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8.2 Speciation

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Last updated over 1 year ago
18 questions
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Question 1
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Question 7
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Question 8
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Question 9
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The red line shows the original population. The blue graph shows the population after natural selection occurred.
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Question 15
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Question 17
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Question 18
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Match the term with the best description for each
Prezygotic Barriers
Formation of a new & distinct species
Postzygotic Barriers
Prevent fertilization from occurring
Allopatric Speciation
Prevent hybrid offspring from being viable/fertile
Sympatric Speciation
New species arise due to geographical isolation
Speciation
New species arise due to reproductive isolation
A new river forms and splits two populations, causing ______________ speciation
Sympatric
Convergent
Allopatric
Extreme
The emergence of a mountain range is an event that would lead to _______________ speciation
Allopatric
Sympatric
The apple maggot fly is originally laid their eggs on hawthorn trees, but when apples were introduced to North America in the 19th century, some maggot flies began to shift to apples as their preferred host. Over time, the flies that specialized in apples and those that specialized in hawthorns began to experience reproductive isolation due to differences in the timing of fruit ripening and the specific environmental conditions of the fruit types. This led to the formation of two distinct populations of flies, despite living in the same geographical area.

What type of speciation is described above?
sympatric speciation
allopatric speciation
A flash flood carried a raft of Amazon ants away from their original population. There is enough distance between the two groups, that they will never meet in nature again. 

What type of reproductive barrier is this? What type of speciation may occur as a result of this event?
2. allopatric speciation may occur
2. sympatric speciation may occur
1. geographic isolation
1. behavioral isolation
1. gametic isolation
1. temporal isolation
The flowers of pink tulips open in the morning, while the flowers of lavender tulips open in the early afternoon. The bees that pollinate these tulips cannot carry pollen back & forth between the two types of tulips because of their flowers being closed at different times of day. 

Which of the following describe(s) the situation above?
mechanical isolation
postzygotic barrier
hybrid sterility
prezygotic barrier
temporal isolation
behavioral isolation
In some species of snails, the direction in which their shells spiral (right-handed or left-handed) prevents mating. A right-handed shell species and a left-handed shell species cannot mate because their reproductive organs are misaligned.

Which of the following describe(s) the situation above?
hybrid sterility
temporal isolation
behavioral isolation
mechanical isolation
a postzygotic barrier
a prezygotic barrier
In some species of cotton (Gossypium), hybrids between different species may initially be fertile and robust, but their offspring (the second generation) are weak and sterile.

Which of the following describe(s) the situation above?
postzygotic barrier
behavioral isolation
hybrid breakdown
mechanical isolation
temporal isolation
hybrid sterility
prezygotic barrier
Male bowerbirds build intricate and decorative nests to attract mates. Different species of bowerbirds have unique building styles, and females are more likely to choose mates that build nests in their species-specific style. Even if two species of bowerbirds live in the same area, they will rarely mate due to this behavioral difference.
prezygotic barrier
postzygotic barrier
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Question 11
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Question 12
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In humans, babies with very low birth weights (under 5 pounds) or very high birth weights (over 10 pounds) are at higher risk for health problems, including difficulty surviving and complications during birth. Babies with a birth weight in the moderate range (around 7-8 pounds) have the highest chances of survival. Over time, natural selection favors this middle ground, leading to ___________ selection for average birth weight in human populations.
Stabilizing
Directional
Disruptive
Giraffes with longer necks can reach higher branches to feed on leaves, giving them an advantage over giraffes with shorter necks, especially during dry seasons when food is scarce. Over generations, natural selection has favored giraffes with longer necks, leading to _____________ selection for increased neck length.
Directional
Stabilizing
Disruptive
In some salmon populations, males exhibit two distinct mating strategies: one that involves competing for mates by being large and aggressive (dominant males) and one that involves sneaking in and fertilizing eggs without fighting (sneaky males). Intermediate-sized males, who are not big enough to compete but not small enough to sneak in, are less successful in reproductive competition.

This is ________________ selection because it favors both large and small males, but not intermediate-sized ones.
Stabilizing
Disruptive
Directional
Gradualism is the idea that evolution happens slowly and steadily over long periods, with small, incremental changes accumulating over time.

Which of the following example(s) demonstrate the idea of gradualism?
Over millions of years, the horse family has undergone minute changes in its size, limb structure, and tooth morphology. Early horse ancestors, like Hyracotherium (or Eohippus), were small and forest-dwelling with multiple toes. Over time, these animals slowly evolved into the modern horse with large, single-hoofed feet adapted for running on open grasslands. This transition took place over 50 million years.
In the African Great Lakes (such as Lake Tanganyika, Lake Victoria, and Lake Malawi), cichlid fish have rapidly diversified into hundreds of species in a relatively short geological timeframe (around 10,000 to 100,000 years). These fish adapted to different ecological niches, such as different types of food and habitats, in a process of explosive speciation. While the cichlids show long periods of stability within each species, the rapid emergence of new species can occur when new ecological niches emerge.
The human skull has evolved over millions of years from early hominins like Australopithecus to modern humans. Over time, small changes in the shape of the skull, such as the enlargement of the braincase and the development of a more prominent chin, occurred gradually. This process involved slight changes in features over hundreds of thousands of years, ultimately leading to the modern human skull.
The Cambrian Explosion, around 541 million years ago, is a classic example. During this period, many major animal phyla appeared in the fossil record in a relatively short period, leading to an apparent burst of diversification. This sudden increase in complexity contrasts with the longer periods of stasis seen in earlier life forms.
Which of the following statements are true about the adaptive radiation of mammals following the P/K extinction event?
(Select all that apply)
Adaptive radiation of mammals led to the development of new body plans and behaviors, allowing them to occupy diverse habitats, such as terrestrial and aquatic environments.
Mammals during this period became more similar to one another as they adapted to similar environmental conditions, reducing the diversity within the mammalian group.
Mammals diversified into many environments due to the extinction of dominant reptile groups
New mammalian groups, such as early primates, carnivores, and herbivores, evolved rapidly in response to the changing climate and the opening of ecological opportunities.
The P/K extinction event had no significant impact on mammalian evolution, as they were already highly specialized before the event.
Phil Connors, a biologist and meteorologist, stumbles upon two populations of groundhogs living in the same geographic area. Despite having very little physical difference and not interbreeding in the wild, Connors discovers that in captivity, the groundhogs from both populations can mate and produce viable, fertile offspring (which are particularly good at predicting whether or not winter is coming).

According to the biological species concept, why should these populations not be considered separate species?
They are physically different enough that they should be considered distinct species, regardless of their ability to breed in captivity.
The inability to interbreed in the wild is enough to classify them as separate species, even though they can interbreed in captivity.
The fact that they can produce viable, fertile offspring in captivity suggests that they are the same species under the biological species concept.
The biological species concept only applies to animals that live in different geographic areas, so these groundhogs should still be considered separate species.
What type of selection is shown in graph 1?
Directional
Stabilizing
Disruptive
What type of selection is shown in graph 2?
Directional
Disruptive
Stabilizing
What type of selection is shown in graph 3?
Disruptive
Stabilizing
Directional