Tag Archives: new species

How do new species form?

by Piter Kehoma Boll

A long, long time ago, I wrote two posts here about the definition of species, explaining briefly the most important horizontal and vertical species concepts. So we all agree that species exists, but how they emerge? How one species become two, or how one species become another?

The phenomenon by which it occurs is called speciation. Well, sort of… It all depends on how you define a species, actually (so be certain to have read the posts I mentioned above).

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Model of a lineage splitting into two lineages that evolve independently and eventually become separated species. Extracted from Hawlitschek et al. (2012)*

Speciation is usually defined as the evolution of reproductive isolation, therefore it deals more with the concept of biological species, but also with the ecological concept and certainly needs some insights on the vertical concepts. If two populations are reproductively isolated, it means that the individuals of one of them are unable or unwilling to breed with those of the other. This usually arrives through genetic and ecological differences that lead to differences in behavior, morphology, physiology. And considering that, we can classify reproductive isolation into two groups: pre-zygotic and post-zygotic isolation.

In pre-zygotic isolation, the two species are reproductively isolated because they do not want or cannot mate and produce an zygote. This may happen simply because of different behaviors in which the two species occupy different places in the environment, mate at different times of the year or even because they are not sexually attracted to each other. There are several experiments using fruitflies that demonstrate how this may evolve pretty fast.

In the late 1980s, William R. Rice and George W. Salt separated individuals of Drosophila melanogaster depending on their preference for dark × light and wet × dry environments, allowing them to mate only with other specimens showing the same preferences. After several generations, the individuals of one group were unable to mate with those of other groups because of their strong habitat preferences, making them unlikely to interact. A similar experiment was performed by Diane Dodd using the species Drosophila pseudoobscura, in which one population was raised with starch as food and other with maltose as food. In this case, after several generations the flies showed a strong preference to mate with individuals of the same group and to reject those of the other group.

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Evolution of reproductive isolation in fruit flies of the species Drosophila pseudoobscura after several generations fed with different sugars.

Such speciation events are called ecological speciation and are also well-documented in the widl, especially regarding fish preferring different habitats, such as shallow × deep water or still × running water. Eventually the individuals will diverge into two groups that are ecologically isolated in the same environment and consequently become reproductively isolated as well.

Post-zygotic isolation is generally a more advanced form of isolation that indicates deep genetic divergences. This is more commonly associated with the notion of biological species and is based on the inability of the individuals of the two species to produce viable offspring. They may mate with each other and even produce a zygote, but this will be unable to developed into an embryo or the offspring will be sterile or otherwise unable to survive enough to breed. A classical example is the mule, the hybrid of a mare and a donkey that is usully sterile.

Equus

A mare, Equus ferus caballus (left), a donkey, Equus africanus asinus (right) and a mule (center). Photos by ‘Little Miss Muffit’ (flickr.com/people/42562654@N00)(mare), Adrian Pingstone (donkey) and Dario Urruty (mule).

In both forms of speciation mentioned above, reproductive isolation usually arises from the accumulation of small differences due to natural selection. This may be enhanced by two phenomena, pleiotropy and genetic hitchhiking.

Pleiotropy is the phenomen by which a single gene have influence over more than one phenotypic trait. For example, a gene that influences the shape of a bird’s bill may also make it change its diet and its song. Several human genetic diseases, such as phenylketonuria (PKU), are examples of pleiotropy.

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The frizzled trait in chickens, which makes the feather curl outward, also leads to delayed sexual maturity and decreased metabolism rate. Photo by flickr user Just chaos.*

Genetic hitchhiking, on the other hand, is the phenomenon by which a gene that is naturally selected carries neighbours genes that are in the same DNA chain with it. In fruitflies, for example, a gene that is linked to courtship behavior may be drawn with the gene linked to a digestive enzyme, so that flies that specialize in one kind of sugar have a different courtship behavior than others specialized in another sugar.

That’s all for now. In a future post, I’ll talk about the geographic and genetic variables in species formation.

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References and further reading:

Bolnick, D. I., Snowberg, L. K., Patenia, C., Stutz, W. E., Ingram, T. & Lau, O. L. 2009. Phenotype-dependent native habitat preference
facilitates divergence between parapatric lake and stream stickleback. Evolution, 63(8): 2004-2016.

Hendry, A. P.2009. Ecological speciation! Or the lack thereof? Canadian Journal of Fisheries and Aquatic Sciences, 66: 1383-1398.

Hoskin, C. J. & Higgie, M. 2010. Speciation via species interactions: the divergence of mating traits within species. Ecology Letters, 13: 409-420.

Maan, M. E., Hofker, K. D., van Alphen, J. J. M. & Seehausen, O. 2006. Sensory drive in cichlid speciation. The American Naturalist, 167(6):
947-954.

Nosil, P. 2008. A century of evolution: Ernst Mayr (1904-2005). Ernst Mayr and the integration of geographic and ecological factors in
speciation. Biological Journal of the Linnean Society, 95: 26-46.

Turelli, M., Barton, N. H. & Coyne, J. A. 2001. Theory and speciation. TRENDS in Ecology and Evolution, 16(7): 330-343.

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*Creative Commons License
This work is licensed under a Creative Commons Attribution 2.5 Generic License.

**Creative Commons License
This work is licensed under a Creative Commons Attribution 2.0 Generic License.

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New Species: March 11 to 20, 2017

by Piter Kehoma Boll

Here is a list of species described from March 11 to March 20. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

Cherax_warsamsonicus

Cherax warsamsonicus is a new crayfish from Indonesia.

SARs

Plants

Fungi

Flatworms

Annelids

Rotifers

Tardigrades

Arachnids

Myriapods

Crustaceans

Insects

Cartilaginous fishes

Ray-finned fishes

Lissamphibians

Reptiles

Mammals

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New Species: March 1 to 10

by Piter Kehoma Boll

Here is a list of species described from March 1 to March 10. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

Pristimantis_attenboroughi

Pristimantis attenboroughi is a new frog species described in the past 10 days and named in honor of Sir David Attenborough.

SARs

Plants

Fungi

Sponges

Entoprocts

Annelids

Kinorhynchs

Nematomorphs

Nematodes

Arachnids

Myriapods

Crustaceans

Hexapods

Ray-finned fishes

Lissamphibians

Reptiles

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New Species: February 21 to 28

by Piter Kehoma Boll

Here is a list of species described from February 21 to February 28. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

nyctibatrachus_manalari

Nyctibatrachus manalari is a new tiny frog described in the past 8 daysdescribed in the past 8 days.

Bacteria

Plants

Fungi

Sponges

Annelids

Nematods

Arachnids

Crustaceans

Hexapods

Cartilaginous fishes

Ray-finned fishes

Lissamphibians

Mammals

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New Species: February 11 to 20, 2017

by Piter Kehoma Boll

Here is a list of species described from February 11 to February 20. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

pseudomacrochenus_wusuae

Pseudomacrochenus wusuae is a new longhorn beetle described in the past 10 days.

SARs

Plants

Fungi

Nematodes

Arachnids

Myriapods

Crustaceans

Hexapods

Tunicates

Ray-finned  fishes

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New Species: February 1 to 10, 2017

by Piter Kehoma Boll

Here is a list of species described from February 1 to February 10. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

heliconia_berguidoi

Heliconia berguidoi is a new plant species from Panama. Photos by R. Flores and C. Black, seen in the lower picture beside one specimen. (License CC BY 4.0)

Archaeans

Bacteria

SARs

Plants

Fungi

Cnidarians

Flatworms

Annelids

Nematodes

Arachnids

Myriapoda

Crustaceans

Insects

Ray-finned fishes

Reptiles

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New Species: January 21 to 31, 2017

by Piter Kehoma Boll

Here is a list of species described from January 21 to January 31. It certainly does not include all described species. Most information comes from the journals Mycokeys, Phytokeys, Zookeys, Phytotaxa, Zootaxa, International Journal of Systematic and Evolutionary Microbiology, and Systematic and Applied Microbiology, as well as journals restricted to certain taxa.

strigula

Strigula acuticonidiarum (left) and Strigula guangxiensis (right) are two new lichens described in the past 11 days.

Bacteria

SARs

Plants

Fungi and allies

Sponges

Mollusks

Annelids

Bryozoans

Nematodes

Arachnids

Myriapods

Crustaceans

Insects

Cartilaginous fishes

Ray-finned fishes

Reptiles

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