Adaptations, convergent evolution and changing population characteristics Flashcards
What are analogous structures?
structures in different organisms that have adapted to perform the same function but have different genetic origins
What is convergent evolution?
it takes place when unrelated species begin to share similar traits
What causes convergent evolution?
organisms adapt to similar environment or other selection pressures
What are selection pressures?
factors that affect the organism’s chances of survival or reproductive success
What is the first step in natural selection?
organisms in a species show variation in their characteristics due to differences in their genes organisms whose characteristics are best adapted to a selection pressure have an increase chance of surviving and successfully reproducing
What are the next steps for natural selection?
successful organisms pass the allele encoding the advantageous characteristics onto their offsprings conversely, the organisms that posses the non-advantageous allele are less likely to pass it on over time the proportion with individuals with the advantageous adaptation increases, therefore the allele that codes for this characteristics increases in the populationss gene pool
How is methicillin-resistant Staphylococcus aureus (MRSA) an exampled of natural selection?
bacteria reproduce rapidly so evolve in a short period of time
when they replicate their DNA can be altered, this usually results in the bacteria dying
however, a mutation in some S. aureus arose that provided resistance to methicillin
when exposes to this, they survived and reporduced, passing the allele to their offspring
the number of resistant individiuals increased over time
How are peppered moths an example of natural selection?
before industrial revolution, most peppered moths were pale, this provided camoflauge against light-coloured tree bark, increasing their chance of survival, as dark ones were easily spotted and eaten
after industrial revolution trees became darker due to loss of lichen and soot
number of dark moths increased as they were now better adapted
How are sheep bowflies an example of natural selection?
they lay eggs in faecel matter around a sheep’s tail - they then hatch and cause sores - can be fatal if left untreated
pesticide diazinon was used to prevent the condition
within 6 years, they developed a high level of resistance
individuals that were more resistant survived and passed this allele on
How was the new strain of Flavobacterium formed?
found in waste water from factories that produce nylon 6
evolved to digest nylon, help clear up factory waste
use enzymes nylonases
they are unlike any other enzyme found in it and do not help digest any other material
What is the founder effect?
when colonising a new area, genetic variation is lost, often resulting in individuals that are physically and genetically different from their source population
How did the founder effect affect the anolis lizards?
released across many islands that had no lizard populations
body shape of populations changed, driven by the flora in their environment
several new species were formed
