Sexual selection (Intro + How does it work)- Week 2, part 1. Flashcards
What is sexual selection?
Is it a mechanism?
What can sexual selection explain?
Despite this, are males and females still similar?
Sexual selection is selection that operates via competition for reproductive opportunities rather than survival (natural selection).
Yes.
Why males and females look + behave differently.
Yes.
Can you have male and female MEMBERS of a species?
Yes- males and females are not a species.
Example- For Ibex, how are males and females different?
Where else can differences between males and females be?
What does sexual selection, as a theory, help to do?
The males horns are bigger and more robust than females.
In colouration.
Explain why these differences exist, what they are for and how they evolved.
Moths and evolution:
Depending on the type of gene a moth has, what can this lead to?
How does the colour of the moth effect it?
Two types of moths;
- Peppered moth- Lots of melanin- Is dark.
- Light speckled moth.
Lighter- easily spotted on a dark surface (tree).
Darker one- easy to be spotted on a light surface.
How did the pollution in Britain effect moths?
Was the last point shown in an experiment?
What was helpful for the moths?
- More pollution- trees dark- benefits dark moths.
- Now- Clean- Benefits light moths.
- Moths eaten when spotted- selection happening.
Yes.
Being camouflaged.
Do some male birds have unique features and act differently in comparison to females?
Give an example of one.
Yes.
Long-tailed widowbirds.
Is everything that evolves good? Does evolution evolve for the good of a species?
Give an example.
No.
Males fighting- could kill them.
What do many species have?
What does dimorphism mean?
Like what?
Give an example.
Pronounced levels of sexual dimorphism.
Two forms.
Males and females looking very different.
Lions- Males have a big bushy mane- Females do not
What are primary sexual characteristics?
What are secondary sexual characteristics?
Give an example.
Did Darwin come up with this whole explanation?
What is pugnacity?
Present at birth- Genitalia.
Differences between males and females that are not related to reproduction.
Males- Have organs for sense or locomotion- Females do not or are less developed- Helps male find female.
Yes.
Pugnacity = tendency to fight.
Give another example of secondary sexual characteristics.
Can females be bigger than males sometimes (like with blanket octopuses)?
Male collared lizards- brighter colours than females.
Yes.
What is behavioural dimorphism?
Give an example.
Give another example.
Differences in how they behave.
Females- engaging in parental care- males don’t.
Males- fighting- for things like territory.
Sex differences in psychology and behaviour:
What does a difference not mean?
Explain.
What do differences reflect?
Give an example.
Difference ≠ superiority.
Differences does not mean one sex is better or worse than the other.
Specializations.
A female spider eating a male does not mean she is better.
What should you beware of?
What does it mean?
What does natural not necessarily mean?
What about humans?
To apply it to humans, what do you need to consider?
Naturalistic fallacy.
Describing how things are does not tell you how it should be.
Good.
Humans are animals but you cannot extrapolate behaviour from one species to predict how humans will behave.
The environment which humans evolved- The selection pressure they faced.
When you see a species where males and females look or behave differently to each other, what can you approach this issue with?
What can you ask about?
When are sexual dimorphisms, like males having bigger and more developed antlers than females (weaponry) produced?
Tinbergen’s four questions.
Proximate cause or mechanisms which makes males look different to females or ultimate causations.
Proximate- during ontogeny.
Sex limited gene expression:
Are the same genes present in both males and females?
What can happen to some genes?
What can the expression be regulated by?
What are hormones?
Explain.
Yes.
Expressed only in one sex (turned off in the other) or just expressed to a greater extent in one sex.
Exposure to hormones (e.g. testosterone).
Hormones- proximate cause- of many sexual dimorphisms.
