Speciation and Environmental Conservation Flashcards
What does natural selection act on?
Alleles, which are inheritable.
Define gene pool.
The total collection of alleles that exists within a population.
Describe variation in a population
Restricted to what’s already present in the gene pool.
New variation can arise by mutation.
Define population.
A group of individuals of the same species, which live in the same geographic area and readily interbreed to produce fertile offspring.
Members of a population belong to the same gene pool.
What must happen for variation to occur in phenotypes?
More than one allele of a gene must exist.
Define polymorphisms.
Phenotypes that vary due to different alleles.
From ‘many forms’.
What causes the frequency of alleles in a population to change?
Mutation: introduced a new allele to the gene pool
Immigration
Emigration
Different rates of reproduction of different individuals
Describe genetic drift.
Occurs because alleles are inherited randomly from parents.
Describes changes to the gene pool that occur by chance and are not driven by selection pressures.
What are some reasons for changes to the gene pool?
Allele frequencies are not the same from generation to generation.
A chance event may kill individuals non-selectively, altering the allele frequencies in the gene pool.
Define bottleneck effect.
Example of genetic drift.
Occurs when a population is drastically reduced in size.
Alleles present in the surviving members of the population may not be representative of the original population.
Define founder effect.
Occurs when a small number of individuals found a new population.
Alleles present in the founding members of the new population may not be representative of the original population.
Define natural selection.
The driving force for adaptive evolution.
The only mechanism that can lead to new species that are better suited to their environment.
The only mechanism that can lead to adaptive evolution.
Define artificial selection.
Occurs when humans select individuals with traits they desire to become the breeding stock.
Relies upon human intervention.
Define selection pressures.
Factors that influence the survival of an individual, population or species.
Examples of selection pressures.
Competition for food, water, and territories -Between individuals within a species -Between different species Predator/prey relationships Competition for mates (sexual selection)
Define sexual selection.
Occurs when individuals with particular traits are more likely to be successful than other individuals in finding a mate.
Can lead to spectacular results.
Can produce sexual dimorphism.
Define sexual dimorphism.
Males and females of a species have different forms.
Describe stabilising selection.
Trait stabilises.
Describe directional selection.
Trait shifts in one direction.
Describe disruptive selection.
Extreme traits are favoured.
Define microevolution.
When natural selection causes the allele frequencies to change in a population.
Any change in the gene pool of a population over time.
Refers to small changes within a gene pool,
Define macroevolution.
Major evolutionary changes above the species level.
Refers to more than one gene pool, or more than one species
Define speciation.
The appearance of new species.
What is key to preventing extinction?
Preservation of genetic diversity.
Larger gene pool, more alleles to draw upon to face the pressure of natural selection.
Define conservation reserves.
Protect endangered species from human influence.
Define wildlife corridors.
Link otherwise isolated conservation areas.
Allow animals to move to new areas when resources become scarce.
Compare large gene pools to small gene pools.
Large gene pools:
Higher variation
Buffer against environmental change
Small gene pool:
Little variation
Little buffer against environmental change
What does SLOSS stand for?
Single large or several small.
What does STR’s stand for?
Short tandem repeats.
Describe STR’s
2-5 base pairs long repeated
Non-coding (introns)
1000’s of them throughout all chromosomes
Highly variable
How do you view STR’s?
PCR
- use specific probes (primer) for STR in PCR
- amplify STR (DNA)
- view amplified STR’s using electrophoresis
Define inbreeding.
The mating of closely related individuals.
Leads to reduced genetic diversity.
How do you avoid inbreeding?
Translocation-increases gene flow
How do you combat small population sizes?
Breeding programs
Establish 2nd/3rd population (insurance population)
How do you combat feral predators?
Baiting
Culling/shooting
Fences
Biological control (rabbits)
How do you combat habitat loss?
Rehabilitate new habitat
Create new habitat
Protect remaining habitat (national parks)
Stop additional destruction
How do you combat habitat degradation?
Protect habitat
Fencing
Fines
How do you combat habitat fragmentation?
Wildlife corridors
Rope bridges
Tunnels
How do you combat inbreeding?
1 population: STR’s-least related individuals mate (breeding program)
2 or more populations-STR’s, translocation, breeding programs
Island populations: translocate from mainland to island (high GD to low GD)
Increase gene flow-wildlife corridors, ladders, tunnels
How do you combat competition?
Control feral competitors
How do you combat disease?
Insurance populations
increase genetic diversity
What are the four parts of natural selection?
Variation
Overproduction
Natural selcetion
Adaption
Describe variation.
Organisms (within populations) exhibit individual variation in appearance and behaviour.
May involve body size, hair colour, facial markings, voice properties, or number of offspring.
Some traits show little to no variation among individuals, for example, number of eyes in vertebrates.
Many variations are caused by mutations to alleles that are inheritable.
Describe overproduction
More offspring are born than can survive-struggle for existence.
High rate of population growth.
Most populations have more offspring each year than local resources can support-struggle for resources.
Each generation experiences substantial mortality.
