Global Change Ecology (BIO347)

Predicting the consequences of human impact a changing biosphere, implications of the lack of species knowledge.

by Trond R. Oskars

Many species and Biodiversity (1) as a whole is currently under a lot of pressure, not only climate change (2, 3, 4), but also increased direct interference by humans (5, 6, 7, 8, 9). This may lead to extinction events, severe shifts in species interactions and ecosystem composition (10, 11, 12). Due to this assessing current and past biodiversity and understanding their interactions and responses to stressors have become more important to try to predict the outcome of the ongoing human driven change of the biosphere (13, 14).

It is a known problem that there are large gaps in the fossil record (14), the older the rocks the bigger the chance that older fossils will not survive to be discovered and cannot be expected to match the diversity represented in more recent fossil assemblages (14, 15, 16). However the fossil record can still tell us a lot about long time stability of organism groups and ecosystems (14, 16), thus gives us the board picture of the effect of stressors comparable to human actions. However for a more detailed view we need data from living species (14).

Here we encounter an additional problem the lack of knowledge of extant species of many groups. About 1.2 to 1.9 million species have been formally described and given a name (17, 18). The number of species that currently exist in the world (not counting bacteria and their kin) varies by the method used, but is has been estimated as high as 8.7 million (18, 19). This leaves the majority (over 80%) of all species unknown or unnamed (20).

This opens for the possibility that species may fail to be recognized, discovered or described before being driven to extinction (13, 18). Even for relatively well known ecosystems (tropical forests) and well-studied animals (vertebrates; amphibians) there are likely still undiscovered species (18, 21, 22, 23, 24). This means that the number of undescribed species may be even higher for unexplored or inaccessible areas or taxa[1].

This also means that we in most cases know little about their roles in the ecosystem, how they interact with other species, and how the extinction may affect the ecosystem as whole.

Describing species takes a long time, averagely 21 years! (20). Much due to the shortage of taxonomists and that most species are rare and only represented by single specimens, leading to many researchers waiting until they have more specimens available[2] (20, 25). Museum collections are reservoirs of many undescribed species, sampled in bulk on long ago expeditions and many of which may already be extinct (20). Another factor is that most taxonomists don’t live in developing countries where Biodiversity is highest (20, 26). Many species can also be relatively well known by those who do live there (23), but have never been formally described or studied in other contexts. If no one has studied a species, how can we know if it is a common, widespread species or a group of similar endemic species? This is especially problematic in cases where their most well-known quality is that they are especially tasty with soy sauce (27*[3]).

 

 

There is an additional dimension to this, what about the already described species? Does everybody agree on what a species is? (This is even further complicated by species concepts).

The problem is how we define what a species is, the method used, and the disagreement between these. Many taxonomists and sytematicists rely either on morphology or DNA to define species. Either they don’t trust one method, or they don’t have a choice, like paleontologists (28) or those researching cryptic species[4] (29).

However, In some cases convergent evolution[5] can make unrelated taxa that have some habits or habitats in common to seem closely related by morphology (30, 31) or populations that seem identical may in fact be evolutionary distinct (32) This may lead to conflict between methods and lead to bad taxonomy in the form of wrongful synonyms[6] (many taxa lumped into one) or undiscovered synonyms (one taxa counted as several). Mora et al. (18) asked 2938 taxonomists about what they felt could limit taxonomic effort[7], most answered synonyms as a major problem on the species level even if did not affect higher taxonomic levels drastically. So likely the general trends in taxa response to stressors can be trusted, but on the species level this resolution may be lacking.

 

How to define speices can wary form disiplines to the methods used within the disiplines.

 

This can be highly problematic in conservation of Biodiversity and ecosystem services. A study by Prie et al. (33) on the freshwater clams Unio in Europe, found three distinct species and several distinct sub species based on DNA. This group is riddled with synonyms based on morphology, which has impacted the conservation status of the species, leading to some of the groups to be isolated and population reduced due to human activities (33).

This lack of knowledge is dangerous as it reduces our ability to conserve species or communities that may be potentially important for ecosystem function (24, 33, 34, 35). Additionally, if enough species are not properly recognized we cannot see the complete picture of biodiversity patterns or estimate extinction rates (21, 24). It also makes it difficult to transform the scientific data into information that can be used by legislators who decide on conservation and the people who actually live alongside the species (however some manage *).

We stand to lose important ecosystem processes and services that may in turn harm other species, or even come to affect human populations (21, 34, 36, 37). Basically we don’t really know what we have lost until it is gone. Due to this it would beneficial not only to protect areas that we know to be especially biodiverse, but also areas that are relatively unexplored or less disturbed by humans, as there are likely a high diversity of undescribed species there (24).

References

 

1. Wilson, E. O. (1988). The current state of biological diversity. In Biodiversity, E.O. Wilson & F.M. Peters, (Eds). 3-18 PP. Washington, DC: National Academy Press. Accessed at http://www.ncbi.nlm.nih.gov/books/NBK219273/ at 20.02.16
2. Walther, G. R., Post, E., Convey, P., Menzel, A., Parmesan, C., Beebee, T. J., et al., & Bairlein, F. (2002). Ecological responses to recent climate change. Nature, 416(6879), 389-395.
3. Walther, G. R. (2010). Community and ecosystem responses to recent climate change. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 365(1549), 2019-2024.
4. Parmesan, C. (2006). Ecological and evolutionary responses to recent climate change. Annual Review of Ecology, Evolution, and Systematics, 637-669.
5. Alongi, D. M. (2002). Present state and future of the world’s mangrove forests. Environmental conservation, 29(03), 331-349.
6. Stuart, S. N., Chanson, J. S., Cox, N. A., Young, B. E., Rodrigues, A. S., Fischman, D. L., & Waller, R. W. (2004). Status and trends of amphibian declines and extinctions worldwide. Science, 306(5702), 1783-1786.
7. Brook, B. W., Sodhi, N. S., & Bradshaw, C. J. (2008). Synergies among extinction drivers under global change. Trends in Ecology & Evolution, 23(8), 453-460
8. Butchart, S. H., Walpole, M., Collen, B., Van Strien, A., Scharlemann, J. P., Almond, R. E, et al. & Carpenter, K. E. (2010). Global biodiversity: indicators of recent declines. Science, 328(5982), 1164-1168.
9. Polidoro, B. A., Carpenter, K. E., Collins, L., Duke, N. C., Ellison, A. M., Ellison, J. C., et al. & Livingstone, S. R. (2010). The loss of species: mangrove extinction risk and geographic areas of global concern. PloS one, 5(4), e10095.
10. Vitousek, P. M., Mooney, H. A., Lubchenco, J., & Melillo, J. M. (1997). Human domination of Earth’s ecosystems. Science, 277(5325), 494-499.
11. Chapin III, F. S., Zavaleta, E. S., Eviner, V. T., Naylor, R. L., Vitousek, P. M., Reynolds, H. L., et al. & Mack, M. C. (2000). Consequences of changing biodiversity. Nature, 405(6783), 234-242.
12. Van der Putten, W. H., Macel, M., & Visser, M. E. (2010). Predicting species distribution and abundance responses to climate change: why it is essential to include biotic interactions across trophic levels. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 365(1549), 2025-2034.
13. Stork, N. E. (1993). How many species are there?. Biodiversity & Conservation, 2(3), 215-232.
14. Blois, J. L., Zarnetske, P. L., Fitzpatrick, M. C., & Finnegan, S. (2013). Climate change and the past, present, and future of biotic interactions. Science, 341(6145), 499-504.
15. Raup, D. M. Taxonomic diversity during the Phanerozoic. Science 177, 1065–1071 (1972).
16. Benton, M. J., Wills, M. A., & Hitchin, R. (2000). Quality of the fossil record through time. Nature, 403(6769), 534-537.
17. Chapman, A. D. Numbers of living species in Australia and the world. (2009): 1-78 PP. Report for the Australian Biological Resources Study. Canberra, Australia. Available form https://www.environment.gov.au/system/files/pages/2ee3f4a1-f130-465b-9c7a-79373680a067/files/nlsaw-2nd-complete.pdf accessed on 20.02.16.
18. Mora, C., Tittensor, D. P., Adl, S., Simpson, A. G., & Worm, B. (2011). How many species are there on Earth and in the ocean?. PLoS Biol, 9(8), e1001127.
19. May, R. M. (2011). Why worry about how many species and their loss?. PLoS Biol, 9(8), e1001130.
20. Fontaine, B., Perrard, A., & Bouchet, P. (2012). 21 years of shelf life between discovery and description of new species. Current Biology, 22(22), R943-R944.
21. Ceballos, G., & Ehrlich, P. R. (2009). Discoveries of new mammal species and their implications for conservation and ecosystem services. Proceedings of the National Academy of Sciences, 106(10), 3841-3846.
22. Geissmann, T., Lwin, N., Aung, S. S., Aung, T. N., Aung, Z. M., Hla, T. H., Grindley, M., Momberg, F. (2011). A new species of snub‐nosed monkey, Genus Rhinopithecus Milne‐Edwards, 1872 (Primates, Colobinae), from northern Kachin State, northeastern Myanmar. American Journal of Primatology, 73(1), 96-107.
23. Hart, J. A., Detwiler, K. M., Gilbert, C. C., Burrell, A. S., Fuller, J. L., Emetshu, M., Hart, T. B., Vosper, A., Sargis, E. J, Tosi, A. J. (2012). Lesula: a new species of Cercopithecus monkey endemic to the Democratic Republic of Congo and implications for conservation of Congo’s Central Basin. PLoS One, 7(9), e44271.
24. Giam, X., Scheffers, B. R., Sodhi, N. S., Wilcove, D. S., Ceballos, G., & Ehrlich, P. R. (2012). Reservoirs of richness: least disturbed tropical forests are centres of undescribed species diversity. Proceedings of the Royal Society of London B: Biological Sciences, 279(1726), 67-76.
25. Lim, G. S., Balke, M., & Meier, R. (2012). Determining species boundaries in a world full of rarity: singletons, species delimitation methods. Systematic biology, 61(1), 165-169.
26. Gaston, K. J., May, R. M.(1992). Taxonomy of taxonomists. Nature, 356, 281-282.
27. Lim K. K. P., Murphy D. H, Morgany, T., Sivasothi, N.,Ng P. K. L. Soong, B. C.,. Tan, H. T. W, Tan, K. S., Tan, T. K. A (1999) Guide to Mangroves of Singapore Peter K. L. Ng and N. Sivasothi (ed). BP Guide to Nature Series published by the Singapore Science Centre, sponsored by British Petroleum. Raffles Museum of Biodiversity Research, The National University of Singapore & The Singapore Science Centre. Online excerpt: http://mangrove.nus.edu.sg/guidebooks/text/2088.htm accessed on 19.02.16
28. Kaiser, G., Watanabe, J., & Johns, M. (2015). A new member of the family Plotopteridae (Aves) from the late Oligocene of British Columbia, Canada. Palaeontologia Electronica, 18(3), 1-18
29. Jörger, K. M., & Schrödl, M. (2013). How to describe a cryptic species? Practical challenges of molecular taxonomy. Frontiers in Zoology, 10(1), 1.
30. May, R. M. (1990). Taxonomy as destiny. Nature, 347(6289), 129-130.
31. Oskars, T. R., Bouchet, P., & Malaquias, M. A. E. (2015). A new phylogeny of the Cephalaspidea (Gastropoda: Heterobranchia) based on expanded taxon sampling and gene markers. Molecular phylogenetics and evolution, 89, 130-150.
32. Hebert, P. D., Penton, E. H., Burns, J. M., Janzen, D. H., & Hallwachs, W. (2004). Ten species in one: DNA barcoding reveals cryptic species in the neotropical skipper butterfly Astraptes fulgerator. Proceedings of the National Academy of Sciences of the United States of America, 101(41), 14812-14817.
33. Prié, V., Puillandre, N., & Bouchet, P. (2012). Bad taxonomy can kill: molecular reevaluation of Unio mancus Lamarck, 1819 (Bivalvia: Unionidae) and its accepted subspecies. Knowledge and Management of Aquatic Ecosystems, (405), 08.
34. Suzán, G., Marcé, E., Giermakowski, J. T., Mills, J. N., Ceballos, G., Ostfeld, R. S., Armien, B,. Pascale, J. M.,Yates, T. L. (2009). Experimental evidence for reduced rodent diversity causing increased hantavirus prevalence. PloS one, 4(5), e5461
35. Mace, G. M. (2004). The role of taxonomy in species conservation. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 359(1444), 711-719.
36. Worm, B., Barbier, E. B., Beaumont, N., Duffy, J. E., Folke, C., Halpern, B. S.,. Jackson J. B. C, Lotze, H. K., Micheli, F., Palumbi, S. R., Sala, E., Selkoe, K. A., Stachowicz, J. J., Watsom, R. (2006). Impacts of biodiversity loss on ocean ecosystem services. Science, 314(5800), 787-790.
37. Dugan, P. J., Barlow, C., Agostinho, A. A., Baran, E., Cada, G. F., Chen, D., et al. & Marmulla, G. (2010). Fish migration, dams, and loss of ecosystem services in the Mekong basin. Ambio, 39(4), 344-348.

 

[1] Taxa- A group of individuals or species that due to one or several methods are seen my Taxonomists or sytematicists to form one discernable unit and given a name.

[2] I have more than once spent two whole days dissecting a specimen less than 1 mm long as it was the only one available.

[3] I am revising the taxonomy of this group, current knowledge is next to none.

[4] Cryptic species- A species that is molecular distinct, but more or less impossible to separate form related species based on morphology.

[5] Convergent evolution- When evolution drives two species that are unrelated to gain a similar morphology, for example due to living in a similar habitat, also possible for related, but not closely related species trough parallel evolution.

[6] Synonymy- Basically when one taxa is regarded as the same as another and the most recent name must be replaced by the oldest available name.

[7] Taxonomic effort- Species discovery rates and to some degree the number of taxonomist working on a group (18).