Introduction: Animal behavior
The study and description of organisms and natural objects, especially their
origins, evolution and interrelationships.
-Darwin was a natural historian. He collected animals, measured them and
described them. The idea of evolution through natural selection also hit
Wallace (he was not well connected).
According to the dictionary - the condition of being fit and healthy; the quality
of being suitable to a fulfill a particular role or task.
According to biology and this course - an organism's ability to survive and
reproduce in a particular environment; the amount of healthy, viable
offspring that contain that organism's genetic material which survive will
determine that organism's fitness.
One way in which you can become fit is through sexual reproduction.
i.e. Penguins - one chance at sexual reproduction a year. In terms of fitness,
this is incredibly tragic. A female penguin has about 12 eggs in her lifetime.
3 common misunderstandings
1. survival of the fittest: the theoretically important kind of fitness is that
which promotes ultimate reproductive survival. Reproduction always
requires some sacrifice of resources and some jeopardy of
physiological well-being, and such sacrifices may be favorably
selected, even though they may reduce fitness in the vernacular sense
of the term. (Two lions who look out at the alpha male and are unable
to have sex due to a power struggle; male peacock that walks around
with massive beautiful feathers that might cause him to become a
victim however sexual selection will allow him to have sexual fitness by
attracting female peacocks; distinct sexual strategies where there is an
alpha beta and gamma but they are equally fit.
2. survival of the species: Walt Disney coined the idea (late 1950s) that
when the pop'n of lemmings gets too high, they voluntarily commit
suicide for the survival of the species. However, organisms only do
things for their own survival or for the survival of their offspring thus Disney promoted a false idea.
3. evolution happened, but it isn't happening now: the white coat of the
polar bear if necessary for the stalking game in the snowy regions in
which it lives. The whiteness was favored by selection b/c darker
individuals were unable to survive VS The white coat of the polar bear
is advantageous for the stalking game in the snowy regions in which it
lives. The whiteness was favored by selection b/c darker individuals
were unable to survuve as well.
i.e. the black bear with white cub - the white cub is not fit for its
environment in the wild. Thus, the white cub is less likely to survive
and reproduce. White coat genes still survive in the black bear gene
pool. So evolution is still slowly working its way.
While studying animal behavior there are two levels of analysis - proximate
proximate: the mechanisms, how things work
â¢ genetics - (how do the genes interact with the environment thus
affecting behavior) and what turns genes on and off.
â¢ sensory-motor mechanisms - adjustments in responsiveness, hormone
systems, nervous system and skeletal system.
ultimate: historical approach (why?); take a look at an animal and
observe a behavioral trait then wonder how did that come about? What
were the challenges that they faced that caused them to become this
way, what changes in the environment might have occured that might
have lead to this elaborate behavior.
â¢ selective processes shaping the history of a behavioral trait - past and
current usefulness of the behavior in promoting lifetime reproductive
â¢ bottom line - reproductive success
i.e. Billy the bully - ultimate: how could bullying have promoted reproductive
success over the coarse of history?
i.e. Japanese Macaques: early 1950s these animals were unhealthy, living on
islands. Their numbers were decreasing and researchers were looking into this issue. These researchers intervened by supplementing their diets with
sweet potatoes. The macaques would eat them, except one macaque (not of
reproductive age) who would wash it and eat it every single time. Her family
started imitating this behavior. By washing off the potato, the macaque gets
rid of the sand. Today Japanese macaques are good in numbers, and they all
have a tendency of washing their food before injesting it. Through social
transmission, this act has become a behaviour. On the ultimate causation,
these animals gain benefit by increasing their physical health thus increasing
their life and having a better chance at reproductive success.
Proximate: benefit of how it tastes in your mouth
Ultimate: physically more healthy, more attractive to mates
Hypothesis: this behaviour allows them to flavor up their food from salt water
in the ocean / this behaviour has allowed them to discover clams, which are
another source of nutrition
Ethology: the study of the proximate mechanisms and adaptive value of
- Lorenz, Tinbergen, Von Frisch
"The method of watching and wondering." Tinbergen
i.e. Beewolf (Europe) - makes a burrow in sand and lays her eggs, then finds a
bee and stings it, paralyzing it and leaves it in its nest. The bee serves as
food for her young ones. Tinbergen watched these wasps, which all rise
together in the morning making a cloud and then disperse. Over the coarse of
the day, they return individually, into their holes in the sand. The wasps fly
directly into the hole with top speed, Tinbergen wondered if this hole was a
home or not.
His students would
1) mark the wasps - noticed that the wasp would return to its own hole.
2) sweep around the nest - takes a broom to sweep the territory where they
have holes in the sand; the wasps were able to find their respective holes,
however the sweeping delayed their process b/c it disrupted their holes.
3) move visible markers - the students moved around rocks, shells, etc.
Nevertheless, the wasp still manages to find its holes.
4) The students built a ring around the wasps nest, then allows the it to get
the picture; then shifts that ring elsewhere. This time the wasps goes into the
ring. This shows how the wasps uses visual cues to find the nest. i.e. Black headed Gull colony - when the eggs hatch, both parents take the
eggshells and flyaway, leaving the chicks open and vulnerable. The young
ones can not fly away. The reason why the parents take the risks of removing
the eggshells is b/c the eggshells are white and shiny and attract alot of
attention from the crows. Therefore, the parents do so in order to protect
their young ones.
Tinbergen did an experiment by manipulating the distance from eggshell to
egg - the results were the closer the eggshell is to the egg, the higher the
risks get for the egg to become a target.
Ethologists take a darwinian approach.
Darwing: 3 commonly observed features of living individuals
4. Variation - members of a species differ in their characteristics.
5. Heredity - parents pass on some of their distinctive characteristics to
6. Differential reproduction - b/c of their distinctive inherited
characteristics, some individuals within a population have more
surviving offspring than others.
*Darwin did not the mechanism through which parental traits get passed on
to offspring. Mendel's genetics explained this process.
Red Queen hypothesis
Sexual reproduction persists b/c it enables many species to rapidly evolve
nnew genetic defenses against parasites that attempt to live off them.
Why sexual reproduction and not asexual? With asexual rep a species can
pass down 100% of their genes, with sexual only half of the genetic material
gets passed down to offspring. The reason why sexual rep is more common
than asexual is b/c variation in genes allows for a higher probability of
survival against the constantly evolving parasites and other environmental
dangers. Sex generate a diversity which provides challenges to the
competitors (viruses, parasites, etc).
-He experimented with smooth and wrinkled pea plants.
-In the parental generation he crossed a dominant smooth pea plant with a
recessive wrinkled pea plant. (SS x ss) -In the F1 generation all the offspring were smooth pea plants, however they
were carriers of the recessive gene (Ss)
-When he crossed the Ss plants in the F2 generations, 1/4 of the offspring
were wrinkled recessive pea plants. This occured because in the previous
generation, both parents were carriers of the recessive gene.
Vid Sickle-Cell Anemia: mutation is tiny yet it is capable of changing the
shape of the hemoglobin produced, this causes resistance to malaria. This
shows how evolution works, since most of this type of occurence is in Africa.
Mutations occur at random and may or may not cause changes.
Darwinian logica at the genetic level:
7. Genetic variation: genes can occur in more than one form. When
alleles of a gene exist the different alleles may lead to the production
of slightly differerent forms of the same protein.
8. Heredity: alleles can be transferred from parent to offspring.
9. Differential reproduction: some alleles are better than others at
producing effects that cause their bearers to transmit copies of their
The process that produces evolutionary change when individuals differ in
heritable traits that are correlated with differences in their individual
*This process is not about species, but individuals
*Fitness does not depend on number of offspring, but on number of viable
Female Hanuman Langur with infant - dominant male kicks out the juvenile
hanumans as it reaches reproductive age; the interloper tries to fight the
dominant male to drive him off in order to get a hand over the dominant
hanuman's troop. The successful interloper also kills off the offspring. The
interloper does this because all the females which are lactating can not be
reproduce. The mothers of these offspring will not be happy when the
interloper tries to kill its babies.
Why commit infanticide?
â¢ Hypothesis 1: social pathology brought on by overcrowding; research experiment done on lab rats in 1940s.
â¢ Hypothesis 2: Group selection ("survival of the species"); this idea is
related to the false belief of altruism however this opposes
reproductive success; a suicidal organism will not be able to reproduce
and pass on his genes to produce more suicidal organisms who will
sacrifice for the good of their species.
Only those groups/populations/species that have population-
regulation mechanisms can survive; those who don't over-eploit
resources and die off. Walt Disney popularized this idea.
â¢ Hypothesis 3: Infanticide imparts a reproductive advantage to the
*Sometimes a female will have sex with an interloper before he tries to enter
the troop. She commits this form of promiscuity in order to protect her
current offsprings from this interloper. If this interloper remembers her scent
after having succeeded in fighting off the other male, this interloper will not
hurt that promiscuous woman's offspring (this occurs in many species i.e.
hanuman langur, prairie vole, etc).
The monogamous prairie vole:
In this species, the female and male mate for life.
Keywords: polygamy includes poligyny and polyandry
The brain of the prairie vole is a complex, highly organized machine
- In their (prairie vole) ventral pallium there are V1-a receptors, which are
sensitive to vasopressin (oxytocin). Vasopressin sends out reward signals to
brain regions. All of the species have the V1aR gene, but a chunk is
sometimes missing in meta vole. Thus, less receptors are encoded causing
less reward signals to be sent after mating. This gene basically affects male
pairing behavior in the prairie vole.
The possible history behind monogamy in the prairie vole
â¢ In a lab setting, male prairie voles are tethered while a female enters
the space. The female has sex with numerous males. This shows that
the monogamy is maintained by the males and not the females. These
mate-guarding males, prevent promiscuity.
â¢ In the ancestral species, however the default mating system would have been polygyny, where males attempt to dominate other males
and control groups of females. Infanticide would have also been
common in ancestral species, due to this struggle for dominance.
â¢ However, the strategy of promiscuity would protect this females future
offspring b/c the males would not risk infanticide if there might be a
chance that he is the father (same for the hanuman langur).
The hypothesis that monogamy in prairie voles is liked to a specific gene was
tested through genetic engineering, where using a safe viral vector the chunk
of gene was inserted in the meta voles. As a result these males became
A form of natural selection that occurs when individuals differ in their ability
to compete with other for mates or to attract members of the opposite sex.
A specific form of natural selection in which characteristics which provide
individuals a selective advantage exclusively for reproduction are selected
Vid - Darwin didn't understand how the male peacocks could have evolved,
due to its tail. Its tail takes alot of energy to grow, it is difficult to carry around
and attracts alot of attention from predators. However, Darwin realized that
this species used this beautiful tail as competitors to attract the choosy
females. Females are much more choosy, b/c they must invest so much time
and energy in bearing offspring so the females must be sure that their mate
is healthy and strong enough to provide good genetic material for the
offspring. Scientists noticed that offspring of peacocks with big tails tend to
survive better and are fitter.
The concept of sexual selection comes into view once again. The female
selects her mate, and the males must impress the female in order to be
selected for. In the bowerbirds, the males make noises to attract the female.
When the female is impressed, the male is allowed to enter the bower and
mate with her. In the video clip the female is actually a robot. After mating,
the female enters the forest and builds a nest to incubate her fertilized eggs.
The male, however re-builds the bower in order to mate with another female.
What does the female get out of this? She gets healthy sperm which promises
healthy, viable, fit offspring. -Great bowerbids contruct more elaborate bowers with decorations.
-Satin bowerbirds like blue colors.
-*Competition between Bowerbirds occurs when males destroy eachother's
artistic work (decorated bowers to impress females).
-This bird has a beautiful voice that it uses in order to attract females. Its
voice is an impersonation of many other bird calls including the cuckoo bird.
The male can immitate the voice of atleast 20 species. It can also immitate
the sounds it hears in its environment (i.e. police siren, car alarm, etc). Its tail
is also important for sexual selection. The variety of sounds the male can do
and how well he does them will ultimately determine its reproductive
-*Males have to be in good shape to project the idea that they are in good
health, and can provide viable sperm. The fact that the Superb Lyre has such
an attract voice can jeoperdize its life, so if it can survive by avoiding danger
and yet be able to perform shows how good he is. This attracts more females.
Parental Investment (Trivers, 1972):
Costly parental activities that increase the likelihood of survival for some
existing offspring, but that reduces that parent's chances of producing
offspring in the future.
Bringing offspring to a reproductively ready (and likely) state is the benefit.
But the benefit comes with the cost of the parental activity itself and perhaps
on the ability to produce further offspring later.
Operational sex ratio:
Ratio of sexually receptive males to sexually receptive females at any given
*See Figure 6
*See table 10.2 in 9e
Ways in which females and males attempt to control repruduction while
interacting with eachother:
Key reproductive decisions controlled primarily by females
â¢ egg investment - what materials and how much of them to place in an egg
â¢ mate choice - which male(s) will be granted the right to be sperm
â¢ egg fertilization - which sperm to use to fertilize each egg
â¢ offspring investment - how much maintenance and care goes to each
embryo and offspring
Ways in which males influences female reproductive decisions
â¢ resources transferred to female - may influence egg investment, mate
choice, or egg fertilization decisions by females
â¢ elaborate courtship - may influence mate choice or egg fertilization
decisions by female
â¢ sexual coercion - may overcome female preferences for other males
â¢ infanticide - may overcome female decisions about offspring
Sex role reversal
A change in the typical behavior patterns of males and females as when, for
example, females compete for access to males, and when males choose
selectively among potential mates.
Female Empid fly: there is a reversal of what happens in peacocks. The males
choose among the competing females.
Ghost Pipefish: the females deposit their eggs into the males pouch, where
these eggs are incubated.
Hippocampus: the female has enough eggs to fill two pouches in two males.
The competition increases for females.
Female Mormon Cricket: the male has one shot at reproduction. In order to
create spermatophore, the male sacrifices 25% of its body weight. After
mating, the male weakens and dies. In this species, the females compete.
Weight correlates with the number of eggs, so the male will choose the
Female Katydid: male creates spermatophore, however the male doesn't die
after reproducing. Early in the year, the females compete for the males b/c
the spermatophore contains alot of nutrients. Later in the season, the male must compete for the female b/c the quality of his spermatophore decreases
A difference in phenotype betweenmales and females of the same species.
Costly investments in traits (weight, size, structures) when the reproductive
pay off is great.
i.e. Elephant seals (males) compete for reproductive success.
One male and one female mate (for life??). The male and female look-alike.
â¢ Polygyny: one male mate with several females.
â¢ Polyandry: one female mates with several males.
In chimpanzees, the dominant male will always mate with reproductively
receptive females. However, when these females are not ovulating the
dominant male will allow the females to have sex with the non-dominant
males. The non-dominant males offer "babysitting services" and helps around
with taking care of the offspring. The females will reward these helpful males
by giving them access to sexl (even though these males are not dominant).
In gray seals, the non-dominant males sneak off under water with the
females for sex (sneaky copulators). The dominant male doesn't realize this,
b/c he is having sex with the females on the rocks and does not know that the
females go have sex under water with other males.
Conditional sexual strategies
Scorpionfly: the males get hold of something nutritious (dead insect) and
then climb a tall blade of grass to prove their strength. Other weaker males
try to climb the blades half way b/c if they are seen by the alpha he will get
beaten down. The alpha has the best strategy, and wins the attention of
numerous females for copulation. Nonetheless, the other scorpionflies that
are halfway on the grass blade will still manage to get some females too. A
third sexual strategy exists for the weakest males of this species. These weak
ones can not climb high on the blades of grass, instead they reside on the
ground and when chance permits they forcibly copulate with any female
nearby (mostly they will be tossed over by the females, however sometimes
they will have success). *these are conditional sexual strategies b/c they can change depending on
the surroundings. Pay off will be different for each
The male remains in contact with the female using a latcher, and when time
permits the male will mate with the female.
Older males who cannot latch on to the females, use satellites. Although, this
method involves knocking off other competitors, it is not as effective as the
*Latcher and satellite are interchangeable.
These are conditional strategies
â¢ alpha - the largest in size, his sexual strategy is to impress the females
with their size.
â¢ beta - medium sized, their sexual strategy involves behaving as a
female and allow the alpha to mount him (tricks the alpha into
believing he is a female).
â¢ gamma - smallest in size, their sexual strategy involves sexual
coersion (rape). The gammas also get tossed over by the alphas.
These 3 strategies are very successful, so all 3 phenotypes still exist: Equal
*These strategies are distinct sexual strategies, not conditional, b/c you
cannot change your size (it is all genetically determined).
*Distinct strategies have equal payoff, conditional strategies do not!
Males will remove their rivals' sperms by entering the female and using their
penis as a bottle brush. The female will have sex with many males in order to
increase variation among her offspring.
The females have sex, store the sperm in sperm storage tubules. Then the
female will go around to copulate with another male, then decides which
sperm will provide better results, and based on that decision she will either eject the sperm or keep it to fertilize her eggs. The likelyhood of sperm
ejection is very high if she has sex with a low-ranking male.
Action taken by males (usually) to prevent a sexual partner from acquiring
sperm from other males. In other words, keep the female occupied.
The male's sexual strategy involves having sex with the female all the time.
The male guards his female in order to make sure his sperm will fertilize his
mate's egg. Then he will guard the nest only.
Good Parent theory
An explanation for mate choice in which choosy individuals select partners on
the basis of how well they will care for their offspring.
Note that "care" can include parenting, or other resources such as a good
food supply or a good territory.
The females make decision while copulating with the male. She will allow the
suitors in, if she thinks he will be a good father she eats him.
*See Table 10.3
The reproductive rate of the animals with the trimmed tails went down, while
the ones in the control group had a much higher rep. rate. This was done in
A measurement was taken while observing the number of eyespots among
peacocks. There was a positive correlation between the # of eyespots a
peacock had and the number of surviving offspring. The females find
Chase Away Selection: a female copulating with an extremely attractive
male, will have a fitness decline. The female will only have a few offspring.
Selection pressure will occur against mating with the 'studs'. Some females
will resist the characteristic by not mating with these attractive males, so ?
Fruit flies: the females select for male size, preferring bigger males. The males release a sperm toxin with his sperm, which destroys not only other
males' sperm but is also bad for her. The bigger the male, the more toxin
released. Eventually, if the female has sex several times with the bigger
males will die b/c of all the destructive toxin which kills off the females early
(halting their reproductive success forever). In this case, the females
copulating with smaller males are doing much better in terms of reproductive
An experiment was done to prove this idea, where females from
monogamous lineage (exposed to the same toxin) are compared to females
from polygynous lineage (exposed to a variety of toxin). Over time, the
polygynous females build up a resistance against the toxin. They are more
resistant tothe toxin b/c they have multiple exposure causing some new
changes in their immune systems.
Refresh concepts - monogamy (either for life or on a seasonal relationship),
polygamy (includes polygyny and polyandry).
The males were given extra testosterone (androgen), which made them more
polygynous. Usually these birds are monogamous. However the reproductive
success of the polygynous males was no different than the monogamous
males. The difference is that b/c of polygyny the males don't contribute to
Then why monogamous?
10. Mate guarding hypothesis - male prevents other males from fertilizing
11. Mate assitance hypothesis - male's assistance increases fitness
12. Female-enforced monogamy - female prevents male from 'straying'
Crane flies show mate guarding, where the male stays connected to the
female for a long time. This is non-agressive.
The male damsel flies keep hold of the female's neck and dips her in the
water to ensure that some of her eggs will be fertilized by his sperm.
Mate assistance is observed in the California (Deer) Mouse. The males
become very parental, ensuring food, nest provisions. An ethological
experiment was done by observing two groups of offspring. The nest without a father (died) had very few surviving offspring. This shows that the father's
assistance is crucial for survival of offspring.
Snow-bunting birds - the same can be observed here where females were
Female-enforced monogamy can be observed in Burying Beetles. The females
are bigger and show agressiveness towards their mates in order to ensure
monogamy. The females deposit their eggs on dead mice so that when the
eggs hatch, the offspring will have a food source until they can emerge from
the nest by themselves and go off to find their own mates. While the female
deposits her eggs in the nest, the male goes on a blade of grass and releases
an attractive pheromone to attract other females. When his originale female
mate detects his attempt towards polygamy, she knocks him off the blade of
grass and brings him back.
They also have a female-enforced monagamous system.
The male works on the nest the whole day. While he maintains the nest, the
female lays 32-40 eggs in one season. The female does not invest parental
care. When the eggs are layed, the male moniters the temperature of each
egg and adjusts the dirt covering the eggs. The female spends her time
eating, b/c each eggs requires alot of energy investment. The pair are
Is it genetic? That is, the offspring are genetically related to both parents.
Or is it social? That is, the parents work together to rear the offspring, but the
male is not the genetic father.
See Table 11.1 Why do females mate voluntarily with more than one male?
Female is larger than the male (she defends territory). The females fight,
while the males choose on the basis of strength and size (representing better
genes). The females lay eggs, and the males end up taking care of the
offspring. The males live on the same territory as the female, and look after
their separate nests. If a female interloper comes in the view, then like the
hanuman langur she will commit infanticide and take over control of the territory and will have access to all of the males.
The females can store the sperm in the tubules and mates with several
males, then chooses which sperm she likes better and ejects the unwanted
sperm. The male does the incubation, once the eggs hatch the chicks are on
their own. It can be unclear whether a male is really a father or not, b/c when
the female has access to more than one male they will never be sure as to
which sperm she used.
Types of Polygyny
13. Female defense polygyny: males guard groups of mates (harem)
14. Resources defense polygyny: males with unusually large amounts of
resources attract several mates.
15. Scramble competition polygyny: males that are unusually good at
finding mates become polygynous.
16. Lek polygyny: males with unusually attractive traits or display
territories attract several mates.
A dominant male exists with several females and offsprings, in a colony. Once
the male offsprings become sexually active, they are kicked out of their
colony so that they won't be a competitive threat to the father. The female
offspring tend to stay, so all the females share genetic information.
Therefore, all the females help eachother b/c they are also carrying your
genes. Their reproductive success, will be your reproductive success.
For polygynous females, the primary female establishes a tolerant
relationship with the secondary female, because they share resources. Even
though, the primary female could have done a lot better in terms of
reproductive success if she was monogamous, she remains in a polygynous
relationship with a male and a secondary female. Also, there is a risk for a
primary female who leaves, she might not get so lucky in terms of rep
success. The secondary female does this sort of polygynous thing, b/c she will
not find a good quality territory.
They are a good example of scramble competition polygyny. When the
females are reproductively ready, they flash. A spotting male will find this
flash attractive. However, flashes will occur together, so several
reproductively ready females are available in one territory, they males must
choose one female (the males have to be good at playing this strategy). The
male has to be better at choosing than the other males.
Thirteen Lined Ground Squirrel
The females establish their nesting territory, by digging a burrow. They are
mammals with an estrous cycle so they are not always reproductively ready.
An explosive breeding assemblage (turtles)
All the females come together, while they are all fertile. They want to collect
sperm and lay their fertilized egg. These females don't spend too much time
on the beach (approximately 8 hours). Hundreds of females gather in one
area, all looking for sperm. The males have to once again make the right
decision in choosing a mate among all the options available.
Similar to the turtles. Satellites (try to be the first one to get in).
Lek mating system:
Peacocks: the males will come together in a small location and show off their
feathers and tails to attract potential mates. The females which are sexually
receptive, and start to wonder around the males. The females will choose.
Male prairie chickens (two morphs)
Northern Sage Grouse: Visually and auditory attraction
If you are going to do it, where do you lek?
17. Hotspots: males go to where females tend to wander
18. Hotshots: males cluster around a particularly attractive male
19. Female preference hypothesis: females prefer to approach groups of
males where, presumably, it is easier and safer to assess the males'
Test one ends here.
Parental Investment - costly parental activities that increase the likelihood
of survival for some existing offspring, but that reduce the parents' chances
of producing offspring in the future.
Bringing offspring to a reproductively ready (and likely) state is the benefit.
But the benefit comes with the cost of the parental activity itself and perhaps
on the ability to produce further offspring later.
American Robin and the Rufous-bellied thrush are closely related species, one
is long-lived while the other has a shorter life span. Experiment: Play the
sound of a Blue Jay (tape recorder) so that the Robin and the Rufous can hear
it. Result: the rate of feeding their chicks goes down for the Robin (b/c its life
span is shorter), because they are afraid that if the Jay notices their nests he
will attack. However, for the Thrush the same experiment results differently.
When they play a tape of an adult predator instead of a nest predator, the
parental feeding decreases for the Rufous, while parental feeding increases
for the Robin.
St. Peter's fish
A fish that hides the offspring in mouth when threat is detected. Since the
male has fertilized all of the eggs, the benefit is equal for both the mother
and father. The cost is different: the male takes care of the offspring . The
female has to re-feed after her first batch of eggs, b/c she has lost alot of
energy (it takes a few weeks before she can be ready for the next clutch of
eggs). It is much more rarer for the female to be parental than the male in
this species. The cost to male is less than the cost to female to be a parental
type. In the long-run it is cheaper for the male so he will tend to be more
parental than the female. However, sometimes females do show parental
investment perhaps when the male is not being parental?
Male takes exclusive care of the nest, he does the incubation. During
breeding season, the male will first dig up a hole in the ground (using his
feet), the he collects vegetation from the woods and fills up his hole with this
vegetation. The rain then soaks the vegetation. The male builds a mount
ontop of this soaky vegetation. The mount warms up the vegetation
underneath, this vegetation starts to rot and releases heat upwards. The sun
will heat up the top of the nest. The male's way of incubating is by creating
this big structure. The female will come and deposit her eggs over the nest.
She will invest alot of energy in her egg. She will deposit and leave and go eat in the woods. The male in the meantime, will incubate the egg (he has
good spatial memory) using his thermal sensor (in his head or tongue). The
heat from the bottom (vegetation) will be constant, however the heat from
the sun will vary. According to temperature he will make adjustments to make
the temp constant. Over the coarse of the season the female will deposit 20-
40 eggs (she will deposit one every 2-3 days). The incubation period is 49
days. Within a couple of hours after hatching, the chicks will fly away.
This case shows us how parental investment of the male can substancially
increase the number of surviving offspring per breeding season. If the female
stopped everytime she layed an egg to incubate, she would pay a very high
cost. By investing so much time and energy in building the nest and
incubating each egg, the male will also increase his benefit. His cost at the
end will be almost nothing.
King Penguin Colony: Antartica
In the summer time they will breed.
Emperor Penguin Colony: Antartica
In the winter they will breed (-55 degrees farhenheit). They lay one egg per
year (12-16 breeding episodes in lifetime). One egg per year for a female
means alot of investment in each egg. The male does all the incubation (65
days) while the mother is away. 20% of the female's body weight is lost when
she lays her egg. So after laying her egg, she transfers it to the male for
incubation. The female has to go feed and bring some food for her offspring
as well. Once the female comes back she will feed the chick, at this point the
male will go out and feed b/c he will lose 35% of his body weight. He returns
with food to share. The maternal behaviour comes back to the mother as
soon as she returns with the food (the first time).
The parents exchange vocalisation inbetween themselves and also
with their offspring (instant imprinting), in order to be able to recognise
one another in a big crowd. This is an example of bi-parental behavior
where the mother and father both contribute to the survival of their
offspring (first it's a switch from one parent to another, later we see
Giant Water Bug
The eggs cannot be left to dry, moisture and oxygen are key to their proper
survival and development. The female 'glues' the eggs to the male's back.
The male swims around in the water, and keeps them moist. The oxygenation
occurs when the male walks around exercising. The female invests incredibly heavily in these eggs. In order to be successful the individuals must be strong
and big. However, the growth is limited to six molts. These animals will not
grow after the sixth molt no matter how much they feed. So in order to be
viable, the offspring must be big enough by the sixth molt. The female
invests alot in each egg, in order to produce eggs which are big enough to
develop into big individuals. This is similar to what occurs in the Malle Fowl.
The females are pregnant for about 2 years. Lactation can occur for 4 years
and can extend to 9 years.
The total lifespan is 2-4 weeks. The success will ultimately depend on how
soon the individual can mate. The female needs protein in order to invest in
her egg (which she gets from stinging). After she lays the eggs in a good
place (no running water). The eggs will be layed ontop of the water and soon
she dies. The female contributes heavily to the survival of her offspring. Two
days later, the eggs will hatch, then enter the larval stage and develop
further in the next few days.
Rattus Norvegicus (Brown Rat)
This species breeds on every continent in the world. They feed on what
humans eat. Once the female gives birth, she goes into a 36-48 hour period
of estrus (she lactates while ovulating). This strategy allows her to get
pregnant again after her first batch. The female gets 24-25 days inbetween
The pups have a reflex where when pinched on their necks they curl up into a
small ball. When the curl up, they become easier to transport by the mother.
They like to hide their offspring.
The mother doesn't hide her offspring when danger approaches (unlike the
rat). Instead the parent (female) acts daringly by threatening back whoever is
trying to attack their offspring. The strategy is the same as the rat?
When the goslings are walking around, the parent protects them by hovering
over them and then attacking the predator.
Osprey (bird) They construct massive structures (nests). One parent incubates, while the
other gathers construction material for their nest. The nest occupies an
incredible amount of time. The parents must keep their "home" in order all
the time. Parental behavior continues until the offspring are viable (are able
to fetch their own food). The parents teach them this.
They are on the move all the time. Transporting becomes very essential for
them. The parents have to keep their offspring warm, b/c they are always on
the move. When the infant gets tired, the mother throws the baby on her flat
back while on the move. Offspring of different ages still receive parental care,
like the humans.
Mostly spend their time on trees instead of the ground.
The parents will create or use an already created den. The female will have
her offspring there, the father isn't around so the mother takes care of the
offspring. She must leave her offspring everyday to hunt for food. The mother
will follow her prey (she will have the same hunting route from day to day).
During lactation she follows a routine. However, after her offspring are old
enough, she will be able to move around more freely. The female moves the
nest atleast once during lactations, in order to protect her offspring from
*Just like the rat, the tigress carries her cubs by the neck (the cubs have a
reflex where they just hang while being carried). Thus, different response in
offspring, however the parental behavior for both is quite similar. The tigers
can count the number of offsprings they have, unlike the rats. The tiger will
carry one offspring at a time and drop each half way. The end result is the
same for rats and tigers.
The female provides the parental care in this case too. The female must look
after her offspring until they are viable (able to hunt food by themselves).
She teaches the offspring how to hunt. She supervises them hunting, and
when she believes they are good at hunting, her parental behavior will come
to an end.
No one had ever seen a kangaroo give birth, the scientists would follow them and check them on a regular basis. What they found consistently was that no
one could see them give birth. Until one day they found a tiny baby (smaller
than the rat) in the pouch stuck on the nipple. It turns out the female only
gives birth at night, never in the day. The baby forms a seal on the nipple,
and you cannot pull the infant off. She gives birth, then using her tongue
spreads the fur, forming a ladder from the uterus to the pouch. The infant will
climb up into the pouch. After the infant climbs into the pouch, she enters an
estrus period where she can get pregnant again. The length of pregnancy is
shorter than time required for the first offspring to be fully developed. The
requirement for the 2 offspring is different (the younger offspring needs milk
rich in fat, and the older one needs milk rich in protein).
"The neonate emerges after only 33 days. Usually only one young is
born at a time. It is blind, hairless, and only a few centimetres long. Its
hind legs are mere stumps; it instead uses its more developed forelegs
to climb its way through the thick fur on its mother's abdomen into the
pouch, which takes about three to five minutes. Once in the pouch, it
fastens onto one of the two teats and starts to feed. Almost
immediately, the mother's sexual cycle starts again. Another egg
descends into the uterus and she becomes sexually receptive. Then, if
she mates and a second egg is fertilised, its development is
temporarily halted. Meanwhile, the neonate in the pouch grows rapidly.
After ca. 190 days, the baby (called a joey) is sufficiently large and
developed to make its full emergence out of the pouch, after sticking
its head out for a few weeks until it eventually feels safe enough to
fully emerge. From then on, it spends increasing time in the outside
world and eventually, after ca. 235 days, it leaves the pouch for the
last time." - Wikipedia
Inclusive fitness: The sum of an individual's direct AND indirect fitness. (i.e.
Your offsprings are 50% related to you, genetically; but your nieces/nephews
carry 25% of your genes too).
Two or three related females will always co-operate. The parents freely give
care to offspring that are not theirs. Two females will lay 3 eggs each, then
will provide care (i.e. incubation) to all 6 eggs by taking turns. They co-
operate, but it takes time, b/c they need to be in-sync. They need to lay eggs
on the same day. When one female lays an egg and the other doesn't, the
one who hasn't layed an eggs will destroy her sister's egg.
They are colonial (have large colonies). They create holes in the ground
(nests). Because they have remarkable vocal recognition, it is very difficult to trick these individuals into taking care of offspring that are not theirs.
However, hundreds of bank swallows nest in small areas and still recognise
their own offspring.
They also create burrows to lay their eggs into. But they are not colonial, thus
don't need offspring recognition (this doesn't exist). In an experiment,
scientists swapped the offspring from two nests. Since they have no voice
recognition abilities, the rough-winged swallows were unable to recognise
Cliff vs Barn Swallows
Cliff swallows have voice recognition, Barn swallows don't.
The females will not give their milk to someone else' offspring (scent
Herring vs Ring-billed Gull
The Ring-billed Gulls go fetch fish and bring it back to their offspring (they
live in colonies). Some parents are not very good at feeding their own
offspring. At some point, the chicks will realize that they have bad parents,
and will soon go begging to the next door for food. The chicks will beg, and
will eventually convince the stranger to adopt them. The chicks' that are
about to starve to death and soon get adopted, their weight goes up.
However, their weight never catches up to the chicks that have good parents.
-Animals have developed ways of making another parent take care of their
offspring without any inclusive fitness benefits for that parent (the one
American Coot (exampe of intra-specific parasitism)
â¢ Sometimes there are no available nests sites for the female. These
females who are able to get their eggs fertilized by a mate but don't
have anywhere to nest in are reffered to as floaters. They keep an eye
on other females, and when they get a chance they will drop one egg;
then move onto another female who is oblivious, to drop off their other
eggs. The more healthy females who have an abundance of eggs, will
also keep an eye on her neighbour to drop off one of her eggs. These
healthy females have their own nests, but just have too many eggs to incubate so they will drop some off in other nests.
Cuckoo (an example of inter-specific parasitism, or brood parasitism)
â¢ These individuals parasitized other species of birds. In a given area,
the less nest sites available, the higher the chance that the cuckoo's
eggs will not be abandoned by the host female.
â¢ CapeRobin parasitized by European Cuckoo: the lighter egg is the
Robin's egg, the darker one's the Cuckoo's. Why did the Robin incubate
the egg knowing that the egg is not the right color? Because color
might be more attractive for the host parent. The Cuckoo invests more
in their egg, such that the Cuckoo's egg will hatch before the host's
eggs. When the Cuckoo will hatch, he will discard the other eggs out of
the nest (this occurs within 1-2 days after hatching). The Cuckoo will
distribute her eggs to other birds' nests. The Cuckoo's offspring grows
bigger than the host (i.e. Reed Warbler feeding its Cuckoo "offspring"),
but the host keeps feeding it until it is able to fly.
â¢ Another example of inter-specific parasitism occurs in the Cowbird.
This bird has a juvenile who will be twice the size of its mom (the host).
Once the offspring is born they will show a gaping response towards the
parent (the offspring releases this behavior so that they could get fed)
â¢ Example of the gaping response for food (Redwinged Blackbirds)
In the video, two cheetahs attack a hyena and are about to eat it, but then
another hyena comes over and eats it. When hyenas give birth (usually
twins), they deposit their offspring in someone else's den (not built by them).
The mom leaves her babies in the den, but comes to feed them milk once or
twice a day. It is very common to see siblicide (killing of a sibling). This occurs
when the twins are left alone in the den. Same sex pair aggression is much
more higher than the mixed sex competition. (Parental favoritism)
This species shows parental favoritism too. In each nesting episode, she will
lay 2 eggs (2 days apart). When she lays her first egg, she immediately starts