serve: – As territorial advertisements – To maintain group cohesion – To identify individuals
Individual Recognition
• Individuals may have unique vocal signatures
• Mother-infant recognition in nursery colonies
• The calls of many social animals (in Chiroptera, Primates,
Carnivora, Proboscidea, Sirenia, and Rodentia) signal
individual identity
Infrasonic Signals
• Sounds below human hearing range – Elephants use 14–24 Hertz infrasound • Low frequencies attenuate slowly • Elephants use infrasound to: – Locate individuals or groups – Signal aggressiveness – Convey reproductive cues
Aquatic Sounds
• Determining direction of sounds produced
underwater is difficult
• Cranial adaptations to hearing underwater
– Thin, dish-shaped area on the dentary bone
– Middle ear suspended from ligaments
– Fatty connection from middle ear to dentary
Underground Communication
• Only a narrow range of frequencies work efficiently • Low frequency sounds are optimal • Seismic signals also effective – Vibrations transmitted through soil – Head tapping – Foot drumming
Tactile Signals
• Allogrooming – Grooming of one animal by another – Important social function in primates – Conveys information on social status – Reinforces social bonds – Dissipates aggression – Ritualized greetings • Non-grooming tactile signals – Precopulatory behaviors – Reciprocal flipper rubbing in dolphins – Bonobo societies • Female-female genital rubbing • Male-male genital rubbing • Oral-genital contact • Tongue-kissing
Kin Selection
• William Hamilton proposed that kin selection is a
type of natural selection in which “the frequency
of a gene in a population will be influenced by
survival and fertility of all individuals carrying that
gene, including relatives”
• Fitness refers to an individual’s success in passing on
genes to future generations
– Offspring share 50% of genes with each parent
– Siblings share 50% of genes with each other
– Cousins share 12.5% of genes in common
– Fitness benefit is same for helping 4 cousins or 1 brother
• Coalitions of male lions
• Alarm calling ground squirrels
Reciprocal Altruism
What it is
• Short-term cost of providing another with a
resource is offset when recipient returns the
favor later
• Evolves only when:
– Donor and recipient recognize one another
– Repayment is likely
– Benefit to recipient > cost to donor
Reciprocal Altruism in Vampire Bats
• May starve to death if no meal for two consecutive nights • Begging for blood meal can save a life • Recipient gains 5% in blood meal or 16 hours until starvation • Share blood meals with roostmates • Donor gives blood to roostmate • Donor loses 5% of body mass or six hours of time to starvation • Recipient gains 5% in blood meal or 16 hours until starvation
Mating Systems
• The costs of producing offspring (individual) are very
different for males and females
• Males
– Produce large numbers of tiny, energetically inexpensive
gametes
– Never certain of paternity
– Maximize fitness by fathering as many offspring as possible
• Female
– Produce few, larger gametes
– Expend energy on pregnancy and lactation
– Invest greatly in each offspring
– Should choose mates carefully
Mating Systems
• Sexual conflict between males and females
– Females invest much more in each offspring
– Females are a limiting resource for males
– Males must compete with each other for females
(male-male competition)
– Females seek best possible mate(s) from many
courting males (female mate choice)
Mating Systems
• Variation in mating systems probably due to:
– Need for males to assist in rearing young
– Ability of males to guard females or their ranges
– Predictability of locating females
Monogamy
• Exclusive mating between one male and one
female during one or more breeding seasons
• < 3% of mammals are monogamous • Even “ monogamous ” species may have extra-pair paternity
• Obligate monogamy
– Little sexual dimorphism – Members of pair interact frequently – Environment has low carrying capacity – Male help necessary to rear offspring – Occurs in some canids, rodents, and sengis
• Polygyny
– Males mate with multiple females, but females
mate with a single male
– Male territory overlaps many females
– Males can defend resources females need
• Promiscuity
– Both males and females mate with multiple
partners
• Female defense polygyny
– Males monopolize several females, forming
defended harems
• Resource defense polygyny
– Males control access to resources required by
females
– Few dominant males secure most matings
– Satellite males may challenge the primary male or
copulate on the sly
