Classification and Biodiversity Flashcards
What is Biodiversity?
a measure of the number and variety of organisms found in a specific geographical habitat
What is a species?
a group of organisms sharing a large number of common characteristics that can interbreed to produce fertile offspring
How is number of species distributed across the globe?
number of species per km^2 increases as you move from the poles to the tropics/equator
What 3 factors can alter biodiversity over time?
human action, succession, and natural selection
Which pole has polar bears?
the north pole (arctic circle)
Which pole has penguins?
south pole
How many major extinctions have there been shown by fossil record?
5
When was the largest major extinction?
250 million years ago. 80% of Earth’s species became extinct
What do extinctions do to biodiversity?
they reduce it, act as a bottleneck for biodiversity
What is the Simpson’s Index?
a calculation done by ecologists that is a measure of diversity which takes into account both richness and evenness of species
What does species richness mean?
number of species present
How is there biodiversity within a species?
same species have same genes but different combinations of alleles
genetic diversity
gene pool
polymorphism
What is genetic diversity?
number of different alleles present in the gene pool
What is the gene pool?
a collection of genes in that species
What is polymorphism?
different types/morphs of one species
polymorphic genes have more than 1 allele at each locus
What are 2 examples of polymorphic species?
Peppered moth (Biston betularia)
Cepea nemoralis
What causes the varying pigementation of bands on the shell of Cepea nemoralis?
controlled by 4 alleles at 1 locus
What is the yellow, pink or brown colour of Cepea nemoralis controlled by?
6 alleles at 1 locus
What is genetic variation?
proportion of polymorphic gene loci across the genome
greater variation in base sequence, gives greater genetic diversity
What does STR stand for?
Short Tandem Repeats
What are STRs?
short sections 20-40 nucleotides long in exons
What does HVR stand for?
Hypervariable regions
What are HVRs?
another name for STRs (short sections 20-40 nucleotides long in exons)
What does SNP stand for?
Single Nucleotide Polymorphisms
What are SNPs?
single base differences between individuals
How are differences in bases seen?
through DNA fingerprints
What could a reduced biodiversity threaten?
crop supplies
medicinal drugs from plants and fungi
living organisms that supply resources like cotton
What does the lincoln index measure?
population of a species in a specific area
What is the method used for the lincoln index?
Mark, Release, Recapture
What are the assumptions made in the Lincoln index?
no migration in the population
no deaths/births
marking doesn’t increase risk of death/predation and is non-toxic
When released they disperse evenly
What is Evolution?
process by which new species are formed from pre-existing ones over many generations
Who came up with the theory of evolution?
Charles Darwin
What did Charles Darwin propose as the force that causes changes in populations?
natural selection (1859)
What Islands and species did Charles Darwin record?
Galapagos Islands and 14 different finch species on them
Hhen did Charles Darwin sail to the Galapagos iSlands? from where? on what ship?
From Plymouth
27th December 1831
On Ship- The Beagle
Where must the species’ of finch come from, what did this mean?
islands were recently formed so any animals on island must have come from mainland 600 miles away. Therefore all species’ on the islands were the same type originally
What were the main differences noticed in finches?
size and shape of their beaks (adaptive traits)
Why did the finches differ?
on galapagos islands population of finches was separated as they inhabited different islands
they then took different evolutionary pathways linked to their food source
What is Adaptive Radiation?
When a group of organisms becomes separated into 2 or more isolated populations. Their inheritable traits differ over time and they become specialised to suit their particular environment
What conclusions did Darwin make on evolution/natural selection?
there is a struggle for survival (competetion) with only the ‘fittest’ surviving
the individuals that survive and reproduce pass on their favourable characteristics to their offspring
successful adults pass on their characteristics to future generations
What is an example of an anatomical trait?
dolphins have streamline bodies
What is an example of a physiological trait?
mammals are endothermic
What is an example of a behavioral trait?
hawthorn flowers emerge in Spring (when most insects emerge), to get pollinated
What is natural selection based on?
In any population there is variation (due to sexual reproduction and mutations)
individuals can produce largen numbers of offspring (overproduction) yet the numbers of adults tends to stay the same each generation (high infant mortality)
species gradually change over many generations
What is speciation?
the splitting of a population into 2 groups which can lead to the formation of a separate species
How may speciation occur?
populations are physically/geographically separated so the populations cannot interbreed
different mutations occur in each population
the environmental conditions/habitats differ
each population has different selective pressures which leads to different gene pools
this results in a difference in physical characteristics and behaviour between each population
