TOPIC THREE: CLASSIFICATION AND BIODIVERSITY

  • CLASSIFICATION:

  • 3.1 Know that the classification system consists of a hierarchy of domain, kingdom, phylum, class, order, family, genus and species.

  • CLASSIFICATION - the process of naming and organising organisms into groups based on their characteristics

  • organisms can be grouped into three domains

    • bacteria

    • archaea

    • eukaryota

  • organisms can be grouped further into five kingdoms

    • Animalia

    • plantae

    • fungi

    • monera ( prokaryotes)

    • protocista

  • they can then be grouped even further into

    • phylum

    • class

    • order

    • family

    • genus

    • species

  • each species is named according to the BINOMIAL SYSTEM

  • the first part of the name is the genus and the second is the species EG Homo sapiens.

  • 3.2 Understand the limitations of the definition of a species as a group of organisms with similar characteristics that interbreed to produce fertile offspring

  • 3.3 Understand why it is often difficult to assign organisms to any one species or to identify new species.

  • 3.4 Understand how gel electrophoresis can be used to distinguish between species and determine evolutionary relationships.

  • the analysis of differences in different organisms to determine the extent of their evolutionary relationship is known as molecular phylogeny

  • the data obtained by molecular phylogeny has been accepted by scientists and this gave rise to new taxonomic groupings

  • an example of a technique used in molecular phylogeny is gel electrophoresis:

  • 1- make wells in agarose wells

  • 2- put DNA fragments cut with restriction endonuclease enzymes in them ( known and unknown )

  • 3- dye the DNA with something that fluoresces( and moves faster than DNA )

  • 4- turn on the current ( runs through the jelly )

  • 5- DNA is negatively charged so it moves towards the anode

  • 6- turn the current off

  • 7- turn the UV light on

  • 8- different bands represent different amino acids and they can be compared to known fragments

  • gel electrophoresis can be used to distinguish between species and determine evolutionary relationships

  • this is because they separate proteins and DNA fragments based on their size and charge

  • when a sample from different species is loaded onto a gel and an electric current is applied molecules move at different rates and distances

  • this creates a unique pattern of bands which by comparing these scientists can identify genetic differences between species

  • similar patterns suggest close evolutionary relationships where as distinct differences indicate distant relationships

  • this technique helps with studying genetic diversity and the genetic distance between species

  • 3.5 Know that DNA sequencing and bioinformatics can be used to distinguish between species and determine evolutionary relationships.

  • can analyse genetic differences and similarities at a molecular level

  • DNA is sequenced to determine the exact order of nucleotides (ATGC)

  • bioinformatics tools then align them to compare species by looking at conserved and divergent regions

  • this allows scientists to trace evolutionary histories and identify genetic traits unique to certain species and understand the genetic basis of adaptation and speciation

NATURAL SELCTION:

  • NICHE: of a species is the role it plays within its ecosystem/habitat

  • species which share the same niche compete with each other and the better adapted species will survive in the basis of natural selection

  • organisms are adapted to their environment in various ways:

    • ANATOMICAL ADAPTATIONS-

    • are physical adaptations either external or internal

    • EG presence of long loops of henle which allow desert mammals to produce concentrated urine to minimise water loss

    • BEHAVIOURAL ADAPTATIONS-

    • are changes in behaviour which improve the organisms chance of survival

    • EG mating calls

    • PHYSIOLOGICAL ADAPTATIONS-

    • are processes involving enzymes and hormones that increase an organisms chance of survival

    • EG regulation of blood flow through the skin

  • NATURAL SELCTION- is the process in which fitter individuals who are better adapted to the environment are more likely to survive and reproduce and pass on the advantageous alleles to their offspring

  • EVOLUTION- is the process by which the frequency of alleles in a gene pool changes over time as a result of natural selection

  • evolution via natural selection:

    • a variety of phenotypes exist within a population due to mutations

    • an environmental change occurs and as a result of that the selection pressure changes

    • some individuals posses advantageous alleles which give them selective advantage and allow them to survive and reproduce

    • the advantageous alleles are passed onto their offspring

    • overtime the frequency of alleles in a population changes

  • if two populations become reproductively isolated new species will be formed

  • this is due to the accumulation of different genetic information in populations over time due to different environments and selection pressures ( this is speciation )

  • speciation can be:

    • allopatric - where the isolation is geographic

    • sympatric - where the isolation is behavioural temporal or gametic

  • THE EVOLUTIONARY RACE BETWEEN PATHOGENS AND MEDICINES

    • pathogenic bacteria evolve adaptions which enable them to survive and reproduce

    • this means that they become resistant to antibiotics due to mutations

    • antibiotics kill all non-resistant bacteria which removes the competition for resistant bacteria which survive reproduce and pass on the resistance alleles to their offspring

    • so eventually a completely resistant population is formed

  • BIODIVERSITY:

  • BIODIVERSITY- the variety of living organisms in a habitat

  • it can be measured in terms of:

    • SPECIES RICHNESS - the number of different species in a habitat

    • GENETIC DIVERSITY - a measure of the genetic variation found in a particular species ( basically the number of alleles in a gene pool)

  • biodiversity can also be measured using the index of diversity

  • which can be calculated using the formula

    Image result for index of diversity calculation

  • D = diversity index

  • N = total number of organisms of all species

  • n = total number of organisms in each species

  • E = the sum of

  • WORKED EXAMPLE -

  • butterflies - 12

  • horses - 19

  • rabbits - 22

  • worms - 14

  • pigeons - 23

    12 + 19 + 22 + 14 + 23 = 90

    90 (90-1)

    — — — — — — — — — — — — — — — — — — —

    E 12 (12-1) + 19 (19-1) + 22 (22-1) + 14 (14-1) + 23 (23-1)

    D = 4.93

  • EDEMISM - is the state of a species being unique to a particular geographical location such as an island and are not found anywhere else

CONSERVATION -

  • there is two types of conservation:

    • IN-SITU - where the organism is kept in its natural habitat

    • EX-SITU - where the organism is kept outside of its natural habitat

  • EX-SITU:

  • CAPTIVE BREEDING PROGRAMS - in which endangered species are carefully bred to increase genetic diversity and population size. genetic diversity is maintained via the exchange of organisms and gametes, keeping stud books, preventing inbreeding and the use of techniques such as IVF

  • REINTRODUCTION PROGRAMMES - aim to release animals bred in captivity into their natural habitat as well as to restore lost habitats

  • SEED BANKS - store a large number of seeds in order to conserve genetic diversity and prevent plant species becoming extinct. storing seeds instead of plants means that a large variety of species can be conserved, its cheaper than storing a plant and takes up less space. the seeds are stored in cool, dry conditions as this maximises storage time and they are checked periodically for viability

  • IN-SITU:

  • EDUCATION PROGRAMMES - which aim to educate people about the importance of maintaining biodiversity, captive breeding programmes as well as illegal trade of animal products like elephant tusks or rhino horns

  • RESERVES - initiatives such as national parks and sites of specific scientific interest aim to conserve habitats and biodiversity

  • one reason for conservation of ecosystems is that they provide ecosystem services

  • these services can be provisioning, regulating, supporting or culturing