Topic 5: Evolution Flashcards
evolution defintion
a change in the heritable characteristics of a population over time
evolution evidence from fossils `
-in the 19th century, studies of rock layers revealed a differences in the fossils contained in each layer.
-plant fossils begin before animal fossils, plant on land appears before animals on land.
-plant suitable for insect pollination appear before insect pollinators.
homologous structures
-have a fundamental similiarity of strucutre by are adapted to different function.
homologous structures suggest a common ancestor, shared by a range of diverse organisms.
related organisms show a wide diversity of a basic structure.
Analogous strucutre
-have no structural similarity but have similar function.
analogous structures are not based on shared ancestry.
-unrelated organisms experience the same selection pressure and gradually evolve to be better suited to that environment.
evidence from homologous strucutres
the pentadactyl limb has a single evolutionary origin, and has become different over time as it performs different functions in different species.
Speciation
due to divergence of isolated populations can be gradual or it can occur abruptly (punctuation equilibrium)
Process of speciation
- Isolation of population
- Isolated populations will experience different selection pressures due to natural selection. Genetic divergence occurs.
- Divergence into different species occurs when the trairs that evolved over time prevent indidvudals from the seperate populations interbreeding. At this point the populations are considered to be seperate species.
Industrial melanisms
melanistics varieties of specices tend to become more frequent, in populations located in polluted indurstrial areas where their darker colouring makes them better camouflaged than the lighter varaiants.
Selection pressures - Density dependent factors
Predators
Availability of resources
Nurtient supply
Diease/pathologenic spread
Accumulation of wastes
Selection Pressures: Density Independent Factors
Phenomena
Aboitic Factors
Weather Conditions
Explaining the process of natural selection
-variation
-overproduction of offspring
-Adapations
-Survival Advantage
-Inhertiance
-Progressive change
Lamarckian theory
-finches that arrives on different islands needed to adapt to the available food source in order to survive.
those that adapted passed on these adaptation to the next generation.
-wrong: not based on need, inherited traits that make them better suited to the environment than other individuals of the same species.
Darwinian
-Finches that arrived on different islands encountered different food sources
-Each population had some variation in beak size and shape
-Those finches with the beaks best suited to that environment were better able to survive and reproduce.
Antibotic resistance
- After an antibiotic is developed and used on patients, bacteria showing resitance appear within a few years
- resistance to the antibiotic spreads to more and more species of pathogenic bacteria
- In each species the proportion of infection that are caused by an resistant strand increases
Gradualism
evolution occurs gradually over time
Punctuated Equlibrium
Short period of rapid evolution followed by long periods without change.
Supported by mass extinctions, sudden enviromental change
Reproductive isolation
presents two populations of the same species from interbreeding. it can be temporal, behavioural or geographic. this can lead to specialisation.
sympatric speciation
speciation due to isolation of gene pools living in the same geographic are
Allopatric speciation
apeciation due to geographic isolation
Speciation in the genus Allum by polyplody
can occur because of meiotic errors
more common in plants because of asexual reproduction
leads to speciation vis reproductive isolation typically poly poids cannot interbreed with dipoloids
polyploidy
when an organism has more than two sets of homologous chromosomes
Gene pool
consists of all genes presents in an inter-breeding population. Evolution requires that allele frequencies change with time in populations
changes in beaks of finches on Daphne major
environmental changes caused change in beak size.
drought caused shortage of soft small seeds and decline in finch population.
survivors had larger beaks that could crack open larger harder seeds
heavy rain caused abundance of soft small seeds
beak size dropped over successive generations.
evolution of antibiotic resistance in bacteria
resistance develops via genetic mutations
resistant bacteria survive, non-resistant bacteria die
resistance passed on, t/f resistant population grows.
development of melanistic insects in polluted areas: Peppered moth
Biston Betularia
peppered moths have several forms,
unpolluted environment: pale lichen on trees provides camoflauge for lighter moths , t/f survives and reproduces passing on lighter wing colour
polluted environment: pollution kills lichen, results in blacker trees: provides camoflauge for sarker moths, t/f survives and passes on gene
Binomal Homenclative
first name capitalise: genus name
second name lowercase: species name
Hierarchy of taxa
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Three domains
Archaea
Eubacteria
Eukaryotic
Four Plant phyla
Byrophyta
Filcinophyta
Conferophyta
Angiospermophyta
Byrophyta
mosses, liverworts ,hornworts
no rats, rhizoids instead, no vascular tissues
simple stems, x leaves or flattened thallis
spores producded in capsule develops at end of stalk
Filcinophyta
leaves divded into leflets curled up in bud
roots, short non-woody stems, vascular tissue
spores produced in spormgia on underside of leaves
Coniferophyta
roots,woody stems, vascular tissue, narrow leaves thick waxy cuticle
Seeds develope from ovules on scales of female cones, males cone produce pollen
Angiospermphyta
Leaf and root structure variable, vascular tissue, woody stems for shrubs and trees
seeds develop from ovules in ovaries of flowers, fruits develop from ovaries to dispense seeds
animal phylum
parifera
chidaria
platyhelmintha
annelida
mollusca
arthropoda
chordata
Portifera
Sponges
No symmetry
No mouth or anus
Porous for filter feeding
Chidaria
jellyfish, coral, sea anemones
radial symmerty, can be divided into equal parts from the centre
mouth, no anus, tentacles, stinging cells
Platyhelmintha
Flatworms
Bilateral symmerty
mouth, no anus
flattened body
Annelida
worms and leeches
billateral symmetry
mouth and anus
bristles
segmented bodies
Mollusca
Snails, Octopi, squis
Bilateral symmetry
mouth and anus
shell
Arthropoda
Insects, arachnids, crustaceans
bilteral symmetry
mouth and anus
exoskeleton
jointed appendages
Chordata
fish
birds
mammals
bilateral symmetry mouth and anus
skin
darsal nerve cord
notochord
limbs
clade
groups of organisms evolves from a common ancestor
evidence obtained from the base seqiences of a gene.
Reclassification of figwort family
Dna evidence showed that species in the family did not all share a common ancestor. Five clades were incorrectly put into the same family
