The figure illustrates the soil zinc tolerance of the grass species Anthoxanthum along a transect from inside a mine to the middle of a pasture outside the mine.
Which one or more of the following processes explain(s) the observed pattern of zinc tolerance in this grass species?
The question focuses on understanding the observed pattern of zinc tolerance in the grass species Anthoxanthum across a transect from inside a mine to a pasture. The given graph shows the variation in zinc tolerance.
The correct answer is Local adaptation. Let's explain why this is the case and rule out the other options:
- Local adaptation: This is the evolutionary process where a population evolves specific traits that confer advantages in their local environment. In the graph, grass species inside the mine have higher zinc tolerance compared to those in the pasture. This pattern suggests adaptation to the high-zinc environment near the mine. Hence, local adaptation is a reasonable explanation for the observed pattern.
- Genetic drift: It is a random process that can cause changes in the frequency of traits in a small population. However, genetic drift does not explain the specific pattern of tolerance related to a distinct environmental gradient observed here.
- Coevolution: This process involves two or more species affecting each other's evolution. The pattern shown in the graph does not indicate interactions between species influencing each other's evolution, so coevolution is not applicable.
- Introgression: Introgression refers to the incorporation of genes from one species into the gene pool of another through hybridization and backcrossing. This process does not explain the specific adaptation to zinc within a single species as observed in the graph.
Therefore, the most plausible explanation for the observed pattern is Local adaptation.
Important Questions from Natural selection
Aphids feed on both alfalfa and clover plants. A researcher collected and reared different genotypes of aphids from separate alfalfa and clover fields. He then measured the fecundity of both aphid groups when fed on each of the two host plants. The figure summarizes the performance of aphid groups originating from alfalfa (dashed) or clover (solid).
Which one or more of the following situations does the figure depict?- Which one or more of the following conditions is/are necessary for the evolution of increased nectar production in an insect-pollinated plant via natural selection?
There are two species, X and Y, with abundances $x$ and $y$, respectively. Species X has growth rate $\alpha$, and species Y has growth rate $\beta$. Assume that the sum of the species abundances is constant over time, i.e., $x + y = 1$. Let $x$ and $y$ follow the rate equations:
$$\frac{dx}{dt} = \alpha x - \varphi x,$$
$$\frac{dy}{dt} = \beta y - \varphi y,$$ where $\varphi$ is the average species fitness.
Which one of the following options correctly represents the expression for $\varphi$?A researcher estimates the relationship between reproductive success ($N$, number of offspring) and horn length ($H$, in cm) in a wild goat as
$N = 40 – 2.2H + 0.04H^2$
Horn length typically varies from 10 cm to 50 cm in this species. Which one of the following graphs correctly represents this relationship?
- A new food requesting behaviour has been observed in bonnet macaques in Bandipur National Park. The macaques extend their hand and make a cooing sound only towards humans, which effectively results in food given to them. If this behaviour is to increase in frequency in the population over time by the process of natural selection, which one or more of the options below is/are necessary condition(s)?
