12

You might want to look for asymmetric dispersal. Asymmetric dispersal has been found in many freshwater fishes (such as bullhead; Junker 2012), freshwater mussel (Terui et al., 2014) and in marine kelp (bull kelp; Collins et al., 2010). That being said asymmetric dispersal does not mean that dispersal goes exclusively one way. Maybe Blondel et al. (2020) ...


5

@Remi.b is correct that you haven't given us very much information, but I think we can reconstruct what's going on. Suppose the population growth rate is written out as $$ \frac{dN}{dt} = N ( b - \delta - \gamma N) $$ then the equilibrium (carrying capacity) occurs when $N>0$ and $dN/dt=0$, i.e. $b - \delta - \gamma K = 0$. Solving this for $K$ gives $(...


4

Expanding on @heracho's answer and Wikipedia, assume pi denotes the probability of having (exactly) i children, and that dm denotes the probability of extinction by the mth generation (note that this includes extinctions by all generations n with n < m). Then dm can be expressed as: $\displaystyle d_m = p_0 + p_1 d_{m-1} + p_2 d_{m-1}^2 + p_3 d_{m-1}^3 + ...


3

To interpret $a$ and $c$ as a birth and mortality rates is somewhat inaccurate, as $a$ and $c$, as written are density-independent rates that grow or shrink populations exponentially. If $a$ were negative, the prey population would shrink and most people would find a problem like that unexciting unless it was, say, a sink population maintained by immigration ...


3

My question concerns the way that $d$ enters the SIR model, because I find it not so plausible: to consider all persons that are infected today and take a fraction $ν$ of them that will have recovered tomorrow. Well, it is in fact not very 'realistic' as you point out, but in the assumptions of the model, we see that the population has no ...


2

Short answer: yes, people have formulated ways to estimate $F_{ST}$ for multiallelic loci, e.g. microsatellites. For a review, see here. Specifically, Nei could define $F_{ST}$ for multiple alleles as $F_{ST} = \frac{(H_t - H_s)}{H_t}$, which is to say the proportion of total heterozygosity that is across rather than within populations. This is agnostic to ...


2

Cats, windows, and cars appear to be the leading causes of avian (bird) deaths: Major sources of anthropogenic bird mortality in the USA [from Fig 2b, Loss et al. (2015)] Cats and vehicles are likely leading causes of death for many small non-avian animals as well. Loss et al. (2013) estimated that 6.3–22.3 billion mammals are killed by free-ranging ...


1

Based on the IUCN Criteria for endangered status there are two broad categories of models to help in determining endangered status. Note that no one methodology is used to determine the status of any species. Rather, a panel of experts consider all available evidence (including numerous modelling studies) and essentially make a determination based on their ...


1

It's quite hard to generalize, but this paper seems to suggest anthropogenic mortality increases with body size in mammals. Hence, small mammal mortality would be caused more by predation/competition/diseases than roadkill, imho. To answer your question why we don't see so many carcasses, I would say that scavenging is very common and i don't see why a '...


1

It's funny: $R_0$ doesn't actually follow as nicely as $1/R_0$ when focusing on the infected class. In a SIS model: $$\frac{\mathrm{d}S}{\mathrm{d}t} = -\beta SI + \alpha I \\ \frac{\mathrm{d}I}{\mathrm{d}t} = \beta SI - \alpha I$$ take finding the steady state of $I$. Whether a disease is able to invade is dependent on whether or not the steady state is ...


1

1/R0 is the threshold fraction. If fraction of population vulnerable to particular infection is more than 1/R0, only then infection can spread further. And if it is less than 1/R0 then infection can not progress and eventually goes away And, 1-1/R0 is the fraction of population which requires vaccination so that we can have herd immunity. (Reference http:/...


1

You're not interpreting that Wikipedia page correctly. That equation provides an example of the Allee effect, but is not exclusive. The Allee effect occurs when the non-zero steady state of a system is not globally attractive, so that such populations may be stable at non-zero population levels for a long time, but are unable to recover once the population ...


1

I am not sure if I quite understand your question, but I think your problem is here: removal (and your d) is a rate (time/removal). It does not matter what time you choose; a day, a week, a year, as long as you adjust your c (which is /time) to same timescale. In other words, if you wish to use d over several days, you need to calculate your contacts over ...


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