Adaption and Sexual Selection

Question 1

Evolution

Answer 1

• the result of opposing forces - mutations, gene glow, non-random mating, gene reshuffling, genetic drift

Question 2

Adaption

Answer 2

• a trait that enhances reproduction and survival relative to ancestors who did not have it
• anatomical, physological, behavioural

Question 3

Fitness

Answer 3

• reproductive success

Question 4

Reznick and Endler (1982)

Answer 4

• guppy spots

Question 5

Spandrels

Answer 5

• something that is a consequence of a trait
• e.g. blood is red due to Hb
• feathers are modified hairs for warmth … not flying

Question 6

Petrie (1993)

Answer 6

• peacock feathers

- peahens lay more eggs for longer feathers

Question 7

Sexual selection

Answer 7

• union of two gametes (eggs and sperm cells)
• usually two individuals needed, but some species can self fertilise such as honey bees
• expensive - 50% of genes wasted
• segregation and recombination of parental alleles
• marsupials keep having sex until they die
• elephant seals

+ increases rate of adaptive evolution of a species in a constantly changing environment
+ reduced risk of becoming extinct - long term advantages
– throw away 50% of a persons genes (costly)
– have to produce males (but some males do not reproduce at all)
– cost of courtship and mating could have been spent evading predators

• may lead to exaggerated features, due to female choice
  e. g. lions mane, deer antlers, long tailed widow bird, peacock feathers

Question 8

Asexual reproduction

Answer 8

• where offspring arises from a single parents, and inherits the genetic material of that parent only
• does not include fertilisation, so no fusion of gametes takes place
• common in bacteria, fungus and some plants
• leads to many offspring and little variation
• exponential growth - identical, and no gene shuffling

Question 9

Intrasexual selection

Answer 9

• competition between members of the same sex. Visual displays in direct contest e.g. elephant seals, sperm competition

Question 10

Intersexual selection

Answer 10

• female choice, sensory bias, in some cases, female preferences evolve before the trait appears
• e.g. guppy females would prefer long, pointy tails - show a greater response to supernormal signals outside the usual range

Question 11

Red Queen hypothesis

Answer 11

• the idea that organisms adapt and change according to their surroundings.
• snails - in a time where snails that reproduces asexually, parasites meant that species dwindled
• snails that reproduce sexually had more of them, as traits that were more successful were kept longer