Human Evolution

Question 1

2 Methods of Evolution

Answer 1

Natural selection and Genetic drift

Question 2

Natural Selection Evolution Outline

Answer 2

The better adapted to the surrounding enviornment, survive to reproductive age and pass trait to next gen. Species fuether adapts this way, genotype dependent

Question 3

Genetic Drift Evolution Outline

Answer 3

Random external event changes balance of allele frequency in population eg natural disasters killing pop in geographical area, bottle neck events. Not species adaptive, not genotype dependent

Question 4

Evolution Def

Answer 4

Changes in pop allele frequencies over time. Allele change is not necessarily for better or worse

Question 5

2 definitions of species

Answer 5

biological species and morphological species

Question 6

Biological Species Def

Answer 6

Group of individuals who can naturally interbreed capable of producing fertile offspring. Doesn’t include asexual organisms or fossils

Question 7

Morphological Species Def

Answer 7

Community with distinctive morphological characters entitling them to specific name. Includes all organisms but very broad (risk of variation)

Question 8

Taxonomic Ranks Outline

Answer 8

Classification and grouping of organisms. Based traditionally on morphological features and presently on genomic comparison

Question 9

Paraphyletic Group Def

Answer 9

Group of organisms that originated from a single common ancestor. Does not contain all descendants of ancestor (for legibility)

Question 10

Monophyletic Group Def

Answer 10

Group of organisms that originated from a single common ancestor. Contains all possible descendants from that ancestor

Question 11

Phylogenetics Def

Answer 11

Study of reconstructing evolutionary history (phylogenetic/family trees) and relationships between groups of organisms (speciation dates, when they brach away from eachother)

Question 12

Comparative Genomics Outline

Answer 12

Multiple sequence alignment, to observe differnces in amino acids and nucleotide sequences. Infers similarities/differences between species. Can understand divergence times theough gentic distance

Question 13

Molecular Clock Outline

Answer 13

Nucleotide substitution rate. Occurs is neutral alleles (no phenitype editing) remians relative constant ovetime. Shown on graph (time on x axis, nucleotide substitutions on y)

Question 14

Pongidae Hypothesis (Disproven)

Answer 14

Humans are an outgroup from other apes. All apeas are closely associated with eachother and humans share are the furthest related (branch of from common ancestor -> human + great apes). Based on morphological comparison

Question 15

Hominidae Hypothesis (Proven)

Answer 15

The chimps closes relative is humans. Human and chimps are close together and associate with all other great apes from there. 2 amino acid differences per protein in all great apes. Humans are directly classed as great apes

Question 16

What is the last common ancestors of all great apes

Answer 16

Australopithecus (originated from East Africa)

Question 17

Other ‘Homo’ Genuses

Answer 17

Homo Habilis, Homo eresctus and Neanderthals (subspecies). A lateral move from Homo Sapiens (not our ancestors). Went extinct and their lines ended with them

Question 18

Homo Sapiens Outline

Answer 18

Anatomically modern humans. Found from Morocco to South Africa (already migrated). Largest extent of homo sapien diversity is still on the continent of Africa

Question 19

Race Outline

Answer 19

Social construct based on observed morphological features. No basis in biological realities. All homosapiens are 99.9% biologically identical (positive for gene based medical treatment)

Question 20

Neanderthals and Homo Sapiens

Answer 20

Introgression events. Neanderthal and Homo sapiens interbreed to produce offspring with mixed DNA. All non-African have 1-2% neanderthal DNA

Question 21

Denisovan and Homo sapiens

Answer 21

Introgression events. Melanesian, paupian and Australian population have ~4% Denisovan genes. Only adaptation visible is resistance to hypoxia in Tibetan people

Question 22

Examples of Human Genetic variation

Answer 22

MC1R (hair colour), SLC24A5 (skin pigment) and lactase expression

Question 23

Balancing Selection in Humans

Answer 23

Genes coding for beta haemoglobin. Homozygous dominant = no anaemia, Heterozygous = increased malaria resistance & no anaemia and homozygous recessive = sickle cell anaemia