List of top Ecology and Evolution Questions on Population ecology

A large forest area is fragmented into multiple smaller patches of different sizes. A researcher estimates the number of bird species in these forest fragments immediately following fragmentation, and then again 20 years later. The relationship between fragment size and species richness is shown in the graph for the two sampling events (immediately after fragmentation: closed circles and solid line; 20 years after fragmentation: open circles and dashed line). The best explanation for the differences in species richness with fragment size between the two sampling events is 

Consider a population that shows logistic growth of the form 
\[ \frac{dN}{dt} = rN \left( 1 - \frac{N}{K} \right) \] where \(\frac{dN}{dt}\) is the population growth rate, \(r\) is the instantaneous rate of increase, \(K\) is the carrying capacity and \(N\) is the population size.
For such a population \((N > 0)\), which one of the following graphs shows the correct relationship between per capita growth rate \((\frac{1}{N} \frac{dN}{dt})\) on the y-axis, and population size (\(N\)) on the x-axis? 

The probability of local extinction increases with body size when there is forest degradation, loss, and fragmentation. Consider the following hypotheses for the vulnerability of larger-bodied species: 

(P) Larger-bodied species tend to have smaller population sizes.
(Q) Larger-bodied species require larger territories/home ranges. 
(R) Larger-bodied species have higher absolute resource and energy requirements.

Which one of the following options correctly lists all potential reasons for the vulnerability of larger-bodied species?