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Are there more species emerging or more species becoming extinct?
What are the new animal or plant species that scientist identified?
What defines a new species?
What defines a new species?
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Under equilibrium conditions, the emergence rate of new species should roughly equal the extinction rate. The total number of species on Earth is unknown, but 50 million is a mid-range estimate, and the background extinction rate as determined from the fossil record is about one in a million species per year. Therefore, on average, about 50 new species would be expected to emerge annually while 50 other species become extinct. At the present time, however, the global extinction rate is about one every 20 minutes. The baseline annual total of 50 is reached in less than 17 hours, and the annual total is over 500,000 species, most of which have never been catalogued.
http://hypertextbook.com/facts/2003/FelixNisimov.shtml
http://www.pbs.org/wgbh/evolution/library/03/2/l_032_04.html
http://www.sciencedaily.com/releases/2002/01/020109074801.htm
The "new" species that continue to be discovered aren't necessarily new in the sense of having recently evolved. Many parts of the world are still relatively unexplored in terms of their biodiversity, and many species are highly localized in distribution, so a thorough sampling almost anywhere can turn up a previously unknown species. (A group of students in my undergraduate parasitology class found one in the local shark they were assigned to dissect.) Science Daily has a "New Species News" page with information on the latest discoveries.
http://www.sciencedaily.com/news/plants_animals/new_species/
The basic definition of a species is a group of organisms which interbreed and produce fertile offspring in the wild. However, this definition is somewhat vague and does not entirely take into account modern genetics. If a species becomes split into two isolated populations by some natural disaster, when do the separate groups become separate species? As soon as the natural barrier forms, the groups are unable to interbreed in the wild, but they may be genetically identical until differing environmental factors have selected for different traits in the two groups. The Wikipedia article actually gives a pretty good discussion of the "species problem."
http://en.wikipedia.org/wiki/Species
http://en.wikipedia.org/wiki/Species_problem
http://hypertextbook.com/facts/2003/FelixNisimov.shtml
http://www.pbs.org/wgbh/evolution/library/03/2/l_032_04.html
http://www.sciencedaily.com/releases/2002/01/020109074801.htm
The "new" species that continue to be discovered aren't necessarily new in the sense of having recently evolved. Many parts of the world are still relatively unexplored in terms of their biodiversity, and many species are highly localized in distribution, so a thorough sampling almost anywhere can turn up a previously unknown species. (A group of students in my undergraduate parasitology class found one in the local shark they were assigned to dissect.) Science Daily has a "New Species News" page with information on the latest discoveries.
http://www.sciencedaily.com/news/plants_animals/new_species/
The basic definition of a species is a group of organisms which interbreed and produce fertile offspring in the wild. However, this definition is somewhat vague and does not entirely take into account modern genetics. If a species becomes split into two isolated populations by some natural disaster, when do the separate groups become separate species? As soon as the natural barrier forms, the groups are unable to interbreed in the wild, but they may be genetically identical until differing environmental factors have selected for different traits in the two groups. The Wikipedia article actually gives a pretty good discussion of the "species problem."
http://en.wikipedia.org/wiki/Species
http://en.wikipedia.org/wiki/Species_problem
tags: extinction, species
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voted helpful: mithrandir, chriswingate, buddawiggi
It depends on whether or not you mean multicellular, eukaryote based plants and animals only, or if you are including single-celled prokaryotes as well.
If you mean plants and animals only, then currently they are disappearing much faster than are new ones emerging, but if you include single-celled prokaryotes, commonly known as bacteria and blue-green algea - then they are appearing quickly, as they always do, because prokaryotes are in a perpetual state of mutation, such that they'll move into any niche as soon as it becomes available.
In other words, today, plants and animals are disappearing faster than at any time since the meteor that destroyed the dinosaurs, and the ecological niches they occupy are being moved in on by new species of bacteria and blue-green algea.
If you mean plants and animals only, then currently they are disappearing much faster than are new ones emerging, but if you include single-celled prokaryotes, commonly known as bacteria and blue-green algea - then they are appearing quickly, as they always do, because prokaryotes are in a perpetual state of mutation, such that they'll move into any niche as soon as it becomes available.
In other words, today, plants and animals are disappearing faster than at any time since the meteor that destroyed the dinosaurs, and the ecological niches they occupy are being moved in on by new species of bacteria and blue-green algea.
What species have emerged in the last million years?
What species have shown up in the last million years?
Homo sapiens for one.
Homo sapiens for one.
A great example of how adaptive bacteria are:
The Microbacterium hatanonis has recently been discovered, and has a very unique living habitat: Inside hairspray!
(Source : http://www.wired.com/wiredscience/2009/05/strangespecies/)
http://www.wired.com/images_blogs/wiredscience/2009/05/hairspray.jpg
The Microbacterium hatanonis has recently been discovered, and has a very unique living habitat: Inside hairspray!
(Source : http://www.wired.com/wiredscience/2009/05/strangespecies/)
More species are becoming extinct. The chinese cycas was considered endangered as soon as it was discovered in 1996.The Indigo Macaw is endangered in part from livestock trampling.More than1,000 new plant and animal species have been discovered in Thailand.In a ten year period naturalist found 519 plants,279 fish,88 frogs,88spiders,46 lizards,22 snakes,15 mammals,four birds,four turtles,two salamanders and one toad.
A new species is a group of actually or potentially interbreeding individuals reproductively isolated from other such groups.All individuals
will meet a certain phenetic criteria.It includes all individuals who are similiar to one another and distinct from other such groups.
A new species is a group of actually or potentially interbreeding individuals reproductively isolated from other such groups.All individuals
will meet a certain phenetic criteria.It includes all individuals who are similiar to one another and distinct from other such groups.
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So this discussion quickly turns into the eternal philosophical question:"If a tree falls over, and no-one heard or saw it fall, did it actually fall?"
Expect a AotD nomination later today for this answer.