Speciation and Community Ecology

Coyne covers speciation and divergent evolution in Chapter 7: "Speciation is a splitting event, in which each ancestral branch splits into two twigs, which themselves split later, and so on as the tree of life ramifies. This means that the number of species builds up exponentially, although some branches are pruned through extinction" (Coyne 179).

Relate the concepts of speciation and divergent evolution to specific terms we learned over the summer when studying community ecology (Chapter 54 of Campbell). In other words, how do the community dynamics we've discussed, for instance responses to competition within a niche, lead to speciation? Answers may refer to the "splitting event" or the eventually "prun[ing] through extinction [of some branches]" (or both), and all responses should include an example scenario.

Maintaining the equilibrium

Biology is all about maintaining a balance; being biological is all about maintaining homeostasis, ecology stabilizes at carrying capacities and climax communities. In our bodies, the endocrine, nervous, etc. systems all help maintain the balance called homeostasis; in the ecological communities, ecological succession and predator/prey relationships maintain the balance of species. Is evolution a struggle to maintain balance? Assess the validity of the following statement:

Evolution is also a balancing act, through the mechanism of natural selection. A large imbalance, such as a great environmental stress, induces "macroevolution," major changes, while small imbalances induces "microevolution," minor changes in species. Even at a relative equilibrium, evolution is still occurring in terms of "stabilizing selection" (133).

Agree or disagree with the statement, and explain and defend your view using evolutionary examples.

Adapt, Migrate, or Die!

When faced with a problem that compromises the survivability of a species, the species really has three options: adapt, migrate, or die. Jerry Coyne brought up many examples of environmental stresses species have faced, such as predation or climate change, and how they have adapted over time to overcome these stresses, such as the development of cryptic coloration. We know many examples of species that have adapted through natural selection, but what about some species that have migrated or died because they did were not able to survive. Describe an environmental stress that can compromise the survival of a species; then, research and describe some ancient species that were affected by the stress in terms of making the species migrate or go extinct.

Dead Genes or Hibernating Genes?

Jerry Coyne states on page 66 that "Atavisms and vestigial traits show us that when a trait is no longer used, or becomes reduced, the genes that make it don't instantly disappear...evolution stops their action by inactivating them, not snipping them out of the DNA". If this is true, it sparks the debate between nature and nurture. If genes are really just inactivated, is it possible for them to be reactivated provided that the species are placed in a replication of the environment where those genes would be necessary to survive? How does this connect to what we have learned about genes and the evolutionary advantage of adaptation?

Artificial Selection v Natural Selection

In chapter 5, "The Engine of Evolution," Coyne brings up animal and plant breeding as a means for people to see the process of natural selection leading to evolution happen in their lifetimes. Why is artificial selection a good parallel to natural selection? Coyne uses the example of dog breeding and the rapid creation of new species as a way to see and understand evolution by selection, saying that "the success of dog breeding validates two of the three requirements for evolution by selection." Which requirements is he referring to and how does dog breeding validate these requirements? Provide another example of artificial selection he discusses that does the same.

Ontogeny recapitulates phylogeny

On page 78, Coyne quotes Ernst Haeckel's biogenetic law, saying that "ontogeny recapitulates phylogeny." Coyne backs this statement up with examples of different organism's path of embryonic development, describing how, for example, human embryos undergo development in a sequence that follows the evolution of its ancestors. Trace another organism's embryonic development and describe how it reflects this organism's evolutionary history. Discuss the concept of 'adding new stuff onto old.' in embryonic development. Is it really more efficient to have, for example, human embryos go through two different kidneys before development of the 'actual' kidney happens? Why not just skip seemingly useless developmental stages?

How does society's preferences reflect sexual selection?

On page 158, Coyne describes sexual selection. He states that "males compete for females" ,therefore males "should be promiscuous," while females should be coy.
Imagine you are trying to convince someone that sex drives evolution. How would you persuade this person, using society's ideas on what is aesthetically appealing and gender roles?

Evolution of Humans

As Coyne notes on page 193, many people were very hesitant to accept that humans evolved from apes. They could swallow the fact that birds descended from reptiles, but the thought that humans, the supposed most advanced species on the planet, came from nothing more than apes was ludicrous to them. After all, we are the species that can think; we are the species that have made the world the way it is; we are the species that rule the world. Even Darwin’s mentor Charles Lyell refused to believe humans evolved from other organisms. Many humans are simply too arrogant to believe that they came from other animals.
Pretend for the time being that I believe in evolution in all organisms except for humans. How would you try to prove to me that humans were, in fact, products of evolution and natural selection, just like everything else? Discuss the evidence that Coyne outlines in the first part of “What About Us?”
I’ll note that this creationist idea of human superiority where humans are the absolute best species and no other species is somewhat of a recurring theme that has come up in our study of biology this year, especially in terms of the environment. Relate the human attitude of creationists to previous biological topics.

Fossil Confirmation of Evolution

On page 96, Mr. Coyne notes that we can usually tell how an organism evolved over time by looking at the fossils in that area. Two of the examples he gives are the fossils of kangaroos that resemble modern-day kangaroos in Australia, and the armadillos (unique in that they have a carapace of bony armor) that match very closely the glyptodonts, ancient armored mammals. What are some other examples of ancient fossilized organisms that resemble fairly closely their modern-day counterparts (their descendants)? What factors might contribute to the similarities that the descendants of the organisms have to their ancestors? What themes of biology can you connect these factors and reasons to?

Which argument(s) do you find most convincing and/or Which argument(s) raise doubts

Coyne argues the truth behind evolution many different ways: Embryology, Vestiges, Fossils, the influence of different environments on similar creatures (geography of life),etc. Which of Coyne's arguments for evolution do you find most convincing? Which arguments raise doubts? Include in your response textual evidence, as well as, knowledge from outside the classroom.

Choosing a Mate

In the Chapter "How Sex Drives Evolution", Coyne describes Darwin as saying that females choose males based on "purely aesthetics". Coyne himself believes that female preferences are adaptive to types of males that help spread the female's genes. In your opinion, which is a more valid statement and why? Furthermore, consider the human species. Can you cite examples of how human females may choose their mates? Please relate to a biological theme.
To continue upon this topic, after consulting Campbell, is it selectively advantageous to have males exhibit elaborate ornamentation or perform rituals and have the female choose its mate? Or would a different system be more evolutionarily viable?

Genetic Drift vs. Natural Selection

EDITED PROMPT:
On page 122, Coyne paradoxically states, "genetic drift is not only powerless to create adaptations, but can actually overpower natural selection." Explain the process of genetic drift. Coyne mentions that genetic drift can cause features that don’t help or hurt the organisms. Then, what is the point of genetic drift? Distinguish between genetic drift and natural selection; in your response discuss randomness and lawfulness. Relate your response to a biological theme.

Convergent Evolution

On page 94, Coyne discusses the idea of convergent evolution, and briefly discusses how convergent evolution is related to common ancestry, speciation, and natural selection. Some examples that Coyne gives of convergent evolution are the white coloration of arctic animals and the similarities of cacti and euphorbs.

Give another example of convergent evolution, discussing what environmental factors and characteristics of lifestyles that could have led to the similar traits.
Also, further expand upon and discuss the relationships between the three portions of the evolutionary theory mentioned above with convergent evolution.

Significance of Biogeography

On page 88, Coyne discusses how biogeographical is such strong support for evolution that Creationists simply pretend that biogeographical evidence doesn't exist. Creationists' theory for the current distribution of species is that two of each species hopped on a ship for 6 weeks, and got off magically at different spots of the word. In contrast, Darwin proposed that specific species distribution occurred because species of plants and animals dispersed, evolved, and then land physically changed. Explain what aspects of this hypothesis are correct and not 100% accurate. What discoveries and developments of technologies have occurred since Darwin that would support his theory? How does this biogeographical evidence support evolution? Why is this evidence so powerful when compared to say, fossil evidence? In your answer, make sure to discuss both continental drift and molecular taxonomy and how they relate to this topic.

Human Dimorphism and Mating Systems

Most modern human cultures are monogamous, where one male mates with one female. In chapter 6, "How Sex Drives Evolution," Jerry Coyne explains that dimorphism, the difference in appearance between males and females, tends to point toward a more polygamous mating system.

Relate human dimorphism, or lack thereof, to our mating system. What are the evolutionary advantages to monogamy (or polygamy) in human society?

Is Race Genetic?

Jerry Coyne stated that “Most biologists stay as far away from [the biological question of race] as they can” (2009, p. 212). Yet, many distinguishing characteristics of races, such as skin color, are genetically inherited from parent to offspring. To what extent do you think the differences between the various races has a genetic and/or evolutionary basis, and to what extent do you think the differences are due to “ ‘gene-culture coevolution’ ” (Coyne, 2009, p. 215)?

The Continuity of Evolution

In the Chapter "What about now?" Mr. Coyne brings up how lactose intolerance has arisen in different human populations. He cites this trait as evidence of "gene-culture coevolution" (218). In other words, a cultural change influences the development of an evolutionary trait. In this case, the raising of cows (cultural change) produced the new evolutionary opportunity to adapt the lactose tolerance gene and obtain a new source of food. Can you think of other examples of gene culture coevolution in a human population? Consult outside sources for guidance. Also, how does the concept of gene-culture coevolution relate to the theme of evolution or the theme of continuity and change?
Furthermore, reflecting back to past units on gene mutations and its relation to evolution, would you say that we are still evolving in a useful way? In other words, are we still influenced by natural selection to adapt in a way that allows for the prolongation of the human species? Or has the proliferation of human technology/influence eliminated the need for natural selection?

Race to Evolve

As we all know, and as Coyne pointed out, "[natural] selection [is] extremely slow, altering populations over thousands or millions of years" (2009, p. 116). But, often times, populations are faced with great, immediate danger. For example, the European honey bees introduced to Japan are faced with attacks by the formidable Asian giant hornets (Coyne, 2009, p. 111). While Japanese honey bees, having coexisted for a long time with Asian giant hornets, are able to fend off Asian giant hornets, European honey bees, being an introduced species to Japan, are not. It is possible that adaptations protecting European honey bees against Asian giant hornets can arise within European honey bee populations and proliferate via natural selection. For European honey bees, the rise of such adaptations is a race against time, for Asian giant hornets can very easily wipe out the European honey bee population of Japan before such adaptations appear within the European honey bee population. To win this race, a population must be able to adapt and evolve quickly. What are some examples of species engaged in a race to evolve before they are obliterated? What are some examples of adaptations that speed up genetic drift?

Vestiges

In Chapter 3, Remnants: Vestiges, Embryos, and Bad Design, Mr. Coyne talks about the vestigial organs of organisms, and how these vestiges never really disappear. He also takes note that we have not yet been able to discover the reason for vestigial organs, and why they aren't simply bred out of a population. On page 62, in the second paragraph, he gives several possible reasons for vestiges, but what do you think? What are other reasons certain organisms never lose particular traits?

Gene Pools

Jerry Coyne points out that members of the same species have a common gene pool. Individuals of the same gene pool are able to “mate with each other and produce offspring that contain combinations of their genes” (172). Physical and genetic characteristics of DNA vary greatly across the diverse kingdoms of life; for example, our (humans’) linear DNA does not even have the same shape as the circular DNA found in bacteria. When the DNA of two individuals differ too greatly to combine and create fertile offspring, the two individuals can be deemed as members of different species. What are some other examples of physical or genetic differences in DNA among different species, and why might the differences prevent individuals from creating fertile offspring?

To Resist or Not to Resist

On page 131, Coyne cites resistance to penicillin as a prime example of natural selection. Penicillin was once very useful in curing infections caused by the bacterium Staphylococcus aureus; however, now, the effectiveness of penicillin has decreased significantly. Briefly explain how this demonstrates natural selection. Also, please relate to a biological theme. Furthermore, some food for thought: could this resistance actually come from the habituation of patients to penicillin as opposed to evolutionary adaptations of the bacterium itself - why or why not?

On pages 131-132, Coyne goes on to consider certain strains of bacteria/viruses that have not evolved resistance to vaccines/antibiotics. What causes certain strains to adapt and others to fail at adapting?

Finally, Coyne states that "when a population that encounters a stress that doesn't come from humans..., natural selection will often produce an adaptive response" (132). Evaluate the truth behind this statement. For instance, can you cite any other examples (besides Staphylococcus) where organisms have formulated an adaptive response to human-induced stress? Or, if you prefer, can you cite any organisms that have adaptive responses to nature-induced stress (salinity, pH...etc)? Be sure to consult Campbell and other sources for your answer.

Speciation Is...

On page 169, Coyne brings up the point that discrete clusters, or species, evolve in all organisms that reproduce sexually. Why are discrete and discontinuous clusters exhibited only in sexually reproductive organisms as opposed to asexually reproductive organisms? Note the significance of mutations, with regards to meiosis, mitosis and/or different types of asexual reproduction as we've previously learned in class. On pages 170-172, Coyne continues to describe the concept of species as a whole. While certain humans may have obviously different characteristics, they are part of the same species. On the other hand, certain Drosophila fruit flies are identical - down to the last microscopic detail - yet, they are different species. Clearly, species are not distinct based on "looks". According to Coyne, what distinguishes whether organisms are the same species or not? How does this relate to any theme in biology? And finally, why do you think Coyne puts such emphasis on how a species arises - in other words, what is the evolutionary significance of speciation?

Purpose to Mutation?

Mutations in the gene is essential to the creation of diversity of species and population. Jerry Coyne states on page page 128 that "Mutations are simply errors in DNA replication." Do you believe that mutations are simply errors? Could mutations occur on purpose in order to create a species that has a higher chance of survival or must all mutations be accidents/errors? Give support for your reasoning from the book/textbook/website.

The question of no "Unintelligent design" in evolution

On page 81, Coyne discusses bad design and how some features of an organism will work well, yet some will not. He gives the example of a flounder, which has a deformed skull, describing how it is "bad design."

Now, consider if organisms had no "unintelligent design." What if the flounder were designed more like a skate or stingray? What if humans had no residual lung volume with unused air? What if all structures in natures were able to efficiently correlate with their functions to create a intelligently designed organism?

Discuss an example of unintelligent design in an organism. Explain how this example is inefficient with respect to its function, and how it can be improved to serve this function. People who are responding to previous responses may want to try to focus on why this structure's function is important.

Genuine Evolutionary Change in Laboratories

On page 139, Jerry Coyne states that laboratories can make certain specimen undergo "genuine evolutionary change" because it provides all three requirements of evolution: variation,
heritability, and the differential survival and reproduction of variants. Jerry Coyne argues that this is better than artificial selection; what is your opinion on the idea these laboratory experiments demonstrate evolutionary change? If so, is it possible for humans to elicit certain mutations to occur in certain specimens; thereby, controlling evolution of these specimen? If not, what are the limits or errors that prevent these experiments from eliciting "genuine evolutionary change"? Give examples and an explanation stating your argument.

The Six Components of the Evolutionary Theory

Coyne lists and explains the six components making up the evolutionary theory from pages 3-13.
1. Evolution
2. Gradualism
3. Speciation
4. Common ancestry
5. Natural selection
6. Processes other than natural selection can cause evolutionary change
Some of these elements are very similar, and all six intertwine ideas and concepts with the others. Choose two or three of the elements to describe, distinguish between and compare. Also, describe how the elements you choose relate to each other. (For example; how are evolution and gradualism different? what do speciation and common ancestry have in common?)

Mimicry Through Coloration

On pg. 171, Coyne explains that there are 7 species of mosquitoes that all look very like except for slight microscopic differences. Each species has a distinct niche, but only one species, Anopheles gambiae carries malaria. As a result, it has been difficult for humans to fight malaria by targeting the mosquito carriers because the resemblance to the harmless mosquito species. Give another example of cryptic coloration. Why is cryptic coloration a selective advantage for these species? What type of mimicry is this? Furthermore, explain the differences between cryptic coloration and aposematic coloration. It will be helpful to cite Campbell or other outside sources in your answer.

No, really, what about us?

In chapter 8, "What About Us?" Coyne brings up the question of whether humans are actually de-evolving. On the one hand, the development of lactose-tolerance in pastoral populations is proof that human evolution has occurred within the last 3,000 to 8,000 years (Coyne 217). On the other hand, medical intervention has made it possible for "less fit" individuals, such as those with bad eyesight and bad teeth, to reproduce (Coyne 218). What do you think? Are humans still evolving, remaining the same, or de-evolving? Give evidence to support your answer. (Remember that the overall goal is merely to survive and reproduce, not necessarily live long.)

Island Adaptation

We read in Chapter 4, The Geography of Life, when introduced to volcanic or foreign islands, mainland species often do amazingly well. According to Mr. Coyne, what are the methods by which these species can arrive at these islands? How does the way the organism arrives at the island affect the success of the organism (see p. 104-109)? Is it possible that the organisms on those islands evolve the exact same way as their mainland ancestors, or that they eventually deviate from the original species? If so, for either staying the same or changing over time, how?

Evolutionary Limits on Health Conditions

Evolution is expected to result in organisms that are most fit to survive and reproduce. Does this mean that evolution does not affect what happens once organisms past the age of reproduction? For example, cancer is uncontrolled cell growth due to mutations in genes that regulate cell division as well as apoptosis. Because a succession of mutations in genes is necessary to result in cancer, cancer usually occurs later in life for humans. Dr. Harvey Lodish, a professor of biology at MIT, states in his textbook, Molecular Cell Biology, that "The occurrence of cancer after the age of reproduction may be one reason that evolutionary restraints have not done more to cancer."

Is this a likely explanation for the reason that evolutionary limits have not done more to reduce the occurrence of cancer, a potentially deadly condition? Does evolution only impact traits of organisms that will have effects before and during the age of reproduction? Are there any other common conditions generally occurring after the age of reproduction that show evidence of this theory? Is there good evidence that disproves the theory? How, if at all, does this theory relate to any themes of biology other than evolution?

Please provide a thorough, informed, well-organized response supported by specific examples and evidence that addresses the multiple aspects of the prompt.

The Fossil Record

It is clear that fossils are great evidence of evolution. Coyne not only devotes an entire chapter to them, but also states that “within these petrified remains lies the history of life”(7). By following the fossil records, it is easy to see how a specific organism changed slowly over time into an organism we see today. By watching the species change, it is easy to see that the final organism clearly evolved and was not created and placed onto the earth.

That being said, imagine you are a scientist with the fossil records conveniently in hand. Your job is to explain to someone why evolution is true quickly. Because time is money, you can only pick one species’ line of fossils to prove to the ignorant one that evolution is true. Which line of fossils would you choose? Which species’ ancestry most completely proves evolution? Explain using how complete that specific line of fossils is (are there missing links?), how much change that species underwent, and if we can see evidence of that species’ relatives on that organism today(bone structure, teeth, ect.).

Evolution and the most fit organism

Evolution has brought a huge variety of species into this world. It has also given organisms traits that can make it more fit or out-compete others. For example, Gnathostomes, along the evolutionary line, developed jaws that allowed these fish to hunt prey ferociously, out-competing other primitive fish.

Now, explain why a particular organism is arguably the most fit life form on Earth. Has the organism been around for millennium, and is still living today? What is the secret to its success? Has the organism appeared within the last millennium, yet has the potential to out-compete other species? Be sure to cite evidence from Coyne's book that supports your evidence on why your organism is the most fit, as well as cite evidence from outside sources.

Please do not argue that humans are the most fit life form on Earth. It's true that intelligence can go so far, but expand your horizons and look at other species.

Science as a Process - Thematic appearance in the book

We have been told to not use this theme for our JAEs, so I just want to bring this theme into light for this blogging project.

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Coyne describes many ways how there is evidence of evolution. Using one piece of evidence from the book, describe how that piece of evidence links with the "science as a process" theme. Be sure to define what the theme means and make connections to sources other than Coyne's book.

Next, compare and contrast with other responses similarities and differences on how their evidence connect to the theme, and what makes your evidence connect to the theme.

Intermediate Stages

On page 39, Coyne mentions that the intermediate stages of the evolution of flight provided a selective advantage to its possessors by allowing them to glide or jump. Give another example of an intermediate stage and its possible selective advantages. Keep in mind the relationship between structure and function (Campbell 7), as well as the examples of derived traits on the chordate phylogeny tree (Campbell 699).

Asexual vs. Sexual Reproduction

In the chapter entitled “How Sex Drives Evolution,” Coyne discusses the evolution of sexual reproduction. On pg. 155-156, Coyne begins to explain the evolutionary advantages of both asexual and sexual reproduction. Expand on Coyne’s list of reasons one type of reproduction is more advantageous than the other using outside knowledge from class. Furthermore, when do organisms that can reproduce in both manners reproduce asexually? When do they reproduce sexually? What does this demonstrate about the two methods of reproduction?

Facilitated Evolution

As humans expand over the Earth's surface, our methods of making life easier for ourselves grow in number and complexity. Not least in these is breeding: selective breeding and domestication are both examples of humans determining the path of evolution, picking and choosing certain traits that are desirable to us, like in the Dog movie we watched in class, from wolf to man's best friend. Mr. Coyne also mentions this in his book, in Chapter 5, the Engine of Evolution, the section Animal and Plant Breeding (p. 125). But to what degree do we as humans have control over evolution? Are there factors we can't control in an organism's evolution? How does our tampering with natural selection help us, and how does our selection of traits help the organism? And now, with the genetic information we have, should we mess around with evolution?

Predator-prey interactions and evolution

To what extent have predator-prey interactions facilitated evolution? Be able to give an example of an interaction in real life.

Coyne's novel and the eight main themes of biology

Argue which one of the eight themes is the most reoccurring theme in the book, not including evolution. Be sure to be able to define what the theme means as well as refute why another theme that appears in the book should not be considered as the most reoccurring theme.

The evolution of land mammals to aqautic mammals

In Chapter 2, Coyne explains that evolutionists believe that whales, aquatic mammals, descended from terrestrial animals. Many creationists believe that whales couldn't have descended from terrestrial animals because animals evolved from aquatic animals to terrestrial animals. Having animals evolve from terrestrial animals to aquatic animals doesn't follow the idea of natural selection and adaptions used to back up the idea for evolution. What evidence do scientists and evolutionists have that whales could have descended from terrestrial animals as explained in the book? How is evolving from terrestrial animals to aquatic animals a selective advantage in some cases like in the case for the whale? What other examples of animals have evolved into something they once had and how is that an example of natural selection. What environmental conditions could have changed to cause the animals to change genetic information? Use outside sources for the last question including your Campbell book.

Island Biography

In Chapter 4 "Geography of Life," Coyne explains how the species present on islands are direct evidence that evolution has occurred. Coyne describes how evolution has caused the unique species make up of islands to form. Now, connect Coyne's observations to the theory of island biodiversity studied in the ecology unit. Why do certain types of islands seem to consistently host more species than others? It maybe helpful to discuss the size of the island, distance of island from mainland, extinction rates and migration rates in your explanation. Furthermore, discuss a current problem that threatens island biodiversity today, the importance of island biodiversity to our society and/or a possible solution to help save island biodiversity.

Vestigial Features or Atavisms?

Starting on page 55, Coyne begins to discuss the "Remnants" of evolution - mainly vestigial features and atavisms. Vestigial features are features of animals that remain from ancestors. Vestigial features have either lost all function or have a new and, usually, reduced function. Atavisms are traits in animals from historical ancestors that are occasionally reawakened through odd gene expression; for example, some humans are born with an atavistic tail (Fig. 14 p63). Both are examples of imperfections that both support the theory of evolution while disproving the theory of creationism. In your opinion, is either observation (vestigial features or atavistic traits) more compelling evidence for evolution than the other one is, or are do both observations support evolution equally?

Different Mating Systems (in reference to sexual dimorphisms)

In Chapter 6 “How Sex Drives Evolution” (more specifically on pgs. 144-146 and 159-161), Coyne discusses sexual dimorphisms. Coyne explains the selective advantage more decorated males have because they are more likely to find a mate (and thus reproduce and pass on their genes). Coyne later acknowledges that not all species follow this pattern of more decorated males. Explain the correlation between polyandry, polygamy and monogamy and the physical appearance of the males and females. (This part should be easily found in Coyne’s book, as well as Campbell).

Furthermore (now using outside knowledge!), explain how the way of polygyny, polyandry or monogamy is a selective advantage for different species. (For example, why is it advantageous for some bird species to be monogamous, it is advantageous for other bird species to be polygamous?) In your explanation it may be helpful to include discussion of survival rates/curves, competition for mates, parental investment (both maternal and paternal), r/K selection, and/or a specific example of a species.

Longevity of Life or Swiftness of Reproduction?

In Chapter 1, Jerry Coyne discusses how Ginkgo Trees and horseshoe crabs have not evolved much over the millions of years that it has existed. Compared to small bacteria that can reproduce after existing for only several minutes, why is it that ginkgo trees and horseshoe crabs have not been out-competed or eliminated? Ginkgo trees can live for hundreds and sometimes even thousands of years, does this mean that those that can survive longer are a "fitter" form? or does a smaller organism that does not live long but can reproduce at a much quicker rate, therefore, have a greater chance of a "fitter" mutation to occur be more preferable as time moves forward? or is there some compromise in between that produces the "ideal" organsim?