Coevolution describes the case in which two or more species affect each other’s’ evolution. For example Charles Darwin talked of coevolution between insects and flowering plants. Coevolution presents itself in many forms such as: host-parasite relationships, predator prey relationships and mutualism. In the sections below coevolution evidences will be discussed as manifested through mutualism. Thus mutualism is coevolution in which the species affect each other’s evolution while forming a mutualistic relationship.
Animal and Flowering Plant Mutualism
There are several evidences indicating coevolution through mutualism. The animal and flowering plants relationship is an example of coevolution through mutualism. This is so considering nearly three quarters of all angiosperms (flowering plants) are pollinated by animals. These animals are majorly insects such as bees and butterflies, birds and bats. Plants are pollinated through the interaction with the animals with the animal gains from the plants varying according to the animal. Birds receive food in form of pollen from the plants while bees use the resins and waxes from the flowers to build their hives. Bees further use some compounds from flowers such as orchids to attract mates. Some insects such as the yucca moth lays eggs in the flowers they interact with the seeds produced acting as food for the developing moth larvae (Landry, 2010).
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It is clear to see that the species above have coevolved over time in order to be able to mutually coexist. There are several aspects of this mutualism that show this coevolution. First the fact that flowers communicate with their pollinators through sense shows coevolution. Second the flowers have developed stripes leading to the nectar and pollen to attract the pollinators. Insects are particularly responsive to blue and ultra-violet, whereas birds respond to red and orange. Third, blooming time of flowers has been shown to coincide with hummingbirds’ breeding season (Sharp, n.d).
The Acacia Plant and Ant Mutualism
Additionally, the association between the acacia plants and the ants shows coevolution through mutualism. Acacia plants provide food through nectar and accommodation through hollow thorns that can be used as nests for the ants. The ants in return protect the acacia plants from herbivores. It has further been found that the presence of ants reduces bacterial content on the surface of the leaves keeping the leaf pathogens in check. For example, the Acacia hindsii species of the native tropical dry forests of Central America exhibits mutualism with ants of the genus Pseudomyrmex (ScienceDaily, 2014).
Acacia plants have developed some features in order to keep the ant colony from starving or from migrating to other acacia plants. The plants are woody with a very high growth rate and a rapid year round sucker production. The plants usually have green leaves throughout the years and are the last to shed their leave in a dry season just so as to keep the ant colony intact (Jahnzen, 257).
Among the factors postulating the ants’ commitment to this mutualism is their aggressive attacks on all species attempting to grow bellow the swollen thorn acacia. The ants further kill seedlings acacias unless they have swollen thorns or nectaries. It is this ruthlessness that is proof for the existence of coevolution in this mutualism (Jahnzen, 266).
The Fig Tree and Fig Wasp Mutualism
The wasp (Ceratosolen fusciceps) and fig species (Ficus racemosa) relationship is one of the oldest examples of coevolution through mutualism. The mutualistic cycle begins with the female fig wasps (foundress) entering the syconia (an inflorescent structure of the fig tree). The wasps pollinate a portion of female flowers, with the pollen from other fig trees while laying eggs into others. The eggs and the pollinated flowers then begin to develop. After maturity the wasp offspring emerge from the larval galls and collect pollen from male flowers. The males mate and fertilize the females who in turn leave the syconia with the collected pollen in search of a new syconia for the cycle to repeat again. The males will spend their entire life in a single fruit (Kline, 2011).
Coevolution is evident in this mutualistic relationship since the reproductive cycles of the wasps and the figs are synchronized.
The Spider Crab and Algae Mutualism
The spider resides in shallow areas of the ocean floor. It is susceptible to several predator attacks. Luckily, the algae, which are greenish or brownish in color reside on the crab’s back camouflaging it from predators view. The crab gains security benefits as the algae gains habitat (Gill, 2015).
Algae generally grow at a slower rate compared to plant species. Although algae is herbivore resistant, in areas with low herbivore population such as shores, algae are quickly outgrown. Thus Algae attach themselves to herbivores such as crabs that help reduce its competition from plants such as sea weeds (Stachowicz & Hay, 383).
In return the spatial complexity, shape and color of the algae benefits the crabs who are able to camouflage from predators such as fish and sharks. The unpalatability of some algae also helps reduce predation of the crabs (Stachowicz & Hay, 384).
References
Gill A., Rupneet & Kiran (2015). Prezi. Mutualism between a spider crab & algae. Retrieved from https://prezi.com/m/lq_uzns9rty9/mutualism-between-a-spider-crab-algae/
Jahnzen D. (1996). Coevolution of Mutualism Between Ants and Acacias in Central America. Evolution, Vol. 20, No. 3. (Sep, 1996), pp. 249-275. Retrieved from https://links.jstor.org/sici?sici=0014-3820%28196609%2920%3A3%3C249%3ACOMBAA%3E2.0.CO%3B2-%23
Kline K., (2011). The Story of the fig and its wasp. Ecological Society of America. Retrieved from https://www.esa.org/esablog/research/the-story-of-the-fig-and-its-wasp/
Landry C. (2010). Mighty mutualisms: The Nature of Plant-pollinator Interactions. The natureEducation Knowledge Project. Retrieved from https://www.nature.com/scitable/knowledge/library/mighty-mutualism-the-nature-of-plant-pollinator-13235427
ScienceDaily (2014).Ants protect acacia plants against pathogens.Max Planck Institute for Chemical Ecology. Retrieved from https://www.sciencedaily.com/releases/2014/01/140115113243.htm
Sharp J. (n.d).Coevolution and Mutualism in Biology. DesertUSA. Retrieved from https://www.desertusa.com/insects/coevolution-mutualism.html
Stachowicz J. & Hay M (1995). Facultative mutualism between an herbivorous crab and a coralline alga: advantages of eating noxious seaweeds. Received: May 1, 1995/ Accepted: September 11, 1995. Retrieved April 30, 2018.
