Chapter 1: The Whale and The Virus

What type of evidence has been used to infer that whales evolved from mammals that used to live on land (rather than from fishes, for example)?

- whales share traits with other mammals, like needing to breath air and giving birth to live young that feed on milk. - whales still have developmental genes for traits that they no longer have, like hind legs. - fossils of early whales display combinations of traits that reveal a gradual transition from terrestrial to aquatic life.

What are some characteristics that distinguish whales from sharks and tunas?

All the whales have fish like bodies, with the same sleek curves and tails you can find on tunas and sharks, they have a number of distinguishing characters. Whales do not have gills, so they cannot extract dissolved oxygen from the water in which they live. Whales must rise to the surface of the ocean in order to breathe. Whales and dolphins have long muscles that run the links of their bodies — much like the long muscles running down your back — whereas tunas have muscles that form vertical blocks from head to tail. Whales lift and lower their tails to generate thrust. Sharks and tuna move their tails from side to side. And whales give birth to live young that cannot get their own food; instead, the young must drink milk produced by their mothers. Only some species of sharks and fishes give birth to live young, but those offspring can feed themselves; sharks and tuna do not produce milk. So despite their fishlike appearance, whales are very different from sharks and tuna.

In the figure what do the arrows above the host cell represent?

Copies/daughter virus is produced by each virus from one generation to the next

What makes hemagglutinin important in the evolution of the influenza virus?

It allows the virus to bind to the cells of its host.

synapamorphy

a derived form of a trait that is shared by a group of related species

natural selection

a mechanism that can lead to evolution, whereby differential survival and reproduction of individuals cause some genetic types to replace (outcompete) others.

phylogeny

a virtual representation of the evolutionary history of populations, genes, or species

biological evolution

any change in the inherited traits of a population that occurs from one generation to the next

mutation

any change to the genomic sequence of an organism

What shares a common ancestor with whales?

humans

genetic drift

is evolution arising from random changes in the genetic composition of a population from one generation to the next

An individuals phenotype is a result of ...

it's genes and the environment in which it develops

viral reassortment

occurs when genetic material from different strains gets mixed into new combinations within a single cell

morphology

refers to the form and structure of organisms

genus (plural: genera)

taxonomic group of a closely related species

phenotype

- a measurable aspect of organisms, such as morphology (structure), physiology, and behavior. - genes interact with other genes and with the environment during the development of the phenotype

Define biological evolution:

- Any process by which populations of organisms change over time. - Any change in the inherited traits of a population that occurs from one generation to the next. - Change within a lineage due to natural selection and other mechanisms.

Why is influenza a worldwide threat?

- because influenza has the potential to kill millions of people from a single outbreak - because mutations in the influenza virus can allow the virus to evade the human immune system - Because viral reassortment can result in the flu crossing over from another species to human

Why do scientists overwhelmingly accept the theory of evolution?

- overwhelming evidentiary support, - explains and predicts independent lines of evidence, - scientists have tested and retested its predictions

lineage

- refers to a chain of ancestors and their descendants - may be the successive generations of organisms in a single population, the members of an entire species during an interval of geological time, or a group of related species descending from a common ancestor.

Where are places that scientists look for evidence of evolution? Where do they NOT look?

- the fossil remains of extinct animals, - comparison of homologous strains in various species, - change across generations in wild populations - NOT: change during an individual organisms lifetime

What kinds of evidence do evolutionary biologists use to test hypotheses about how different species are related to each other?

Evolutionary biologists consider observations of living species, DNA, and fossils. Scientists make comparisons between living species and fossils of extinct species to study shared anatomical traits. More recently, they have begun comparing DNA. Close relatives will share more traits, both physical and genetics, inherited from their common ancestor. So scientist can develop hypothesis for how these traits changed over time and how they evolved between different lineages and test them with additional evidence.

How do you mutations become more or less common in a population over the course of generations?

Mutations may be detrimental or even lethal; they may be harmless; or they may be beneficial in someway. Detrimental mutations should become less common over the course of generations because individuals with those mutations shouldn't do very well relative to other individuals. If a mutation is beneficial, however - one that helps an organism fight off diseases, thrive in its environment, or improve its ability to find mates, for example - that individuals should produce more offspring on average than individuals without the mutation. Mutations can also become more or less common in a population due to chance, a process called genetic drift.

What is the best description of natural selection?

Natural selection occurs when heritable characteristics cause some individuals to survive and reproduce more successfully than others.

fossil

Preserved evidence from a past geological age, including impressions and mineralized remains of organisms embedded in rocks

Explain how phylogeny helps us understand the evolutionary history of populations, genes, and species?

The simplest answer is that phylogenies can relate the entire evolutionary history of a species in a single image. From this image, one can infer the myriad genetic changes that had to occur for related species to branch off from one another to form new populations of species.

Why do baleen whales still have genes for building teeth?

Their ancestors had teeth and they inherited these genes from them, even though the genes no longer function.

What role does viral reassortment play in flu pandemics?

When two viral strains in fact the same cell, their genetic material can become mixed as copies of their RNA are bundled into new virus particles. The new combination of genetic material can you give rise to new beneficial characteristics of the virus, for example, characteristics that permit bird flus to invade human cells. Humans who have never been exposed to the characteristics of bird flus may have no antibodies to fight the infection, in the virus can reproduce rapidly. A bird flu virus that gains the capacity to spread from human to human through reassortment may spread rapidly over large geographic areas leading to a serious pandemic.

homologous

characteristics are similar in two or more species because they are inherited from a common ancestor