Lecture 9&10

Question 1

What are the 3 types of environments

Answer 1

Modes of environmental effects on growth:
1. unconstrained
- environment is supportive, individual achieves full potential
2 patterned or channelled
- growth is shaped by environmental pressures leading to developmental adaptations in response to challenges
3. constrained
- phenotypic plasticity does not allow for a complete adaptation
- growth is constrained and the full impact of the challenges depends on timing and severity of the insult

Question 2

The relationship between mothers and unborn offspring is marked by?

Answer 2

(the baby’s first environment is the mother)

1. constrains in the quality of the mothers environment, which necessarily translate into the quality of the fetus’s environment
2. the conflicts of interests between the players invovled

Question 3

External Constraints –> Internal Effects

Answer 3

• in constrained environments, the fetus may be able to adapt to the pressures of the environment
• adaptation and survival will depend on the nature and intensity of the constraint
• in certain cases (e.g., IUGR: Intrauterine Growth Restriction), survival is possible but it comes at a cost which can be developmental issues or future health problems

The resulting post-natal phenotypes may represent:
1. the unavoidable costs of prenatal constraints
2. the costs of prenatal adaptations to those prenatal challenges
3. predictive adaptive responses

Question 4

1. Unavoidable costs have unavoidable results

Answer 4

No benefits associated - the result of not having enough resources. A small phenotype, for example, could simply be the result of scarce energetic resources

Question 5

2. The costs of prenatal adaptations

Answer 5

Surviving in utero challenges may require changes in developmental trajectories, often trade-offs such as lower quality post-natal phenotype (e.g., prioritising neural development may result in increased risk of metabolic syndrome later in life)

• The adaptations made to survive prenatal challenges often come with trade-offs. For example, if a fetus prioritizes neural development to ensure proper brain function, it may do so at the expense of other areas, such as metabolic health. This can lead to an increased risk of metabolic syndrome later in life.

Question 6

3. predictive adaptive responses

Answer 6

Phenotypic changes that do not provide immediate advantages but may aid with predictable future challenges (e.g., early exposure to elevated maternal cortisol may affect stress axis activity later in life - those changes may be adaptive)

• PARs refer to phenotypic changes that may not provide immediate advantages but are thought to prepare the organism for predictable future challenges.
• early exposure to elevated levels of maternal cortisol can influence the development of the stress axis in the offspring. This suggests that the fetus is capable of “predicting” future stressors based on the maternal environment and adapting accordingly
• While these changes may not seem beneficial in the short term, they can be adaptive in the long run, helping the individual cope with similar stressors later in life

Question 7

How can developmental plasticity help survive pre or post-natal challenges?

Answer 7

Developmental plasticity refers to the ability of an organism to change its development in response to environmental cues.

Example of developmental adaptation - Daphnia: Daphnia, commonly known as water fleas, can grow protective structures, such as helmets and spikes, when they detect chemical cues (pheromones) indicating the presence of predators. This is a clear illustration of how environmental signals can trigger adaptive changes in morphology.
- the ability to develop these protective features in response to perceived threats enhances the chances of survival for Daphnia in predator-rich environments. This example shows the importance of developmental plasticity as a mechanism that allows organisms to respond dynamically to their surroundings.

Question 8

conflicts can start in utero

Answer 8

Mother-offspring relationships are marked by conflicts of interests between all people involved (usually: mother, fetus, and father)

There can even be intra-genomic conflicts, suggesting that there can even be conflicts within the genome of an individual. This refers to situations where different genes can have competing interests, possibly inherited from each parent, further complicating the interaction during development.

Question 9

Intra-genomic conflict hypothesis

Answer 9

Predicts different replication strategies by individual genes within a genome leading to conflicts that affect the phenotype

This phenomenon could be the result of different transmission strategies within parent (e.g., meiotic drive) or competition between genes of different parental origins

Meiotic drive: segregation distortion during meiosis (e.g., some alleles are over-represented in oocytes)
- In meiotic drive, certain alleles (versions of a gene) can manipulate the meiotic process to ensure that they are more likely to be included in the gametes, thus increasing their representation in the offspring.

Question 10

genotype, phenotype, and environment equation

Answer 10

phenotype = genotype + environment

Some genes are part of other genes environment

The presence of particular alleles on the genome can affect the transmission of other alleles AND affect the expression of other alleles!

Question 11

What would benefit genes, according to their parental origin

Answer 11

Maternal genes:
- maximise inclusive fitness of the mother
- modulate investment according to offspring quality
- sensitive to tradeoffs between offspring quantity and quality
- sensitive to tradeoffs between current and future offspring

Paternal genes:
- survive at (almost) all costs
- take as much from mom as possible (despite costs to siblings)

paternal genes prioritize the immediate survival and success of the offspring, often at the expense of the mother’s resources or the well-being of siblings. The paternal strategy is more about extracting as much benefit as possible to ensure the survival and competitiveness of their specific genes. This can lead to conflict between maternal and paternal genetic interests, as the latter may push for greater resource allocation that is not always in line with the mother’s long-term genetic fitness strategy.