Ecology examines how organisms interact with each other and with their physical environment. This fundamental definition distinguishes it from fields like paleontology or biochemistry.

Evolution is defined as a change in heritable traits in a population over many generations. It is not about short-term individual changes but about genetically based shifts in populations.

The development of antibiotic resistance in bacteria is a clear example of natural selection where environmental pressures favor survival traits. The other examples relate to individual behavior or short-term responses, not evolutionary processes.

An ecosystem is defined by the interactions between living organisms and their abiotic surroundings. This concept highlights the interdependence of biotic and nonbiotic components within an environment.

A food chain shows a simple, direct pathway of energy transfer from one organism to another, while a food web reflects the complex and interconnected feeding relationships in an ecosystem. This distinction is crucial for understanding ecosystem dynamics.

Genetic drift has a more pronounced effect in small populations because random sampling errors in allele frequencies can lead to significant genetic changes. This process may result in the fixation or loss of alleles over generations.

Gene flow involves the exchange of genetic material between populations and tends to homogenize genetic differences. By introducing new alleles into a population, it reduces the genetic divergence that might otherwise occur due to isolation.

Character displacement occurs when species with overlapping habitats evolve differences in traits to minimize competition. This divergence helps in the effective partitioning of resources and promotes coexistence.

A keystone species plays a crucial role in maintaining the overall structure and balance of an ecosystem. Its removal can cause dramatic shifts in the ecosystem, affecting many other species and their interactions.

Mutualism is an interaction where both species benefit from the relationship, as in the case of bees obtaining nectar while simultaneously pollinating flowers. The other interactions mentioned do not provide reciprocal benefits.

Evolutionary adaptation occurs through genetic changes over many generations and is heritable. In contrast, acclimation is a temporary, non-heritable adjustment in response to environmental changes.

Allopatric speciation occurs when populations become geographically separated, limiting gene flow and leading to divergence. Geographic isolation is the key factor that distinguishes allopatric speciation from other types.

A drastic environmental change can favor individuals that possess traits beneficial in the new conditions, thereby driving natural selection. Over time, this results in evolutionary changes within the population.

The competitive exclusion principle explains that two species competing for the same limited resources cannot stably coexist. Over time, one species will outcompete the other, leading to the exclusion of the less competitive species.

Carrying capacity refers to the maximum number of individuals that an environment can support over the long term. It is determined by the availability of resources and the ability of the environment to sustain a population.

Phylogenetic trees are constructed by comparing genetic and morphological data to reveal the evolutionary relationships among species. They help scientists test hypotheses about shared ancestry and diversification patterns.

Keystone species, despite often not being the most abundant, have a large influence on ecosystem dynamics. Their presence helps to regulate community composition and maintain biodiversity by controlling the populations of other species.

r-selected species exploit unstable environments by producing a large number of offspring with minimal parental investment, resulting in low survival rates. In contrast, k-selected species favor quality over quantity, producing fewer offspring that have a higher chance of surviving due to greater parental care.

The theory of punctuated equilibrium suggests that species remain relatively unchanged for long periods, with significant evolutionary changes occurring rapidly in short bursts. Gradualism, on the other hand, posits that evolutionary changes occur slowly and steadily over time.

Invasive species can significantly disrupt native ecosystems by competing with local species for resources, altering established food webs, and modifying habitat structures. These changes can reduce biodiversity and destabilize the ecological balance.