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3

Since you are asking for the biological interpretations about these parameters, it is important to realize that the model you are presenting is a non-dimensionalized version of this model: $$\frac{dx_1}{dt} =b_1x_1\Big(1- \Big(\frac{x_1 + \beta_{12}x_2}{K_1} \Big)\Big)$$ $$\frac{dx_2}{dt} =b_2x_2\Big(1- \Big(\frac{x_2 + \beta_{21}x_1}{K_2} \Big)\Big),$$ ...

1

You just have 6 parameters in this model and you can easily perturb each of them individually while holding the others constant. This will let you know the individual effect of different parameters. To assess the global sensitivity of the system to "environmental" perturbations, what you can do is to a random multivariate sampling of parameters. You will ...

2

Many species of animals use flocking/ schooling/ shoaling/ etc as a mechanism to confuse predators. A few examples are tuna, starlings, goldband fusiliers. tuna and goldband fusiliers use their reflective scales to blind and confuse the predator, whereas starlings use sheer numbers to overpower and throw off their predator. The large groups tend to scare ...

0

When groups of prey use certain mechanisms to defend against predators, those mechanisms are known as antipredator defenses. For example, groups of tuna and starlings flock together to confuse predators. A reduction in this defense would be 'reduced antipredator defense'. Groups of prey also exhibit shared antipredator vigilance, as in certain members of a ...

1

A low predator density is not synonym with "threat of extinction". Of course large predators are more prone to extinction because of lower numbers, but they usually exist in lower densities than prey (look, for instance, Lotka-Volterra equations and graphics, and also biomass and food pyramids). The risk of extinction is usually caused by fragmentation of ...

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A few people thought it would be interesting to see what the distribution looked like if we plotted the number of people dying at each age, so I took data from the SSA (which admittedly isn't global data, but it's probably fairly reflective of the world overall) and plotted the number of deaths per 100,000 at each age. This looks like it makes sense - the ...

1

Species interactions Generalities Species interact. Species actually interact a lot. One can classify species interactions into categories based on the effect that the interaction has on their fitness (≈ reproductive success). Here is a table of possible biological interactions (comes from [wiki][1]), where a + indicates "beneficial", a - indicates ...

11

Let's see! I took the most recent WHO data from here and did a quick an dirty analysis in R. Here is the histogram as well as a normal distribution with the same mean and standard deviation as the actual data: Does not look very normally distributed. In fact, the shapiro test confirms this impression: Shapiro-Wilk normality test data: ...

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Not surprisingly, the WHO has a lot of data, I think especially interesting for you is this interactive figure, which you can find here: Other data on this topic can be found on the WHO website here, in the Wikipedia or from the Worldbank.

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