Unit 2 Topic 4C Biodiversity Flashcards
Consequences of human using resources on earth
- Harmful effect on environment, aquatic, terrestrial ecosystems & atmosphere, climate.
- Negatively impacting the species and habitats in these ecosystems (Species can go extinct, causing biodiversity to be destroyed)
- Global temperature rising, frequency of extreme weather events increasing (Many plants and animals can no longer survive)
Factors affecting biodiversity
habitat destruction ,overexploitation of resources, hunting, agriculture, climate change
Why do we measure biodiversity
- monitor effects of human activities / natural environment changes on biodiversity
- guiding conservation policy and planning
Define ecosystem
Different biological communities, where living organisms, interact with one another and with their physical environment.
Define biodiversity
A measure of the variety/ variation of living organisms and their genetic differences in a habitat/ an area
- Looks at the range and variety of genes, species and habitats within a particular region.
- Rich biodiversity allows large-scale, interlinked ecosystems to function and self-regulate
Define habitat
Place where an organism lives, characterised by abiotic and biotic factors in te environment
Define abiotic factors
non living and physical elements
define biotic factors
organisms living in the habitat
population, community
What are the effects of increase in biodiversity
- increase in biodiversity, increase in productivity and rate of growth and reproduction of organisms
- increase in sustainbility of species, allowing ecosystems to function and self regulate
- providing more sustainable supply of natural resources
Which three levels is biodiversity access in
- species (no. of different species and their relative abundance)
- differences (between individuals in a species, population of the same species, communities and ecosystems)
- poluation (genetic variation within a population)
Importance of biodiversity
- Allowing ecosystems to resist changes in the environment, especially climate change and diseases
- Provide genetic variation allowing development of crops, livestock, fisheries and forests
- Enable further improvement by cross-breeding and genetic engineering
- Provide potential of possible chemicals to develop new medicines
Three reasons for rich biodiversity
- Stable ecosystem (Allows many complex relationships to develop between species)
- Presence of high levels of productivity (Photosynthesis rates are very high, support more niches)
- Organisms grow and reproduce rapidly (Mutations more likely to occur, leading to adaptations, allowing organisms to exploit more niches)
Reasons for low biodiversity
- environment with extreme conditions (unstable, presence of unfilled niches)
- lost biodiversity due to natural events
Variations in biodiversity
- biodiversity varies with the tie of the day
- biodiversity varies through the year
Define biodiversity hotspot
areas with particularly high level of biodiversity
- measured by species richness and endemic species
- tropical regions have area of high marine and freshwater species richness
Define endemism
phenomenon when a species evolves in geographical isolation and is only found in one place
Define endemic species
species can only be found in one specific area
- at risk of extinction, due to limited range
- more vulnerable to species newly introduced to an area
- area of greatest biodiversity are not hte same as areas with greatest number of endemic species
What are the two ways to mesure species diversity
- species richness: number of different species in an area
- spceies abunance: relative number of individuals in different species in an area
What is genetic diversity
dversity of alelles and genes in the genome of a species /population
- greated allel variety, higher genetic diversity
How do natural selection cause higher genetic diversity
- occurs in an population with geentic variations
- better adapted, increase chance to survive
- passing on of advantageous allels to future generation
How do mutations cause increased genetic diversity
- increase the gene pool of population by increasing number of different alleles available
- some are silent mutations
- Result in Advantageous feature: Allele is selected for, allele frequency increases in the population
- Result in Disadvantageous feature: Allele is selected against, natural selection leads to the remove of such allele from the gene pool
Higher genetic diversity
- species helps population adapt to and survive changes in the environment
- changes in biotic factors ie. new predators, pathogens, competition with other species
- changes in abiotic factors ie. temperature, humidity, rainfall, light intensity, pH…
Limited genetic diversity
- Limited in populations that are very small or isolated
- Inbreeding may occur, leading to a higher proportion of homozygotes, resulting in lower genetic diversity
- Inbreeding may mean that genetic diseases caused by recessive alleles can become more common
What are two ways to measure genetic diversity
- using phenotype / genotype
- using heterozygosity index
How do we use phenotype to see the genetic diversity
- different alleles are responsible for the variety of phenotypes observed within a species
- greater variety of phenotypes within a species, higher than genetic diversity
How do we use genotype to see the genetic diversity
- organism’s genotype is determined by the different alleles found within the cells
- different alleles have different order of bases in DNA molecules
- base orders determined by sequencing DNA of individuals in species
- higher number of different alleles, the greater the genetic diversity within a species
What is the heterozygosity index
H = number of heterozygotes / number of individuals
What does a higher heterozygosity index indicate
- Higher genetic variation ( varieties of alleles/ heterozygosity )
- Better adapted, increasing the chance to survive/ reproduce
- Increasing genetic diversity
What does a lower heterozygsity index indicate
- lower genetic variation
- lower chance of having advantageous alleles to adapt to the changes in the environment
- decreasing chance of survival and reproduction
- increasing possibility to become extinct
What is niche
- role of organism within the ecosystem, including its habitat and its effect on other organism
Why do different species occupy different niches
- Decrease competition among species for different food and other resources
- All have higher chance to survive and reproduce in the habitat
- Can coexist in the same habitat
Why do two species occupy same niche in same habitat
- Better adapted species dominate and may outcompete/ eliminate the other species in the long term
- Hence cannot exist in the same habitat
- One/ Both species evolve towards a different niche (niche shift)
- Reducing the competition between them
- Such that they can coexist in the same habitat.
Anatomical adaptaion
Form and structure of an organism that increases chance of survival in its habitat (physical)
Anatomical adaptation of seals and whales
- thick layer of blubber
- good heat insulator, reducing heat loss from the body
- keeping the body warm, maintaining body temperature in cold water
Physiological adaption
Process inside the body of an organism that increases chance of survival in its habitat
How do diving mammals like seals have physiological adaptaion
- Undergo bradycardia ( Great drop in heart rate )
- Blood is pumped less rapidly around the body, oxygen in blood is used less rapidly
- Diving mammals can stay underwater for a longer time to hunt for food
What is behavioural adaptaion
The way an organism acts that increases chance of survival in its habitat
( Metabolism, inside the organism )
How do kangaroos rats have behavioural adaptaion
- Stay in underground holes during the day in its desert habitat
- To reduce water loss from the body by sweating
- To prevent dehydration in the hot and dry desert habitat
What is gene pool
Sum total of all alleles in a population at a given time
What is allele frequency
Relative frequency ( proportion ) of a particular gene in a population
What is Hardy-Weinberg Equation
p2 + 2pq + q2 =1
p +1 =1
p = frequency of dominant allele in a population
q = frequency of recessive allele in a population
Hardy-weinberg equilibrium theory
Population is not evolving, allele frequencies in the population will remain stable from one generation to the next
Why do we use Hardy-Weinberg equation
- Allows for the calculation of allele and gene frequencies within a population
- Allows for predictions to be made about how these frequencies will change in future generations.
- If allele frequencies in a population change over time, it means that migration/ mutation/ natural selection… has happened
(past paper) The wild blackberry was introduced to Santa Cruz in 1970 and has since spread over much of the island. This has resulted in the reduction of the native endemic forest. Explain why the spread of the wild blackberry affects the biodiversity of the island. (5)
- reduction of biodiversity
- as forest is habitat for many species of plants
- population will decrease because loss of forest will result in reduced habitat for animals / reduced food / increased competition between animal species
- causing reduction in species richness
- loss of forest will result in reduction of genetic diversity
- due to reproduction in smaller populations
(past paper) How natural selection resulted in longer beaks.
- variation in beak length due to mutation
- selection pressure-food supply
- birds with longer beaks able to reach food
- more likely to survive and reproduce passing on advantageous alleles, increasing allele frequency in population
(past paper) How does genetic diversity affect chances of survival of tasmanian devils?
- low genetic diversity reduce chance of survival
- small gene pool
- less chance of having advantageous alleles
(past paper) It is suggested that both of the Hawaiian honeycreeper species evolved from the same common ancestor. Explain how these two species of honeycreeper could have evolved from the same common ancestor. (6)
- geographical isolation
- reproductive isolation
- where original population becomes divided by a geographical barrier such as rivers, oceans, mountains and deserts
the separated population become isolated where:
- no gene flow between populations
- different mutations occur
- exposed to different environmental conditions / different selection pressures
- selection / survival of the fittest with advantageous allele, being better adapted
- breed and pass on advantageous allele
- resulting in change in allele frequency
over time, the morphological, physiological, behavioural features of the island population became so different from the mainland population that the two populations could no longer interbreed
(past paper) Why river crocodiles are going extinct
- habitat loss
- deforestation = lack of food
- polluation of river due to untreated waste
- hunting poaching / overfishing
- may not be able to adjust to climate change
How does zoos help conserve endangered species and increase genetic diversity
- captive breeding programmes: captured and bred in zoos to increase population and genetic diversity
- reintroduction programmes: return back to natural habitat when population is large enough
- education programs about importace of preserving endangered species and harmful human activities leading to extinction
(past paper) Describe the role of zoos in the conservation of endangered Sehuencas water frogs. (6)
- design a captive breeding program
- encourage vegetation to attract more mates
- genetic diversity should be enhanced and maintained by allowing DNA analysis from frogs in Bolivia and frog in zoo
- breed them using stud book and DNA profiling
- decrease in breeding and encourage out breeding
- exchange of gametes between zoos
- exchange animals between zoos
- use IVF and AI for fertilisation and introducing advantageous alleles such as allele coding for resistance to fungal infection.
- protect from predators
- prepare them to be reintroduced to wilflife, encouraging wild behaviour
- raise awareness and educate local people about endangered species
What do seed banks do and what are the advantages?
store plant seed
- to conserve endangered species and genetic diversity
- cheaper than storing fully grown plants
- lots of seeds stored in the small space
(past paper) Two of the methods used in seed banks are:
- store seeds from many different plants of the same species, instead of many seeds from just one plant
- regularly germinate samples of the stored seed, allowing them to grow into adult plants
explain the advantages of these methods. (4)
- increased genetic diversity of the seed stores
- because more seeds from different individuals increases the probability of having more alleles
- adult plants allow pollination to occur
- to produce new seeds for storage
- to replace those seeds stored for a long time
