NATURAL SELECTION & ADAPTATION

Nota:

• Males - sandy beach --> hv deeper body, higher success - rocky stream --> disadvantage Females -river/stream --> larger& longer, burrow into the rocks better --> lay eggs better

Nota:

• deep beaks tend to be wide and shallow beaks tend to be narrow

1. Orgnms hv the capacity to increase in numbers
2. # often remain constant
   1. competitive
   2. limited resources
   3. not all offspring survive

1. 1) Indv within popn are VARIABLE in traits
2. 2) some variations are inherited
3. 3) some are more successful at surviving & reproducing
4. 4) survival & reproduction is NON-RANDOM (indv w the most favourable variations - naturally selected

1. 1) favourable traits hv greater survival & reproductive success
2. 2) "favourable traits" will be passed on more frequently
3. 3) "favourable traits" will in crease in freq in the next gen.
4. * Evolution : characteristics in the popn change slightly w each generation

Nota:

• - beak shape & size, adapted to diet, change over time

1. variation in beak depth (post 1)
2. variation is heritable (post 2)
3. A large propn of birds did not survive (post 3)
4. On average those that survived the drought had deeper beaks (post 4)

1. Selection in favour/against a particular trait
2. Fitness consistently increases/decreases w value of a trait
3. Changes average value of trait in popn

1. selection for intermediate characteristic of a continuous trait
2. Average value of trait does not change
3. e.g. birth weight humans

1. Maintains 2 extremes
2. lead to a popn splitting

   Nota:

   • bill width vs seed cracking performance
3. e.g. African finch beak size

Nota:

• * shell polymorphism  -colour (yellow/brown) -Banding pattern (bands or not, how many bands)

1. - count freq of yellow shell fragments at the anvils compared to the freq in surrounding popn in the woodlands
2. Camouflage- in grass: yellow + banding, ground(dirt) : brown

Nota:

• -caterpillars (Lepidoptera) feed poison plants- protective -retain until adult -predator attack the adult- foul taste, sick -Aposematic (warning) colour patterns - predator recognize and learn not to attack

1. a) Batesian Mimicry (1 sp (the mimic) gains in fitness by resembling another (the model)
   1. model has an attribute that discourage predators while mimic x.
   2. Fitness benefit for mimic depends on: - how closely it resembles, -the ratio of distasteful models and tasty mimics
2. b) Mullerian Mimicry (2 distasteful model sp resemble each other)
   1. Fitness benefits: - greater # showing same colouration and are actually distasteful, warn the predator, the greater the models, the greater the fitness

1. may be a necessary consequence of physics/chem (e.g. red colour of blood)
2. may have evolved through genetic drift (e.g. geographic colour variation some birds)
3. May have evolved bcz it was correlated w another feature that was adaptive (e.g. beak w medium ground finch)

1. Perform controlled manipulative experiments to show higher fitness of individuals with a particular trait. (e.g. benefits of female polyandry in pseudoscorpians)

   Nota:

   • why polyandry is an adaptive strategy? Prediction: expect polyandrous females to have more offspring (greater reproductive success) than monoandrous females. -true in large popn 2 hypotheses: 1) Females gain material benefits for themselves or their offspring 2) Females gain genetic benefits for their offspring
   1. Multiple mated females have greater reproductive success than singly mated females by gaining genetic benefits for their offspring

1. A series of observations on a species that shows individuals with the trait have higher fitness than those without it. (e.g. beak size in African finches), (e.g. behavioural thermoregulation in garter snakes)

1. Use comparisons among species to test predictions based on the adaptiveness of a trait (e.g. testes size in male primates

   Nota:

   • why do some animal sp have larger testes than others? - testes mass scales w body size -larger testes- greater sperm - advantage in sperm competition
   1. taxa w female multiple mating hv larger testes per unit body mass than in single male system (e.g. primates, bats, ungulates etc)

Nota:

• Cloned lines of genetically identical individuals Tested whether they swam towards or away from a light source for 10 different genotypes from three different lakes

1. = genotype x environment reaction, which shows that the plasticity can evolve