Ch 14 Pt 2 Biology

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College Biology 120

In 2004, scientists announced the discovery of the fossil remains of some extremely short early humans on the Indonesian island of Flores. The new species has been named Homo floresiensis. One hypothesis is that H. floresiensis evolved from Homo erectus, another early human species. How did a population of H. erectus become isolated on this remote island? Early humans constructed boats and rafts, so perhaps they were blown far off course by strong winds during a storm.

H. erectus averaged almost 6 feet in height, but the remains show that adults of H. floresiensis were only about 3 feet tall. It's hypothesized that limited resources on this hot and humid island (only 31 square miles) exerted selection pressure and succeeding generations began to shrink in size. Small bodies require less food, use less energy, and are easier to cool than larger bodies. Evolution of small size in similar circumstances has been observed in many other species, but never before in humans. This find demonstrates that evolutionary forces operate on humans in the same way as on all other organisms.


The evolution of Homo floresiensis is an example of...

Allopatric Speciation

The geographic isolation of a population from other members of the species and the subsequent evolution of reproductive barriers between it and the parent species describes ________ speciation.

Allopatric

Uplift and formation of a mountain range divides a freshwater snail species into two isolated populations. Erosion eventually lowers the mountain range and brings the two populations together again, but when they mate, the resulting hybrids all produce sterile young. This scenario is an example of...

Allopatric Speciation

In which of the following situations would speciation be most likely to occur?

Seven monkeys escape from an amusement park and zoo in South Florida. To everyone's surprise, they establish a small but viable population, coexisting successfully with humans in a partly suburban environment very different from their native African habitat.

In 2004, scientists announced the discovery of the fossil remains of some extremely short early humans on the Indonesian island of Flores. The new species has been named Homo floresiensis. One hypothesis is that H. floresiensis evolved from Homo erectus, another early human species. How did a population of H. erectus become isolated on this remote island? Early humans constructed boats and rafts, so perhaps they were blown far off course by strong winds during a storm.

H. erectus averaged almost 6 feet in height, but the remains show that adults of H. floresiensis were only about 3 feet tall. It's hypothesized that limited resources on this hot and humid island (only 31 square miles) exerted selection pressure and succeeding generations began to shrink in size. Small bodies require less food, use less energy, and are easier to cool than larger bodies. Evolution of small size in similar circumstances has been observed in many other species, but never before in humans. This find demonstrates that evolutionary forces operate on humans in the same way as on all other organisms.


If H. floresiensis were reunited with H. erectus at a much later date, but the two populations could no longer interbreed, it would be correct to conclude that H. floresiensis...

had evolved reproductive barriers.

Diane Dodd raised different fruit fly populations on different food sources. She found that after about 40 generations, the evolution of reproductive isolation was under way. The mechanism of evolution responsible for this was...

Natural Selection

Humans are diploid and have 46 chromosomes (or two sets). How many sets of chromosomes are found in each human gamete?

1

Humans are diploid and have 46 chromosomes. How many chromosomes are found in each human gamete?

23

_____ is the process by which haploid gametes form a diploid zygote.

Fertilization

A particular diploid plant species has 48 chromosomes, or two sets. A mutation occurs and gametes with 48 chromosomes are produced. If self-fertilization occurs, the zygote will have _____ set(s) of chromosomes.

4

Which of these terms applies to an organism with extra sets of chromosomes?

Polyploid

Mutant tetraploid plants _____.

are unable to interbreed with a diploid plant

Most polyploid plants arise as a result of _____.

hybridization

Speciation without geographic isolation is called ________ speciation.

Sympatric

Organisms that possess more than two complete sets of chromosomes are said to be...

Polyploid

Most polyploid species arise from...

the hybridization of two parent species.

When a tetraploid flower pollinates a diploid flower of the parental species, the resulting offspring will be...

triploid and sterile.

Sympatric speciation commonly occurs through ________ in plants, but is more likely to occur through ________ in animals.

polyploidy . . . habitat differentiation and sexual selection

The emergence of many diverse species from a common ancestor is called...

Adaptive Radiation

Which of the following would tend to promote adaptive radiation?

An organism colonizes an isolated area that is habitable but relatively devoid of life.

According to island biogeography, what is the relationship between an island's distance from the mainland and the number of species present on the island?

The farther an island is from the mainland, the fewer the number of species found on the island

Why is a new island more hospitable to colonizers than an older island is?

The intensity of both competition and predation is less on the newer island.

What is the relationship between colonizing success and the number of species already established on an island?

As the number of established species on an island increases, colonizing success also decreases.

The number of species on an island remains relatively constant when _____.

the rate of successful colonization equals the extinction rate

Two bird species overlap in a hybrid zone. They are isolated by a slight difference in the male songs and by the females' tendency to select males with the "correct" song. Hybrid offspring tend to have reduced fertility compared to either of the parent species. What effect might natural selection have in this situation?

Natural selection might favor males with more distinctive calls and/or females that are more "choosy." As a result, the reproductive barrier between the two species could be reinforced.

Which butterfly has changed gradually but significantly from its ancestor through microevolutionary events that were not part of a speciation event?

Butterfly D

The ________ suggests that speciation occurs in brief spurts.

punctuated equilibrium model

The emergence of a new plant species over a brief period of time, followed by a long period of little change, is consistent with which of the following theories?

punctuated equilibrium

Which of the following descriptions best represents the gradual model of speciation?

Speciation occurs regularly as a result of the accumulation of many small changes.

One of the finest available sequences of fossils shows how horses have changed slowly and by subtle steps from small shrub-browsing ancestors to the large, grass-grazing modern horse. A large number of fossil species have been named, and it is often difficult to decide on the identity of a fossil horse because transitional forms are common. This record of evolution best fits the idea of...

the gradual model of speciation.

The fossil record shows that for many plant and animal groups, the time between speciation events...

varies greatly, but averages 6.5 million years.

How are refined sugar and high fructose corn syrup different?

High fructose corn syrup contains more fructose than refined sugar.

What, in part, fueled the use of high fructose corn syrup?

High fructose corn syrup is cheaper to produce than refined sugar.

Which organ converts fructose to fat?

Liver

Approximately how much sugar does the average American consume each year?

90 pounds

Which of the following is in the correct order leading to the development of heart disease?

fat accumulation, insulin resistance, metabolic syndrome

In ___________, a population isolated by a geographic barrier becomes a new species as it accumulates changes by natural selection or genetic drift.

allopatric speciation

In __________, a new species may arise as mating and gene flow are reduced between populations that share the same area.

Sympatric Speciation

Many plant species have formed by, _________, in which accidents in cell division result in extra sets of chromosomes.

Polyploid Speciation

Both allopatric speciation and sympatric speciation depend on the establishment of ________, which prevent(s) gene flow between a new species and its parent species.

Reproductive Barriers

____________ occur(s) when a species gives rise to many new species after colonizing a region with diverse habitats.

Adaptive Radiation

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