Ch5: Sexual Selection & Coevolution

Question 1

Define intersexual selection, what is it balanced by?

Answer 1

Kind of mate choice, where an organism chooses their mate based on:
- a sex’s ornamental traits
- these traits are an expression of the fitness of the mate; as the trait is selected against (ENERGETICALLY COSTLY), and hence those with larger traits have to be fitter to survive

These traits are balanced by natural selection

Question 2

Define intrasexual selection, what is it balanced by?

Answer 2

male-male competition (can be female-female competition), where males have ARMAMENTS to increase their competitiveness to fight/intimidate others of the same sex.
- forms of ritualisation have allowed for some competition to end before physical fits (SAVES ENERGY)

These traits are balanced by natural selection as the traits and fighting are energetically expensive (survival cost outweigh reproductive benefits)

Question 3

Describe sexual selection after mating.

Answer 3

Traits that allow animals, generally females, to choose whether they wish to reproduce after mating; females choose what sperm to fertilise their eggs

Question 4

Describe sperm competition, why is this bad for males?

Answer 4

When females mate with multiple males, the sperm compete to fertilise eggs.

If the males do not fertilise their eggs, this is a waste of energy for them

Question 5

Describe sexual conflict, and what factors denote it;

Answer 5

Competing interests of males and females, causing evolution of competing traits to manipulate;
- whether mating occurs
- re-mating
- fertilisation of egg by sperm

Question 6

Define coevolution;

Answer 6

when (2) species evolve in response to each other, as their interactions exert SELECTIVE pressures on each other.

Creating a cycle of adaptive and counter-adaptive adaptations

Question 7

Describe the Red Queen Hypothesis

Answer 7

Interacting species that exert pressure on each other must adapt in response to each other in order to continue surviving (gain adaptive mutations)

Ex~ pathogen vs host or predator vs prey

Question 8

What is the difference between crypsis and aposematism?

Answer 8

Crypsis: an evolved trait to AVOID detection by predators, by blending in with the environment

Aposematism: Displaying/using key features to show that prey is INEDIBLE/hazardous to predators
- Visual CUE to predators

Question 9

Define antagonistic coevolution, give some examples

Answer 9

Species that interact where 1 benefits and the other is negatively affected by said interactions evolving in response to each others SELECTIVE PRESSURE

Ex~ plant v herbivore, brood parasitism, and host-parasitism

Question 9

What is the difference between Müllerian mimicry and Batesian mimicry?

Answer 9

Müllerian mimicry: 2 hazardous species look similar, and benefit from the avoidance of both their predators

Whereas Batesian mimicry: is when a harmless species mimics a hazardous species

Question 10

Define mutualistic coevolution, give some examples

Answer 10

Species that both benefit from their interactions, evolving in response to the pressures they place on each other and from the environment

Ex~ plant-pollinator; plants ensure pollen is going to plant of same species, pollinator gets food (nectar) (ie~ moths with long tongues are selected for specific plants
Ex~ fish cleaning