Biodiversity Flashcards
Define genetic diversity
Number of different alleles of a gene in a population
Define natural selection
- Process that leads to evolution in populations
- Results in species becoming better adapted to their environment
Define evolution
The change in allele frequency over many generations in a population
Explain the process of natural selection
1) New alleles for a gene are created by random mutations
2) If new allele = increased chances of survival in that environment = likely to survive + reproduce
3) Survivors pass on advantageous allele to next generation via reproduction
4) Over many generations = new allele increases in frequency in population
Types of selection
1) Directional
2) Stabilizing
Describe directional selection
- Genetic diversity in a population but 1 extreme = selective advantage
- Change in the environment = organisms with selective advantage survive + reproduce
- Modal trait changes towards an extreme
- e.g. antibiotic bacteria
Describe stabilizing selection
- The modal trait = selective advantage
- No change to environment = organisms with modal trait survive + reproduce
- Extremes are lost = decreased SD + decreased range
- Modal trait remains same
- e.g. human birth weights
Define a courtship ritual
A sequence of actions that are unique to the species used to identify own species to mate with
Describe how the courtship ritual is preformed
- Performed by males
- Sequence of dance/sounds/release of pheromones/display color/fighting
- Females observe to identify + decide male to mate with as limited eggs/mating season
Importance of courtship
TO ENSURE SUCCESSFUL REPRODUCTION:
- Recognize own species + opposite sex
- Synchronize mating behaviour by displaying sexually mature + in season
TO ENSURE SURVIVAL:
- Form pair bond so there are 2 parents present to take care of offspring
- Choose strong/healthy mate = pass on advantageous alleles to offspring
What can studying courtship rituals tell us?
- Courtship rituals are genetically determined = more similar sequence = more similar DNA base sequence
- More similar the courtship sequence in between different species = more closely related
Define the binomial system
- Universal method
- 1st part = genus/ 2nd part = species
- Written in italics with genus in capital
- Tells us how closely related organisms are depending on the genus
Why do different species look similar?
1) Live in similar environments
2) Similar selection pressures
3) Similar alleles with selective advantage
4) Produce similar proteins = similar characteristics
Define hierarchy
- Smaller groups arranged within larger groups
- No overlap between groups
What are the taxas of the classification system?
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Why do we need a classification system?
- To understand the relationships between organisms
- Keep track of change e.g. evolution + impact of climate/humans
- Universal system
Methods to classify organisms originally + disadvantage
- Based on visible similarities e.g. appearance, behaviour, fossils
DISADVANTAGE: - Members of same species look completely different
- Different species look similar so can be mistaken for each other
Modern methods of classification
- DNA sequencing
- mRNA sequencing
- Amino acid sequencing
- Immunological comparison of self-antibody shapes
Define phylogenetic classification
Arranges species into groups according to their evolutionary origins + relationships
What is shown by a phylogenetic tree
- All organisms share a common ancestor
- Tells us which organisms are related and how closely related they are
Describe decrease of diversity caused by farming
1) Destruction of hedgerows: Provide habitat for insects/birds but in the way of farming machinery = replaced by fences
2) Selective breeding: Plants/animals with desirable characteristics bred to pass onto future generations = narrowing gene pool
3) Monoculture: Only growing 1 plant species in whole field = low diversity with 1 type + attracts same type of consumer
4) Over-grazing: Reduce plants effect rest of food chain
5) Filling in ponds/draining wetland: To make space for crops
Compromises between conservation + farming
- Remove a small number of hedgerows not all
- Selective breeding only allowed for certain species
- Crop rotation yearly with mono-cultures
Define index of diversity
Calculation to measure the relationship between the number of species in the community + number of individuals in each species
The Simpson’s diversity index
D= N(N-1)/Σn(n-1)
N= Total number of organisms of all species
n= Total number of organisms of a particular species
D= SDI
