Advantageous Traits
What do we call a characteristic that increases and individuals chance of surviving and reproducing?
An advantageous trait (also called a beneficial trait or adaptation that increases fitness).
Name two nonliving (abiotic) factors in an environment that can affect organisms.
Temperature, water availability, sunlight, soil type, pH, salinity, and oxygen level.
What term describes all the individuals of one species living in the same area at the same time?
What is an adaptation?
An adaptation is a heritable trait that increases an organism's ability to survive and reproduce in a particular environment.
State, in one sentence, what natural selection is.
Natural selection is the process by which individuals with heritable traits that increase their survival and reproduction become more common in a population over generations
Give one example of an advantageous trait for a rabbit living in a snowy environment.
White fur for camouflage in snow (reduces detection by predators), thicker fur for warmth, fat stores for energy.
How can a sudden change in the environment (like a volcanic eruption) affect which traits are advantageous?
A sudden environmental change can alter selective pressures (e.g., ash covering plants reduces visibility or food supply). Traits that aided survival before may no longer help, while different traits (e.g., tolerance to ash, ability to find new food) become advantageous. This can shift which alleles increase in frequency.
How can limited resources affect population size?
Limited food, water, or shelter increases competition, which can reduce survival and reproduction rates, causing population size to decrease or stabilize at carrying capacity. It may also increase mortality or cause migration.
Define genetic variation.
Genetic variation is the differences in DNA sequences or alleles among individuals in a population.
What trait helps a duck survive
Webbed feet, helps a duck swim faster and escape predators.
Explain why an advantageous trait might become more common in a population over several generations
Individuals with the advantageous trait have higher survival and/or reproductive success. They leave more offspring that inherit the trait, so the trait's allele frequency increases in the population over generations (natural selection).
Describe how climate (temperature and precipitation) can influence which species live in an area.
Climate determines available habitats and resources. Species adapted to certain temperature and moisture ranges will thrive there; others cannot survive or reproduce. Over time, only species with traits suited to local climate persist, shaping the community composition.
Describe how competition within a population can influence which individuals reproduce most.
Individuals better at obtaining resources (stronger, faster, better camouflaged, more efficient foragers) are more likely to survive and reproduce. This means traits that improve competitive ability are selected for because those individuals contribute more offspring.
Distinguish between a structural adaptation and a behavioral adaptation with one example of each.
Structural adaptation: a physical feature (thick fur, long beak).
Behavioral adaptation: an action or pattern of activity (migration, nocturnal feeding).
Example pair: webbed feet (structural) vs. flocking behavior (behavioral).
Define "trait"
A trait is a specific characteristic or feature of an organism that can be observed or measured.
Describe how an advantageous trait differs from a neutral trait and a disadvantageous trait.
An advantageous trait increases an individual’s fitness (higher chance to survive and reproduce). A neutral trait has little or no effect on fitness (no advantage or disadvantage). A disadvantageous trait decreases fitness (reduces survival or reproduction).
Explain how human changes to the environment can alter natural selection in a local population.
Human actions (deforestation, pollution, urbanization, introducing new species, climate change) change habitats and selective pressures. They can favor traits like pollution tolerance, nocturnal behavior, or resistance to pesticides, altering allele frequencies and population structure.
Explain how a population bottleneck might change genetic diversity in a population.
A bottleneck (sharp reduction in population size) randomly removes many individuals and their alleles, reducing genetic diversity. Remaining population may have different allele frequencies due to chance (genetic drift), which can limit adaptive potential and increase inbreeding.
Explain why an adaptation that is beneficial in one environment might be harmful in another.
Adaptations are context-dependent. A trait that increases fitness under one set of environmental conditions may be maladaptive under different conditions (e.g., thick fur is beneficial in cold climates but can cause overheating in hot climates).
What is the common definition of a species used in many science classes
A species is a group of organisms that can interbreed in nature and produce fertile offspring.
A population of beetles lives on dark and light bark. Scientists observe dark beetles increase in number while light beetles decrease. Explain, using the phrase "advantageous trait," what likely happened.
Dark coloration was an advantageous trait on dark bark because it provided better camouflage from predators. Dark beetles survived and reproduced more often than light beetles, increasing the frequency of alleles for dark coloration.
Give a specific example of an environmental pressure that could cause directional selection.
Example: Gradual warming climate causes birds with longer beaks (able to access deeper nectar as flowers change shape) to have higher fitness.
Using an example, explain how population size and genetic diversity together affect a population’s ability to adapt to a new disease.
Large populations with high genetic diversity are more likely to have individuals with resistance alleles; these survivors can reproduce and spread resistance, enabling adaptation.
Small or low-diversity populations might lack resistant variants; disease can cause severe declines or extinction because there’s limited raw material for selection.
Describe how fossil evidence or comparative anatomy can show that a species has adapted over time.
Fossils reveal transitional forms and changes in morphology across time, showing gradual modifications consistent with adaptation (e.g., whale ancestors with leg bones). Comparative anatomy (homologous structures) shows related species share modified versions of the same structures, indicating descent with modification and adaptations to different niches.
How does natural selection differ from artificial selection? Provide one clear difference.
Natural selection is driven by environmental pressures and survival/reproductive success without human intent; artificial selection is driven by humans intentionally breeding individuals with desired traits.
Difference: the selective agent (nature vs. humans) and the goals (survival fitness vs. human-preferred traits).