Lecture 3- Sexual selection

Question 1

what is the goal of sexual selection:

Answer 1

-Animals will have traits that maximize their reproduction success
-although traits decrease survival, in improving fitness it increases reproduction

Question 2

Intrasexual selection:

Answer 2

When individuals intimidate, deter or defeat same sex rivals

(territory defense, fighting/ direct competition)

Question 3

Intersexual selection:

Answer 3

Individuals make themselves more attractive to the opposite sex
(mate choice or preference)

Question 4

Describe the skew changes of female crabs who prefer larger claws:

Answer 4

-Mutations that allow larger claws will thrive
-increase in claw size over time
-natural selection limit increase in claw size

Question 5

Flashy sex vs choosy sex:

Answer 5

Flashy: Sex with greater variance in reproduction will evolve more elaborate traits

Choosy: Sex with greater investment in reproduction will be more selective about who to mate with

Question 6

Why are females choosy and males flashy?

Answer 6

-Females have greater investment in reproduction
-Males are more aggressive and territorial

-males can be more selective when there is greater paternal investment

Question 7

What is Batemans Gradient

Answer 7

There was a relationship between mating success and reproductive success

-Investment might limit reproductive output of females
-mating frequently doesn’t improve reproductive success for females
-sexual selection is stronger on males

or vice versa

Question 8

Females can increase the quality of offspring by

Answer 8

choosing a better mate

Question 9

What are the 3 models explaining sexual selection, explain them:

Answer 9

-Direct benefits: Females gain something (healthy offspring, protection…)

-Good genes: Males who are genetically more resistant to parasites/ infections (survive longer, less likely infect females)

-Sensory bias/ exploitation: Females have bias for sensory stimulus (preferred colours/ sensitive to sounds)

Question 10

Explain the tungara frog example:

Answer 10

-males produce a whine and chuck call
-females prefer the chuck, even if males did not produce this
-preference for chucks appeared before chucks appeared
-mutation leads to some frogs creating this chuck, making them more preferred
-offspring will have this mutation

Question 11

What is phylogeny? What is a derived trait?

Answer 11

-History of organismal lineage that changes over time
-Derived trait is a recent trait rather than ancestral trait