Life cycles animals lecture 7

Question 1

What are life history traits?

Answer 1

Life history traits are characteristics of organisms that influence their survival, growth, and reproduction throughout their lifespan.

Question 2

How are adaptations of organisms viewed in the context of trade-offs?

Answer 2

Adaptations are seen as a set of trade-offs between multiple functions and activities, where the correct standard for assessing an adaptation is its contribution to the organism’s fitness across various life functions.

Question 3

Define trade-offs in the context of life history traits.

Answer 3

Trade-offs represent the costs incurred in terms of fitness when a beneficial change in one trait is linked to a detrimental change in another. These trade-offs often involve resource allocation decisions between different functions, such as survival, growth, and reproduction.

Question 4

Give an example of a trade-off between life history traits.

Answer 4

An example of a trade-off is the relationship between the size and number of offspring. Investing more resources in producing larger offspring may result in fewer offspring being produced.

Question 5

What is the trade-off related to the cost of reproduction?

Answer 5

The trade-off related to the cost of reproduction involves investing resources in current reproduction, which can have consequences for future survival and reproduction.

Question 6

Name the three main approaches to studying trade-offs.

Answer 6

The three main approaches to studying trade-offs are genetic level, phenotypic level, and intermediate level, which includes physiological and developmental costs.

Question 7

What is an intra-individual level trade-off?

Answer 7

An intra-individual level trade-off involves evaluating the investment or effort an individual puts into reproduction compared to other functions such as survival and growth, both at the same moment and at different moments in their life.

Question 8

Give an example of an intergenerational level trade-off.

Answer 8

An intergenerational level trade-off involves the investment parents make in reproduction and the probability that their offspring will survive to the next generation, balancing current reproduction with future fitness.

Question 9

How do microevolutionary trade-offs differ from macroevolutionary trade-offs?

Answer 9

Microevolutionary trade-offs occur within species and involve variations in resource allocation among individuals, while macroevolutionary trade-offs occur between species and involve comparative analyses of traits among different species and families.

Question 10

What are some of the most important and studied trade-offs in life history traits?

Answer 10

Some of the most important and studied trade-offs include those between current and future reproduction, parental survival, offspring size and number, and reproduction versus growth.

Question 11

How does resource allocation in reproduction relate to parental survival?

Answer 11

Increasing investment in current reproduction often leads to a decline in parental survival rates, as observed in species that stop eating to feed their offspring.

Question 12

Describe the trade-off between current and future reproduction in Gobi species.

Answer 12

In Gobi species, where males provide parental care and females lay eggs inside male nests, the number of offspring produced is limited by the availability of males, leading to a trade-off between current and future reproduction.

Question 13

What is the relationship between reproduction and growth in terms of trade-offs?

Answer 13

Investing heavily in current reproduction can decrease an individual’s growth rate, as energy allocated to reproduction competes with resources needed for growth.

Question 14

Define capital breeding and income breeding.

Answer 14

Capital breeding involves individuals storing all the resources needed for reproduction before the reproductive season, while income breeding involves gaining additional resources during the reproductive season.

Question 15

How do changes in resource availability affect resource allocation between reproduction and survival?

Answer 15

Changes in resource availability can lead to adjustments in resource allocation between reproduction and survival, with individuals adapting their allocation strategies based on the energy available.

Question 16

How do interactions between genotype and environment affect the relationship between life history traits?

Answer 16

• Interactions between genotype and environment can result in unexpected changes in the relationship between life history traits, leading to variations in trait expression across different environmental conditions.
• genotypes with fast, intermediate, and slow growth rates were compared across good and poor habitat conditions. The performance of these genotypes varied depending on the habitat, demonstrating that the relationship between size and age (traits) can change based on genotype-environment interactions

Question 17

Give an example of alternative reproductive strategies in fish species.

Answer 17

Salmon exhibit alternative reproductive strategies, where dominant males invest in defending territories or females, while subordinate males invest in producing large amounts of sperm to increase their fertilization success.

Question 18

How does fishing activity impact the evolution of life history traits in commercial species?

Answer 18

Fishing activity exerts selective pressure on commercial species, favoring individuals that mature earlier and at smaller sizes, which can lead to shifts in age and size at maturity over generations.

Question 19

What factors influence the decision-making process regarding resource allocation in organisms?

Answer 19

The decision-making process regarding resource allocation in organisms is influenced by genetic factors, environmental conditions, available resources, and selective pressures.

Question 20

How do organisms balance investment in reproduction with investment in survival?

Answer 20

Organisms balance investment in reproduction with investment in survival by allocating resources to current reproduction while considering the potential consequences for future survival and reproduction.

Question 21

Describe the concept of capital breeding.

Answer 21

• individuals store resources needed for reproduction before the reproductive season begins
• ensuring they have sufficient energy reserves to support reproductive efforts.

Question 22

Explain the concept of income breeding.

Answer 22

Income breeding involves individuals acquiring additional resources during the reproductive season to support reproductive efforts, supplementing the resources they already possess.

Question 23

What are some examples of life history traits that may be subject to trade-offs?

Answer 23

Examples of life history traits subject to trade-offs include size at maturity, age at maturity, reproductive effort, survival rates, growth rates, and investment in offspring.

Question 24

How does resource availability affect the allocation of resources between reproduction and growth?

Answer 24

Resource availability influences the allocation of resources between reproduction and growth, with organisms adjusting their allocation strategies based on the quantity and availability of resources.

Question 25

What is the difference between microevolutionary and macroevolutionary trade-offs?

Answer 25

Microevolutionary trade-offs occur within species and involve variations in resource allocation among individuals, while macroevolutionary trade-offs occur between species and involve comparative analyses of traits among different species and families.

Question 26

How do interactions between genotype and environment influence the expression of life history traits?

Answer 26

Interactions between genotype and environment can result in variations in the expression of life history traits, with individuals exhibiting different trait phenotypes in response to environmental conditions.

Question 27

Give an example of how fishing activity can impact the life history traits of commercial fish species.

Answer 27

Fishing activity can impact the life history traits of commercial fish species by exerting selective pressure favoring individuals that mature earlier and at smaller sizes, leading to changes in age and size at maturity over generations.

Question 28

What are some potential consequences of changes in age and size at maturity in commercial fish populations?

Answer 28

Potential consequences of changes in age and size at maturity in commercial fish populations include alterations in population dynamics, reproductive success, and genetic diversity, which can affect the long-term sustainability of fisheries

Question 29

Provide an example of a species used in experiments to study the impact of fishing on life history traits.

Answer 29

Menidia menidia, a small fish species inhabiting the North East Atlantic Coast, has been studied to understand latitudinal variations in growth rates and the effects of selective removal on life history traits.

Question 30

What experiment was conducted using Menidia menidia to study the impact of selective removal on life history traits?

Answer 30

In the experiment, three populations of Menidia menidia were subjected to selective removal of large individuals, small young individuals, or random removal of individuals, over four generations to observe changes in growth rates, size, and reproductive investment.

Question 31

Provide an example of alternative reproductive strategies observed in salmon

Answer 31

Salmon exhibit alternative reproductive strategies, where dominant males invest in defending territories or females, while subordinate males invest in producing large amounts of sperm to increase their fertilization success.

Question 32

Describe a reproductive tactic observed in Gobi species and its implications for resource allocation.

Answer 32

In Gobi species, males provide parental care and females lay eggs inside male nests. The limited availability of males and nests leads to a trade-off between current and future reproduction, with females adjusting egg clutch sizes based on perceived future reproductive opportunities.

Question 33

What trade-offs are observed in the alternative reproductive strategies of salmon?

Answer 33

In salmon, the trade-offs involve the allocation of resources between different reproductive tactics. Dominant males invest in defending territories or females, while subordinate males invest heavily in producing sperm to increase fertilization success, balancing investment in reproductive effort with potential mating opportunities.

Question 34

Describe the trade-offs involved in the reproductive tactic of Gobi species.

Answer 34

In Gobi species, the trade-offs revolve around the limited availability of males and nesting sites, leading to adjustments in reproductive investment by females. The trade-off is between current and future reproduction, with females adjusting egg clutch sizes based on the perceived future reproductive opportunities, balancing immediate reproductive success with potential future opportunities.

Question 35

What trade-offs are observed in the life history traits of Menidia menidia in response to selective removal experiments?

Answer 35

• trade-offs involve changes in growth rates, size, and reproductive investment in response to selective removal experiments.
• Removal of small young individuals leads to delayed maturity and increased growth rates
• removal of large individuals results in decreased population size and alterations in reproductive investment, balancing resource allocation between growth and reproduction.

Question 36

What scenarios are depicted in the graph?

Answer 36

In general when resources availability changes females can differently allocate them between reproduction (R) and survival (S). The total amount of energy that an animal can obtain from resources is given by A=R+S and in the graphs we can see different scenarios. In the biggest graph are reported 3 different scenario: A1, A2, A3. Each scenario is characterized by a different availability of resources and so a different amount of energy A obtained from them (most energy in A3). Depending on the energy, the animal can change the parameter B which is the portion of resources allocated to reproduction. With B = 0.5 for example it means that 50% of resources are allocated to reproduction and the remaining is allocated for other functions. We can then have 2 main conditions (represented by the two smaller graphs):

1. Upper graph: in this situation we have a big change in resources availability but a small change in the proportion of allocation. This means that the 2 traits will be positively correlated because the female will allocate more resources in both traits.
2. Bottom-right: in this situation we have instead a small change in resources availability, but we have a big change in the proportion of allocation. In this case the two traits are negatively correlated because the female will invest more in reproduction than in other traits or vice versa.

Question 37

Describe the scenarios depicted in the graph and their implications.

Answer 37

Scenario A1 represents a situation with a large change in resource availability but a small change in energy allocation proportion (B), leading to a positive correlation between reproductive investment and other functions. Scenario A3, with the highest energy availability, allows for greater flexibility in energy allocation, while Scenario A2 shows intermediate conditions.

Question 38

What interactions can influence the relationship between two traits?

Answer 38

The relationship between two traits can be influenced by interactions between an organism’s genotype and its environment, leading to variations in trait expression.

Question 39

How are different genotypes represented in the graph?

Answer 39

The graph represents three different genotypes based on their growth rates: genotypes with fast, intermediate, and slow growth rates, depicted by lines 1, 2

Question 40

What environmental conditions are considered in the interaction between genotype and environment?

Answer 40

Different environments, categorized as good habitat and poor habitat conditions, are considered in the interaction between genotype and environment, affecting the performance of different genotypes.