Evidence for Evolution (Siva-Jothy)

Question 1

Theories of the history of life?

Answer 1

• Creationism
• Transformism
• Evolution

Question 2

Creationism

Answer 2

Each species have their own path, no cross between species.

Question 3

Transformism

Answer 3

Allows for slight change and adaptation

Question 4

Evolution

Answer 4

Increase in diversity over time, tree of life.

Question 5

Ring Species

Answer 5

A ring species is a connected series of neighbouring populations that can interbreed with relatively closely related populations, but for which there exists at least two ‘end’ populations in the series that are too distantly related to interbreed.

• Latitudinal distribution
• Clinal distribution: The gradual change in certain characteristics exhibited by members of a series of adjacent populations of organisms of the same species.

Question 6

Homology

Answer 6

Basis of classification, are phenotypes homologous or not?

-Not homologous if it shares a common function, e.g. wings of birds/bats are completely different, they did not share a common ancestor (they are analogous).

Question 7

Homologous chracteristics

Answer 7

Traits which are similar between species but not because they share a common function (i.e. they share a common ancestor).
E.g. Darwins Finches; they all evolved from common ancestors but bills are not used for different functions.

Question 8

Evidence shows:

Answer 8

• The form of species is not fixed

- Species are not distinct in time and place.

Question 9

Ways in which selection acts

Answer 9

• Directional
• Stabilising
• Disruptive

Question 10

Directional selection

Answer 10

Selection is pushing the population in one direction.

-The mean value can go up or down.

Question 11

Stabilising selection

Answer 11

This is the most common trait. The mean value stays the same but variance has decreased.

Question 12

Disruptive selection

Answer 12

This selects against the mean trait value. The mean trait stays the same, but variance increases.

Question 13

Batesian Mimicry

Answer 13

Model is distasteful, mimic is palatable (with no defence mechanism)
Mimics avoid predation by looking and behaving like models, e.g. harmless insects mimic wasps to avoid predators because they look distasteful.
-This only works if the population of models exceeds mimics, because otherwise the association made by the predator between the wasp and the distastefulness will be lost

An example of disruptive selection. It pushes organisms into very tight discrete categories.
There is an issue with mimicry in that it affects reproduction, as males don’t know which species to mate with.

Question 14

Batesian Mimicry - Papilio dardanus

Answer 14

Other butterflies, mimicked by dardanus, are distasteful, there’s a substance in their abdomen than makes the predator throw up. The bird becomes violently sick and so learns not to eat them again.
Papilio dardanus have a variety of different forms that mimic other species of butterflies that are more distasteful.

Question 15

Ways of detecting natural selection

Answer 15

Looking for correlations between characters and spatial or temporal variation in the environment

• Spatial variation
• Man-induced variation
• Temporal variation in the environment
• Biological introductions

Looking directly for differences in fitness

Question 16

Spatial Variation

Answer 16

Variation spatially between populations.

Cepea nemoralis: Snails, with variation in colour and banding pattern

Question 17

Looking for differences in fitness

Answer 17

Fitness: A genetic contribution to subsequent generations.

Fitness can be measured as Lifetime Reproductive Success