Coextinction

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Coextinction and cothreatened refer to the phenomenon of the loss or decline of a host species resulting in the loss or endangerment of another species that depends on it, potentially leading to cascading effects across trophic levels. [1] The term was originated by the authors Stork and Lyal (1993) [2] [3] and was originally used to explain the extinction of parasitic insects following the loss of their specific hosts. The term is now used to describe the loss of any interacting species, including competition with their counterpart, and specialist herbivores with their food source. Coextinction is especially common when a keystone species goes extinct.

Contents

Causes

The most frequently cited example is that of the extinct passenger pigeon and its parasitic bird lice Columbicola extinctus and Campanulotes defectus. Recently, C. extinctus was rediscovered on the band-tailed pigeon, [4] and C. defectus was found to be a likely case of misidentification of the existing Campanulotes flavus . [5] However, even though the passenger pigeon louse was rediscovered, coextinctions of other parasites, even on the passenger pigeon, may have occurred.[ citation needed ] Several louse species, such as Rallicola extinctus , a huia parasite, probably became extinct together with their hosts. [6]

Recent studies have suggested that up to 50% of species may go extinct in the next 50 years. [7] This is in part due to coextinction; for example the loss of tropical butterfly species from Singapore is attributed to the loss of their specific larval host plants. [7] To see how possible future cases of coextinction would play out, researchers have made models to show probabilistic relationships between affiliate and host extinctions across co-evolved inter-specific systems. The subjects are pollinating Ficus wasps and Ficus, primate parasites, (Pneumocystis Fungi, Nematode, and Lice) and their hosts, parasitic mites and lice and their avian hosts, butterflies and their larval host plants, and ant butterflies and their host ants. For all but the most host-specific affiliate groups (e.g., primate Pneumocystis fungi and primates), affiliate extinction levels may be modest at low levels of host extinction but can be expected to rise quickly as host extinctions increase to levels predicted in the near future. This curvilinear relationship between host and affiliate extinction levels may also explain, in part, why so few coextinction events have been documented to date. [7]

Investigations have been carried out into coextinction risk among the rich Psyllid fauna Hemiptera – Psylloidea inhabiting acacias (Fabaceae-Mimosoideae: Acacia) in central eastern New South Wales, Australia. The results, suggest that A. ausfeldii hosts one specialist psyllid species, Acizzia, and that A. gordonii hosts one specialist psyllid, Acizzia. Both psyllid species may be threatened at the same level of their host species with coextinction. [8]

Interaction patterns can be used to anticipate the consequences of phylogenetic effects. By using a system of methodical observations, scientists can use the phylogenetic relationships of species to predict the number of interactions they exhibit in more than one-third of the networks, and the identity of the species with which they interact in about half of the networks. Consequentially, simulated extinction events tend to trigger coextinction cascades of related species. This results in a non-random pruning of the evolutionary tree. [9]

In a 2004 paper in Science , ecologist Lian Pin Koh and colleagues discuss coextinction, [10] stating

"Species coextinction is a manifestation of the interconnectedness of organisms in complex ecosystems. The loss of species through coextinction represents the loss of irreplaceable evolutionary and coevolutionary history. In view of the global extinction crisis, it is imperative that coextinction be the focus of future research to understand the intricate processes of species extinctions. While coextinction may not be the most important cause of species extinctions, it is certainly an insidious one." (Koh et al. 2004)

Koh et al. also define coendangered as taxa "likely to go extinct if their currently endangered hosts [...] become extinct."

One example is the extinction of many species of the genus Hibiscadelphus, as a consequence of the disappearance of several of the Hawaiian honeycreepers, its pollinators. There are also several instances of predators and scavengers dying out or becoming rarer following the disappearance of species which represented their source of food: for example, the coextinction of the Haast's eagle with the moa, or the near-extinction of the California condor after the extinctions of its primary food, the dead carcasses of North American Pleistocene megafauna; in the latter, the condor survived by possibly relying on beached marine mammals.

Coextinction may also occur on a local level: for example, the decline in the red ant Myrmica sabuleti in southern England, caused by habitat loss, resulted in the extirpation of the large blue butterfly (which is dependent on the ant as a host for its larvae) from Great Britain. In this case the ant avoided extirpation, and the butterfly has since been reintroduced to the island.

Another example of a species that could currently be experiencing coextinction is the rhinoceros stomach bot fly (Gyrostigma rhinocerontis) and its host species the endangered black rhinoceros and white rhinoceros (Diceros bicornis and Ceratotherium simum). The fly's larvae mature in a rhinoceros's stomach lining, having entered the body via the digestive tract, and so are dependent on rhinoceros species to reproduce. [11]

Consequences

Coextinction can mean loss of biodiversity and diversification.[ citation needed ] Coextinction can also result in loss of evolutionary history.[ citation needed ]

Coextinction can extend beyond biodiversity and has direct and indirect consequences on the communities of lost species. One main consequence of coextinction that goes beyond biodiversity is mutualism, by loss of food production with a decline in threatened pollinators. Losses of parasites can have negative impacts on humans or the species.[ citation needed ]

A consequence of removing specialist parasites from rare hosts is the problem of where the parasites will go once their host is extinct. If the parasites are dependent on only those species than there are parasite species that are at risk of extinction through co-endangerment.

A study conducted in New Caledonia has shown that extinction of a coral reef-associated fish species of average size would eventually result in the co-extinction of at least ten species of parasites. [12]

Risks

The host specificity and life cycle is a major factor in the risk of coextinction. Species of mutualists, parasites, and many free-living insects that have staged life cycles are more likely to be a victim of coextinction. This is due to the fact that these organisms may depend on multiple hosts throughout their lives in comparison to simple life cycled organisms. [13] Also, if organisms are evolutionary flexible, then these organisms may escape extinction. [14] [15]

The area with that has the greatest effect of coextinction is the tropics. There is a continued disappearance in the habitat, human intervention, and a great loss in vital ecosystem services. This is threatening because the tropics contain 2/3 of the all known species but they aren't in a situation where they can be fully taken care of. Along with forest loss other risk factors include: coastal development, overexploitation of wildlife, and habitat conversion, that also affect human well-being. [16]

In an effort to find a stop to coextinction, researchers have found that the first step would be to conserve the host species in which other species are dependent on. These hosts serve as major components for their habitat and need them to survive. In deciding what host to protect, it is important to choose one that can benefit an array of other dependent species. [17]

See also

Related Research Articles

<span class="mw-page-title-main">Extinction</span> Termination of a taxon by the death of its last member

Extinction is the termination of a taxon by the death of its last member. A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" after a period of apparent absence.

<span class="mw-page-title-main">Louse</span> Order of insects

Louse is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result of developments in phylogenetic research.

<span class="mw-page-title-main">Jamaican petrel</span> Species of bird

The Jamaican petrel is a small possibly extinct seabird in the gadfly petrel genus, Pterodroma. It is related to the black-capped petrel.

<span class="mw-page-title-main">Community (ecology)</span> Associated populations of species in a given area

In ecology, a community is a group or association of populations of two or more different species occupying the same geographical area at the same time, also known as a biocoenosis, biotic community, biological community, ecological community, or life assemblage. The term community has a variety of uses. In its simplest form it refers to groups of organisms in a specific place or time, for example, "the fish community of Lake Ontario before industrialization".

<span class="mw-page-title-main">Philopteridae</span> Family of lice

The Philopteridae are a family of Ischnocera, chewing lice. They are parasitic on birds.

Rallicola extinctus is an extinct species of phtilopterid louse. The parasite was only known to live on the now extinct huia and is thought to have become extinct with its host. Like its host, it was endemic to New Zealand's North Island.

<span class="mw-page-title-main">Fish diseases and parasites</span> Disease that affects fish

Like humans and other animals, fish suffer from diseases and parasites. Fish defences against disease are specific and non-specific. Non-specific defences include skin and scales, as well as the mucus layer secreted by the epidermis that traps microorganisms and inhibits their growth. If pathogens breach these defences, fish can develop inflammatory responses that increase the flow of blood to infected areas and deliver white blood cells that attempt to destroy the pathogens.

<span class="mw-page-title-main">Conservation biology of parasites</span>

A large proportion of living species on Earth live a parasitic way of life. Parasites have traditionally been seen as targets of eradication efforts, and they have often been overlooked in conservation efforts. In the case of parasites living in the wild – and thus harmless to humans and domesticated animals – this view is changing. The conservation biology of parasites is an emerging and interdisciplinary field that recognizes the integral role parasites play in ecosystems. Parasites are intricately woven into the fabric of ecological communities, with diverse species occupying a range of ecological niches and displaying complex relationships with their hosts.

<span class="mw-page-title-main">Paraneoptera</span> Superorder of insects

Paraneoptera or Acercaria is a superorder of insects which includes lice, thrips, and hemipterans, the true bugs. It also includes the extinct order Permopsocida, known from fossils dating from the Early Permian to the mid-Cretaceous.

Conservation is the maintenance of biological diversity. Conservation can focus on preserving diversity at genetic, species, community or whole ecosystem levels. This article will examine conservation at the species level, because mutualisms involve interactions between species. The ultimate goal of conservation at this level is to prevent the extinction of species. However, species conservation has the broader aim of maintaining the abundance and distribution of all species, not only those threatened with extinction. Determining the value of conserving particular species can be done through the use of evolutionary significant units, which essentially attempt to prioritise the conservation of the species which are rarest, fastest declining, and most distinct genotypically and phenotypically.

<span class="mw-page-title-main">Eichler's rule</span> Coevolutionary principle regerding parasites and hosts

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Columbicola extinctus, also known as the passenger pigeon chewing louse, is an extant species of phtilopterid louse. It was once believed to have become extinct with its only known host, the passenger pigeon, prior to its rediscovery living on band-tailed pigeons.

Conservation-induced extinction is where efforts to save endangered species lead to the extinction of other species. This mostly threatens the parasite and pathogen species that are highly host-specific to critically endangered hosts. When the last individuals of a host species are captured for the purpose of captive breeding and reintroduction programs, they typically undergo anti-parasitic treatments to increase survival and reproductive success. This practice may unintentionally result in the extinction of the species antagonistic to the target species, such as certain parasites. It has been proposed that the parasites should be reintroduced to the endangered population. A few cases of conservation-induced extinction have occurred in parasitic lice.

Campanulotes is a genus of lice in the disputed, probably paraphyletic, family Philopteridae, the chewing lice, or in the family Goniodidae.

Campanulotes elegans is a species of lice in the disputed, probably paraphyletic, family Philopteridae, the chewing lice, or in the family Goniodidae.

<span class="mw-page-title-main">Cospeciation</span> Form of coevolution in which the speciation of one species dictates speciation of another species

Cospeciation is a form of coevolution in which the speciation of one species dictates speciation of another species and is most commonly studied in host-parasite relationships. In the case of a host-parasite relationship, if two hosts of the same species get within close proximity of each other, parasites of the same species from each host are able to move between individuals and mate with the parasites on the other host. However, if a speciation event occurs in the host species, the parasites will no longer be able to "cross over" because the two new host species no longer mate and, if the speciation event is due to a geographic separation, it is very unlikely the two hosts will interact at all with each other. The lack of proximity between the hosts ultimately prevents the populations of parasites from interacting and mating. This can ultimately lead to speciation within the parasite.

Colpocephalum californici, the California condor louse, is an extinct species of chewing louse which parasitized the California condor. In an example of coextinction, it became extinct when the remaining, Critically Endangered California condors were deloused and treated with pesticides during a captive breeding program.

<i>Rallicola</i> Genus of lice

Rallicola is a genus of chewing louse. It is an ectoparasite of rails and other birds. It was named by Thomas Harvey Johnston and Launcelot Harrison in 1911. There are two subgenera aside from the nominotypical subgenus: Aptericola, whose species are found on kiwi birds, and Huiacola, a monospecific subgenus consisting of Rallicola extinctus, once found on the huia.

<span class="mw-page-title-main">Harrison's rule</span>

Harrison's rule is an observation in evolutionary biology by Launcelot Harrison which states that in comparisons across closely related species, host and parasite body sizes tend to covary positively.

Nyeema Charmaine Harris is an American environmental scientist who is Associate Professor and Director of the Applied Wildlife Ecology Laboratory at the University of Michigan. Her research considers mammalian carnivores and conservation.

References

  1. ↑ Jönsson, M. T.; Thor, G.; Roberts, D. L. (2012). "Estimating Coextinction Risks from Epidemic Tree Death: Affiliate Lichen Communities among Diseased Host Tree Populations of Fraxinus excelsior". PLOS ONE. 7 (9): 1–10. Bibcode:2012PLoSO...745701J. doi: 10.1371/journal.pone.0045701 . PMC   3458109 . PMID   23049840.
  2. ↑ Stork, Nigel E.; Lyal, Christopher H. C. (25 December 1993). "Extinction or 'co-extinction' rates?". Nature. 366 (6453): 307–8. Bibcode:1993Natur.366..307S. doi: 10.1038/366307a0 . ISSN   0028-0836.
  3. ↑ Turvey, Samuel T (May 28, 2009). Holocene Extinctions. Oxford University Press. p. 167.
  4. ↑ Clayton, D. H.; Price, R. D. (1999). "Taxonomy of New World Columbicola (Phthiraptera: Philopteridae) from the Columbiformes (Aves), with descriptions of five new species". Ann. Entomol. Soc. Am. 92 (5): 675–685. doi: 10.1093/aesa/92.5.675 .
  5. ↑ Price, R. D.; Clayton, D. H.; Adams, R. J. Jr. (2000). "Pigeon lice down under: Taxonomy of Australian Campanulotes (Phthiraptera: Philopteridae), with a description of C. durdeni n.sp". Journal of Parasitology. 86 (5): 948–950. doi:10.1645/0022-3395(2000)086[0948:PLDUTO]2.0.CO;2. PMID   11128516. S2CID   30970563.
  6. ↑ Mey, E. (1990). "Eine neue ausgestorbene Vogel-Ischnozere von Neuseeland, Huiacola extinctus (Insecta, Phthiraptera)". Zoologischer Anzeiger. 224 (1/2): 49–73.
  7. 1 2 3 Koh, LP; Dunn, RR; Sodhi, NS; Colwell, RK; Proctor, HC; Smith, VS (2004). "Species coextinctions and the biodiversity crisis". Science. 305 (5690): 1632–1634. Bibcode:2004Sci...305.1632K. doi:10.1126/science.1101101. PMID   15361627. S2CID   30713492.
  8. ↑ Powell, Fiona A.; Hochuli, Dieter F.; Symonds, Celia L.; Cassis, Gerasimos (2012). "Are psyllids affiliated with the threatened plants Acacia ausfeldii, A. dangarensis and A. gordonii at risk of co-extinction?". Austral Ecology. 37 (1): 140–148. doi:10.1111/j.1442-9993.2011.02257.x.
  9. ↑ Rezende, Enrico; et al. (23 August 2007). "Non-random coextinctions in phylogenetically structured mutualistic networks". Nature. 925. 448 (7156): 925–8. Bibcode:2007Natur.448..925R. doi:10.1038/nature05956. hdl: 10261/38513 . PMID   17713534. S2CID   4338215.
  10. ↑ Koh, Lian Pin; Dunn, Robert R.; Sodhi, Navjot S.; Colwell, Robert K.; Proctor, Heather C.; Smith, Vincent S. (2004). "Species Coextinctions and the Biodiversity Crisis". Science . 305 (5690): 1632–1634. Bibcode:2004Sci...305.1632K. doi:10.1126/science.1101101. PMID   15361627. S2CID   30713492.
  11. ↑ Colwell, DD; Otranto, D; Stevens, JR (2009). "Oestrid flies: eradication and extinction versus biodiversity". Trends Parasitol. 25 (11): 500–4. doi:10.1016/j.pt.2009.07.011. PMID   19762281.
  12. ↑ Justine, JL.; Beveridge, I.; Boxshall, GA.; Bray, RA.; Miller, TL.; Moravec, F.; Trilles, JP.; Whittington, ID. (2012). "An annotated list of fish parasites (Isopoda, Copepoda, Monogenea, Digenea, Cestoda, Nematoda) collected from Snappers and Bream (Lutjanidae, Nemipteridae, Caesionidae) in New Caledonia confirms high parasite biodiversity on coral reef fish". Aquat Biosyst. 8 (1): 22. doi: 10.1186/2046-9063-8-22 . PMC   3507714 . PMID   22947621.
  13. ↑ Moir, ML; Vesk, PA; Brennan, KEC; Keith, DA; Hughes, L; McCarthy, MA (2010). "Current constraints and future directions in estimating coextinction". Conserv. Biol. 24 (3): 682–90. doi:10.1111/j.1523-1739.2009.01398.x. PMID   20067486.
  14. ↑ Bronstein JL, Dieckmann U, Ferrièrre R. 2004. Coevolutionary dynamics and the conservation of mutualisms. In Evolutionary Conservation Biology, ed. R Ferrièrre, U Dieckmann, D Couvet, pp. 305–26. Cambridge, UK: Cambridge Univ. Press
  15. ↑ Robert, Colwell K., Dunn R. Robert, and Nyeema Harris. "Coextinction and Persistence of Dependent Species in a Changing World." Annual Review of Ecology, Evolution, and Systematics 48 (n.d.): 183-203.
  16. ↑ Bradshaw, Corey JA; Sodhi, Navjot S; Brook, Barry W (2009). "Tropical turmoil: a biodiversity tragedy in progress". Frontiers in Ecology and the Environment. 7 (2): 79–87. doi:10.1890/070193.
  17. ↑ Moir, M. L.; Vesk, P. A.; Brennan, K. E. C.; Keith, D. A.; McCarthy, M. A.; Hughes, L. (2011). "Identifying and Managing Threatened Invertebrates through Assessment of Coextinction Risk". Conservation Biology. 25 (4): 787–796. doi:10.1111/j.1523-1739.2011.01663.x. PMID   21453365. S2CID   8358406.
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