Group of black-headed gulls mob a crow, which reduces the crow's ability to steal the gulls' eggs.
Success depends on the element of surprise.
If a research shows that a group of people can alert each other to an attack, the predator's chance of success is reduced by choosing the location that is as close to the group as possible.
The other members of the flock are aware that one pigeon is taking paper and will follow suit.
The larger the group, the less time an individual forager needs to be isolated visually.
Animals in herds tend to spend more time looking out for each other.
The predator needs to get to the center of the herd.
Complex behavior that occurs in groups is more likely to be escaped by the individual that happens to be scanning when a predator approaches.
Group living provides protection in sheer numbers and the bee's only means of escape is to tear away part of its abdomen.
The stinger is usually left behind and dies in the process.
The predator takes one prey animal per attack.
In any given attack, we will look at the reasons for the apparent altruistic behavior of vidual antelope in a herd of 100, in which an individual incurs costs to himself for the benefit of others.
Evaluate the arguments against group selection.
Predict which types of relatives will be the recipients of altruistic acts.
Most altruistic acts benefit the individual's close relatives.
We will look at the concept of kin selection, which Attack success on flocks by predator indirectly promote the spread of an organism's genes, and see how this plays out in an extreme form in the genetics of social insect colonies.
The larger the number of wood pigeons, the less likely an attack will be successful.
A group containing altruists would have a survival advantage over a group composed of selfish individuals.
The idea of group selection seemed straightforward and logical, that a group that consisted of selfish individuals would overexploit its resources and die out, but the fitness of a group with altruists would be enhanced.
Group selection was criticized in the late 1960s.
American evolutionary biologist George C. Williams was the leader of the charge.
Men Hanuman langur use resources for themselves or their offspring and may act aggressively toward mothers and population in which individuals limit their resource use.
When the females become cies of bird in which a pair lays only two eggs and the males can father their own offspring, consider a spe even kill their young.
A population explosion is prevented by laying two eggs.
There is a bird that lays three eggs.
If the population is not overexploiting its resources, sufficient food may relatives share many of the same genes, altruist individuals increase be available for all three young to survive.
The two-egg genotype is more common than the three-egg one if this happens.
There is a 50% chance of segregating into an egg or sperm.
They share half their mother's genes and half their ability to assess and predict future food availability and population den father's, and cousins by sity within their own habitat.
There isn't much evidence that they can.
Grandparents adjust their clutch size according to their age.
Competition in which individuals strive to command as much of a resource as they can is what controls population size.
The reproductive success of a relative is enhanced by pink hatched circles.
It is possible for an organisms to pass on its genes and save the lives of 5 siblings, offspring, but it is also possible for it to produce 100 offspring each.
The benefit is more important than the cost in protecting its brothers and sisters.
Belding's ground squirrels own their reproductive output.
Squirrels are favored by natural selection when individuals acting as sentries and watching for prey.
The relationship is called tor.
An altruist act is likely to cause offspring or brothers or sisters.
The altruistic act saved the lives of its three sisters.
kin selection is thought to favor this act of alarm calling.
Many insects are soft-bodied.
They use a bad taste or toxin to deter predators and advertise this condition with bright warning colors.
After a predator kills and eats a caterpillar, the bright warn ing colors help the predator learn to avoid similar individuals in the future.
Animals with warning colors aggregate in groups because they hatch from the same egg mass.
The death of one indi vidual is likely to benefit its siblings, which are less likely to be attacked by the same predator in the future, and thus its genes are more likely to be passed on to the next generation.
The genes for bright color and a warning posture are passed on from generation to generation.
A prairie dog sentry is issuing an alarm call to warn other people of the presence of a predator.
The sentry draws attention away from the others but becomes an easier target.
The similarity between the ministra caterpillar and the one in the human body shows a bright, striped warning pattern.