assessing biodiversity Flashcards
how can genetic biodiversity be assessed
Genetic biodiversity can be assessed by determining the number of alleles (different forms of genes) at different loci (positions of genes on a chromosome) within a given species. This provides a measure of the variation within a species. The more genetic variation there is within a species, the more biodiverse the species is.
polymorphism
Polymorphism is where a species has a number of different forms; a great example of this is the banded snail Cepaea nemoralis.
Banded snails have shells of different colours and the shells have different numbers of bands. This is the result of having many different alleles for the same gene. Many different alleles for the same gene, leading to different forms of the same organism is called genetic polymorphism.
how can genetic polymorphism be assessed
Genetic polymorphism can be assessed by determining the number of alleles at any one gene locus and the proportion of the population that has a particular allele.
how can genetic biodiversity be measured (dna)
Genetic biodiversity can also be measured more easily by taking samples of DNA from individuals in the population and determining DNA sequences. Gel electrophoresis can be used to produce genetic fingerprints of different individuals; the more variation in banding patterns the higher the genetic diversity of the species.
The analysis of nucleotide sequences in the DNA reveals similarities and differences in base sequences. The more variation in base sequences, the higher the genetic biodiversity in the species.
overall, what can be used to assess genetic polymorphism?
-the differences in nucleotide sequences
-the number of loci that have multiple alleles
-the number of alleles at a locus
biodiversity and natural selection
Biodiversity has arisen through the process of natural selection. Natural selection is the key mechanism in the evolution of species.
steps in natural selection
Mutations cause variation in individuals that can be inherited.
All organisms overproduce offspring, leading to competition within a species (intraspecific competition) for resources.
Some variation confers a selective advantage to the individuals in a species. This means they are better fitted to survive a selection pressure. A selection pressure is something that causes the death of an organism, like predation, disease or climate. For example, some colours or numbers of bands on the banded snails provide better camouflage from predators.
The individuals that have a selective advantage survive and reproduce, passing the alleles to their offspring.
Over many generations the allele frequencies of the favourable variation increase.
adaptations through natural selection
Through natural selection, organisms with selective advantages become adapted to particular environments.
These adaptations can be anatomical, physiological or behavioural. Different organisms will have different adaptations to enhance their survival of the same selection pressure.
fennec foxes (sahara desert) anatomical adaptations
Their anatomical adaptations include:
being small in size
large ears to give a higher surface area to volume ratio to lose heat
a long snout to bring the temperature of inspired air closer to body temperature before it enters the lungs
a fur colour that provides camouflage.
fennec fox physiological adaptations
kidney’s with long loops of Henle so that concentrated urine with a low volume is produced, thus losing less water
breathing faster when temperatures are high to lose more heat.
fennec fox behavioural adaptations
being crepuscular (active at dawn and dusk) when temperatures are cooler
digging dens to shelter in during the day.
