10 Sexual Selection

Question 1

Alturism

Answer 1

Behaviour beneficial to others but costly to self

Question 2

Hamiltons rule - fitness benefits can be gained (3)

Answer 2

1. Directly through producing and raising own offspring
2. Indirectly through helping to raise offspring related individuals (kin selection)
3. Total fitness (inclusive fitness) = direct fitness + indirect fitness

Question 3

Adaptive phenotypic plasticity

Answer 3

Property of a given genotype to produce different phenotypes depending on the different environmental conditions, thereby enhancing organisms life

Contains same genes but different expression of the genes, tailored to enhance survival For the environment encountered

Genetic systems that produce adaptive epigenetic variation

Question 4

Ultimate plasticity (2)

Answer 4

1. Brain system alter behaviour to maximise survival prospects
2. Behaviour and learning —> associative learning (spotting patterns) / insight learning (experimental play to solve problems)

Question 5

Natural selection

Answer 5

Adaptation to a constant challenge - favouring mutations that increase survival in the environemt

Also - adaptation to varying challenges - favouring mutations that alter gene expression to produce phenotypes that fit current status of a variable environment

Question 6

What may selection cause

Answer 6

Complex cognition - learning and complex behaviour to maximise fitness in changing worlds

Question 7

How is natural selection good?

Answer 7

Natural selection works on natural genetic and variations, and with constraints:

1. Population size limits efficient of selection
2. Poor fitness of intermediate form
3. Next form not genetically pure

Question 8

Efficacy of selection

Answer 8

1. Evolution can proceed by genetic drift or selection
2. Magnitude of drift it depends on population size

= large changes in small population size

Question 9

Does complex design imply a designer?

Answer 9

Irreducible complexity - not necessarily rejected by particular case studies in which natural selection is a good explanation (is it confirmed when we can’t explain them?)

Question 10

When does selection occur

Answer 10

variation in the phenotype / some of this variation is heritable / the phenotype is associated with the ability to secure mates

THEN the next generation will be biased towards individuals with higher ability to secure mates

Question 11

Where sexual selection occurs the outcome varies by sex (females)

Answer 11

fewer potential offspring / invest more in outcome of each (fitness defined by mate quality / choosy about potential mates)

Not universal - different where males show parental care

Question 12

Where sexual selection occurs the outcome varies by sex (males)

Answer 12

many potential offspring / invest little in each (fitness defined by mate quantity not quality / compete for access)

Not universal - different where males show parental care

Question 13

Sexual selection criteria (females and males)

Answer 13

Females - Intersexual (choose makes based on phenotype)

Males - Intrasexual (compete for access for females) (where sexual selection is strong the males die young)

Question 14

Post copulatory sexual selection definition

Answer 14

Where females mate with more than one male, she has sperm from more than one male in reproductive tract - sperm competition

Question 15

Post copulatory sexual selection adaptations

Answer 15

Co-operative sperm behaviour

Question 16

Post copulatory sexual selection (getting rid of sperm)

Answer 16

Cloacal pecking in dunnocks

Ebonly jewelwing

Question 17

Post copulatory sexual selection prevention

Answer 17

Ejaculate plugs - preventing remating

Sperm size which prevents displacement

Question 18

Intersexual sexual selection: female choice

Answer 18

Where is female choice most commonly found

Where females care for progeny and males don’t COMBINED WITH where males cant physically monopolize access to females

Question 19

Intersexual sexual selection: female choice (direct benefits)

Answer 19

Female picks males who will provide for progeny

Nuptial gifts in insects

Good territory, provisioning

Question 20

Intersexual sexual selection: female choice (indirect genetic benefits)

Answer 20

Exaggerated traits are a way of telling males with ‘good genes’ from ‘bad genes’

They represent ‘honest signals’ of quality (unlike non exaggerated traits)

Question 21

Sexual conflict

Answer 21

Male adaptation to manipulate female to mate with him, to not relate with rivals

However female adaptation is to avoid manipulation and to remate

—> continuous evolutionay chases

Question 22

Why does natural selection not act for ‘the good of the species’

Answer 22

Operates on genetic variation among individuals, so a trait can benefit the individual and not the whole species

Question 23

Why Altruism Represents a ‘Problem to Be Solved’ in Evolution

Answer 23

If natural selection favors individual fitness, how could altruistic behaviors evolve? Why would individuals sacrifice their own survival or reproduction to help others?

Question 24

Genetic mechanism underpinning plasticity

Answer 24

Controlled by genes that allow for the activation of different traits in response to environmental signals - don’t change the genetic code but influences how an organisms phenotype will develop in different environments

Flexibility that enables organisms to survive in a variety of conditions without needing genetic evolution in each generation

Question 25

How does learning allow adaptation to variable environments

Answer 25

Allows organisms to adjust behaviours based on experience and past environmental conditions, enhancing survival in changing environments

Question 26

Why natural selection cant create a ‘perfect organism’

Answer 26

1. Genetic constraints - evolution is limited by genetic variation and some traits may not evolve because the necessary mutations are too rare 2. Trade offs - adaptations in one context may reduce fitness in another 3. Historic constraints - evolution builds on existing traits (past evolutionary shapes current adaptations)

Question 27

Irreducible complexity definition

Answer 27

Idea that certain biological systems are too complex to have evolved through gradual evolutionary steps - suggests these systems require all parts to function and cant have evolved from simpler systems

Question 28

Irreducible complexity debate

Answer 28

Complexity can arise through gradual modifications over time

Question 29

Sexual vs Natural selection

Answer 29

Natural selection favors traits that enhance survival Sexual selection favors traits that increase mating success, even if they reduce survival

Question 30

Theories of female choice

Answer 30

1. Good genes hypothesis - pick males with superior genetic quality 2. Direct benefits - pick mates that provide immediate benefits such as protection or parental care 3. Resource acquisition - select males who can provide better resources