Biology Evolution (Pt. 1) Flashcards
(24 cards)
Explain how a population that has great genetic diversity is able to respond to changes in environment better than a population with little genetic diversity
A population with high genetic diversity is better equipped to respond to environmental changes than a population with low genetic diversity because it possesses a wider range of traits. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. This allows the population to adapt more effectively to new challenges and environments, increasing its chances of survival and reproduction.
Distinguish between variation and adaptation
Variation refers to the differences observed between individuals within the same species, which can be caused by both genetic and environmental factors, while adaptation describes the traits that increase an organism’s ability to survive and reproduce in its environment, which is a result of natural selection acting on variation
What is an adaptation, with an example
An adaptation is a characteristic, typically structural, behavioral, or physiological, (determined by a gene) that helps an organism survive and reproduce in a particular environment
For example, camouflage is an example of an adaptation that allows animals to blend into their surroundings for protection or hunting, such as the Arctic fox, whose brown/gray fur in the summer changes to white fur in the winter for both protection and hunting, exhibiting seasonal camouflage.
What is a variation, with an example
Differences between individuals, which may be structural, behavioral, or physiological. Sources of variation include: (1) Individuals inherit different alleles from their parents due to crossing over, (2) random mutations (changes in DNA that are random). Furthermore, not all variations become adaptations. Environmental conditions determine whether a variation in an individual has a positive or negative effect, or no effect at all on an organism’s ability to survive and reproduce, and the variation becomes an adaptation when individuals with the helpful variation survive and pass this variation on to their offspring.
The shift in wing color in peppered moths during the Industrial Revolution, where darker moths became more common in polluted areas, is a classic example of natural selection driven by environmental variation.
Explain, using an example, how alleles may be an advantage in one environmental condition, but a disadvantage in another
Alleles can be advantageous in one environment and disadvantageous in another due to the changing selective pressures of natural selection. An allele that confers a specific trait, like resistance to a particular disease, may be beneficial in a habitat where that disease is prevalent but may be not beneficial, or even be detrimental, in an environment where it is not.
For example, before the Industrial Revolution, light-colored peppered moths were better camouflaged against light-colored tree bark and were at an advantage. As industrialization polluted the air, making tree bark darker, the dark-colored peppered moths had an advantage in these new conditions because they were better camouflaged against the dark tree bark and therefore more likely to survive and reproduce.
Describe and give an example of a rapidly reproducing species and how a beneficial mutation will spread through the population
A new allele that resulted from a random mutation that was previously insignificant in a population may provide selective advantage to some individuals when the environment changes, especially when that population reproduces rapidly.
E.g. antibiotics and drug resistant bacteria: some bacteria are resistant to antibiotics because of a new allele from a random genetic variation. These resistant individuals can survive to pass on these changes to their offspring and it can then spread rapidly since reproduction is so quick. This means antibiotics only work in the short term, because they become less and less effective.
What is a physiological adaptation + an example
Internal changes (processes or functions in that body that change) that help an organism survive and reproduce successfully in a particular environment
For example, hibernation allows Richardson’s ground squirrel to survive in climates with harsh winters. All body processes slow down, including slower breathing, burning fat more slowly, and mental function slowing down, to preserve energy.
What is a structural adaptation + an example
A physical characteristic that an organism has that helps it survive and reproduce successfully in a particular environment
For example, the needle-sharp talons and excellent vision of an owl are structural adaptations that make owls excellent predators in their environment.
What is a behavioral adaptation + an example
Something that an organism does that helps it survive and reproduce successfully in a particular environment
For example, many animals, like birds and salmon, move from one location to another (a process called migration), often in response to seasonal changes or resource availability. This movement helps them access food or avoid harsh environmental conditions
KEY POINT:
Populations change, NOT individuals.
Explain how evolution, as it was conceived of by Jean-Baptiste Lamarck, differs from Natural Selection
Darwin’s theory of Natural Selection and Jean-Baptiste Lamarck’s theory of evolution both recognized evolution as a process of change over time, however Lamarck believed that when organisms adapted to their environments by acquiring traits, these changes occurred in their lifetimes. He also believed that with disuse, organisms would lose parts because they did not need them (like the missing eyes and digestive system of a tapeworm), and with perfection with use and need, the constant use of an organ would lead that organ to increase in size (like the large ears of a night-flying bat), and that organisms would then transmit these acquired characteristics to the next generation. Darwin, on the other hand, emphasized natural selection, where individuals with advantageous traits survive and reproduce more successfully, leading to changes in species over time.
Explain the process of natural selection proposed by Darwin and Wallace using all of the 6 following points:
a. Overproduction of offspring
b. variation among individuals
c. limited resources
d. competition
e. differential reproductive success (“fitness”)
f. adaptation
Natural selection as proposed by Darwin and Wallace: organisms typically produce more offspring than the environment can support, ensuring that at least some will reach adulthood and reproduce. The environment has a finite amount of resources like food, shelter, and mates, which can only support a limited population size. Within a population, individuals exhibit genetic variations in their traits, which can be inherited from their parents. Due to limited resources, individuals within a population compete with each other to access them, leading to survival of the fittest, which is when individuals with advantageous traits (genetic variations) that better enable them to compete and survive are more likely to reproduce and pass on their advantageous genes to their offspring. Over time, the population adapts to its environment with these successful traits (adaptations) that become more prevalent in the population because of natural selection.
Explain (using the 6 points for natural selection) how the following demonstrate Darwinian selection:
a. peppered moths
Peppered moths produce more offspring than can survive, and the environment has a limited supply of resources, like food and shelter, creating competition between individuals for these resources. Within the population, some moths are light-colored, while others are dark-colored, this variation is crucial for natural selection to act upon. Due to limited resources, the moths with the most advantageous coloration for their environment will have a better chance of surviving and reproducing. In the pre-industrial era, light-colored moths were better camouflaged against the light-colored tree bark, giving them a survival advantage. However, during the Industrial Revolution, the darker-colored moths, who blended in better with the soot-stained trees of the Industrial Revolution and were harder to spot by predators, had a higher survival rate and produced more offspring than the lighter-colored moths. The proportion of dark-colored moths in the population increased during the Industrial revolution because their coloration was an adaptation to the changing environment, allowing them to better avoid predators.
Explain (using the 6 points for natural selection) how the following demonstrate Darwinian selection:
b. bacteria
Bacteria produce a large number of offspring, which increases the chance that some will inherit beneficial resistance genes. Within a bacterial population, there are genetic variations, some of which might confer resistance to a specific antibiotic. When exposed to an antibiotic, only the bacteria with resistance genes can survive and access resources like nutrients. Bacteria compete for these limited resources, leading to a selective pressure where resistant bacteria outcompete susceptible ones. Resistant bacteria, due to their ability to survive the antibiotic environment, have a higher chance of reproducing and passing on their resistance genes to their offspring, thus increasing their fitness in the population. Over time, the proportion of antibiotic-resistant bacteria in the population increased because this resistance was an adaptation to the changing environment.
Explain how the following specifically support some aspect of evolutionary theory with an example:
a. The fossil record (in general and transition fossils)
The fossil record, and particularly transitional fossils, strongly support the theory of evolution by demonstrating how species have changed over time and how they are related to each other. Fossils provide a chronological history of life, showing the existence of extinct species and how they transitioned into more modern forms. Transitional fossils, in particular, showcase intermediate traits between ancestral and descendant species, highlighting the gradual nature of evolution.
EXAMPLES:
Fossil evidence documents the transition of whales from land-dwelling animals to marine mammals.
The fossil record, particularly the discovery of Archaeopteryx, demonstrates the transition from dinosaurs to birds. Archaeopteryx exhibits features of both dinosaurs (like jaws with teeth) and birds (like feathers and wings).
Explain how the following specifically support some aspect of evolutionary theory with an example:
b. Homologous anatomical structures
Homologous anatomical structures support the evolutionary theory by providing strong evidence for common ancestry and divergent evolution. These structures, similar in underlying form but modified for different functions in different species, indicate a shared evolutionary history. Their existence suggests that species evolved from a common ancestor, with those structures being modified over time through natural selection to adapt to different environments.
EXAMPLE:
An example of homologous structures are the limbs of humans, cats, whales, and bats. Regardless of whether it is an arm, leg, flipper or wing, these structures are built upon the same bone structure
Explain how the following specifically support some aspect of evolutionary theory with an example:
c. Analogous anatomical structures (what theory does this support)
Analogous anatomical structures, while appearing similar and serving similar functions, do not support the idea of shared ancestry. Instead, they are evidence of convergent evolution, where different organisms evolve similar traits independently in response to similar environmental pressures or ecological niches. This theory suggests that organisms, even if not closely related, can develop analogous features as a result of natural selection favoring those traits in specific environments.
EXAMPLE:
Dolphin and Shark Flippers/Fins: Both use these structures for swimming, but their bone structures and evolutionary origins are vastly different. Dolphins are mammals with flippers homologous to human arms, while sharks are fish with fins derived from scales
Explain how the following specifically support some aspect of evolutionary theory with an example:
d. Vestigial anatomical structures
Vestigial anatomical structures, like the human appendix or the pelvic bones in whales, support the theory of evolution by demonstrating that organisms have retained structures from their ancestors that are no longer essential for their survival or reproduction. These structures are homologous to functional structures in related species, providing evidence of shared ancestry and the gradual modification of traits over time.
EXAMPLE:
Whales, despite being marine mammals, still have remnants of pelvic bones (pelvis) and femur. These bones are vestigial, indicating their evolutionary ancestry from land-dwelling mammals.
Explain how the following specifically support some aspect of evolutionary theory with an example:
e. Molecular Homology (DNA and proteins)
Molecular homology, the shared similarities in DNA sequences and protein structures between species, provides strong evidence for evolution by descent with modification. It suggests that species share a common ancestor, and the degree of similarity reflects the recency of their shared ancestry. This means that more closely related species will have more similar DNA and protein sequences than distantly related species.
EXAMPLE:
E.g. The homologous gene for insulin in humans, cows, chickens, and chimpanzees is inherited from a common ancestor.
Explain how the following specifically support some aspect of evolutionary theory with an example:
f. Endosymbiotic Theory of Eukaryotic cell evolution
The Endosymbiotic Theory of Eukaryotic cell evolution supports evolutionary theory by demonstrating that evolution can occur through symbiosis, rather than solely through natural selection. Specifically, it shows how eukaryotic cells could have evolved from simpler prokaryotic cells through a symbiotic relationship where one cell lived inside the other. The theory also highlights how symbiotic relationships can drive evolutionary changes, such as in the case of endosymbiosis, where the host cell and the endosymbiont (the engulfed cell) develop a mutualistic relationship, where both benefit from the association. Over time, the endosymbiont can lose its independent life and become an integral part of the host cell, contributing to its function. This also provides a plausible explanation for the origin of complex organelles like mitochondria and chloroplasts, which are thought to have evolved from once-free-living prokaryotes.
Explain how the following specifically support some aspect of evolutionary theory with an example:
g. Biogeography (can you explain the observation made by the “Wallace line”?)
The “Wallace Line,” a biogeographical boundary separating the fauna of Asia and Australia in the Malay Archipelago, supports the theory of evolution by highlighting the role of geographical isolation and speciation. It demonstrates how distinct species can evolve in different regions, even when in close proximity, due to barriers like deep sea trenches, leading to unique biodiversity on either side of the line. West of the line, species like tigers, elephants, and orangutans dominate, while east of the line, species like marsupials, monotremes, and cockatoos flourish.
Explain the following statement:
· Phylogenetic trees are constantly being revised, based on evidence
Phylogenetic trees are being constantly revised as in they’re constantly finding new evidence suggesting that two organisms may be closer or further apart than previously thought
What do nodes represent on phylogenetic trees? What about hatch marks? What are clades?
Nodes:
- Common ancestor
Hatch marks:
- Shared traits with all the species after the hatch mark
Clade:
- A clade represents a group of organisms that share a common ancestor, including all of its descendants
Define mimicry, with an example
A structural adaptation in which a harmless species resembles a harmful species in coloration or structure.
EXAMPLES:
1. The viceroy butterfly is palatable to predators, but the monarch butterfly is not. The viceroy is similar in structure & coloration to the monarch. By catching and eating monarch butterflies, predators learn to avoid both butterflies because the coloration & structure warns them that this prey tasts bad.
2. (Another example) coral snake and king snake.
