lec141

aristotle

life arises out of nothing

francesco redi

disproved spontaneous generation, tested using flies and raw meat - flies only emerged from meat that had been visited by other flies

darwin

wrote on the origin of species by means of natural selection

alfred russel wallace

independently came up with the same idea as darwin and wrote a joint paper with him

process of evolution

variation within population, variation is heritable, competition, selection, results in adaptation and evolution

carl linnaeus

came up with binomial naming system with genus and species names

charles lyell

showed evolution had time to work and concluded that the earth was older than 6000 years, wrote 'principles of geology'

thomas malthus

'an essay on the principle of population' - understanding population growth

gregor mendel

monk who showed that traits were heritable

ronald fisher

statistician who wrote 'the genetical theory of natural selection'

watson and crick

discovered dna structure

sewall wright

'evolution and the genetics of populations', basis for modern population genetics

george williams

modern view, individuals compete against each other and only succeed if they reproduce, selection acts on individuals, not species

richard dawkins

'the selfish gene' - selection acts at gene level

direct evidence

experiments with guppies found that the effect of predation reduced colouration within the population through natural selection

endemic

unique to region

biogeography

Geographic distribution of species

how were some species able to move across continents

land masses joined during ice ages and formed bridges so species could move

fossilisation process

organism dies, soft bits rot away, sediment settles and solidifies, water dissolves bones and leaves a cavity, minerals deposited forms a cast

stratigraphy

using layers of known age to place fossils in time

archaeopteryx

fossil that links birds and reptiles

structural homology

similarities in structures eg bone, in different organisms but adapted for function, suggests common ancestry

analogous characteristics

features with similar appearance and function but fundamentally different, separate evolutionary origins

homologous features

share common ancestry but not always similar functions

convergent evolution

independent evolution of similar features in different lineages

embryology

similarities between vertebrate embryos

comparative behaviour

the more similar the social behaviour, the more closely related

biochemistry

dna contains record of evolutionary change

hierarchical organisation of life

ability to divide life into a hierarchy suggests a history of branching and divergence

3 domains of life

Bacteria, Archaea, Eukarya

six kingdoms of life

Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia

archaebacteria

prokaryotes, no peptidoglycan cell wall, extreme environments

eubacteria

prokaryotes, peptidoglycan cell wall

protists

eukaryotic, mostly unicellular, algae are multicellular, heterotrophic/photosynthetic

fungi

eukaryotic, mostly multicellular except yeast, heterotrophic. usually non motile, chitin cell wall

plantae

eukaryotic, multicellular, non motile, usually terrestrial, photosynthetic

animalia

eukaryotic, multicellular, motile, heterotrophic

how long ago did life begin

3.8 billion years ago

stromatolites

precambrian colonies of cyanobacteria, produced oxygen

origin of eukaryotes

ancestral prokaryote, infolding of plasma membrane, engulfing of aerobic heterotrophic and photosynthetic prokaryotes, endosymbiotic relationships

what happened at the end of an ice age, early cambrian period

explosion of eukaryotic diversity

when was land colonised by plants/animals

500 mya

effects of mass extinctions

creates ecological space for survivors , removes organisms occupying some niches, adaptive radiation, new species emerge

example of adaptive radiation

Darwin's finches - had no competition so could diversify

80 mya

primate ancestors from 'euarchonta' superorder

50 mya

prosimians and simians split

features of prosimians

binocular vision, grasping fingers, mostly nocturnal and arboreal

two groups of first simians

new and old world monkeys

simians features

overlapping field of vision, opposable thumbs, live in groups, mostly diurnal

4 genera within hominidae

humans, chimps, gorilla, orangutans

ape characteristics

larger brain relative to body, flexible behaviour, no tail, some social

features of chimps

posterior attached skull, spine slightly curved, arms longer than legs, long narrow pelvis, femur angled out

features of australopithecus

inferior attached skull, s-shaped spine, arms shorter than legs, bowl shaped pelvis, femur angled in, round jaw, brain size 35% of humans, walked upright

Ardipithecus ramidus

4.4mya, chimp sized brain, broader diet than modern chimps. partly bipedal

bipedal

walking on feet

australopithecus afarensis

3.2mya, 'lucy', human like teeth, apelike head

homo habilis features

used stone tools, 2.5mya, short, long arms, larger brain, shorter jaw

homo erectus

2mya, 5ft, thick skull, larger brain, prominent brow ridge, rounded jaw, may have been able to talk, social

neanderthal man

600,000ya, 12-14cm shorter than modern humans, large skulls, bigger brains than humans, used tools and cared for injured

cro-magnon man

Homo sapiens sapiens; replaced the Neanderthal Man, successful hunters, loss of body hair, could run greater distances

macroevolution

evolutionary change over long periods of time on a large scale

microevolution

basis of natural selection, population progressively adapts to its environment, change at/below species level

population

group of individuals of the same species living in a particular geographical location

natural selection

individuals with heritable advantageous characteristics produce more successful offspring than those without

genotype

genetic makeup of an organism

phenotype

observable characteristics, depends on genotype and environment

chromosomes

gene carrying structures found in nucleus

allele

alternative forms of a gene

supercoiling

nearly every cell contains your whole genome

karyotyping

used for pairing and ordering chromosomes

mitosis

daughter cells are identical to parent

binary fission

one cell divides into two cells of similar size, both have same genetic material

budding

new individuals split off from parent, bud cell is smaller

parthenogenesis

development of an unfertilised egg, no genetic input from males, obligate in some species, facultative in others

vegetative reproduction/fragmentation

new individuals form without production of seeds/spores, new plants form out of stolons/bulbs/shoots

meiosis

separation of homologous chromosomes, sister chromatids separate. haploid gametes

independent assortment

how the chromosomes line up

crossing over

exchange of DNA between homologous chromosomes

advantages of sexual reproduction

lots of variation, can improve survival in a changing environment

advantages of asexual reproduction

in a stable environment the best genotype is reproduced

less energy used

mutations

deletion, duplication, inversion - flipped over, reciprocal translocation - moved

SNP

single nucleotide polymorphisms, single point mutations which can change amino acid

polyploidy

multiple sets of chromosomes

autopolyploidy

error in mitosis/meoisis, single species genome duplication, offspring can increase from diploid to tetraploid

allopolyploidy

two different related species interbreed, hybridise and chromosome number doubles, can result in reproductive isolation, may be able to reproduce asexually

molecular variation

can occur at DNA, RNA and protein level, variation can be determined by comparing these structures, most DNA is noncoding and changes due to mutation/genetic drift and can affect gene expression

evolutionary forces that effect changes

mutation, gene flow, genetic drift, natural selection

mutations

changes in genetic code

effects of mutations

current organism is likely to be well adapted so more likely to be detrimental, more important if it happens in cells that produce gametes, small effects on large populations

gene pool

all the alleles in a population

gene flow

movement of genes between populations, genetic exchange due to migration of fertile individuals between populations

genetic drift

chance alterations in a populations allele frequencies, can be caused by bottlenecks - severe reduction in population size and variation

founder effects

one/few individuals become founders of a new isolated population, can be detrimental, reduces variation, non-random distribution of genes

natural selection

differential success in reproduction, driven by climate, predator avoidance, pesticide resistance

stabilising selection

average is favoured, removes extremes from population

directional selection

one extreme is favoured

disruptive selection

favours both extremes, average individuals at a disadvantage

population growth

initial rapid growth of low density population, growth rate slows - max population size reached

k-selection

density dependent