16. Biodiversity, Taxonomy And Species

Question 1

Whats the definition of species, species richness, biodiversity, niche and community?

Answer 1

Species: group of similar organisms that can reproduce together to produce fertile offspring.
Species Richness: measure of the number of different species in community.
Biodiversity: number of different species and number of individuals of each species within a community.
Niche: position/function of organism in community.
Community: all the individuals of all species living together in the same area at the same time.

Question 2

How do you calculate index of diversity? And what does a higher value mean?

Answer 2

Species diversity index (d)= (N(N-1)) / (the sum of n(n-1) )
N- total number organisms of all species living together
n - total number of organisms of each species.
Higher value of d, greater species diversity, more stable on ecosystems likely to be as more diff species so more likely some species able to change in environment.
Index of diversity is of relationship between no of species in community and no of individuals in each species.

Question 3

How does farming reduce biodiversity?

Answer 3

• natural plants/animals lost when area cleared so less species as area can only support limited amount of biomass so less alleles within species so less genetic variation. Also reduces variety of food sources/ vol of food available and habitats.
• remove hedgerows, overgrazing, create monoculture
• use pesticides + inorganic fertiliser, effluent runoff into H2O, not rotating crops.

Question 4

How agriculture reduces species diversity?

Answer 4

• desired species makes up lot of biomass in area, reducing availability for other species.
• selective breeding for desired trait reduces alleles within populations reducing genetic diversity.
• other species may be excluded by removal, cutting or use of pesticides.
• leads to many individuals of same species = low species diversity.

Question 5

Why does a higher diversity lead to a more complex food web?

Answer 5

• more habitats available.
• greater variety plants species as food sources for herbivores so more prey for carnivores
• more flowering plants mean more insects.

Question 6

How are organisms named?

Answer 6

Binomial name using genus and species

Question 7

What is meant by hierarchical classification and the names of each group?

Answer 7

Putting organisms into taxa groups based on shared characteristics/evolutionary relationships.
Larger groups divided into smaller groups with no overlapping between groups.
From largest to smallest: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
As move down, fewer organisms in each group and one type organism in species.
Domain also has Archaea, Bacteria and Eukarya.

Question 8

What are phylogenetic and why are they used?

Answer 8

Study of evolutionary history. Use a phylogenetic tree and organisms which shared the same common ancestor ore recently have branches which are closer together.
Organisms which shared same common ancestors more recently are more closely related than those shared less recently.

Question 9

What are the difficulties with taxonomy?

Answer 9

• species evolve over time.
• considerable variation can exist within a species.
• cant always see reproductive behaviour: as species become extinct + no fossil record, reproduce asexually, practical/ethical issues so cant study in lab.

Question 10

What is courtship behaviour and how does it increase successful mating?

Answer 10

It is genetically determined so organisms which are more closely related display similar patterns of courtship behaviour. (E.g. behaviour (dance/nest making), visual display (specific light pattern), pheromones (release chemicals)) it is species specific.
Increases successful mating: attract same species/opposite sex. Make sure female sexually reproductive at the time. Stimulate release of gamete, form pair bond.

Question 11

What are the different modern classification methods?

Answer 11

• Genetic comparisons: compare base sequence of DNA, base sequence of mRNA, amino acid sequence of proteins encoded by DNA/mRNA. More DNA have in common, more closely related as more base pairing, more H bonds so higher temp needed to separate.
• Comparing proteins: related organisms have similar base sequences so similar amino acid sequences within their proteins.
• Immunological comparisons: Similar proteins will bind the same antibodies if antibodies are made in response to 1 species protein able to bind to protein for another species and clump to form solid precipitate, they share an ancestor more recently. The greater number of similar antigens, more precipitate formed so more closely related the species.