Sexual selection

• Male-male competition where males compete for a female 2. Female mate choice (due to aesthetics?)

Used the widow bird, cut tails off some and glued on to others to produce an abnormally long tail Found preference for an exaggerated trait

• Starts with the difference in gametes (anisogamy) - Females have greater investment in offspring whereas males have greater reproductive potential

In Ephippiger • Good conditions mean that female crickets are more fussy and males never reject mates • Bad environmental conditions means that female crickets are less fussy and males reject mates

Cricket Cyphoderris strepitans • Females feed on males hind wings during copulation • Males have evolved hooks to secure females, if shaved virgins have no disadvantage (full wings) but non-virgins need them to secure a female for copulation

Process by which there is an increasing frequency of traits and preferences in a population through selection arbitrary attractive traits - coevolution of male sexual signals and female preferences

If males evolve different signals/attractive traits in different locations which are then not attractive to other female populations

Where females/offspring gain an advantage through a choice of mate

Where sexually dimorphic males will provide good territory, help feed the offspring/female

Some insects evolve fly-like appendages on legs to trick females

Whereby females select traits that are expensive and deleterious as male with the best genotype is likely to be the one with the biggest handicap Trait should be condition-dependent

Yes, demonstrated with flies in lab conditions with choice mating vs random mating

That females preferred longer tails and that longer tails had increased mite resistance, even when fostered in a different nest