Evolution and Natural Selection Overview

Natural selection favors bacteria with mutations that make them resistant to antibiotics. These resistant bacteria survive and reproduce, passing on their resistance genes to their offspring. Over time, the frequency of resistance genes in the population increases, leading to the evolution of antibiotic resistance.

Multidrug-resistant organisms are bacteria that have evolved resistance to multiple antibiotics. They are a serious concern because they are difficult to treat, making infections caused by them more challenging and potentially fatal.

Artificial selection is a process where humans intentionally breed organisms with desired traits. This process can lead to significant changes in the genetic makeup of a population over time. For example, farmers have selectively bred corn for larger kernels and higher yields.

<p>Artificial selection demonstrates that evolution occurs because it shows that significant changes in a population's traits can be achieved through selective breeding over generations. This process mirrors natural selection, where environmental pressures favor certain traits, leading to evolutionary change.</p> Signup and view all the answers

<p>Climate change can alter environmental conditions, creating new selection pressures that favor organisms with traits that enable them to survive and reproduce in the changing environment. This can lead to evolutionary change, as populations adapt to the new conditions.</p> Signup and view all the answers

<p>Increased chance of survival of some offspring due to variation, and increasing the likelihood of at least some offspring finding a suitable mate.</p> Signup and view all the answers

<p>Resources become limited and competition increases as population size increases.</p> Signup and view all the answers

<p>The maximum number of individuals that the environment can support.</p> Signup and view all the answers

<p>Direct competition occurs when organisms fight directly for resources, while indirect competition occurs when organisms use up resources, leaving less for others.</p> Signup and view all the answers

<p>Selection pressures are factors that influence the survival and reproduction of organisms. An example of a biotic selection pressure is predation.</p> Signup and view all the answers

<p>They are density-independent, meaning their effect is not related to population density.</p> Signup and view all the answers

<p>Intersexual selection (mate choice) and intrasexual selection (competition for mates).</p> Signup and view all the answers

<p>The extravagant plumage of male peacocks may be a result of intersexual selection, as females prefer males with more elaborate tail feathers.</p> Signup and view all the answers

<p>Natural selection is the process where individuals with certain traits are more likely to survive and reproduce in a given environment. This happens because variations exist within a population, and these variations can affect survival and reproduction. For example, a variation might provide camouflage, making an individual less vulnerable to predators. This variation, if heritable, is more likely to be passed on to the next generation. Over time, individuals with this advantageous variation will become more numerous in the population, leading to an adaptation of the population to the environment.</p> Signup and view all the answers

<p>Overusing antibiotics creates an environment where only the most resistant bacteria can survive. This happens because antibiotics kill off susceptible bacteria, leaving the resistant bacteria to reproduce. This resistance can be genetic and thus passed on to future generations. As a result, the antibiotic loses its effectiveness, and infections become harder to treat.</p> Signup and view all the answers

<p>A pathogen is a disease-causing organism. Examples include bacteria like <em>Salmonella</em> and viruses like influenza (flu). Antibiotics are chemicals that block specific processes in bacteria, stopping them from multiplying and causing harm. Examples include penicillin and amoxicillin. Antibiotics do not work against viral infections.</p> Signup and view all the answers

<p>Antibiotics target specific cellular structures or metabolic processes that are only found in bacteria, such as cell walls or protein synthesis. Viruses lack these structures or processes and instead rely on the host's cells to reproduce, making them impervious to antibiotics.</p> Signup and view all the answers

<p>Saprotrophic fungi are organisms that obtain nutrients by decomposing dead organic matter. They naturally produce antibiotics as a way to compete with other microbes, such as bacteria, for resources. By killing off competing bacteria, the fungi have greater access to the available nutrients and can grow more successfully.</p> Signup and view all the answers

<p>Phenotypic mismatches occur when an organism's traits, developed under previous environmental conditions, become less suited to the new, changing environment due to climate change.</p> Signup and view all the answers

<p>Disrupted phenology refers to changes in the timing of biological events, such as migration, breeding, or flowering, due to climate change. These disruptions can lead to mismatches between organisms and their resources, impacting their survival and reproduction.</p> Signup and view all the answers

<p>A selection pressure favors certain traits that increase survival and reproduction. Individuals with those traits are more likely to pass them on, gradually increasing the frequency of the advantageous trait in the population.</p> Signup and view all the answers

<p>The two main types of selection pressures Endler studied were natural selection, caused by predators, and sexual selection, driven by female preference for certain male traits.</p> Signup and view all the answers

<p>In populations with predators, male guppies tended to have fewer spots, likely due to the selective pressure against flashy males that were easier for predators to spot.</p> Signup and view all the answers

<p>Female guppies prefer males with more spots, which drove the evolution of flashier males in populations with fewer predators. This reflects the role of sexual selection in shaping guppy coloration.</p> Signup and view all the answers

<p>Endler's research demonstrated that guppy coloration is influenced by both natural and sexual selection. The relative strength of these pressures determines the optimal coloration strategy for male guppies.</p> Signup and view all the answers

<p>Models are used to simplify complex systems and make predictions about how they will behave under different conditions.</p> Signup and view all the answers

<p>Heritable characteristics are passed down from parents to offspring, meaning they are encoded in the genes. Natural selection acts on the traits that are expressed in individuals, influencing their survival and reproduction. Since only heritable traits are passed on, natural selection can only favor or disfavor these characteristics, ultimately leading to evolutionary change.</p> Signup and view all the answers

<p>If all individuals within a species were identical, there would be no differences in traits for natural selection to act upon. Variation allows some individuals to be better suited to their environment, increasing their chances of survival and reproduction, while others are less adapted and may have lower survival or reproductive rates. This differential survival and reproduction based on variations in traits is essential for natural selection to occur.</p> Signup and view all the answers

<p>Mutations are the original source of new alleles, introducing completely novel genetic variation into a population. Sexual reproduction, on the other hand, shuffles existing alleles through recombination and independent assortment, creating new combinations of genes and therefore variation. While mutations directly introduce new alleles, sexual reproduction reshuffles and recombines existing alleles, increasing genetic diversity.</p> Signup and view all the answers

<p>Consider a population of rabbits. Rabbits are known to reproduce quickly and have multiple offspring per litter. If all offspring survive and reproduce at the same rate, the population would grow exponentially. However, due to limited resources like food and shelter, the environment can only support a certain number of rabbits. This overproduction of offspring leads to competition for resources, ensuring only the fittest survive and reproduce.</p> Signup and view all the answers

<p>Overproduction leads to competition for resources because more offspring are produced than the environment can sustainably support. This competition can be direct, such as fighting over food, or indirect, like using resources faster than others, leading to shortages. Individuals with traits that allow them to outcompete others for these limited resources are more likely to survive and reproduce, driving natural selection.</p> Signup and view all the answers

<p>Overproduction of offspring increases the chances that some individuals will survive to reproduce, ensuring the continuation of the species even in challenging environments. Additionally, this overproduction creates a wider pool of genetic variation for natural selection to act upon, increasing the species' ability to adapt to environmental changes.</p> Signup and view all the answers

<p>Direct competition involves individuals directly interacting and fighting for resources. This might be observed in animals fighting over territory or food. Indirect competition occurs when individuals use resources at different rates, leading to depletion for others. For example, if two species of insects consume the same plant, the species that consumes it faster would indirectly outcompete the other.</p> Signup and view all the answers

<p>Temperature is an abiotic selective pressure. Organisms living in extremely cold environments may develop adaptations like thicker fur or insulation to survive. Those with better insulation would be more likely to survive the cold, reproduce, and pass on their adaptations, leading to evolution in the population.</p> Signup and view all the answers

<p>Natural selection favors bacteria with mutations that provide resistance to antibiotics. When an antibiotic is introduced to a population of bacteria, those with the resistant genes are more likely to survive and reproduce, passing on their resistance to their offspring. Over time, the frequency of resistant bacteria in the population increases, leading to the development of antibiotic resistance.</p> Signup and view all the answers

<p>The two major mechanisms of sexual selection are intrasexual selection and intersexual selection. Intrasexual selection involves competition between members of the same sex for access to mates, often leading to the evolution of traits that enhance fighting ability or dominance displays. Intersexual selection involves mate choice, where individuals of one sex choose mates based on specific traits, leading to the evolution of features that attract potential mates.</p> Signup and view all the answers

<p>Adaptation refers to a trait or characteristic that helps an organism survive and reproduce in its environment. Fitness, on the other hand, is a measure of an organism's reproductive success, meaning its ability to contribute genes to future generations. A more adapted organism typically has higher fitness.</p> Signup and view all the answers

<p>Climate change can alter the environment in various ways, such as changes in temperature, precipitation, and available resources. These changes can create new selective pressures, favoring organisms with traits that allow them to cope with the altered environment. Individuals lacking these traits may have reduced survival or reproductive rates, leading to changes in allele frequencies within the population.</p> Signup and view all the answers

<p>The evolution of multidrug antibiotic resistance in bacteria poses a serious threat to human health. Infections caused by these bacteria are harder to treat, potentially leading to longer hospital stays, higher treatment costs, and increased morbidity and mortality. This makes treating infections more challenging and can lead to the reemergence of diseases previously considered controllable.</p> Signup and view all the answers

<p>Selective breeding involves humans deliberately choosing individuals with desired traits to reproduce, effectively manipulating the gene pool of a population. By continually selecting for these traits over generations, breeders can rapidly increase their frequency in subsequent generations, leading to noticeable changes in the population's characteristics within a relatively short time.</p> Signup and view all the answers

<p>An example of artificial selection in domestic animals is the selective breeding of dogs. Humans have selected for various traits in dogs, resulting in a wide range of breeds with distinct characteristics such as size, coat type, temperament, and behavior. For example, the dachshund was bred for its short legs and long body, making it effective at hunting badgers, while the Great Dane was bred for its size and muscular build, making it a formidable guard dog.</p> Signup and view all the answers

<p>Antibiotics target specific biochemical processes that occur in bacteria but not in eukaryotes, including humans. Viruses, on the other hand, rely on the host cell's machinery for replication. Antibiotics cannot interfere with these processes, meaning they have no effect on viral infections. Therefore, antibiotics are ineffective against viruses.</p> Signup and view all the answers

Change in heritable characteristics of a population over time.

Mechanism by which individuals with favorable traits survive and reproduce.

Traits that can be passed down from parents to offspring.

Change in DNA sequence that can introduce new alleles.

Species produce more young than the environment can support.

Maximum population size an environment can sustain.

Environmental factors that influence survival and reproduction.

Includes mutation, meiosis, and sexual reproduction.

A measure of an individual's ability to survive and reproduce in its environment.

Chemicals that inhibit bacterial processes but not eukaryotic cells.

Organisms that obtain nutrients by decomposing organic matter.

The evolution of bacteria that are no longer affected by antibiotics.

Resistant bacteria survive and reproduce due to selective pressure from antibiotics.

Bacteria that have developed resistance to multiple antibiotics.

Intentional breeding by humans to select traits in plants or animals.

Changes in climate create new challenges affecting species survival.

When an organism's traits do not fit its environment due to climate change.

Changes in the timing of life cycle events in organisms due to environmental changes.

The varying rates of survival among individuals due to specific traits in response to selection pressures.

Change in the prevalence of traits over generations due to selection pressures.

Differences in coloration among individuals, often affected by predation and mate preferences.

Using simplified representations to understand complex phenomena.

No model can account for every detail; they simplify complex realities.

A type of natural selection where individuals with certain traits are more likely to reproduce based on mate choice.

A trait that increases an individual's fitness in a specific environment.

The effects of changing climate on species adaptation and evolution.

The selective pressures that determine coloration traits in guppies based on their habitat.

The process by which humans breed plants and animals for particular genetic traits.

A rapid increase in population size under ideal conditions.

Struggle among organisms for limited resources.

Factors that influence reproductive success in a population.

Biotic are living factors; abiotic are non-living environmental factors.

Direct is face-to-face combat for mates; indirect is competing without direct conflict.