Ecological trap

Ecological traps are scenarios in which rapid environmental change leads organisms to prefer to settle in poor-quality habitats. The concept stems from the idea that organisms that are actively selecting habitat must rely on environmental cues to help them identify high-quality habitat. If either the habitat quality or the cue changes so that one does not reliably indicate the other, organisms may be lured into poor-quality habitat.

Overview

Ecological traps are thought to occur when the attractiveness of a habitat increases disproportionately in relation to its value for survival and reproduction. The result is preference of falsely attractive habitat and a general avoidance of high-quality but less-attractive habitats. For example, Indigo buntings typically nest in shrubby habitat or broken forest transitions between closed canopy forest and open field. Human activity can create 'sharper', more abrupt forest edges and buntings prefer to nest along these edges. However, these artificial sharp forest edges also concentrate the movement of predators which predate their nests. In this way, Buntings prefer to nest in highly altered habitats where their nest success is lowest.[1]

While the demographic consequences of this type of maladaptive habitat selection behavior have been explored in the context of the sources and sinks, ecological traps are an inherently behavioral phenomenon of individuals.[2] Despite being a behavioural mechanism, ecological traps can have far-reaching population consequences for species with large dispersal capabilities, such as the grizzly bear (Ursus arctos).[3] The ecological trap concept was introduced in 1972 by Dwernychuk and Boag[4] and the many studies that followed suggested that this trap phenomenon may be widespread because of anthropogenic habitat change.[2][5][6]

As a corollary, novel environments may represent fitness opportunities that are unrecognized by native species if high-quality habitats lack the appropriate cues to encourage settlement; these are known as perceptual traps.[7] Theoretical[8] and empirical studies[1][4] have shown that errors made in judging habitat quality can lead to population declines or extinction. Such mismatches are not limited to habitat selection, but may occur in any behavioral context (e.g. predator avoidance, mate selection, navigation, foraging site selection, etc.). Ecological traps are thus a subset of the broader phenomena of evolutionary traps.[5]

As ecological trap theory developed, researchers have recognized that traps may operate on a variety of spatial and temporal scales which might also hinder their detection. For example, because a bird must select habitat on several scales (a habitat patch, an individual territory within that patch, as well as a nest site within the territory), traps may operate on any one of these scales.[9] Similarly, traps may operate on a temporal scale so that an altered environment may appear to cause a trap in one stage of an organism’s life, yet have positive effects on later life stages.[5] As a result, there has been a great deal of uncertainty as to how common traps may be, despite widespread acceptance as a theoretical possibility.[2] However, given the accelerated rate of ecological change driven by human land-use change, global warming, exotic species invasions, and changes in ecological communities resulting from species loss, ecological traps may be an increasing and highly underappreciated threat to biodiversity.

A 2006 review of the literature on ecological traps provides guidelines for demonstrating the existence of an ecological trap.[2] A study must show a preference for one habitat over another (or equal preference) and that individuals selecting the preferred habitat (or equally preferred habitat) have lower fitness (i.e., experience lower survival or reproductive success). Since the publication of that paper which found only a few well-documented examples of ecological traps, interest in ecological and evolutionary traps has grown very rapidly and new empirical examples are being published at an accelerating rate. There are now roughly 30 examples of ecological traps affecting a broad diversity of taxa including birds, mammals, arthropods, fish and reptiles.

Because ecological and evolutionary traps are still very poorly understood phenomena, many questions about their proximate and ultimate causes as well as their ecological consequences remain unanswered. Are traps simply an inevitable consequence of the inability of evolution to anticipate novelty or react quickly to rapid environmental change? How common are traps? Do ecological traps necessarily lead to population declines or extinctions or is it possible that they may persist indefinitely? Under what ecological and evolutionary conditions should this occur? Are organisms with certain characteristics predisposed to being "trapped"? Is rapid environmental change necessary to trigger traps? Can global warming, pollution or exotic invasive species create traps? Embracing genetic and phylogenetic approaches may provide more robust answers to the above questions as well as providing deeper insight into the proximate and ultimate basis for maladaptation in general. Because ecological and evolutionary traps are predicted to add in concert with other sources of population decline, traps are an important research priority for conservation scientists. Given the rapid current rate of global environmental change, traps may be far more common than it is realized and it will be important to examine the proximate and ultimate causes of traps if management is to prevent or eliminate traps in the future.

Polarized light pollution

Polarized light pollution is perhaps the most compelling and well-documented cue triggering ecological traps.[10] Orientation to polarized sources of light is the most important mechanism that guides at least 300 species of dragonflies, mayflies, caddisflies, tabanid flies, diving beetles, water bugs, and other aquatic insects in their search for the water bodies they require for suitable feeding/breeding habitat and oviposition sites (Schwind 1991; Horváth and Kriska 2008). Because of their strong linear polarization signature, artificial polarizing surfaces (e.g., asphalt, gravestones, cars, plastic sheeting, oil pools, windows) are commonly mistaken for bodies of water (Horváth and Zeil 1996; Kriska et al. 1998, 2006a, 2007, 2008; Horváth et al. 2007, 2008). Light reflected by these surfaces is often more highly polarized than that of light reflected by water, and artificial polarizers can be even more attractive to polarotactic aquatic insects than a water body (Horváth and Zeil 1996; Horváth et al. 1998; Kriska et al. 1998) and appear as exaggerated water surfaces acting as supernormal optical stimuli. Consequently, dragonflies, mayflies, caddisflies, and other water-seeking species actually prefer to mate, settle, swarm, and oviposit upon these surfaces than available water bodies.

See also

Notes

  1. ^ a b Weldon, A.J.; Haddad, N.M. (2005). "The effects of patch shape on Indigo Buntings: Evidence for an ecological trap". Ecology. 86 (6): 1422–1431. doi:10.1890/04-0913.
  2. ^ a b c d Robertson, B.A.; Hutto, R.L. (2006). "A framework for understanding ecological traps and an evaluation of existing evidence". Ecology. 87 (5): 1075–1085. doi:10.1890/0012-9658(2006)87[1075:AFFUET]2.0.CO;2. ISSN 0012-9658. PMID 16761584.
  3. ^ Lamb, C.T..; Mowat, G.; McLellan, B.N.; Nielsen, S.E.; Boutin, S. (2017). "Forbidden fruit: human settlement and abundant fruit create an ecological trap for an apex omnivore". Journal of Animal Ecology. 86 (1): 55–65. doi:10.1111/1365-2656.12589.
  4. ^ a b Dwernychuk, L.W.; Boag, D.A. (1972). "Ducks nesting in association with gulls-an ecological trap?". Canadian Journal of Zoology. 50 (5): 559–563. doi:10.1139/z72-076.
  5. ^ a b c Schlaepfer, M.A.; Runge, M.C.; Sherman, P.W. (2002). "Ecological and evolutionary traps". Trends in Ecology and Evolution. 17 (10): 474–480. doi:10.1016/S0169-5347(02)02580-6.
  6. ^ Battin, J. (2004). "When good animals love bad habitats: Ecological traps and the conservation of animal populations". Conservation Biology. 18 (6): 1482–1491. doi:10.1111/j.1523-1739.2004.00417.x.
  7. ^ Patten, M.A.; Kelly, J.F. (2010). "Habitat selection and the perceptual trap". Ecological Applications. 20 (8): 2148–56. doi:10.1890/09-2370.1. PMID 21265448.
  8. ^ Delibes, M.; Gaona, P.; Ferreras, P. (2001). "Effects of an attractive sink leading into maladaptive habitat selection". American Naturalist. 158 (3): 277–285. doi:10.1086/321319. PMID 18707324.
  9. ^ Misenhelter, M.D.; Rotenberry, J.T. (2000). "Choices and consequences of habitat occupancy and nest site selection in sage sparrows". Ecology. 81 (10): 2892–2901. doi:10.1890/0012-9658(2000)081[2892:CACOHO]2.0.CO;2. ISSN 0012-9658.
  10. ^ Horvath et al., in press as of Jan, 2013

References

  • Crespi, B.J. (2001). "The evolution of maladaptation". Heredity. 84 (6): 623–9. doi:10.1046/j.1365-2540.2000.00746.x. PMID 10886377.
  • Gilroy, J.J.; Sutherland, W.J. (2007). "Beyond ecological traps: perceptual errors and undervalued resources". Trends in Ecology and Evolution. 22 (7): 351–356. doi:10.1016/j.tree.2007.03.014. PMID 17416438.
  • Horváth, Gábor; Kriska, György; Malik, Péter; Robertson, Bruce (2009). "Polarized light pollution: a new kind of ecological photopollution". Frontiers in Ecology and the Environment. 7 (6): 317–325. doi:10.1890/080129.
  • Horváth, G; Zeil, J. (1996). "Kuwait oil lakes as insect traps". Nature. 379 (6563): 303–304. doi:10.1038/379303a0.
  • Horváth, G; Bernáth, B; Molnár, G. (1998). "Dragonflies find crude oil visually more attractive than water: Multiple-choice experiments on dragonfly polarotaxis". Naturwissenschaften. 85 (6): 292–297. doi:10.1007/s001140050503.
  • Horváth, G; Malik, P; Kriska, G; Wildermuth, H. (2007). "Ecological traps for dragonflies in a cemetery: the attraction of Sympetrum species (Odonata: Libellulidae) by horizontally polarizing black gravestones". Freshwater Biol. 52 (9): 1700–1709. doi:10.1111/j.1365-2427.2007.01798.x.
  • Kriska, G; Horváth, G; Andrikovics, S. (1998). "Why do mayflies lay their eggs en masse on dry asphalt roads? Water-imitating polarized light reflected from asphalt attracts Ephemeroptera". J Exp Biol. 201 (Pt 15): 2273–86. PMID 9662498.
  • Kriska, G; Malik, P; Szivák, I; Horváth, G. (2008). "Glass buildings on river banks as "polarized light traps" for mass-swarming polarotactic caddis flies". Naturwissenschaften. 95 (5): 461–467. doi:10.1007/s00114-008-0345-4. PMID 18253711.
  • Schwind, R. (1991). "Polarization vision in water insects and insects living on a moist substrate". J Comp Physiol A. 169: 531–540. doi:10.1007/bf00193544.

Further reading

Abiotic component

In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them underpin all biology.

Abiotic components include physical conditions and non-living resources that affect living organisms in terms of growth, maintenance, and reproduction. Resources are distinguished as substances or objects in the environment required by one organism and consumed or otherwise made unavailable for use by other organisms.

Component degradation of a substance occurs by chemical or physical processes, e.g. hydrolysis. All non-living components of an ecosystem, such as atmospheric conditions and water resources, are called abiotic components.

Bacterivore

Bacterivores are free-living, generally heterotrophic organisms, exclusively microscopic, which obtain energy and nutrients primarily or entirely from the consumption of bacteria. Many species of amoeba are bacterivores, as well as other types of protozoans. Commonly, all species of bacteria will be prey, but spores of some species, such as Clostridium perfringens, will never be prey, because of their cellular attributes.

Copiotroph

A copiotroph is an organism found in environments rich in nutrients, particularly carbon. They are the opposite to oligotrophs, which survive in much lower carbon concentrations.

Copiotrophic organisms tend to grow in high organic substrate conditions. For example, copiotrophic organisms grow in Sewage lagoons. They grow in organic substrate conditions up to 100x higher than oligotrophs.

Decomposer

Decomposers are organisms that break down dead or decaying organisms, and in doing so, they carry out the natural process of decomposition. Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substrates to get their energy, carbon and nutrients for growth and development. While the terms decomposer and detritivore are often interchangeably used, detritivores must ingest and digest dead matter via internal processes while decomposers can directly absorb nutrients through chemical and biological processes hence breaking down matter without ingesting it. Thus, invertebrates such as earthworms, woodlice, and sea cucumbers are technically detritivores, not decomposers, since they must ingest nutrients and are unable to absorb them externally.

Dominance (ecology)

Ecological dominance is the degree to which a taxon is more numerous than its competitors in an ecological community, or makes up more of the biomass.

Most ecological communities are defined by their dominant species.

In many examples of wet woodland in western Europe, the dominant tree is alder (Alnus glutinosa).

In temperate bogs, the dominant vegetation is usually species of Sphagnum moss.

Tidal swamps in the tropics are usually dominated by species of mangrove (Rhizophoraceae)

Some sea floor communities are dominated by brittle stars.

Exposed rocky shorelines are dominated by sessile organisms such as barnacles and limpets.

Energy Systems Language

The Energy Systems Language, also referred to as Energese, Energy Circuit Language, or Generic Systems Symbols, was developed by the ecologist Howard T. Odum and colleagues in the 1950s during studies of the tropical forests funded by the United States Atomic Energy Commission. They are used to compose energy flow diagrams in the field of systems ecology.

Evolutionary trap

The term evolutionary trap has retained several definitions associated with different biological disciplines.

Within evolutionary biology, this term has been used sporadically to refer to cases in which an evolved, and presumably adaptive, trait has suddenly become maladaptive, leading to the extinction of the species.

Within behavioral and ecological sciences, evolutionary traps occur when rapid environmental change triggers organisms to make maladaptive behavioral decisions. While these traps may take place within any type of behavioral context (e.g. mate selection, navigation, nest-site selection), the most empirically and theoretically well-understood type of evolutionary trap is the ecological trap which represents maladaptive habitat selection behavior.

Witherington demonstrates an interesting case of a "navigational trap". Over evolutionary time, hatchling sea turtles have evolved the tendency to migrate toward the light of the moon upon emerging from their sand nests. However, in the modern world, this has resulted in them tending to orient towards bright beach-front lighting, which is a more intense light source than the moon. As a result, the hatchlings migrate up the beach and away from the ocean where they exhaust themselves, desiccate and die either as a result of exhaustion, dehydration or predation.

Habitat selection is an extremely important process in the lifespan of most organisms. That choice affects nearly all of an individual’s subsequent choices, so it may not be particularly surprising the type of evolutionary trap with the best empirical support is the ecological trap. Even so, traps may be relatively difficult to detect and so the lack of evidence for other types of evolutionary trap may be a result of the paucity of researchers looking for them coupled with the demanding evidence required to demonstrate their existence.

Feeding frenzy

In ecology, a feeding frenzy occurs when predators are overwhelmed by the amount of prey available. For example, a large school of fish can cause nearby sharks, such as the lemon shark, to enter into a feeding frenzy. This can cause the sharks to go wild, biting anything that moves, including each other or anything else within biting range. Another functional explanation for feeding frenzy is competition amongst predators. This term is most often used when referring to sharks or piranhas. It has also been used as a term within journalism.

Lithoautotroph

A lithoautotroph or chemolithoautotroph is a microbe which derives energy from reduced compounds of mineral origin. Lithoautotrophs are a type of lithotrophs with autotrophic metabolic pathways. Lithoautotrophs are exclusively microbes; macrofauna do not possess the capability to use mineral sources of energy. Most lithoautotrophs belong to the domain Bacteria, while some belong to the domain Archaea. For lithoautotrophic bacteria, only inorganic molecules can be used as energy sources. The term "Lithotroph" is from Greek lithos (λίθος) meaning "rock" and trōphos (τροφοσ) meaning "consumer"; literally, it may be read "eaters of rock". Many lithoautotrophs are extremophiles, but this is not universally so.

Lithoautotrophs are extremely specific in using their energy source. Thus, despite the diversity in using inorganic molecules in order to obtain energy that lithoautotrophs exhibit as a group, one particular lithoautotroph would use only one type of inorganic molecule to get its energy.

Mesotrophic soil

Mesotrophic soils are soils with a moderate inherent fertility. An indicator of soil fertility is its base status, which is expressed as a ratio relating the major nutrient cations (calcium, magnesium, potassium and sodium) found there to the soil's clay percentage. This is commonly expressed in hundredths of a mole of cations per kilogram of clay, i.e. cmol (+) kg−1 clay.

Mycotroph

A mycotroph is a plant that gets all or part of its carbon, water, or nutrient supply through symbiotic association with fungi. The term can refer to plants that engage in either of two distinct symbioses with fungi:

Many mycotrophs have a mutualistic association with fungi in any of several forms of mycorrhiza. The majority of plant species are mycotrophic in this sense. Examples include Burmanniaceae.

Some mycotrophs are parasitic upon fungi in an association known as myco-heterotrophy.

Organotroph

An organotroph is an organism that obtains hydrogen or electrons from organic substrates. This term is used in microbiology to classify and describe organisms based on how they obtain electrons for their respiration processes. Some organotrophs such as animals and many bacteria, are also heterotrophs. Organotrophs can be either anaerobic or aerobic.

Antonym: Lithotroph, Adjective: Organotrophic.

Overpopulation

Overpopulation occurs when a species' population exceeds the carrying capacity of its ecological niche. It can result from an increase in births (fertility rate), a decline in the mortality rate, an increase in immigration, or an unsustainable biome and depletion of resources. When overpopulation occurs, individuals limit available resources to survive.

The change in number of individuals per unit area in a given locality is an important variable that has a significant impact on the entire ecosystem.

Perceptual trap

A perceptual trap is an ecological scenario in which environmental change, typically anthropogenic, leads an organism to avoid an otherwise high-quality habitat. The concept is related to that of an ecological trap, in which environmental change causes preference towards a low-quality habitat.

Planktivore

A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton.

Population cycle

A population cycle in zoology is a phenomenon where populations rise and fall over a predictable period of time. There are some species where population numbers have reasonably predictable patterns of change although the full reasons for population cycles is one of the major unsolved ecological problems. There are a number of factors which influence population change such as availability of food, predators, diseases and climate.

Recruitment (biology)

In biology, especially marine biology, recruitment occurs when a juvenile organism joins a population, whether by birth or immigration, usually at a stage whereby the organisms are settled and able to be detected by an observer.There are two types of recruitment: closed and open.In the study of fisheries, recruitment is "the number of fish surviving to enter the fishery or to some life history stage such as settlement or maturity".

Relative abundance distribution

In the field of ecology, the relative abundance distribution (RAD) or species abundance distribution describes the relationship between the number of species observed in a field study as a function of their observed abundance. The graphs obtained in this manner are typically fitted to a Zipf–Mandelbrot law, the exponent of which serves as an index of biodiversity in the ecosystem under study.

Source–sink dynamics

Source–sink dynamics is a theoretical model used by ecologists to describe how variation in habitat quality may affect the population growth or decline of organisms.

Since quality is likely to vary among patches of habitat, it is important to consider how a low quality patch might affect a population. In this model, organisms occupy two patches of habitat. One patch, the source, is a high quality habitat that on average allows the population to increase. The second patch, the sink, is very low quality habitat that, on its own, would not be able to support a population. However, if the excess of individuals produced in the source frequently moves to the sink, the sink population can persist indefinitely. Organisms are generally assumed to be able to distinguish between high and low quality habitat, and to prefer high quality habitat. However, ecological trap theory describes the reasons why organisms may actually prefer sink patches over source patches. Finally, the source-sink model implies that some habitat patches may be more important to the long-term survival of the population, and considering the presence of source-sink dynamics will help inform conservation decisions.

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