BIOLOGY 1M03 TEST 2 - MCMASTER QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026
What is fusion? - Answers When two isolated populations come into contact, they may fuse - go back
together
- Adaptive differences may be small
- Adaptive differences may be overwhelmed by gene flow
What is divergence through reinforcement - Answers Reinforcing the distinction between two species;
they avoid mating using coloration, timing , courtship rituals...
What is speciation through hybridization - Answers Creating a new species out of a hybrid
What is competitive exclusion? (think of similarity in niche) - Answers One species might eliminate the
other species, either by competition, or by better success in mating
Competitive exclusion prevent two species from occupying the same niche at the same time
Competitive exclusion = The idea that two species cannot occupy the exact same niche at the same
time.
What is allopolyploidy? - Answers An individual that is a hybrid of two different species and that
possesses more than two sets of chromosomes (derived from hybridization).
What is a sister taxa? - Answers Two taxa that share a common node
What is a clade? - Answers A clade is a grouping that includes a common ancestor and all the
descendants (living and extinct) of that ancestor. (monophyletic group)
Which should you use: phenetic analysis or cladistic analysis? - Answers Cladistic analysis makes use
of the phylogenetic model of organisms evolving from each other to infer phylogenies
Phenetic analysis ignores the phylogenetic model of organisms evolving from each other while
inferring phylogenies
Which is better => Cladistic analysis
When should we use phenetic analysis
=> When our data are only distances, with no characters available - e.g., certain molecular
techniques .
=> When we don't have enough baseline information
In simple terms: phenetic = physical properties, cladistic = evolutionary relationships.
What is homology? - Answers A similarity that is due to common ancestry
What is homoplasy? - Answers Homoplasy is the development of organs or other bodily structures
within different species, which resemble each other and have the same functions, but did not have a
common ancestral origin.
Why is a phylogenetic tree an imperfect model of the true history of life? - Answers Because of sex
and gene transfer?
What is co-evolution? - Answers Coevolution, or coevolution, is the reciprocal evolutionary change in
a set of interacting populations over time resulting from the interactions between those populations.
Usually, the interacting populations are different species, like plant-pollinator, predator-prey, or host-
parasite. Caused by close ecological interactions.
What is taxonomic bias - Answers Research is not proportional to organisms' frequency in nature or
when organisms from a particular taxonomic group are researched disproportionately to others
What is living in sympatry - Answers Sympatric species have overlapping geographic ranges, but in
ecology, a narrower definition is often used that describes species that not only have overlapping
ranges, but that live in the same local community such that they are close enough to interact.
What is the advantage and disadvantage of gene duplication? - Answers One or more genes may be
accidentally duplicated so that the genome has two copies of each gene
- Chromosomal duplication by polyploidy is one way this can happen
This may make the organism less efficient, and thus be selected against
It may also allow for innovation. Why?
- Answer: Because one copy can continue to do the old function, while the other evolves a new
function
What is adaptive selection - Answers Selecting for beneficial alleles and thus increasing their
frequency in the population, while selecting against deleterious alleles and thereby decreasing their
frequency—a process known as adaptive evolution.
What is:
, Stabilizing selection
Directional selection
Frequency-dependents election
Heterozygote advantage - Answers Stabilizing selection: Stabilizing selection is a form of natural
selection wherein individuals with moderate or average phenotypes are more fit (more likely to
survive and reproduce).
Directional selection: Directional selection is defined as the change in a phenotype or genotype of a
population in one direction away from the mean (average) in a particular environment over time.
Frequency-dependent selection: Frequency-dependent selection is defined as a situation where
fitness is dependent upon the frequency of a phenotype or genotype in a population. Ex: the more
blue butterfly, the more noticeable a red butterfly is
Heterozygote advantage: an individual who is heterozygous at a particular gene locus has a greater
fitness than a homozygous individual
What is observer bias? - Answers Observer bias occurs when a researcher's expectations, opinions, or
prejudices influence what they perceive or record in a study. It usually affects studies when observers
are aware of the research aims or hypotheses.
Why do clades with a history of radiation may be more successful? - Answers A clade that has
radiated in the past may have advantages even after it contracts (disappearance/shortening of range)
They've explored more kinds of environments
They're found in more different specific places
- e.g., marsupials in Australia
They've had more chances to adapt
- May have a few very successful species (like us) 3
Environment, specific places, chances to adapt
Why did it take humans 150K years to start spreading? - Answers Conditions were good and there was
no evolutionary pressure to spread
Which would have more sexual dimorphism, a male amongst a group of women, or a group of
interacting males and females? Which scenario would include males with bigger genitals? - Answers
One male with a group of females would demonstrate more dimorphism and they would have smaller
genitals than the other group. They don't use it as part of sexual competition, rather they use their
strength and dominance over the other males.
What are the criteria's of a primates and what is stereoscopic vision - Answers Primates: Any placental
mammal of the order Primates, typically having flexible hands and feet with opposable first digits,
good eyesight, and, in the higher apes, a highly developed brain.
Criteria's:
- Highly developed stereoscopic vision
- Versatile limbs
- Large brains
Taken literally, stereoscopic vision describes the ability of the visual brain to register a sense of three-
dimensional shape and form from visual inputs. In current usage, stereoscopic vision often refers
uniquely to the sense of depth derived from the two eyes.
What are adaptive loops - Answers Sometimes adaptations can reinforce each other:
- Bigger brains may increase selection for adaptive foraging
- Needing to process more types of food may increase selection for clever hands
- More clever hands may increase selection for good stereoscopic vision
- Ability to see and manipulate things in front of you may increase selection for bigger brains . .
Why does genetic information allow scientist to make more reliable phylogenetic trees? - Answers
Because genetic information allows us to measure a greater number of traits.
What is adaptive foraging? - Answers The ability to switch between types of food, and to learn to use
new types of food
What is fusion? - Answers When two isolated populations come into contact, they may fuse - go back
together
- Adaptive differences may be small
- Adaptive differences may be overwhelmed by gene flow
What is divergence through reinforcement - Answers Reinforcing the distinction between two species;
they avoid mating using coloration, timing , courtship rituals...
What is speciation through hybridization - Answers Creating a new species out of a hybrid
What is competitive exclusion? (think of similarity in niche) - Answers One species might eliminate the
other species, either by competition, or by better success in mating
Competitive exclusion prevent two species from occupying the same niche at the same time
Competitive exclusion = The idea that two species cannot occupy the exact same niche at the same
time.
What is allopolyploidy? - Answers An individual that is a hybrid of two different species and that
possesses more than two sets of chromosomes (derived from hybridization).
What is a sister taxa? - Answers Two taxa that share a common node
What is a clade? - Answers A clade is a grouping that includes a common ancestor and all the
descendants (living and extinct) of that ancestor. (monophyletic group)
Which should you use: phenetic analysis or cladistic analysis? - Answers Cladistic analysis makes use
of the phylogenetic model of organisms evolving from each other to infer phylogenies
Phenetic analysis ignores the phylogenetic model of organisms evolving from each other while
inferring phylogenies
Which is better => Cladistic analysis
When should we use phenetic analysis
=> When our data are only distances, with no characters available - e.g., certain molecular
techniques .
=> When we don't have enough baseline information
In simple terms: phenetic = physical properties, cladistic = evolutionary relationships.
What is homology? - Answers A similarity that is due to common ancestry
What is homoplasy? - Answers Homoplasy is the development of organs or other bodily structures
within different species, which resemble each other and have the same functions, but did not have a
common ancestral origin.
Why is a phylogenetic tree an imperfect model of the true history of life? - Answers Because of sex
and gene transfer?
What is co-evolution? - Answers Coevolution, or coevolution, is the reciprocal evolutionary change in
a set of interacting populations over time resulting from the interactions between those populations.
Usually, the interacting populations are different species, like plant-pollinator, predator-prey, or host-
parasite. Caused by close ecological interactions.
What is taxonomic bias - Answers Research is not proportional to organisms' frequency in nature or
when organisms from a particular taxonomic group are researched disproportionately to others
What is living in sympatry - Answers Sympatric species have overlapping geographic ranges, but in
ecology, a narrower definition is often used that describes species that not only have overlapping
ranges, but that live in the same local community such that they are close enough to interact.
What is the advantage and disadvantage of gene duplication? - Answers One or more genes may be
accidentally duplicated so that the genome has two copies of each gene
- Chromosomal duplication by polyploidy is one way this can happen
This may make the organism less efficient, and thus be selected against
It may also allow for innovation. Why?
- Answer: Because one copy can continue to do the old function, while the other evolves a new
function
What is adaptive selection - Answers Selecting for beneficial alleles and thus increasing their
frequency in the population, while selecting against deleterious alleles and thereby decreasing their
frequency—a process known as adaptive evolution.
What is:
, Stabilizing selection
Directional selection
Frequency-dependents election
Heterozygote advantage - Answers Stabilizing selection: Stabilizing selection is a form of natural
selection wherein individuals with moderate or average phenotypes are more fit (more likely to
survive and reproduce).
Directional selection: Directional selection is defined as the change in a phenotype or genotype of a
population in one direction away from the mean (average) in a particular environment over time.
Frequency-dependent selection: Frequency-dependent selection is defined as a situation where
fitness is dependent upon the frequency of a phenotype or genotype in a population. Ex: the more
blue butterfly, the more noticeable a red butterfly is
Heterozygote advantage: an individual who is heterozygous at a particular gene locus has a greater
fitness than a homozygous individual
What is observer bias? - Answers Observer bias occurs when a researcher's expectations, opinions, or
prejudices influence what they perceive or record in a study. It usually affects studies when observers
are aware of the research aims or hypotheses.
Why do clades with a history of radiation may be more successful? - Answers A clade that has
radiated in the past may have advantages even after it contracts (disappearance/shortening of range)
They've explored more kinds of environments
They're found in more different specific places
- e.g., marsupials in Australia
They've had more chances to adapt
- May have a few very successful species (like us) 3
Environment, specific places, chances to adapt
Why did it take humans 150K years to start spreading? - Answers Conditions were good and there was
no evolutionary pressure to spread
Which would have more sexual dimorphism, a male amongst a group of women, or a group of
interacting males and females? Which scenario would include males with bigger genitals? - Answers
One male with a group of females would demonstrate more dimorphism and they would have smaller
genitals than the other group. They don't use it as part of sexual competition, rather they use their
strength and dominance over the other males.
What are the criteria's of a primates and what is stereoscopic vision - Answers Primates: Any placental
mammal of the order Primates, typically having flexible hands and feet with opposable first digits,
good eyesight, and, in the higher apes, a highly developed brain.
Criteria's:
- Highly developed stereoscopic vision
- Versatile limbs
- Large brains
Taken literally, stereoscopic vision describes the ability of the visual brain to register a sense of three-
dimensional shape and form from visual inputs. In current usage, stereoscopic vision often refers
uniquely to the sense of depth derived from the two eyes.
What are adaptive loops - Answers Sometimes adaptations can reinforce each other:
- Bigger brains may increase selection for adaptive foraging
- Needing to process more types of food may increase selection for clever hands
- More clever hands may increase selection for good stereoscopic vision
- Ability to see and manipulate things in front of you may increase selection for bigger brains . .
Why does genetic information allow scientist to make more reliable phylogenetic trees? - Answers
Because genetic information allows us to measure a greater number of traits.
What is adaptive foraging? - Answers The ability to switch between types of food, and to learn to use
new types of food
