207 research outputs found
Models of genetic drift as limiting forms of the Lotka-Volterra competition model
The relationship between the Moran model and stochastic Lotka-Volterra
competition (SLVC) model is explored via timescale separation arguments. For
neutral systems the two are found to be equivalent at long times. For systems
with selective pressure, their behavior differs. It is argued that the SLVC is
preferable to the Moran model since in the SLVC population size is regulated by
competition, rather than arbitrarily fixed as in the Moran model. As a
consequence, ambiguities found in the Moran model associated with the
introduction of more complex processes, such as selection, are avoided.Comment: 5 pages, 4 figure
Feasibility and stability in large Lotka Volterra systems with interaction structure
Complex system stability can be studied via linear stability analysis using
Random Matrix Theory (RMT) or via feasibility (requiring positive equilibrium
abundances). Both approaches highlight the importance of interaction structure.
Here we show, analytically and numerically, how RMT and feasibility approaches
can be complementary. In generalised Lotka-Volterra (GLV) models with random
interaction matrices, feasibility increases when predator-prey interactions
increase; increasing competition/mutualism has the opposite effect. These
changes have crucial impact on the stability of the GLV model.Comment: Manuscript is 8 pages long, containing 4 figures. Pages 9 to 25 is
the Supplemental Materia
Maternal transmission as a microbial symbiont sieve, and the absence of lactation in male mammals
Gut microbiomes of mammals carry a complex symbiotic assemblage of microorganisms. Feeding newborn infants milk from the mammary gland allows vertical transmission of the parental milk microbiome to the offspring’s gut microbiome. This has benefits, but also has hazards for the host population. Using mathematical models, we demonstrate that biparental vertical transmission enables deleterious microbial elements to invade host populations. In contrast, uniparental vertical transmission acts as a sieve, preventing these invasions. Moreover, we show that deleterious symbionts generate selection on host modifier genes that keep uniparental transmission in place. Since microbial transmission occurs during birth in placental mammals, subsequent transmission of the milk microbiome needs to be maternal to avoid the spread of deleterious elements. This paper therefore argues that viviparity and the hazards from biparental transmission of the milk microbiome, together generate selection against male lactation in placental mammals
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