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Flashcards in Evolution Deck (45):

Define the term evolution, explaining how evolution has led to bioddiversity by altering populations and not individuals.

Evolution: Refers to the permanent genetic change in population that occurs over successive generations. Evolution has led to biodiversity by altering populations not individuals because it defines as a gradual change in population, not changes in an individual as life progresses.


Define Gene Pool:

Gene Pool: the set of different genes in an interbreeding population.


Define Genome:

Genome: the complete set of genes or genetic material present in a cell or organism.


Describe and explain the processes of discovery that led Darwin to formulate his theory of evolution by natural selection.

Darwin set sail on the HMS Beagle in 1831 and travelled throughout the world with Robert Fitzroy. Along the way they went to the Galapagos Islands where Darwin observed many biological specimens that helped him eventually formulate his theory of natural selection. He found that there was a high level of diversity in a small area, leading him to conclude that each species adapted to its environment. (13 species of finches). After reading Malthus' work on overpopulation and competition he formulated his theory but didn't want to publish it until 1859 when Alfred Russell Wallace found evidence for the exact same theory, and, motivated by the competition, he published his theory.



Overproduction: is when a population is producing more offspring the the space or resources allows.



Competition: The competition between organisms for space, and resources.



Variation: any difference between cells, individuals, organims, or groups of organisms of any species caused by genetic differences.



Adaptations: differeation in the structure or function of an organims or any of it's parts that result from natural selection.


Natural selection:

Natural Selection: the process whereby organisms better adapt to their enviroment tred to survice and produce more offspring.



Speciation: an evolutionary process by which a new species comes into being.


Structural adaptations:

Structural adaptations: affect the shape or arrangement of physical features of an organism. ex) blowholes of whales, needles of cactus relocated to prevent water loss.


Demonstrate, through examples, what the term "fittest" means in the phrase "survival of the fittest".

Means that organims that are better adapted to suit their inviroment will survive. ex) black and white peppered moths, giraffes during drought, finches with longer beaks survive more then finches with smaller beaks. Smaller pengiuns in the galapogos.


Explain how natural selection leads to changes in populations.

Natural selectionleads to changes in the populations by acting on the phenotype of an organism, so that individuals with favourable phenotypes are more likely to survive and reproduce then those with less favourable phenotypes. The genotypes associated with the favourable phenotype will then increase in frequency over the following generations.


Define antibiotic resistant bacteria:

Developed because some organsims developed adaptations that allowed them to survive in the presence of antibiotics and pesticides.


Define pesticide resistant insects.

Pesticide resistant insects: decreased susceptibility of insects of a pesticide that was previously effective to controlling the pests.


Describe how disruptive selection acts on variation:

Favours both extreme phenotypes and selects against the average. ex) medium sized fish get out competed for territory by larger fish. Smailler fish are able to sneak in and fertilize eggs before being detected.


Describe how directional selection acts on variation.

Favours individuals with rare phenotypes, selects against common phenotypes ex) antibiotic resistant bacteria.


Natural selection:

Natural selection is the process in which favourable hertable traits become more common in successive generations of a populations of reproducing organisms, and unfavourable heritable traits become less common.


Define and provide an example of natural selections

Natural Selection:
the process in nature by which organism better adapt to their environment to survive and reproduce more than those less adapted.

ex) In a habitat with green and red bugs, red bugs are easily spotted and are eaten more, therefore the green bugs survive.


Define and provide an example of gene flow

Gene Flow:
the movement of genes from one population to another population.

ex) A bee carrying pollen from one flower population to another. or a deer from herd A mating with a deer from herd B


Define and provide an example of genetic drift

Genetic Drift:
Populations of organisms are constantly changing and adapting to their environment. Drastic changes in environmental condition can sometimes cause drastic changes to the gene pool of the population. When chance events occur it can cause changes in frequencies of alleles in a population.

ex) a man steps on a bunch of bugs, most of the green bugs in the population were killed, leaving brown bugs to be the major concentration of the population.


Define and provide an example of non-random mating.

Non- Random Mating:
can occur when individuals prefer mates with particular superior physical characteristics or by the preference of individuals to mate with individuals similar to themselves.

ex) Peacocks- where a female peacock choose the most vibrant and colourful male peacock to mate with. The female chooses this base on physical traits.


Define and provide an example of founder effect.

Founder Effect:
The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors. When a new colony is started by a few members of the original population

ex) a population of 200 birds in colony A has 3 members that start colony B making the genetic makeup of the 3 members abundant.


Define and provide an example of bottleneck effect.

Bottleneck Effect:
A sharp reduction in size of a population due to environmental effects.

ex) Earthquakes wipes out a colony of 100 and leaves only 5 organisms left which makes their genetics more abundant.


Describe and provide examples of how populations can become reproductively isolate through geographic isolation.

Geographic Isolation:
A population of animals, plants or other organisms that are separated from exchanging genetic material with other organisms of the same species.

ex) isolation by barriers (a river)

isolation by distance (separating dolphins by location)

Isolation after an event (earthquake divides population)

Isolation by separation (small town that doesn't meet with others)


Describe and provide examples of how populations can become reproductively isolate through niche differentiation

Niche Differentiation:
the process by which competing species use the environment differently in a way that helps them co-excist

ex) Many caribbean lizards share common foods, though they avoid competition by occupying different geographic locations.


Describe and provide examples of how populations can become reproductively isolate through altered behavior

Altered Behaviour:
Change in actions in organisms due to the changes in their environment.


Describe and provide examples of how populations can become reproductively isolate through altered physiology

Altered physiology:
Change in body of organisms due to changes in physical environments (adaptations)


pre-zygotic isolating mechanisms.

-Habitat preference
-behavioural incompatibility: by be sexually active at different times of the year
-Structural incompatibility: sex organs make it physically impossible
-Physiological incompatibility: sperm and egg fail to unite.


With the use of examples differentiate between convergent evolution and divergent evolution.

Divergent Evolution:
the process in which an ancestral species gives rise to a number of new species adapted to different environmental conditions. This after occurs when a species colonized a new environment in which there are unoccupied ecological niches.

Convergent Evolution:
Occurs when unrelated species occupy the same environment and are subjected to similar environmental pressures, the organisms often develop analogous structures


Define and provide an example of Allopatric speciation vs Sympatric speciation

Allopatric Speciation:
Populations become geographically separated, each being subjected to different natural selection pressures and finally establishing reproductive isolation mechanisms.
ex) Galapagos finches (species separated into two groups)

Sympatric Speciation:
A population forms a new species within the same area as the parent species.
ex) apple maggot flies had speciation as new generations inhabited European introduced apple trees with different apple productions seasons.


Define and provide an example of geographic isolation vs reproductive isolation.

Geographic Isolation:
Barriers include: mountains, rivers, and oceans. These barriers isolate species and prevent interbreeding.
ex) grand canyon squires are different on either sides.

Reproductive Isolation:
Prevents successful interbreeding between organisms.
ex) pre and post zygotic isolating mechanisms.


Define and provide an example of hybridization

occurs when two different forms of a species that are normally reproductively isolated mate and produce offspring along a boundary called a hybridization zone. In some cases , the genetic variation of the hybrids is great than that of either parent and permits the population of hybrids to evolve adapting to their environments. the hybrid eventually diverge from both parent populations.

ex) coyote and gray wolf reproduce to create a red wolf.


Define and provide an example of polymorphism

Allows a species to change or blend in to protect itself. i.e. camouflage, under these circumstances only insects with the same colour can associate and mate. Therefore similarly collared insects are reproductively isolated from the other subpopulations and their gene pool with diverge.

ex) white and black butterflies, darker butterflies blended with the trees.


Define and provide an example of polyploidy

Occurs when an individual has more the two copies of each chromosome (normally cells are diploid 2n) Polyploidy occurs as a result of non-disjunction in mitosis, A tetrapod zygote can be established when a diploid sperm fertilizers a diploid egg, this will change the chromosome number and thus may result in a change of characteristic resulting in a new species.


Define and provide an example of adaptive radiation.

Adaptive Radiation:
the relatively rapid evolution of many species from ancestral species. It occurs when the ancestral species colonizes an area where diverse geographic/ ecological conditions are available fro colonization. Different species will form as different subpopulations of a species occupy and distinct niche.

ex) darwins finches.


Explain the difference between punctuated equilibrium and gradualism.

Punctuated Equilibrium:
Refers to spurt of rapid change followed by long periods of stasis (no change) Periods of stasis occurred during times when the environment was relatively stable. Rapid change occurred withe the environment changed rapidly.

Refers to the gradual change of species over time. Change is slow and occurs due to small periodic changes in the gene pool. firs proposed by Darwin.


What gene is linked to the evolution of the eye?

The gene that is linked to the evolution of the eye is the Pax-6 gene.


Would the difference in eye structure be the result of covergent or divergent evolution? Homologous or analogous structures?

Difference in the eye structures would be the result of divergent evolution because the structures would change based on adaptation of the environment and survival needs, and branching from a single ancestral being. Would also be an homologous structure having not all similarities were inheritable just based on ecosystem.


State the MAJOR differences between homologous and analogous strucures. WHich tupe of structure is likely the result of divergent evolution? Convergent evolution? Provide an example of each type of structure.

Homologous Structure:
Because each species has evolved from the same ancestor they will share structures. Thesis structures have changed over time to best suit their environment.

ex) pentadactyl (5 digit limb)

Analogous Structure:
Species that have evolved from different ancestors, though because of their environmental needs they start to share structure that they adapted to have.

ex) fish fins.


Behavioural adaptations:

Behavioural adaptations: are associated with how organims respond to their enviroment. ex) Miration by birds, Hibernation of bears, bending of sunflowers to face the sun.


Physiological adaptations:

Physiological adaptations: are variations in organism's metabolic processes across a species, ex) antibiotic resistant bacteria, pesticide resistant insects.


Describe how stabilizing selection acts on variation:

favours individuals with common phenotypes, and selects against those with extremem phenotypes. ex) babies with low birth weights may suffere more health complications, so do babies with with high birth weights


Artificial selection:

Artificial selection: is when humans ensure individuals with the more desirable traits are aloowed to reproduce. ex) dog breeding


Post-zygotic isolating mechanisms.

Hybrid inviability: the fertilized egg may fail to develop properly. Fewer young produced and have low survivability.

Hybrid Sterility: the hybrid of two species may be viable but sterile unable to breed ex: the mule

Hybrid breakdown: the first generation may be fertile by the subsequent generations are infertile or non-viable.