nnn Flashcards
Heritability/variation:
variation in heritable traits makes some organisms better suited to their environment
than others.
Survival of the fittest:
Organisms whose heritable traits are better suited to the environment need to
reproduce and leave behind more offspring.
Struggle for existence:
high birth rates and a shortage of life’s ‘basic needs’ forces organisms to compete for
resources (more offspring produced than can survive)
how did lamarck and darwin ideas differ
Lamarck believed that traits could be acquired or lost within a lifetime and that these acquired traits could
then be passed on to the next generation. Lamarck’s ideas referred to an ‘individual’ being able to change.
(use and disuse)
What Darwin identified is that favorable traits were inherited due to an organisms ability to survive and
reproduce. His research identified that organisms do not evolve as INDIVIDUALS but rather as POPULATIONS.
Lamarck was correct with regard to species changing over time..
what role does DNA play in evolution
DNA plays a big role in evolution for its role in genetic information storage. DNA is passed on from
parent to offspring and holds the instructions for all characteristics/traits/functions an organism will
possess. (DNA is found in all living things – suggesting common ancestry)
describe how each of the following plays a role in evolutionary change Mutations Genetic drift Gene flow Non-random Natural selection
a. Mutations change an organisms DNA and can be transferred in offspring. Mutations can
increase the variation of a gene pool (additional traits)
b. Genetic drift is the change in the gene pool of a small population due to chance. Genetic drift
can drastically reduce the variation of a gene pool and lead to change over time.
c. Gene flow exchanges genetics with migration of fertile individuals or gametes between
populations. Gene flow can reduce (emigration – individuals leaving population) or increase
(immigration – individuals entering population) the variation of a gene pool.
d. Non-random mating is when mates are chosen on the basis of a specific trait which can lead to
changes similar to natural selection (not necessarily the most fit organisms). Sometimes called
sexual selection where organisms mate with one another based on a certain trait/characteristic.
e. Natural selection favors certain traits in a population based on fitness (survival and
reproduction). Overtime the population/gene pool will shift towards the most fit individuals.
Homologous structures:
Structures which are similar in different species of common ancestry. The
structures may have a different external form and function because of the environments influence on
the species over time. Provide evidence of common ancestry and change over time. (Divergent
evolution – organisms occupy different niches and change in different ways over time but are still
linked to a common ancestor)
Homologous structures and similarities in embryonic development suggest evidence of common
ancestry and the gradual change of life overtime
Analogous structures:
Analogous structures: display evidence that although unrelated, an environment/niche can shape
UNRELATED organisms in similar ways. Example: fly vs bird wing. Internal structure is different, but
external structure/function is similar. Provides evidence for the environments influence on
evolutionary change; even with unrelated organisms. (Convergent Evolution – similar environmental
pressures lead to similar adaptations)
fitness
Fitness is how well an organism can find a mate and the necessary resources to survive. Adaptations
refer to the specific characteristics/traits that allow the organism to survive/reproduce in the
environmental conditions.
Artificial selection
Artificial selection is refers to the human ability to select desirable traits by only allowing the organisms
with those traits to breed and reproduce. Darwin believed a similar process happened in nature except
that natural stresses like environment conditions and finding food shelter and a mate take the place of
farmers in deciding which organisms will survive and breed.
what is Hardy Weinberg principle and what are the 5 factors that are necessary for it to be true
The Hardy Weinberg principle is used to describe a non-evolving population.
5 factors needed to make
it true are large population size, no migration, no net mutations, random mating, and no natural
selection. Essentially the OPPOSITE of the FIVE MECHANISMS OF EVOLUTIONARY CHANGE!
what are The Founder effect and the bottleneck effect populations gene pool?
explain.
The Founder effect and the bottleneck effect lead to smaller gene pools with a reduction in genetic
variation. Overtime these smaller populations can re-establish themselves and differ significantly from
the initial gene pool.
describe 3 types of reproductive isolation and how does reproductive isolation lead to new species
Behavioural isolation: Behavioral isolation occurs when two populations are capable of
interbreeding but have differences in courtship rituals or other reproductive strategies that involve
behavior.
Temporal isolation: Temporal isolation occurs when two species reproduce at different times.
Geographical isolation: Geographic isolation occurs when two populations are separated by
geographic barriers such as rivers or mountains.
All three examples eventually lead to reproductive isolation which describes two groups of organisms
that no longer interbreed with one another OR produce fertile offspring. When reproductive isolation
has occurred you have a new species. Think the definition of species..
how did fossils help to document the descent of modern species from an ancient ancestor
Fossils document change over time by allowing us to see the change in structures over many many
many generations. It allows us to see that these changes are gradual.
Darwin found fossils of many organisms that did not resample any living species what do you think that means. explain
Fossils that did not resemble living species could indicate mass extinction of a particular species. It
could also indicate that the changes over millions of years have been so significant that they no longer
resemble an ancient ancestor.
