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Coevolution

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In a broad sense, biological coevolution is "the change of a biological object triggered by the change of a related object."[1] Coevolution can occur at multiple levels of biology: it can be as microscopic as correlated mutations between amino acids in a protein, or as macroscopic as covarying traits between different species in an environment. Each party in a coevolutionary relationship exerts selective pressures on the other, thereby affecting each others' evolution. Coevolution of different species includes the evolution of a host species and its parasites (host-parasite coevolution), and examples of mutualism evolving through time. Evolution in response to abiotic factors, such as climate change, is not coevolution (since climate is not alive and does not undergo biological evolution). Evolution in a one-on-one interaction, such as that between predator and prey, host-symbiont or host-parasitic pair, is coevolution. But many cases are less clearcut: a species may evolve in response to a number of other species, each of which is also evolving in response to a set of species. This situation has been referred to as "diffuse coevolution."

Bumblebees and the flowers they pollinate have coevolved so that both have become dependent on each other for survival.

There is little evidence for coevolution driving large-scale changes in Earth's history, since abiotic factors seem to guide the shifts in the abundance of major groups (e.g., mass extinction, expansion into ecospace).[2] However, there is evidence for coevolution on the level of populations and species, for example, the concept of coevolution was briefly described by Charles Darwin in On the Origin of Species, and developed in detail in Fertilisation of Orchids.[3][4][5] It is likely that viruses and their hosts may have coevolved in a number of differing scenarios.[6]

One model of the coevolution processes was Leigh Van Valen's Red Queen's Hypothesis. Emphasizing the importance of the sexual conflict, Thierry Lodé privileged the role of antagonist interactions (notably sexual) in evolution leading to an antagonist coevolution.[7]

The existence of mitochondria within eukaryote cells is an example of coevolution as the mitochondria has a different DNA sequence than that of the nucleus in the host cell. This concept is described further by the endosymbiotic theory.

Coevolutionary algorithms are also a class of algorithms used for generating artificial life as well as for optimization, game learning and machine learning. Pioneering results in the use of coevolutionary methods were by Daniel Hillis (who coevolved sorting networks) and Karl Sims (who coevolved virtual creatures).

In his book The Self-organizing Universe, Erich Jantsch attributed the entire evolution of the cosmos to coevolution.

In astronomy, an emerging theory states that black holes and galaxies develop in an interdependent way analogous to biological coevolution.[8]

Models

Coevolution branching strategies for asexual population dynamics in limited resource environments have been modeled using the generalized Lotka–Volterra equations.[9]

Specific examples

Hummingbirds and ornithophilous flowers

Hummingbirds and ornithophilous flowers have evolved to form a mutualistic relationship. It is prevalent in the bird's biology as well as in the flower's. Hummingbird flowers have nectar chemistry associated with the bird's diet. Their color and morphology also coincide with the bird's vision and morphology. The blooming times of these ornithophilous flowers have also been found to coincide with hummingbirds' breeding seasons.

Flowers have converged to take advantage of similar birds.[10] Flowers compete for pollinators and adaptations reduce deleterious effects of this competition.[10] Bird-pollinated flowers usually show higher nectar volumes and sugar production.[11] This reflects high energy requirements of the birds.[11] Energetic criteria are the most important determinants of flower choice by birds.[11] Following their respective breeding seasons, several species of hummingbirds co-occur in North America, and several hummingbird flowers bloom simultaneously in these habitats. These flowers seem to have converged to a common morphology and color.[11] Different lengths and curvatures of the corolla tubes can affect the efficiency of extraction in hummingbird species in relation to differences in bill morphology.[11] Tubular flowers force a bird to orient its bill in a particular way when probing the flower, especially when the bill and corolla are both curved; this also allows the plant to place pollen on a certain part of the bird's body.[11] This opens the door for a variety of morphological co-adaptations.

An important requisite for attraction is conspicuousness to birds, which reflects the properties of avian vision and habitat features.[11] Birds have their greatest spectral sensitivity and finest hue discrimination at the long wavelength end of the visual spectrum.[11] This is why red is so conspicuous to birds. Hummingbirds may also be able to see ultraviolet "colors" (Stiles 1981). The prevalence of ultraviolet patterns and nectar guides in nectar-poor entomophilous flowers allows the bird to avoid these flowers on sight.[11] Two subfamilies in the family Trochilidae are Phaethorninae and Trochlinae. Each of these groups has evolved in conjunction with a particular set of flowers. Most Phaethorninae species are associated with large monocotyledonous herbs, and members of the subfamily Trochilinae are associated with dicotyledonous plant species.[11]

Angracoid orchids and African moths

Another example of coevolution is pollination of Angraecoid orchids by African moths. These species coevolve because the moths are dependent on the flowers for nectar and the flowers are dependent on the moths to spread pollen so they can reproduce. The evolutionary process has led to deep flowers and moths with long probosci.

Old World Swallowtail and Fringed Rue

An example of Antagonistic Coevolution is the Old World Swallowtail (Papilio machaon) caterpillar which lives on Fringed Rue (Ruta chalepensis) plant. Rue plant produces etheric oils which repel plant-eating insects. The Old World Swallowtail caterpillar developed resistance to these poisonous substances, thus reducing competition of other plant-eating insects.

 
Old World Swallowtail (Papilio machaon) caterpillar on Fringed Rue (Ruta chalepensis) plant

Garter snake and Rough-skinned newt

Coevolution can occur between predator and prey species as in the case of the Rough-skinned Newt (Taricha granulosa) and the common garter snake (Thamnophis sirtalis). In this case, the newts produce a potent nerve toxin that concentrates in their skin. Garter snakes have evolved resistance to this toxin through a set of genetic mutations, and prey upon the newts. The relationship between these animals has resulted in an evolutionary arms race that has driven toxin levels in the newt to extreme levels. This is an example of co-evolution because both organisms changed to better increase their chance of survival

California buckeye and pollinators

When bee-hives are kept whose bee species that have not coevolved with the California Buckeye, toxicity to aesculin, a neurotoxin present in the flower nectar of the Aesculus californica tree may be noted; this toxicity is only thought to be present in the case of honeybees and other insecta, which species did not coevolve with A. californica.[12]

Acacia ant and Swollen thorn acacia tree

The ant (Pseudomyrmex ferruginea) provides protection for the tree (Acacia cornigera) against preying insects and other plants competing for sunlight, and the tree provides nourishment and shelter for the ant and the ants' larvae.[13][14] Nevertheless, some ant species can exploit tree rewards without reciprocating and thus have been branded with a myriad of not-very-flattering names such as 'cheaters', 'exploiters', 'robbers', and 'freeloaders'. Although cheater ants impose important host costs via damage to tree reproductive organs, their net effect on host fitness is not necessarily negative and, thus, becomes difficult to forecast.[15]

Yucca Moth and the yucca plant

 
A flowering yucca plant that would be pollinated by a yucca moth

In this mutualistic symbiotic relationship, the yucca plant (Yucca whipplei) is pollinated exclusively by species of yucca moths (Tegeticula maculata). These moths also rely on the yucca plant for survival.[16] Yucca moths tend to only visit the flowers of one species of yucca plant. In the flowers, the yucca moth eats the seeds of the yucca plant, while at the same time gathering pollen on special mouth parts. The pollen of the yucca plant is very sticky, and will easily remain on these parts when the moth moves to the next flower. The yucca plant also provides a place for the yucca moth to lay its eggs, deep within the flower. This protects the eggs from any potential predators.[17] The adaptations that both species exhibit characterize co-evolution because the species have evolved to become dependent on each other.

Technological coevolution

Computer software and hardware can be considered as two separate components but tied intrinsically by coevolution. Similarly, operating systems and computer applications, web browsers and web applications. All of these systems depend upon each other and advance step by step through a kind of evolutionary process. Changes in hardware, an operating system or web browser may introduce new features that are then incorporated into the corresponding applications running alongside.

Bibliography

See also

References

  1. ^ Yip; Patel, P; Kim, PM; Engelman, DM; McDermott, D; Gerstein, M; et al. (2008). "An integrated system for studying residue coevolution in proteins". Bioinformatics. 24 (2): 290–292. doi:10.1093/bioinformatics/btm584. PMID 18056067. {{cite journal}}: Explicit use of et al. in: |author= (help)
  2. ^ Sahney, S., Benton, M.J. and Ferry, P.A. (2010). "Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land" (PDF). Biology Letters. 6 (4): 544–547. doi:10.1098/rsbl.2009.1024. PMC 2936204. PMID 20106856.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Thompson 1994, pp. 24–27
  4. ^ Darwin 1859, pp. 94–95
  5. ^ Darwin 1862, pp. 1–4, 197–203
  6. ^ C.Michael Hogan. 2010. Virus. Encyclopedia of Earth. Editors: Cutler Cleveland and Sidney Draggan
  7. ^ Lodé, Thierry (2007). La guerre des sexes chez les animaux, une histoire naturelle de la sexualité. Paris: Odile Jacob. ISBN 2738119018.
  8. ^ Britt, Robert. "The New History of Black Holes: 'Co-evolution' Dramatically Alters Dark Reputation".
  9. ^ G. S. van Doorn, F. J. Weissing (2002). "Ecological versus Sexual Selection Models of Sympatric Speciation: A Synthesis" (online, print). Selection. 2 (1–2). Budapest, Hungary: Akadémiai Kiadó: 17–40. doi:10.1556/Select.2.2001.1-2.3. ISBN 1588-287X. ISSN 1585-1931. Retrieved 2009-09-15. The intuition behind the occurrence of evolutionary branching of ecological strategies in resource competition was confirmed, at least for asexual populations, by a mathematical formulation based on Lotka–Volterra type population dynamics. (Metz et al., 1996). {{cite journal}}: Check |isbn= value: length (help); Unknown parameter |month= ignored (help)
  10. ^ a b Brown James H., Kodric-Brown Astrid (1979). "Convergence, Competition, and Mimicry in a Temperate Community of Hummingbird-Pollinated Flowers". Ecology. 60 (5): 1022–1035. doi:10.2307/1936870.
  11. ^ a b c d e f g h i j Stiles, F. Gary (1981). "Geographical Aspects of Bird Flower Coevolution, with Particular Reference to Central America". Annals of the Missouri Botanical Garden. 68 (2): 323–351. doi:10.2307/2398801.
  12. ^ C. Michael Hogan (2008) California Buckeye: Aesculus californica, GlobalTwitcher.com, N. Stromberg ed.
  13. ^ National Geographic. "Acacia Ant Video".
  14. ^ See also Acacia: Symbiosis
  15. ^ Palmer TM, Doak DF, Stanton ML, Bronstein JL, Kiers ET, Young TP, Goheen JR, Pringle RM (2010). "Synergy of multiple partners, including freeloaders, increases host fitness in a multispecies mutualism". Proceedings of the National Academy of Sciences of the United States of America. 107 (40): 17234–9. doi:10.1073/pnas.1006872107. PMC 2951420. PMID 20855614.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ^ Hemingway, Claire (2004). "Pollination Partnerships Fact Sheet" (PDF). Flora of North America: 1–2. Retrieved 2011-02-18. Yucca and Yucca Moth
  17. ^ Pellmyr, Olle (1999-08). "Forty million years of mutualism: Evidence for Eocene origin of the yucca-yucca moth association" (PDF). Proc. Natl. Acad. Sci. USA. 96 (16): 9178–9183. doi:10.1073/pnas.96.16.9178. PMC 17753. PMID 10430916. Retrieved 2011-02-18. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

Further reading

  • Futuyma, D. J. and M. Slatkin (editors) (1983). Coevolution. Sunderland, Massachusetts: Sinauer Associates. pp. 555 pp. ISBN 0878932283. {{cite book}}: |author= has generic name (help)
  • Thompson, J. N. (1994). The Coevolutionary Process. Chicago: University of Chicago Press. pp. 376 pp. ISBN 0226797597.
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