56 Questions
What is the ultimate goal of an individual's behaviour, morphology, and physiology according to modern evolutionary biology?
To maximise its fitness
What is the term for the degree to which an individual’s genes are present in the next generation as a result of assisting in the breeding of related individuals?
Indirect fitness
What is the genetic relationship between a parent and its offspring?
r = 0.5
According to inclusive fitness theory, how much genetic reward would an individual get from helping its parent raise one more offspring?
As much as producing one of its own offspring
What is the term for an individual's total fitness, which includes both direct and indirect fitness?
Inclusive fitness
Why is it difficult to measure an individual's inclusive fitness directly?
Because it is extremely difficult to measure
What is a common proxy measure used to approximate an individual's inclusive fitness?
Lifetime reproductive success
Why is it often better to use lifetime reproductive success as a proxy for inclusive fitness in non-social species?
Because offspring number and survival are simply down to the actions of the mother
What is the outcome if both prisoners inform on each other?
Both get 2 years in prison
Why do silent prisoners not reproduce?
Because they are in prison
What happens to the silent gene when a mutation arises that changes an informer to a silent prisoner?
The silent gene disappears from the population
What is the characteristic of a truly monogamous population of breeders?
The LRS of males and females is equal
What happens to the dishonest males in a population?
They spread their genes more successfully
What is the problem faced by Male 1 in the example?
He is raising the red pup that is not his
What is Strategy 1 for Male 1?
He does not feed any of the pups, they all die, and then he mates with Female 1 again
What is the benefit of Strategy 2 for Male 1?
He does not waste time and energy feeding the red pup
What is the purpose of Strategy 3 for Male 1?
To guard his female while she is sexually receptive, so that he never ends up with a red pup in his den
What is the concept that arises from the prisoner's dilemma?
Evolutionary Stable Strategies
What is a major challenge in studying juvenile survival?
Lack of data on litter size at birth
Which of the following processes is NOT responsible for the accumulation of favourable heritable traits in a population?
Artificial selection
What is the primary focus of inter-sexual selection?
Female choice of mate
What is the term for an animal that exhibits parent-like behavior to a juvenile of a related individual?
Alloparent
What is the concept that describes the reciprocal helping behavior between individuals?
Reciprocal altruism
What is the game theory concept that describes the optimal strategy in a 2v2 player game?
The Prisoner's Dilemma
What is the primary reason why females in social mammal species compete with one another?
Reproductive suppression
What is the term for the process by which favourable heritable traits aimed at assisting unrelated individuals accumulate in a population?
Reciprocal altruism
What is the outcome when both prisoners remain silent in the Prisoner's Dilemma?
Both prisoners get 1 year in prison
What is the term for the process by which individuals try to get something without giving anything back in social interactions?
Cheating
What is the primary reason why mothers of vulnerable juveniles hide them?
To increase the survival chances of the juveniles
What is the significance of studying juvenile survival?
It is essential for understanding the species' population dynamics
What is the difference between natural and sexual selection?
Natural selection is concerned with survival, while sexual selection is concerned with reproduction
What is the primary focus of inter-sexual selection?
Female choice of mates
What is the term for favourable heritable traits that increase an individual's ability to secure or attract mates?
Sexual selection
What is the primary reason for the conflict between the sexes?
Males and females have different reproductive strategies
What is the purpose of alloparent care?
To provide additional care to the juvenile
What is the concept that describes the reciprocal helping behavior between individuals?
Reciprocal altruism
What is the game theory concept that describes the optimal strategy in a 2v2 player game?
Prisoner's Dilemma
What is the term for an individual's total fitness, which includes both direct and indirect fitness?
Inclusive fitness
What is the primary mechanism by which an individual's genes are present in the next generation?
Survival of the individual's offspring
What is the key difference between direct and indirect fitness?
Direct fitness involves the individual's own offspring, while indirect fitness involves the offspring of related individuals
What is the significance of the genetic relationship between a parent and its offspring in terms of fitness?
It is equal to 0.5
Why is it difficult to measure an individual's inclusive fitness directly?
Because it is difficult to quantify the effects of indirect fitness
What is the primary advantage of using lifetime reproductive success as a proxy for inclusive fitness?
It takes into account the individual's reproductive success over its lifetime
Why is it often better to use lifetime reproductive success as a proxy for inclusive fitness in non-social species?
Because offspring number and survival are simply down to the actions of the mother
What is the primary challenge in using lifetime reproductive success as a proxy for inclusive fitness in social species?
It does not account for the social group's positive or negative effects
What is the primary reason why biologists use proxy measures to approximate an individual's inclusive fitness?
Because it is difficult to measure inclusive fitness directly
What is the main reason why the 'silent' gene cannot invade the population of informers in the prisoner's dilemma?
The reward for informing is always better than the reward for remaining silent.
What is the main difference between the reproductive strategies of monogamous and non-monogamous species?
The level of parental care provided by each sex.
What is the consequence of a male's decision to not feed any of the pups in response to being cheated in a monogamous species?
He loses all his offspring, including the ones he sired.
Why is the concept of evolutionary stable strategies important in understanding interactions between individuals of the same species?
It provides a way to model the evolution of a particular trait.
What is the main advantage of guarding a female while she is sexually receptive in a monogamous species?
It prevents the male from being cheated on.
What is the outcome of a population of silent prisoners in the prisoner's dilemma?
The silent prisoners always get 1 year in prison.
Why do informers have an advantage over silent prisoners in the prisoner's dilemma?
Because they get a shorter sentence than silent prisoners.
What is the main difference between a truly monogamous population and a population with a mixture of monogamous and non-monogamous individuals?
The investment in parental care by each sex.
What is the main consequence of a mutation that enables one sex to produce offspring that are raised by other individuals?
The mutation spreads rapidly through the population.
What is the main benefit of using the concept of evolutionary stable strategies to study interactions between individuals of the same species?
It helps us to understand the evolution of a particular trait over time.
Study Notes
Fitness and Evolution
- In modern evolutionary biology, all aspects of an individual's behavior, morphology, etc. are concerned with maximizing that individual's fitness.
- Fitness is the degree to which an individual's genes are present in the next generation as a consequence of that individual's morphology, physiology, behavior, etc.
- Individuals are seen as "vessels for DNA."
Components of Fitness
- Direct fitness: the degree to which an individual's genes are present in the next generation as a result of breeding by the individual concerned.
- Indirect fitness: the degree to which an individual's genes are present in the next generation as a result of assisting in the breeding of related individuals.
- Parent-offspring: r = 0.5, full brother-sister: r = 0.5, half brother-sister: r = 0.25.
Inclusive Fitness
- An individual's total fitness is known as its inclusive fitness.
- Inclusive fitness = direct fitness + indirect fitness.
- It is extremely difficult to measure an individual's inclusive fitness directly.
Measuring Fitness
- Lifetime reproductive success (LRS) = number of young produced by an animal in its lifetime.
- Easier to estimate for females than males, as mammal mating strategies are often covert.
- Often better for non-social species, offspring number and survival simply down to actions of the mother.
- Within social species, you need to account for mother's behavior, father's behavior, positive/negative effects of the social group.
Challenges in Measuring Fitness
- Juveniles are vulnerable to predators, making it difficult to know litter size at birth.
- Juvenile survival often followed key events in their lifetimes: emergence from den, end of suckling period, attainment of sexual maturity.
- But should really be followed to the point where they breed, and then their offspring.
Long-term Studies
- Examples of long-term studies include Hoogland's black-tailed prairie dogs, Clutton-Brock's red deer, Soay sheep, meerkat, and Lebouef's elephant seals.
- All studies where animals could be observed directly, but this raises questions over the applicability of the results.
Natural Selection and Sexual Selection
- Natural selection: the process by which favorable heritable traits accumulate in a population due to differential reproduction of genotypes.
- Sexual selection: the process by which favorable heritable traits that increase ability to secure or attract mates accumulate in a population.
Intra-sexual and Inter-sexual Selection
- Intra-sexual selection: generally male-male competition, affects e.g. body mass, horns, antlers.
- Inter-sexual selection: generally female choice, concerned mainly with which individual male a female chooses to mate with, affects e.g. male ornaments, body size, social status, male behavioral displays.
Kin Selection and Alloparenting
- Kin selection: the process by which favorable heritable traits aimed at assisting related individuals accumulate in a population.
- Alloparent: an animal exhibiting parent-like behavior to a juvenile of a related individual.
- Alloparent care: parent-like behaviors undertaken by a non-parent, including allosuckling, provisioning, babysitting, teaching.
Altruism and Reciprocity
- Altruism/reciprocity/reciprocal altruism: the process by which favorable heritable traits aimed at assisting unrelated individuals accumulate in a population.
- This can lead to cheating, manipulation, counter-cheating, and counter-manipulation.
Game Theory and the Prisoner's Dilemma
- Game theory: a way of identifying optimal strategies in the context of the risk versus the reward for different behavioral strategies in a 2v2 player game.
- The Prisoner's Dilemma: a classic example of a game theory problem, where the best strategy is to inform, leading to the concept of Evolutionary Stable Strategies.
Evolutionary Stable Strategies
- Strategies that cannot be invaded by another new strategy.
- In our example, if a mutation arose that would change an informer to a silent prisoner, that silent prisoner would go to jail for 3 years, that is the worst payout.
- The silent gene would not invade the informer population.
Fitness and Evolution
- In modern evolutionary biology, all aspects of an individual's behavior, morphology, etc. are concerned with maximizing that individual's fitness.
- Fitness is the degree to which an individual's genes are present in the next generation as a consequence of that individual's morphology, physiology, behavior, etc.
- Individuals are seen as "vessels for DNA."
Components of Fitness
- Direct fitness: the degree to which an individual's genes are present in the next generation as a result of breeding by the individual concerned.
- Indirect fitness: the degree to which an individual's genes are present in the next generation as a result of assisting in the breeding of related individuals.
- Parent-offspring: r = 0.5, full brother-sister: r = 0.5, half brother-sister: r = 0.25.
Inclusive Fitness
- An individual's total fitness is known as its inclusive fitness.
- Inclusive fitness = direct fitness + indirect fitness.
- It is extremely difficult to measure an individual's inclusive fitness directly.
Measuring Fitness
- Lifetime reproductive success (LRS) = number of young produced by an animal in its lifetime.
- Easier to estimate for females than males, as mammal mating strategies are often covert.
- Often better for non-social species, offspring number and survival simply down to actions of the mother.
- Within social species, you need to account for mother's behavior, father's behavior, positive/negative effects of the social group.
Challenges in Measuring Fitness
- Juveniles are vulnerable to predators, making it difficult to know litter size at birth.
- Juvenile survival often followed key events in their lifetimes: emergence from den, end of suckling period, attainment of sexual maturity.
- But should really be followed to the point where they breed, and then their offspring.
Long-term Studies
- Examples of long-term studies include Hoogland's black-tailed prairie dogs, Clutton-Brock's red deer, Soay sheep, meerkat, and Lebouef's elephant seals.
- All studies where animals could be observed directly, but this raises questions over the applicability of the results.
Natural Selection and Sexual Selection
- Natural selection: the process by which favorable heritable traits accumulate in a population due to differential reproduction of genotypes.
- Sexual selection: the process by which favorable heritable traits that increase ability to secure or attract mates accumulate in a population.
Intra-sexual and Inter-sexual Selection
- Intra-sexual selection: generally male-male competition, affects e.g. body mass, horns, antlers.
- Inter-sexual selection: generally female choice, concerned mainly with which individual male a female chooses to mate with, affects e.g. male ornaments, body size, social status, male behavioral displays.
Kin Selection and Alloparenting
- Kin selection: the process by which favorable heritable traits aimed at assisting related individuals accumulate in a population.
- Alloparent: an animal exhibiting parent-like behavior to a juvenile of a related individual.
- Alloparent care: parent-like behaviors undertaken by a non-parent, including allosuckling, provisioning, babysitting, teaching.
Altruism and Reciprocity
- Altruism/reciprocity/reciprocal altruism: the process by which favorable heritable traits aimed at assisting unrelated individuals accumulate in a population.
- This can lead to cheating, manipulation, counter-cheating, and counter-manipulation.
Game Theory and the Prisoner's Dilemma
- Game theory: a way of identifying optimal strategies in the context of the risk versus the reward for different behavioral strategies in a 2v2 player game.
- The Prisoner's Dilemma: a classic example of a game theory problem, where the best strategy is to inform, leading to the concept of Evolutionary Stable Strategies.
Evolutionary Stable Strategies
- Strategies that cannot be invaded by another new strategy.
- In our example, if a mutation arose that would change an informer to a silent prisoner, that silent prisoner would go to jail for 3 years, that is the worst payout.
- The silent gene would not invade the informer population.
This quiz covers the concept of fitness in evolutionary biology, including direct and indirect fitness, and how individuals maximize their fitness to ensure the presence of their genes in the next generation.
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