Chapter 44: Animal Behaviour and Responses to the Enviornment Flashcards
behaviour
defined as the way in which organisms respond to a particular situation or stimulus
single-cell organisms exhibit complex avoidance behaviours
- swimming away from light or predators
- ## motile, single-celled ciliate Senior coeruleus is capable of decision making and learning
- fungi and plants have senses analogous for those of animals, exhibit behaviour
- while learning, memory, and behaviour have long been associated with animals having nervous systems, there is growing acceptance that non-neural organisms such as bacteria, slime moulds, and plants can also exhibit complex behaviours
the prey species also study the behaviours of their predators and develop defensive strategies against them, how is this info passed down
- this information is passed down from one generation to the next
EXAMPLE: KILLER WHALES
- British Columbia
- mother and grandmother orcas filmed teaching young orcas how to spy-hop to locate seals and how to leap out of the water and use their tails to stun and kill their prey
- killer whales off the coast of Argentina teach their young how to self-strand, to surprise and capture sea lions on the beach
- the orcas surf on incoming waves to grab seal pups, becoming stranded themselves in the process, but use the following wave to pull them back to deeper water
- antarctic orcas use wave-washing as a strategy for hunting seals
what is wave-washing for orcas
- basking on ice floes, this is cooperative behaviour in which groups of orcas first chip away at the ice floe, diving below it at the last moment and allowing the wave they have created to wash the seal off the far side, where other orcas in the pod are waiting to capture it.
- when young orcas are present, the pod will often push the seal back onto the ice floe and then regroup to repeat the behaviour again for the benefit of the young
the study of plant and animal behaviour by humans was a natural progression
- 12 000 years ago, all humans were hunter-gatherers
- indigenous hunting societies around the globe have relied on knowledge of the behaviours of their food species for survival
- this knowledge of the relationship of living things with one another and with their environment has traditionally
-
most knowledge of behaviour begins with
observation
what do organisms do in response to different stimuli
- most knowledge of behaviour begins to observation
proximate causes
refer to the mechanistic bases of the behaviour
ultimate causes
refer to the evolutionary bases of the behaviour
nature
- how much of an organism’s behaviour is a function of what they inherited as opposed to be environment and setting in which they develop and are nurtured
instinctive behaviour
- behaviours that are inherited
nurture
- behaviour based on the environment and setting in which they develop and are nurtured
how can instinctive behaviours be grouped
- feeding
- defence
- mating
- parental care
what do we assume about instinctive and nature
they have a strong genetic basis and that natural selection has preserved instinctive behaviours because they construe adaptive advantages
learned behaviours
determined by the environment an animal grows up and lives in
are not performed accurately or completely the first time they respond to a specific stimulus
behaviours change in response to what stimuli?
the environmental stimuli and individual experiences as it develops
how do behavioural scientists generally define learning
process in which experiences change an organism’s behavioural responses
young herring gulls
- the responses of young herring gulls chicks to cardboard cutouts of an adult herrings gull head and bill
- they waves these models in front of the chicks and recorded how often a particular model elicited a pecking response from the chicks
- chicks peck on the red side at the bottom of an adults mouth to have the adult open their beak wide and feed them *
results: young gulls pecked at the model of the bill with a red spot almost as often as pecking at just a head with a red spot, but barely pecked the model without a red spot
= begging behaviour by young herring gulls is triggered by SIGN STIMULUS = red spot on parents bill
fixed action patterns are triggered by what form of stimuli
sign stimuli
- young herring gull chicks use a begging response, a fixed action pattern to secure food from parents by pecking on red spot on bill
the role of natural selection in moulding behaviour
- moulded behaviour of some parasitic species to exploit the relationship between sign stimuli and fixed acton patterns for their own benefit
- in effect, they may break another species’ code
i.e. birds that are brood parasites lay their eggs in the nests of other species of birds, when the parasite’s egg hatches, the nesting mimics sign stimuli ordinarily exhibited by its host’s own chicks - the parasitic chick begs for food by opening its mouth, bobbing its head, and calling more vigorously than the host’s chicks
female greater honeyguides
lay their eggs in the nests of several host species that nest in dark hollows
- greater honeyguides are not territorial, so more than one female may lay her eggs in the nest of a host
When a female lays her eggs:
- a female greater honeyguide minimizes future competition among nestlings by selectively piercing the eggs of other greater honeyguides in the nest
After hatching:
- greater honeyguides chicks kill other nestlings, whether conspecifics of the young of the hosts
- both egg piercing and killing nestlings increase the chances of the chick surviving and reproducing
genetic differences between individuals can translate into
- behavioural differences between them
- single genes do not directly control complex behaviour patterns, the alleles of the gene instead determine the kinds of enzymes that cells can produce, influencing biochemical pathways involved in the development of an animal’s nervous system
- the resulting neurological differences translate into behavioural differences between individuals that have certain alleles and those that don’t
Wingless pathway
- controls a series of development interactions shared by almost all eukaryotic organisms, most of which do not possess wings
- named after the original discovery of the wingless gene
- mutant genes of the pathway (fruit flies) cause alterations in the wings and other segmental structures
Nardos Lijan experiment on the wingless pathway
- constructed an artificial copy of the Dv11 gene with the central section scrambled so no functional proteins could be made
- introduced the artificial proteins into embryonic cells, and they interbreed the heterozygotes to produce individuals that carried two copies of the altered Dv11 gene and no normal copies
= individuals without the normal gene copies are knockout mice because the normal gene is completely missing
knockout mice
- grew to maturity with no apparent morphological defects in any tissue examined, including the brain
- their motor skills seemed normal
- social behaviour differed from CTRL mice
= mice with at least one copy of the normal gene didn’t participate in social grooming and groups
= knockout mice isolated themselves and slept alone
Heterzygotes behaved normally
the neural circuit of the brain inhibits the startle response of normal mice, and the reaction of knockout mice suggested that this inhibitory circuit was altered
Dvl1 gene
- one of the first genes identified that modified developmental pathways affecting complex social behaviour
- the similarity in startle reflex intensity between the knockout mice and humans with neurological or psychiatric disorders suggests that mutations in the Dvl genes and the wingless developmental pathway underlie some human mental illnesses
the importance of knockout genes
- tool to explore the specific roles of different genes and the genetic differences between individuals that underlie behavioural differences between them
imprinting
- occurs when animals learn the identity of a caregiver or the key features of a suitable mate during a critical period
- newly hatched geese imprint on their mother’s appearance and identity
- when they reach sexual maturity, young geese try to mate with other geese exhibiting the visual and behavioural stimuli on which they had imprinted as youngsters
critical period
a stage of development early in life
ethology
study of animal behaviour
- Konrad Lorenz is one of its founders
Konrad Lorenz experience with imprinting
- when he tended to a group of newly hatched greylag geese, they imprinted on him rather than on an adult of their own species
- male geese followed Lorenz and attempted to court humans once they reached sexual maturity
classical conditioning
- Ivan Pavlov, a Russian physiologist demonstrated this with dogs
- dogs salivate where the saliva contains enzymes that break down sugars, giving the dogs and indication of the value of food
- Pavlov rang a bell just before offering food to dogs
- after 30 trials where dogs received food immediately after the bell rang, the dogs associated the bell with feeding time and drooled a bunch when it rang
= bell became a conditioned stimulus
operant conditioning
trial-and-error learning is another form of associative learning
- here animals learn a link to a voluntary activity
operant
has favourable consequences, with reinforcement
for example
- a rat will explore a cage that may be equipped with a bar that released food when it was pressed by accident [operant] and the rat would immediately receive a morsel of food [reinforcement] after a few experiences, a hungry rat learned to press the bar more frequently
insight learning
occurs when an animal abruptly learns to solve problems without apparent trial-and-error attempts
- example: captive chimpanzees solved a novel problem, how to get banana hung far out of reach, the chimps studied the situation and then stacked several boxes, stood on them, and used a stick to knock the fruit to the floor
habituation
- occurs when animals lose their responsiveness to frequent stimuli not immediately followed by the usual reinforcement
- can save the animal the time and energy of responding to stimuli that are no longer important
current belief on behaviours
includes both instinctive and learned components
- few behaviours are determined by entirely genetic or environmental factors
how do most behaviours develop
through complex gene-environment interactions
- some behaviours have a stronger instinctive component while others have a strong learning component
instinctive behaviours can be modified in response to what
particular experiences
hormones
- underlie the performance of many specific behaviours
- often work by directly stimulating target cells, by regulating the development of neurons and neural networks
example: African cichlid fish
- some adult males maintain nesting territories at the bottom of a lake and territory holders and brightly coloured and attract females with elaborate behavioural displays
- these males aggressively defend their territories against neighbouring territory holders and incursions by non-territorial males
- non-territorial males are much less colourful and aggressive, they don’t control a patch of suitable nesting habitat they do not attract females
differences in GnRH levels
produce differences in male behaviour and coloration
- in the hypothalamus of the brain of territorial males, large, biochemically active cells product GnRH
- GnRH stimulates testes to produce testosterone and sperm
- the testosterone is released into the circulation and carried to the brain of the fish, where it helps modulates the activity of nerve cells that regulate sexual and aggressive behaviour
- w/o GnRH, male fishes don’t court females or attack other males
Russell Fernald
- his students manipulated the territorial status of males
- some territorial males were stripped of their territories and some non-territorial males were provided with territories
- as a ctrl, the territorial status of other males was unaltered
- 4 weeks later, Fernald and his students compared experimental and control fishes
- they considered coloration + behaviour as well as the size of the GnRH producing cells in the brains
= territorial males that had been changed to non-territorial males had lost their bright colours and stopped being combative
- GnRH producing cells were also smaller than those of territory-holding controls, and males that gained territory developed bright colours and displayed aggressive behaviours toward other males, their GnRH producing cells in the brain were bigger that control fish
what affects the size of cells that produce GnRH
- the processing of information that transmit input to the hypothalamus
- it then affects the size of cells that produce GnRH which dictates the hormonal state of the male
- a decrease in GnRH production turns a fiesty territorial male into a subdued drifter
= males that regain territorial status develop higher levels of GnRH and show vigorous sexual and aggressive behaviour
zebra małe finches
- females don’t sing, but males do because they have higher levels of estrogen (at development and childhood its the same amount, because they sing to get attention from their parents)
- estrogen acts on target neurons in the higher vocal centre of the developing brain, and invokes a complex series of biochemical changes resulting in the production of more nerve cells in the parts of the brain regulating singing
brains of developing females
- don’t produce estrogen and females do not sing courtship songs
- in the absence of estrogen, the number of neurons in the higher vocal centre of females declines over time
- if young female zebra finches are given estrogen, they produce more nerve cells in the higher vocal centre and they can sing
specific stimuli, the songs of familiar or unfamiliar males, which alter genetic activity of nerve cells that control adult birds’ behaviour
changes in the concentrations of hormones over time
also affect behaviour
bees
as honeybees age:
- workers perform different tasks
NURSES: adults younger than 15 days
- tend to care for larvae and maintain the hive
FORAGER:adults older than 15 days
- make foraging excursions from the hive to collect food
= change in behavioural is induced by juvenile hormone, which increases as you age
- hormones stimulates genes in certain brain cells to produce proteins such as octopamine that affect the nervous system
Octopamine
stimulates neural transmissions and reinforces memories
- concentrated in the antennal lobes
- helps the bee recognize doors of flowers where it can collect nectar and pollen
illustration of how genes and hormones interact in the development of behaviour
what do hormones change in cells
- directly and indirectly change genetic activity and enzymatic biochemistry in these cells
- when the target cells are neurons, changes in biochemistry translate into changes in the animal’s change
anatomical and physiological basis
- embedded primarily or entirely in the nervous system
- song development in a different bird species is an example [white crowned sparrows]
white crowned sparrows and Marler’s Experiment
- white-crowned sparrows sing a song that no other species sings
- Peter Marler took newly hatched white-crowned sparrows from nests in the wild and reared them individually in soundproof cages in his laboratory
*juvenile males in both groups first started to vocalize
150 days: birds produced whistles and twitters that only vaguely resembled the songs of adults
200 days: these males were right on target, producing a song that was indistinguishable from the one they heard before
species specific songs for birds includes what 2 components
instinctive and learned
What did Marler’s Experiment show
- show that acoustical experience shaped singing, suggesting that a sparrow chick’s brain must acquire and store info present in songs of other males
- when the young male starts the sing, its nervous system matches its vocal output to the stored memory of the song it had heard earlier
- if young birds don’t hear the song, they never will produce the full song
- even with recordings, they couldn’t replicate the song fully
= therefore, must be generated by appropriate stimuli
nuclei
clusters of nerve cells
- help make song learning and song production possible
hormones alter what
the development of neurons and neural networks that are involved in the singing of courtship songs in males
- in the same species, the ability of the males to discriminate between the songs of strangers and those of neighbours = neuronal control
territories
spaces defended by individual males or breeding pairs
- defence of the territory ensures that residents have exclusive access to food and resources
importance of nucleus in forebrain of zebra finches
- allows them to discriminate between the songs of neighbours and those of strangers
- cells in this nucleus fire frequently the first time the zebra finch hears a neighbour song
- as the song keeps playing=the cells of the nucleus cease to respond, as the bird is habituated to a familiar song
ZENK
- molecular and cellular technique that identifies the role of specific genes in habitual learning (getting used to a stimuli)
- when a zebra finch is exposed to songs of potential conspecific rivals, the gene called ZENK rapidly becomes active within neurons in the song-controlling nuclei of the bird’s brain
= produces an enzyme that changes the structure and function of those neurons
- these events enhance the ability to detect and respond to new intruding conspecifics
salting of highways in Canada and Moose
- prevents dangerous buildups of ice on road surfaces
- after snow plowing and runoff, the salt usually accumulates in roadside ditches
Moose use these salty pools to supplement their mineral intake, moose at roadsides will come close to high-speed traffic to lick the pool which endangers them and the drivers
SOLUTION:
- Roy Rea decreased the attractiveness of roadside salt pools by removing salty soils, altering drainage patterns, and filling pools with mulch, rock, and dog + human hair
- decreased moose visitations
Chewing Trees
- trees respond to herbivores chewing them by secreting defensive chemicals into their foliage
- secretions are greater in lower foliage than higher up foliage which is out of reach for herbivores
MOOSE AND CHAINSAWS
- In Canada, moose are attracted to the sounds of chainsaws
- they associated the sound with felled trees which gives them access to upper foliage with less chemicals
Vietnam War and Tigers
Tigers learned to associate the sound of artillery with an opportunity to eat
- the tigers’ behaviour meant that some wounded soldiers waiting for treatment may have been attacked by tigers looking for food
one of the strongest re-enforcer of behaviour
food
sea otters by California coastal waters
- sea otters will dive and collect food (sea urchins) from the bottom and bring their catch to the surface to eat it
- otters resurfaced with empty beverage cans
- these otters would lie on their backs in the ocean swells, take a can and bite it open
- biologists discovered many cans had young octopods (octopus) in it where they were exploiting new opportunities for shelter and the otters were exploiting new opportunities for shelter
Chimpanzees in Senegal
- researchers observed Chimps hunting Senegal galagos where they used grass stalks to fish for termites and worked in gangs to hunt young baboons
- the discovery that savannah chimps in Senegal used spears to impale Senegal galagos hidden in tree hollows further demonstrated chimps’ repertoire of tool use
= they also planned hunts in advance
Western Scrub Jays
- cache food in preparation for the next day’s breakfast
- demonstrating that animals consciously plan ahead shows that animal executes a novel action or combination of actions anticipating an emotional state different from the one at the time of planning
- these behaviours aren’t genetically based, such as those associated with hibernation and migration
signaller
individual transmitting information
signal receiver
is the one receiving the signal
- behaviour seen as mimicry and the success of nest parasites occurs when one species breaks the signal codes of another, exploiting them to advantage
in what ways do animals communicate
- use sensory modalities to transmit signals:
- acoustical
- chemical
- electrical
- vibrational
- visual
= some signals combine these
= sometimes the animal itself is a signal (i.e. colourful butterflies appearing poisonous)
Acoustical Signal and Bird Songs
- song of male whippoorwill or red-eyed vireo
- advertises his presence to females and may help him secure a mate
- same song is heard by other males, recognize it as a territorial display
- after the eggs were laid, the same song is heard by the young developing in the eggs
= this exposure influences the songs to which animals respond when they mature,
other birds rubbing one feather against another for communication
Acoustical Signal and Yelling Ravens
- in winter, raven will yell when they see a deer carcass
- this attracts hungry ravens
= this behaviour puzzled Bernd Heinrich, who noted:
- when paired territory-holding adult ravens found a carcass, they fed quietly and didn’t yell
- he noted that young raven without territories yelled when they came across which attracted other ravens and overwhelmed the birds efforts to defend their carcass and territory
why?
- non-territorial ravens used yelling to exploit the food supply
- whereas residents just ate
reproductive benefits?
- benefit of resident ravens was enhances by uninterrupted feeding, but non-territorial ravens succeeded in their trespassing when they called others to support them against the territory holder
Pacific Herring
communicate with conspecifics by farting passed from the anus
Skunks and Visual Signals
- striped skunk’s black-and-white stripes constitute a visual signal warning predators that it will spray
Example of visual signals
1) humans facial expressions and body languages
2) bioluminescent signals in animals living in darkness
3) the crown feathers of a royal flycatchers (bird)
= these are often exaggerated and stereotyped to enhance their functions and signals
Chemical Signals
Dogs perceive these though chemicals in the urine, conveys information about other dogs that have urinated there
- PHEROMONES; distinctive volatile chemicals that are released in minute amounts to influence the behaviour of conspecifics
ant example
- worker ants have a battery of glands which release different pheromones
i.e. one set of pheromones recruits fellow workers to battle colony invaders
i.e. another set stimulates workers to collect food discovered outside the colony
silkworm moth
- use it to attract mates
- females will produce bombykol which will stimulate receptors on antennae of males
- males will fly upwind and look for the female
Using Pheromones to lure prey
ex. female bolas spiders
- use a sticky ball of web impregnated with a chemical that mimics the odour of sex pheromones secreted by female moths
- male moths respond to the lure of these odours approach the web and are captured
- some species of the spider will adjust the production of the pheromone to mimic the times of maximum activity
tactile signals
- can operate only over very short distances, but for social animals living in close company they play a significant role in the development of friendly bonds between individuals
electric signals
- used by some freshwater fish species used weak electrical signals to communicate
- this is especially effective for species living in murky tropical rivers where visual signals can’t be seen
- these fish have electric organs that produce electric signals that vary in intensity, duration, and frequency
- gives the fish a repertoire of signals
what can electric discharges signal
- threats
- submission
- readiness to breed
Karl von Frisch and honeybee
- demonstrated that the honeybee dance involves tactile, acoustic, and chemical signals
- when a foraging honeybee discovers a source of pollen or nectar, it returns to its colony
- there, in the darkness in dances on the vertical surface of the honey comb, the dancer moves in a circle attracting a crowd of workers, and some workers follow and maintain physical contact with the dancer
DANCE TELLS
- other bees info about food source, quality of It, and the distance and direction observers will need to fly to locate it
when does the bee perform a round dance
- when food source is less than 75m
- tight circles: swinging its abdomen back and forth
- bees that surround the dancer produce a brief acoustical signal that stimulates the dancer to regurgitate a sample of the food it discovered = chemical cue
waggle of a bee =
production of a brief buzzing sound
- the angle of the waggle run relative to the vertical honeycomb indicates the direction of the food source relative to the position of the Sun
*duration of wiggles and buzzes carry information about distance to the food, the more time spent wagging and buzzing= father away the food is from the hive
simple eyes
measure light intensity
- blackening the ocelli of dancing bees
- use the Sun as a directional compass
echolocation
animals emit vocal calls and then listen to those echoes of the calls
= USED FOR NAVIGATION, FORAGING, AND HUNTING
- an echolating animal stores the outgoing signal in its brain and compares it with the returning echoes
- the differences between what the animal says and what it hearts contains information about the objects around it
bats and echolocation
bats, dolphins, whales, and shrews and birds all use it
= bats have highly developed ears which allow them to easily hear the returning echoes
- when an echolocating bat or dolphin produces echolocation signals, the signals are audible to some other animals as well
- when a bat is foraging, potential prey hear the signals and move away from the sound source to evade the approaching predator
- when the bat is too close, moths with ears dive to the ground or use erratic flight to evade the bats
- moths with ears sensitive to bat echolocation evade attacks 40% of the time
- but insects that don’t have the detection will die 90% of the time
whales and echolocation
- killer whales use echolocation to detect, track, and locate the salmon they eat
- transient killer whales in the same area feed on marine mammals
- these killer whales rarely echolocate as their prey, such as seals, can hear emitted sounds and will quickly leave the water when they hear the echolocation calls of approaching whales
language is communication but
not all forms of communication have to come in the form in language
i.e.
syntax and symbols are present in honeybee dancing
i.e.
vervet monkeys use signals for different predators
i.e.
chickadees use different alarm calls to alert others of danger
i.e.
captive trained chimps and gorillas have used ASL
geographic range of animal species
- include a mosaic of habitat types
- breeding ranges of white-crowned sparrows can encompass forests, meadows, housing developments, and city dumps
- a Kirtland’s warbler is found in young jack pine forests, at the individual level
= they need to pick habitats with resources
kinesis
movement
- change in the rate of movement or the frequency of turning movements in response to environmental stimuli
- wood lice typically live under rocks and logs or in other damp places
- arthropods aren’t usually attracted to moisture so when a wood louse encounters dry soil, it’ll scramble and turn often
- when it finds moist soil it moves less bc without moisture it’ll get dehydrated and die
taxis
= ordered movement
- response directed either towards or away from a specific stimulus
- cockroaches exhibit negative phototaxis, meaning they avoid light and seek darkness
- negative phototaxis= make cockroaches less vulnerable to predators that use vision to find their food
insects inheriting preferences for the plants they eat
- adults often lay their eggs only on appropriate food plants, effectively selecting habitats where their offspring will live and feed
vertebrates and exhibiting innate preferences
- demonstrated by two closely related species of European birds, blue tits and coal tits
= adult blue tits forage mainly in oak trees; coal tits in pine trees and when they were given the choice they went to these respective ones likely because they feed best there
barnacles being sessile species
- often anchor onto substrate but are motile as larvae
- they can live on whales or ship hulls
- motile animals have a home range, the space they regularly traverse during their lives
- home ranges become territories when they’re defended
territory quality and male reproductive success
- males defending the best territories attract the most females, which offer males the greatest opportunities to mate with the most females
territorial defence
always a costly activity
- patrolling territory boarders, performing displays hundreds of times per day, and chase intruders which takes time and energy
territorial displays do what
increase the animal’s likelihood of being injured or detected and captured by a predator
- territorial behaviour has its benefits including access to females
when is migration complete
when the same individuals later return to their natal site
migration
seasonal movement of individuals to and from different areas readily applies to many birds and other animals
= doesn’t describe all migratory patterns (for butterflies for ex.)
- seasonal changes for butterflies include other organisms where it depends on the growth patterns of milkweed leaves which they eat as caterpillars
woodland caribou
- numbers in decline due to habitat loss, over-hunting, and other factors
- listed as a species of special concern
- by using Indigenous knowledge on their observations of foraging strategies and distributions of caribou [TEK]
- they were able to develop a habitat sustainability index to predict how caribou chose habitat by examining their use or avoidance of a resource relative to its availability
HSI vs TEK
HSI- better predicted habitat selection in response to indexes of vegetation and winter snow cover
TEK- better predicted habitat quality in an area that burned 60 years earlier and now lacked caribou
TEK and hunting bowhead whales
- population of whales declined to fewer than 1000 individuals
- local Inuit depended on the whales for food, fuel, and shelter
- estimated that population size would be closer to 7000 [TEK]
- estimates of the Western Science was based on premise that whales couldn’t swim offshore ice and didn’t feed during migration
results
= 8000 whales, TEK was very accurate
Erin Baerwald and Robert Barclay
- assessed possibility that young hoary and silver-haired bats migrated with their mothers
- assessed micro satellite (Non-functional) genotypes and stable isotopic values in tissues obtained from bats killed
= 133 hoary bats
= 87 silver-haired bats
at wind turbines - 0 Evidence that the ants were close genetic relatives or lived nearby, therefore these species migrate alone
what cues are used in orientation and navigation
1) piloting
- visual way-finding mechanism, involves the use of familiar landmarks to guide the journey
i.e. salmon use olfactory cues to pilot their way from the ocean where they breed and lay eggs to the stream where they hatched
i..e female digger wasps nest in soil, these wasps used visual landmarks to find their nests [researcher used pinecones which a wasp used as a landmark, wasps use geometry]
2) compass orientation
3) navigation
- most complex way-finding mechanism, occurring when an animal moves toward a specific destination using a compass and mental map of where it is in relation to destination
- hikers use this to find their way home
celestial navigation
form of navigation that’s some birds that migrate at night use
- use the position of stars
INDIGO BUNTINGS
- indigo buntings direct migration using celestial cues
- Stephen Emlen confined them to a cage lined with blotting paper and he placed ink pads on the cage bottoms and kept it in an outdoor enclosure so that the birds had a full view of the night sky
- bird moved=inky footprints in the direction
CLEAR NIGHTS IN FALL= FOOT PRINTS SOUTH
CLEAR NIGHTS IN SPRING=FOOT PRINTS NORTH
CLOUDY NIGHTS=EVENLY DISTRIBUTED FOOTPRINTS IN ALL DIRECTIONS
Biologists and GPS systems
use GPS and radio transmission to follow animals
- arctic terns=seabrids that make annual migrations
- light-sensing geolocators allowed biologists to document the details of their movement paths
(EXACT MECHANISMS ARE STILL UNDER INVESTIGATION)
Homing Pigeons
- can navigate their homes from any direction
- use the Sun’s positions as their compass and olfactory cues as their map
Xie Can and cryptochromes
used an electron microscope to observe assemblies of proteins called crypto chromes that are sensitive to magnetic fields [MagR]
- flies missing this protein lost their magnetic sense
trying to test if flies could use the earths magnetic field for navigation
Advantages of not migrating
- some species such as Brazilian free-tailed bats don’t move
- exploitation of local resources
-reflecting detailed local knowledge
[food, nest sites, mates, and local communities of preds and prey]
Risks of Migration
- time and energy cost
- risk of death by exhaustion or predation
Why Migrate?
for birds: seasonal changes in food supply
- insects can be more abundant in higher-latitude environments
= great for rearing offspring
- avoiding the northern winter is adaptive because endotherms must increase their metabolic rates to stay warm in cold climates
- summer days are longer at high latitudes than tropics giving adult birds more time to feed and rear offspring
- migration to breeding grounds may provide conditions for reproduction [low predation, or warm H2O temp as examples]
mating systems
evolved to maximize reproductive success in response to amount of parental care that offspring require
two types:
MONOGAMY
-describes the situation in which a male and female form a pair bond for a mating season or in some cases for the individuals’ reproductive lives
POLYGAMY
- occurs when one male has active pair bonds with more than one female [POLYGYNY] or one female has active pair bonds with more than one male [POLYANDRY]
Promiscuity
- occurs when males and females have no pair bonds beyond the time It takes to mate
IN POLYGYNY
- males often contribute nothing but sperm
IN POLYANDRY
- females only contribute eggs
(usually, females will bear the costs of housing and feeding developing young)
altricial
naked and helpless
- characterizes baby robins when they hatch
- they beg for food and both parents can bring it to them
when do males and females achieve higher rates of reproduction
when both parents are actively involved in raising young
- females usually provide milk [mammal-specific]
- in monogamy, males can bring food to mom that she will use to feed kids with
MALES AND HIGH QUALITY TERRITORIES
- males having high-quality territories, allow females to raise young on their own
Polygynous
- mating with several females
- males role=sperm donor and protector of the space instead of an active parent
i.e. red-winged blackbirds
*MALES HOLD LARGE-RESOURCE-FILLED TERRITORIES THAT SUPPORT SEVERAL FEMALES
- these males will be attractive to females even if a female already lives on the territory**
Polygyny
- prevalent among mammals because, compared to males, females make a much larger investment in raising young (through egg development and caring for young)
when do promiscuous mating systems occur
- when females are with males only long enough to receive sperm and there is no pair bond
- these males make no contribution to raising young {Sage-grouse and hammer-headed bats}
what do Sage-grouse and hammer-headed bats form
LEKS
- congregations of displaying males
where females only come to mate
sexual dimorphism
- one sex is larger or more colourful than the other (outcome of sexual selection)
- when males compete for females, they’re often larger than females and have ornaments and weapons such as horns and antlers, for attracting females and for butting, stabbing or intimidating rival males
the purpose of adornments or weapons
simultaneously warns off other males and attract the attention of females
- peacocks strut in front of peahens while spreading a gigantic fan of tail feathers which they shake, rattle, and roll
= indicative that these males are healthier, that they can harvest resources efficiently or have managed to survive to an advanced age
- reflect positive genetic quality, making them more likely to fertilize the female’s egg
males fighting with other males
- males that win these fights have exceptional reproductive success because they mate with many females, but only after engaging in violent and relentless combat with rivals
- females struggles attracts other males who attempt to interrupt mating
- only the largest and most powerful males are not interrupted in their copulations and they inseminate the most females
females exercising a more active mate choice
- mating only after inspecting several partners
- active female mate choice is most apparent at leks
leks
- display groups where each male holds a small territory from which it courts attentive females
- the male is the only resource on the territory
= females will observe ornaments on males and choose
- they favour those that regularly come to the lek and defend a small territory of land vigorously
peahens favour males whose tails have
ornamental eyespots
- in an experiment, some peahens were mated to peacocks with highly attractive tails and others with less impressive tails
- offspring reared in uniform conditions
- offspring of impressive dad survive longer and better
handicap hypothesis
- females select males that are successful: the ones with ornate structures
- these may impede locomotion and attract predators [i.e. big feathers may make them more visible]
BUT, females select them because even with that ornamentation they’ve managed to survive so long
larger species of birds and tropical species tend to be
more ornamented
when are females more colourful than males
- in species that breed cooperatively
- reflects female-female competition
- bird species where males are more colourful typically show strong sexual selection and male-male competition
= females tend to be less colourful than males
human social structure
live in large social units composed primarily of non relatives
what does the level of social interactions depend on
seasons, reflecting the timing of reproduction
- influenced by changes in day length
African Lions and Infanticide
- lions live in prides = 1 male adult with several females and their young
- males usually sire the young born to the females in their pride to achieve a high reproductive output
- females benefit from group support including caring for young and foraging for food
*therefore, female lions in prides yield more offspring than solitary female lions**
- females in a pride are genetically related more than often and their estrus cycles are usually synchronized
- males fight to be the pride leader
- they protect their females from other males
WHAT HAPPENS WHEN A NEW MALES TAKES OVER A PRIDE
- he kills all nursing young, bringing the females into estrus
- they will not enter estrus and be reproductive while they’re still nursing their young
- benefits the male because it increases his chances of reproducing and he doesn’t have to wait until females weaned off young and females aren’t big enough to defend their babies + if she takes her baby and leaves the pride her efficiency as a hunter declines and reproductive success plummets
why are lions efficient in a pride
- hunting together
- raise more young
- threat posed by spotted hyenas which live in clans, and they often outnumber and chase lions from their kills even though they’re smaller
- many of the lions’ main prey also live in group and defences affect the lions’ hunting success
groups of cooperating predators frequently
capture prey more effectively than they would on their own
- white pelicans often encircle a school of fish before attacking, so being part of a group provides a better yield than being alone
prey subject to intense predation may benefit from
group defence
- more pairs of watchful eyes or ears to detect an approaching danger
- it may also translate into multiple lures = when a predator attacks, its more difficult to focus on an individual, when you’re part of a group that’s attacked it may be someone other than you that’s captured diluting the risk to just one group member
I.E. muskoxen form a circle around young against wolf attacks so attackers are confronted with horns and hooves
I.E. insects such as Australian sawfly caterpillars also show cooperative defensive behaviour, when predators disturb them all group member rear up, writhe, and then expel pungent and sticky oils from eucalyptus leaves, the oils are toxic to birds
cost of living in groups
- can be very expensive
- when thousands of royal penguins crowd together in huge colonies, the pressure on local food supplies is greater increasing the risk of starvation
- communal living may facilitate the spread of contagious diseases and parasites
I.E. nestlings of cliff swallows are stunted in growth because the nest swarm with blood-feeding, bedbug-like parasites, that more from nest to nest
avoiding and recognize diseases groups
- Caribbean spiny lobsters live in group and avpod conspecifics injected by a lethal virus
- Quinn Webber and his colleagues found that big brown bats using buildings as Sommer roosts were more vulnerable by viruses that those in the trees because the rates in a building roost are so close to eachother
social animals usually live in groups characterized by some form of structure
= some individuals may dominate others
[ dominance hierarchy ]
- manifested in access to resources
- dominant individuals get priority access to food/mate/sleeping sites
- sometimes, only dominate individuals reproduce
- dominance hierarchies may be absolute, when the same individual always gets first priority
relative dominance hierarchies
- an individuals status depends on the circumstance
- one individual may dominate at a food source, while another may dominate in access to mates
costs of dominance
- in animals such as wild dogs, and grey wolves, dominant animals must constantly defend their status
- dominants often have high levels of cortisol and other stress-related hormones in their blood
- elevated cortisol= high BP, disruption of sugar metabolism, and other pathological conditions
subordination
- subordinate group members like all members of the group, gain protection of predators
- they may also gain experience by helping dominant individuals raise young, over time, subordinate individuals can rise in a dominance hierarchy and avoid some of the side effects of dominance
subordinate members are like the backup members or characters
not all animals that live in groups are
social
- implying a level of organization in the group
behavioural ecologist William D Hamilton recognized what
genetic relatives effectively propagates the helper’s genes because families share alleles inherited from ancestors
- by calculating the degree of relatedness, we can quantify the avg percentage of alleles shared by relatives
what does the kin selection hypothesis suggest
- that the extend of altruism behaviour exhibited by one individual to another is directly proportional to the percentage of alleles they share
therefore, individuals are more likely to help close relatives bc by increasing a relatives fitness they are helping to propagate their own alleles too (since families share alleles)
test this by drawing a family tree to show genetic links and then measuring the degree of relatedness
how can we calculate the total relatedness between any two individuals
by multiplying out of the probabilities across links btwn them
btwn a nephew or niece and an aunt or an uncle is 0.25, and btwn first cousins is 0.125
kin selection
based on the idea that individuals should be more likely to help close relative because increasing a close relative’s fitness means that the individual is helping to propagate some of its own alleles
= kin selection
sibling helpers
KIN BEHAVIOUR: are individuals who delay their own reproduction to assist in raising siblings or half-sibling
- phenomenon common among animals in which inexperienced parents are not very successful and reproducing offspring on their own
- by helping, they gain experience and realize some genetic benefit
a male grey wolf helps his parents rear 4 pups to adulthood, these pups are his younger full siblings sharing _______ of his genes, so on avg the helper has crated “BY PROXY” ______ copies of any allele they shared
We also measure the costs, if he found a mate, sired offspring and raised two of them, each would have carried ______ of his alleles, preserving only ______ copy of a given allele
0.50
2 (0.50 x 4 = 2)
half
1 (0.50 x 2 = 1)
- in this situation, reproducing on his own would have produced fewer copies of his alleles in the next gen. than produced fewer copies of his alleles in the next gen than helping to raise his siblings
altruism
involves doing something that costs the actor while enhancing the situation of another individual (the receiver)
- demonstrates why parental behaviour is genetically selfish not altruistic
reciprocal altruism
- individuals will help non relatives if they’re likely to return the favour in the future
- bc each member of the partnership can potentially benefit from the friendship
- drivers hypothesized that reciprocal altruism would be favoured by NS as long as cheaters, individuals who don’t reciprocate, are denied future aid
dolphins and aid-giving behaviour
- dolphins attend injured group members to assisting with difficult birds
- use group behaviour to protect themselves from attacks by sharks
- Richard Connor and Kenneth norris proposed that the persistent threats of attacks by sharks and perils of living in the ocean combined to provide dolphins with opportunities to help eachother and other species
dolphins = reciprocal altruists
longer-lived species are more likely to develop what form of behaviour
cooperative
= helps explain the evolution of blood-sharing behaviour in vampire bats
- these are the only bats that feed on mammalian blood
- diff species share food
- individual unccesful in foraging can return to its root and beg blood from a successful forager amongst its roost mates
- donor will regurgitate some blood meal to the recipient
FOR THEM FAMILIARITY NOT RELATEDNESS DROVE THEM TO SHARE FOOD
eusocial
- many species of animals, particularly, bees, ants, termites and wasps live in colonies
- in this colony, thousands of genetically related individuals seem like sterile workers and live and work together for the reproductive benefit of a single queen and her mate
i..e bees
- they work for the queen and maintain the hive, feed the queen and her larvae to build new honeycomb and foraging for nectar and pollen
ultimate sacrifice: stinging intruders because stinging tears open the bee’s abdomen, leaving the stinger and the poison sac behind in the intruders skin and killing the bee
in bees and other eusocial insect how Is sex determined?
- genetically through haplodipolofy
- female bees are diploid because they receive a set of chromosome from each parent
- male bees, however, are haploids because they hatch from unfertilized eggs, and all the sperm carried by a drone will be genetically identical
- when a queen bee mates with 1 male all her worker offspring will inherit exact exactly the same set of alleles from their male parent, ensuring at least a 50% degree of relatedness among them
- workers are related to each other by an average of 25% through their female parents
= 75% related, higher degree of relatedness than they would have to any offspring that could’ve produced
its important for worker bees to devote their lives to care for their siblings because
- 75% related and they could become miss Canada one day
Naked Mole Rats
- eusocial animals with non breeding workers
- share an exceptionally high proportion of alleles
- live in mazes of subterranean tunnels
- in one colony
= single queen + 1-3 males are breeders
dispersal
mechanism that can reduce the chances of insecticides matings and inbreeding
Honer and colleagues lab
- used microsattelite profiling to that females preferred mates that had been born into or immigrated into the clan after she was born
what gives us our cognitive abilities
larger brains
