Evolution I Flashcards

Question

Neo-Darwinists and their contributions + what is Neo-Darwinism

Answer 1

* Gregor Mendel came up with a mathematical formula that became the basis for evolutionary biology * Then, Francis Crick and James Watson worked out the structure of DNA, and how genes are passed on through generation- half DNA from each parent to make new combinations. * This natural variety, and random mutations (when something 'goes wrong' in the someone's genes and leads to disabality or an advantage) make up the changes we see in species over long periods of time. The best changes survive. * Life itself started with the first molecule of DNA, although scientists do not know how atoms manages to form living cells, and developed through mutations.

Answer 2

**Eohippus** Height: ~0.4 m Habitat: Lush green vegetation Anatomy of feet: 4 digits in forelimb and 3 digits in hindlimb **Mesohippus** Height: ~0.6 m Habitat: Dry conditions, forests and thick grasslands Anatomy of feet: 3 digits each, conspicuous **Merychippus** Height: ~1.0 m Habitat: Prairies, speed important to escape enemies Anatomy of feet: Slow reduction of digits 2 and 4 **Equus** Height: ~1.6 m Habitat: Dry grasslands (exposed to predators; man tames horses for war) Anatomy of feet: 2, 4 digits reduced to form SPLINT BONES on either side of metacarpal and metatarsal bones

Answer 3

* All variations in the environment * Nature favours the superior trait * Natural selection and survival of the fittest **Change in population**

Answer 4

Hugo de Vries: * Evolution results from mutation * Evolution is sudden and spontaneous * Mutation are random and directionless Darwin * Evolution results from variation * Evolution is gradual * Variation are small and directional and so is mutation

Answer 5

Gene pool refers to the total number of genes of every individual in a population, It usually involves a particular species within a population. A large gene pool indicates high genetic diversity, increased chances of biological fitness and survival ## Footnote biological fitness: ability of an organism to reproduce during its lifetime

Answer 6

Genetic drift is the change in frequency of an existing gene variant in a population due to random sampling of organisms. The alleles in the offspring are a sample of those in the parents and chance has a role in determining whether a given individual survives and reproduces.

Answer 7

* In one generation, two brown beetles happened to have four offspring which survive to reproduced. * Several green beetles were killed when someone stepped on them and had no offspring * The next generation would have a few more brown beetles than the previous generation, but only by chance. * These chance changes from generation to generation are known as genetic drift.

Answer 8

1. Founder effect 2. Bottle neck effect

Answer 9

The founder effect can occur if a small number of individuals colonize a new area Example: * The gene pool for a population of flowers has genetic diversity that results in red, yellow and blue phenotypes * A bird carries a few seeds to a new location. These seeds 'found' a new population * Alleles for yellow flower colour increase in the new small population through genetic drift.

Answer 10

A chance event greatly reduces the size of the population. The surviving individuals have allele frequencies different from those of the original population. Example: * Initial population has equal frequencies of red and yellow alleles * Chance event reduces the size of the population and now allele frequencies are different from those of the original population. * Which generates a new population with strong dominance of red over yellow alleles

Answer 11

* Stabilising selection: Nature does not favour the extremities * Directional: E.g. long neck of giraffe * Disruptive: Induced mutation, unable to adapt ## Footnote explain graphically see from slides

Answer 12

The original proportion of genotypes in a population remains constant if * population size is large * random mating is occurring * no mutations * no genes are introduced or lost i.e. no genetic drift * no selection occurs i.e. all genotypes can survive and reproduce equally well.

Answer 13

(p+q)^2= p^2 + 2pq + q^2 = 1 p= frequency of allele A q= frequency of allele a p^2= frequency of individual AA q^2= frequency of individual aa 2pq= frequency of individual Aa

Answer 14

* Industrial melanism * Resistance of mosquitoes to DDT - Dichlorodiphenyltrichloroethane * Resistance of microbes to antibiotics

Answer 15

Characters that are structural or functional in living organisms tens to develop over a period of time which enable them to survive and reproduce within the limits of a particular environment.

Answer 16

* Peppered moth (grey) - *Biston betularia* (abundant) (UNDERLINE) * Camouflaged due to lichen coloured trunks of oak trees * Black mutant variety- *Biston carbonaria* (rare) (UNDERLINE) conspicuous and more susceptible to predation

Answer 17

* Enormous production of smoke and deposition of soot on tree trunks * Tree trunks turned black * Black mutant variey- *Biston carbonaria* camouflaged * Grey variety moth- *Biston betularia* conspicruous and thus suscpetible to predation

Answer 18

* Coal was replaced by oil and electricity as major source of energy * Deposition of soot on tree trunks was negligible * The tree trunks were filled with lichens * Thus grey moth population increased and black mutant variety is rare

Answer 19

1. Nictitating membrane in the eye 2. Vermiform appendix at the end of the caecum 3. Coccyx- tail vertebrae and tail muscles 4. Non-functional muscles of the pinna 5. Wisdom teeth 6. Segmental muscles of the abdomen 7. Nipples in male

Answer 20

Scale leaves of *Ruscus* and those of underground stems