7.6

In a mainland-island model of migration, where the island population harbors a deleterious recessive allele at a higher frequency than the mainland, what evolutionary outcome is least likely, assuming a constant migration rate and weak selection against the allele on the mainland?

Consider a scenario involving two diallelic loci, A and B, each with two alleles (A1, A2 and B1, B2 respectively) in a mainland-island system. Selection favors the A1B1 genotype on the mainland and the A2B2 genotype on the island. If migration occurs primarily from the mainland to the island, which of the following is the most plausible outcome regarding linkage disequilibrium (LD) in the island population?

In a spatially structured population subject to both local adaptation and migration, what condition would most likely lead to the evolution of a 'migration load' that is disproportionately borne by a specific subset of the population?

Consider a scenario where a population of plants is divided into two patches: one with high soil nitrogen and one with low soil nitrogen. Local adaptation leads to the evolution of nitrogen-efficient genotypes in the low-nitrogen patch. Gene flow occurs via pollen dispersal. Which of the following conditions would LEAST likely lead to the maintenance of genetic divergence between these patches?

A large, randomly mating population is suddenly subdivided into many small, isolated subpopulations. Initially, all subpopulations have the same allele frequencies. Considering only the effects of genetic drift and migration (no selection or mutation), what is the expected long-term outcome for the genetic variance among subpopulations?

Imagine two populations of butterflies inhabiting adjacent meadows. Population A is significantly larger than Population B. Butterflies occasionally migrate between the meadows. If a novel, beneficial mutation arises in Population B, what factor would LEAST likely influence the probability of that beneficial allele becoming fixed in the metapopulation (both meadows combined)?

In a species where offspring dispersal is limited, leading to viscous populations, how does this influence the spatial scale of local adaptation and the effectiveness of selection?

A researcher is studying a plant species with highly localized adaptation to heavy metal contamination in soil. They observe a sharp genetic cline for heavy metal tolerance alleles across a boundary between contaminated and uncontaminated soil. Which of the following scenarios would most strongly suggest that selection, rather than simply limited gene flow, is primarily maintaining this cline?

Consider a scenario where a species of freshwater fish exhibits local adaptation to different levels of salinity in adjacent estuaries. Researchers discover a single, large-effect gene responsible for salinity tolerance. What evolutionary outcome is LEAST likely if the gene is under strong selection and migration rates are moderate?

Imagine a species inhabiting a heterogeneous environment with two distinct habitat types, A and B. Local adaptation favors different genotypes in each habitat. However, habitat choice is also under genetic control, with some individuals exhibiting a strong preference for habitat A and others for habitat B. How does this genetic covariance between habitat preference and local adaptation influence the overall pattern of genetic divergence between the two habitats?

A population of plants is divided into two adjacent patches, one with serpentine soil and one with normal soil. Serpentine soil is toxic to most plants, so selection favors serpentine-tolerant genotypes in that patch. However, serpentine tolerance comes at a fitness cost in normal soil. If gene flow occurs via pollen dispersal, what evolutionary outcome is LEAST plausible if climate change causes the boundary between the two soil types to gradually shift?

Consider a source-sink metapopulation system where a mainland population (source) continuously supplies migrants to a smaller island population (sink). The island habitat is of lower quality, resulting in lower fitness for all genotypes. What is the most likely long-term evolutionary outcome for the island population if there is no local adaptation?

A researcher is studying a species of insect that exhibits cryptic coloration to match its host plant. They find that populations on different host plants have diverged in color. They hypothesize that this divergence is due to selection for camouflage. Which of the following findings would most strongly support the hypothesis of adaptive divergence, as opposed to neutral divergence due to genetic drift?

In a species with strong local adaptation and limited dispersal, what is the predicted relationship between environmental heterogeneity, gene flow, and the maintenance of biodiversity?

Imagine two partially reproductively isolated populations experiencing secondary contact after a period of allopatric divergence. Hybrids between the two populations have lower fitness than either parental type. What is the most likely evolutionary outcome if selection against hybrids is strong and dispersal is limited?

In a metapopulation context, a 'rescue effect' occurs when migration from a source population prevents the extinction of a sink population. However, what is the potential evolutionary cost to the sink population of relying on this rescue effect?

Consider a scenario where a species is expanding its range into a novel environment. Individuals at the leading edge of the expansion experience different selection pressures than individuals in the core of the range. What evolutionary processes are most likely to occur specifically at the range edge?

In a scenario of migration-selection balance, what is the predicted effect of increased habitat fragmentation on the level of local adaptation?

Imagine a species with a complex life cycle, where larvae develop in freshwater streams and adults live in terrestrial habitats. Two stream populations are connected by adult migration. One stream is heavily polluted. What evolutionary outcome is LEAST likely?

A population of insects is divided into two patches. Patch A is under strong selection for resistance to a particular pesticide, while Patch B is pesticide-free. Resistance is conferred by a single dominant allele. What factor is LEAST likely to affect the rate at which the resistance allele spreads through the entire metapopulation?

Consider a scenario where two populations of a plant species are adapting to different soil types: one to serpentine soil (high in heavy metals) and the other to normal soil. They are close enough that gene flow via pollen is possible. Over time, what outcome would LEAST suggest that selection is maintaining the divergence?

What is the most likely evolutionary outcome in a scenario where a small island population receives a constant influx of migrants from a large mainland population with different allele frequencies, but experiences recurrent bottleneck events that drastically reduce its size?

Consider a scenario where two adjacent populations of a plant species are locally adapted to different soil conditions. A narrow hybrid zone exists between them. What condition would LEAST likely contribute to the maintenance of this hybrid zone?

How does the presence of non-additive (e.g., epistatic) genetic interactions influence the relationship between migration rate and the maintenance of local adaptation in a spatially structured population?

A researcher is studying a population of fish in a lake that is divided into two distinct habitats: a shallow, vegetated area and a deep, open-water area. Fish in the shallow area are smaller and have higher reproductive rates, while fish in the deep area are larger and have lower reproductive rates. They hypothesize that this is due to local adaptation. What factor, if observed, would most strongly suggest that this is a case of plasticity rather than genetic adaptation?

What is the most significant challenge to predicting long-term evolutionary outcomes in a metapopulation where both migration and selection are highly variable and influenced by unpredictable environmental fluctuations?

Consider a scenario where a population of butterflies, exhibiting aposematic coloration, is subdivided into several isolated patches. In one patch, a novel mutation arises that enhances the warning signal's efficacy, but also renders carriers more susceptible to a specific parasitoid. Assuming migration between patches is rare, and the parasitoid is unevenly distributed, what complex evolutionary trajectory is most probable?

In a metapopulation of a plant species with specialized pollination syndromes, where one population exhibits adaptation to a more efficient but less common pollinator, and another to a generalist pollinator, what complex interaction between gene flow, selection, and pollinator behavior would most likely determine the long-term evolutionary trajectory?

Consider a population of migratory birds where individuals exhibit varying degrees of philopatry (tendency to return to their birthplace). Assuming a sudden environmental shift that drastically alters habitat quality in some breeding areas but not others, how will the interaction between philopatry, gene flow, and local adaptation most likely shape the spatial distribution of genetic variance in the long term?

In a species of annual plant inhabiting a heterogeneous landscape with patches of high and low nutrient availability, and where seed dispersal is primarily local but occasionally long-distance, what evolutionary dynamics are most likely to govern the interaction between local adaptation, gene flow, and the spatiotemporal distribution of genetic variation?

Imagine a scenario involving two plant populations adapting to heavy metal contaminated vs. uncontaminated soils where there's a single major gene for resistance. However, epigenetic modifications influence the gene's expression differently in the two populations. Given moderate gene flow, what evolutionary trajectory is most plausible considering both genetic and epigenetic factors?

Consider a species of freshwater fish divided into two lake basins connected by a narrow channel. One basin is oligotrophic (nutrient-poor), and the other is eutrophic (nutrient-rich). Fish exhibit different foraging strategies and body morphologies adapted to their respective environments. If the connecting channel widens, leading to increased migration, what complex evolutionary outcome is most likely, assuming assortative mating is absent?

In a plant species exhibiting self-incompatibility, consider two populations: one with high self-incompatibility allele diversity and another with low diversity due to a founder effect. If migration occurs primarily from the high-diversity population to the low-diversity population, what is the most complex evolutionary outcome concerning mating patterns and genetic diversity in the recipient population?

Consider two sister species of insects that occasionally hybridize in a narrow contact zone, but hybrids exhibit reduced fertility due to complex epistatic interactions. If climate change causes a shift in habitat suitability, leading to range expansion and increased hybridization, what compound evolutionary scenario is most likely?

Imagine a scenario where a plant species has distinct ecotypes adapted to serpentine and non-serpentine soils with a trade-off in competitive ability. If a new invasive species colonizes the non-serpentine soil, outcompeting the local ecotype, what indirect evolutionary consequences are most likely to unfold, considering gene flow and selection?

Consider a metapopulation of a frog species where some populations are infected with a virulent chytrid fungus. Certain genotypes exhibit resistance, but also have lower mating success. Increased connectivity due to habitat fragmentation alters migration patterns. Which scenario is least possible?

Imagine a plant species with two ecotypes, one adapted to drought and the other to flood conditions, separated by a steep environmental gradient. If climate change leads to more erratic rainfall patterns, increasing the frequency of both extreme droughts and floods, what multifaceted evolutionary response is most likely?

Two populations of a fish species are isolated except for rare flood events that connect them. One population lives in a stable, resource-rich environment, while the other lives in a highly variable environment with frequent disturbances. If increased flood frequency leads to higher migration rates, what is the most likely evolutionary outcome and how will this affect the long-term adaptive potential of the species?

A moth species exists in distinct light and dark morphs due to industrial melanism. The environment becomes cleaner, reducing pollution. However, a new predator preferentially targets the previously camouflaged light morph due to altered visual perception in the cleaner environment. How will this interplay of selection, migration, and novel ecological interactions reshape morph frequencies in the moth population?

Consider two populations of a plant species adapting to serpentine and non-serpentine soils, respectively. If a fungal pathogen emerges that is particularly virulent on the serpentine-adapted ecotype, how might this ecological shift influence the genetic architecture and evolutionary trajectory of the species, considering gene flow and selection?

In a species of butterfly with distinct wing patterns for camouflage in different habitats, imagine a scenario where habitat fragmentation increases, but simultaneously, the remaining habitat patches become more homogenous due to climate change. Predict the complex evolutionary outcome regarding the maintenance of wing pattern diversity, considering the interplay of gene flow, selection, and environmental change.

Consider a plant species where flowering time is genetically determined, but also influenced by environmental cues. Two populations exist: one in a stable climate and another in a highly variable climate with unpredictable temperature fluctuations. If gene flow between these populations increases due to human-mediated dispersal, what multifaceted evolutionary dynamic will likely unfold regarding flowering time and adaptation to local climate?

Two populations of a bird species occupy adjacent islands with slightly different food sources. One island has primarily hard seeds, favoring birds with larger beaks, while the other has softer seeds, favoring smaller beaks. If a rare storm event leads to a temporary land bridge connecting the islands, facilitating migration, what evolutionary outcome is least plausible?

In a species of coastal fish, two populations exist: one adapted to high-salinity environments and the other to low-salinity environments in adjacent estuaries. If sea level rise leads to increased saltwater intrusion into the low-salinity estuary, what complex evolutionary response is most likely, considering gene flow and potential trade-offs?

Consider a plant species with two distinct flower color morphs, where pollinator preference favors one morph in one habitat and the other morph in another habitat. If habitat fragmentation reduces pollinator movement and increases self-pollination rates within each fragment, what multifaceted evolutionary outcome is most likely regarding flower color diversity and local adaptation?

In a population of lizards where tail regeneration is possible but energetically costly, two subpopulations exist: one with high predation pressure and one with low predation pressure. If increased habitat connectivity leads to higher migration rates between these subpopulations, what complex evolutionary outcome is most probable regarding tail regeneration frequency and overall fitness?

Consider a plant species with two ecotypes adapted to high and low soil salinity. Gene flow occurs through pollen dispersal. If climate change causes increased storm surges that deposit saltwater further inland, what complex eco-evolutionary dynamics are most probable along the newly affected areas, considering gene flow, selection, and potential for rapid adaptation versus local extinction?

Two grass populations exist on either side of a mountain range. One side experiences consistently high winds, leading to selection for shorter plant height and increased root investment. The other side is sheltered, favoring taller plants with less root allocation. If a tunnel is constructed through the mountain, dramatically increasing gene flow via seed dispersal, what is the most likely long-term evolutionary outcome?

A species of salamander is divided into two populations: one in a pristine stream with high oxygen levels and another in a polluted stream with low oxygen levels. The low-oxygen population has evolved enhanced gill surface area. If a restoration project improves water quality in the polluted stream, rendering oxygen levels more similar to the pristine stream, how will this environmental change influence the evolutionary trajectory of the salamander populations, considering gene flow?

Consider two populations of a plant species adapted to high and low soil nitrogen levels. If anthropogenic nitrogen deposition increases nitrogen availability across the entire landscape, what ensuing evolutionary events is most likely and how will this affect the long-term adaptive potential of the species?

A butterfly species has two distinct wing color morphs controlled by a single gene: one cryptic (camouflaged) and one aposematic (warning coloration). Initially, the cryptic morph is more common. A novel, highly mobile avian predator that learns quickly enters the ecosystem. Evaluate how the interaction between selection pressure, gene flow, and the predator's behavior will influence the morph frequencies over time.

Two populations of a beetle species exist in adjacent habitats: one on a light-colored sandy beach and the other on dark volcanic rock. Beetle color is genetically determined. If increased storm frequency mixes sand and rock, creating a heterogeneous environment, what is the most probable evolutionary response and how will it alter selective patterns, given genetic migration?

Two populations of a plant species are in separate, but adjacent habitat. One population is adapted to high altitude and the other to low altitude. If climate change causes the high altitude habitat to shrink, increasing population density in both habitats, describe the effects and give an estimate of the amount of variance in the hybrid zone. Assume Mendelian genetics at the 10 important loci.

A small island population of birds is founded by a few individuals carrying a rare, recessive allele that confers resistance to a novel toxin in their primary food source. The mainland population lacks this allele. Over time, migrants from the mainland arrive on the island. What complex evolutionary scenario is most likely to unfold, considering selection, gene flow, and the potential for inbreeding depression on the island?