Ecological Factors Affecting Community Invasibility

Abstract

What makes a community invasible? For over a century ecologists have sought to understand the relative importance of biotic and abiotic factors that determine community composition. The fact that we are still exploring this topic today hints at both its importance and complexity. As the impacts from harmful non-native species accumulate, it has become increasingly urgent to find answers to the more applied aspects of this question: what makes a habitat vulnerable to invasion by additional species, and which species are likely to invade? Answers to these questions will not only aid in targeting conservation efforts but will also advance our understanding of marine community ecology.Although the relative importance of abiotic vs. biotic factors in making a habitat invasible varies, abiotic factors undoubtedly serve as the first "filter" to invasions, limiting establishment of non-native (=exotic) species to conditions approximating their native ranges. As obvious examples, tropical corals will not establish in boreal waters, and temperate rocky intertidal species will not colonize tropical shores. Similarly, species cannot invade a community if propagules do not arrive at the site. Other chapters in this volume cover the influence of abiotic factors and propagule supply (Chap. 7, Johnston et al.; Chap. 8, Miller and Ruiz; Chap. 19, Hewitt et al.), so we only briefly review these factors. In this chapter we focus on the question of predicting invasion success of non-native species that are (1) transported to the habitat in question (i.e., propagule supply is not extremely limiting) and (2) physiologically capable of surviving in the climatic regime. We begin with the observation that even in areas of suitable habitat within the current range of an introduced species, there is often dramatic variation in the density, presence, and overall success of the invader. We seek to explain this variation in terms of processes that control the availability of resources. These include not only abiotic and physical factors that determine base resource levels, but also interactions between species or between organisms and their environment that increase resource availability (through disturbance) or decrease resource availability (through competitive processes), or create new resources (through facilitation) (Fig. 12.1

Out of the tropics, but how? Fossils, bridge species, and thermal ranges in the dynamics of the marine latitudinal diversity gradient

“…Such extinction-mediated range expansions are a common theme for modern and ancient biodiversity at many scales, from mass extinctions (59, 78, 82) through smaller-scale natural perturbations (72,87) to present-day invasions mediated by anthropogenic disturbance (88,89), although counterexamples and alternative models exist (90,91). The very noisy diversity-area relationship for the 20+ temperatezone marine provinces [statistically insignificant for the most prominent biogeographic schemes (92,93)] suggests that extinction keeps the temperate zones far from saturation, thus promoting entry of taxa from the tropics (87), presumably with some amount of temperate zone origination and biotic interchange, e.g., along the Aleutians in the North Pacific (34), over the Arctic (34), and across the temperate Southern Hemisphere (94).…”

Recommendations on methods for the detection and control of biological pollution in marine coastal waters

“…Bioinvasion studies lack being more analytical and predictive because of uncertainties about vectors involved in the transportation process (Minchin, 2007a), numbers of established and spreading NIS, propagule pressure (Johnston et al, 2009), biological traits of invaders (Karatayev et al, 2009) and their environmental tolerance limits (Olyarnik et al, 2009), their functional role (Crooks, 2009) and the impacts on environment, economy and human health (Olenin et al, 2007).…”

Stable Engraftment of Bifidobacterium longum AH1206 in the Human Gut Depends on Individualized Features of the Resident Microbiome

“…Although invasion ecology currently lacks a unifying theory that addresses these questions (Guo et al, 2015), it provides a useful framework for understanding probiotic functionality and impact and ultimately may advance their application. For example, according to theory, specific traits that overcome the environmental filters of the ecosystem are required for biological invasions (Mächler and Altermatt, 2012;Olyarnik et al, 2009). The inability of commercial probiotic strains to persist in the human gut might therefore stem from the absence of key adaptations necessary to successfully compete in this ecosystem.…”