On the evidence of an Allee effect in herring populations and consequences for population survival: A model-based study

Evidence for age-structured depensation effect in fragmented plant populations: The case of the Mediterranean endemic Anchusa sardoa (Boraginaceae)

“…As successfully introduced in Sibly et al (2005), Miranda and Lima (2010) and Saha et al (2013), the idea embodied in the density-based analysis to the population dynamics is to relate the demographic growth to the population size, according to the form…”

“…These mechanisms are well-known to be at the basis of the so-called Allee effect (Allee et al, 1949) which describes a dramatic and nonlinear dependence of the demographic growth upon the actual size of a population. In practical terms, the Allee effect introduces an intrinsic multistability (including the null-density equilibrium) by which a population could go extinct whenever its demographic size is led below a critical threshold due to external agents (Lande, 1993(Lande, , 1998Ferdy and Molofsky, 2002;Liebhold and Bascompte, 2003;Clerc et al, 2010;Shi and Shivaji, 2006;Dennis, 1989;Amarasekare, 1988;Budroni et al, 2011;Saha et al, 2013). This effect is believed to be common to many low-density populations (Le Cadre et al, 2008;Forsyth, 2003;Arrigoni and Diana, 1999) but quite difficult to isolate, particularly in plant species.…”

Big Bang Bifurcation Analysis and Allee Effect in Generic Growth Functions

“…This procedure leads to the Verhulst logistic equation, by expanding f (N ) as a Taylor series in a neighborhood of N = 0, see also [Schreiber, 2001]. On the other hand, many stochastic models of population growth can be approximated by a diffusion process (including a discrete time birth-death process), where the infinitesimal mean (defined also by f (N )) specifies the underlying deterministic trend, see, for example, [Saha et al, 2013]. The previous works are examples of different approaches in the use of the population size function f (N ) associated to the differential equation that defines the growth model under study.…”

“…We note that there exist abundant theoretical models that can account for the Allee effect. Some of them incorporate the Allee effect by multiplying the per capita growth rate by a term that becomes negative when the population density is below a certain threshold and positive otherwise, a case known as multiplicative Allee effect, see, for example, [Lewis & Kareiva, 1993;Rocha et al, 2013;Rocha et al, 2015aRocha et al, , 2015dRocha et al, , 2016Saha et al, 2013]. Other models add a predation term which causes the Allee effect, which is known as Holling type II functional response, see [Dennis, 1989] and [Kramer et al, 2009].…”

The Effectiveness of Concrete Artificial Reefs of Pulau Payar, Kedah

“…Studies on the Pulau Payar's biodiversity by [20]- [22] on Bidong's reefs provides a good benchmark for the health of the ecosystem. Essentially, the use of density measure, normally in term of number per unit area [23] or sometime in volume [24] is another good indicator for effective reef assessment.…”