Adaption Flashcards
Define adaption
Organism being well equipped (structure, function, behaviour) to living in their environment
Basic def of evolution
A change in allele freq in a population from one generation to the next
What is modern synthesis (Neo-Darwinism)
The combination of Mendelian theory and Darwin’s theory of evolution
Processes that can affect allele frequencies within populations over successive generations
- mutation
- migration in/out of population
- genetic drift
- natural selection
Niche construction theory
A population that changes the environment = gives itself and other species an ecological inheritance with altered selection pressures
E.g. earthworms change soil ecosystem drastically so they create and control a niche other surrounding organisms must adapt to
Molecular clock theory
Zuckerlandl & Pauling (1960)
DNA evolves at a relatively constant rate = two species with common ancestor should have genetic differences relative to divergence
Useful for estimating evolutionary timescale
Useful if orgs have little fossil records
Find the divergence date of two species to find average change over time
Weir and Schluter (2008)
E.g. any bird species= 2% change every million years
However since found rates can vary so a relaxed molecular clock used to account for this
What are the theories for giraffe neck adaptation
- competing browser hypothesis; longer neck = better food resources so better survivor.
- necks for sex; males use as mating display and to fight to impress females
- vigilance hypothesis; higher view point helps observe predators = more likely to survive
Describe genotype fitness
- Genotype is relative to other genotypes in population
- measure of ability to produce offspring
- surmises survival, mate finding and reproduction
- depends on environment..fitness in one doesn’t mean fitness in another
Describe sexual selection
influences an animals ability to copulate with a mate
Often powerful enough to produce harmful adaptations
Male competition and female choice
Bayesian mimicry
An edible mimic that deceives predators by resembling a toxic model
An example of Bayesian mimicry
Toxic and mimic frogs in Ecuador
- there is a border between 2 toxic. One slightly yellow colouring
- nontoxic frog called A. Zaparo mimics the slightly less toxic frog in the north mimics the more toxic frog in the south
- A.zaparo mimics the less toxic frog at the border because predators learn to generalise the more toxic model but not the lesser
E.g of natural selection creating complex organs
- need to be attained in small steps, each one being advantageous
- show intermediate structures where possible
- e.g. evolution of eye: Dan-Eric Nilsson et al.
- shape of eye evolved in simulation With theoretical intermediates that increased visual acuity
- 1829 steps of 1% change required
Pre-adaptation
If a structures function changes considerably without much chnage to a structure itself. Was pre-adapted to new function
- happens by chance
- e.g. birds feathers for insulation also adapted for aerofoil used in flight
Are animals perfectly adapted to their environment?
- Natural selection slow. Time lag between environmental change and change by selection
- Developmental/physical factors constrain when phenotypes fitter than individuals homozygous at a locus
- Character has evolved top local optimum which may not be the over all optimum
How do we recognise adaptation?
- character fits too well in its environment to have arisen by chance
- appearance of complex design
- aids survival and reproduction
- often no pre-existing problem in enviro the animal has to surmount. As animal interacts new challenges arise and they adapt to it
