# The advantage of being slow: the quasi-neutral contact process

## TL;DR

This paper investigates how a slower biological clock can confer a competitive advantage in finite spatial ecosystems, especially under resource limitations and environmental variability, challenging traditional expectations.

## Contribution

It introduces a quasi-neutral contact process model showing that slower species can outcompete faster ones under certain conditions, highlighting the role of stochasticity and spatial structure.

## Key findings

- Slower species have an advantage in small, resource-limited systems.
- Environmental fluctuations further favor slower species.
- Slower clocks can lead to coexistence despite competitive exclusion principles.

## Abstract

According to the competitive exclusion principle, in a finite ecosystem, extinction occurs naturally when two or more species compete for the same resources. An important question that arises is: when coexistence is not possible, which mechanisms confer an advantage to a given species against the other(s)? In general, it is expected that the species with the higher reproductive/death ratio will win the competition, but other mechanisms, such as asymmetry in interspecific competition or unequal diffusion rates, have been found to change this scenario dramatically. In this work, we examine competitive advantage in the context of quasi-neutral population models, including stochastic models with spatial structure as well as macroscopic (mean-field) descriptions. We employ a two-species contact process in which the "biological clock" of one species is a factor of $\alpha$ slower than that of the other species. Our results provide new insights into how stochasticity and competition interact to determine extinction in finite spatial systems. We find that a species with a slower biological clock has an advantage if resources are limited, winning the competition against a species with a faster clock, in relatively small systems. Periodic or stochastic environmental variations also favor the slower species, even in much larger systems.