Species in the Coleoptera have a hard exoskeleton, particularly on their forewings ( elytra, singular elytron ).

Species have functional traits that are uniquely adapted to the ecological niche.

The decisions of the Supreme Court in cases such as Calvert Cliffs Coordinating Committee v. U. S. Atomic Energy Commission ( broadly reading the procedural requirements of the National Environmental Policy Act ), Tennessee Valley Authority v. Hill ( broadly reading the Endangered Species Act ), and, much more recently, Massachusetts v. EPA ( requiring EPA to reconsider regulation of greenhouse gases under the Clean Air Act ) have had policy impacts far beyond the facts of the particular case.

In The Origin of Species, he wrote, " If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.

Studies of Charles Darwin's notebooks have shown that Darwin arrived separately at the idea of natural selection which he set out in his 1859 book On the Origin of Species, but it has been speculated that he may have had some half-forgotten memory from his time as a student in Edinburgh of ideas of selection in nature as set out by Hutton, and by William Charles Wells and Patrick Matthew who had both been associated with the city before publishing their ideas on the topic early in the 19th century.

Species in this order typically have the following characteristics, although there are exceptions to all of them:

Species ( often dubious ones now known to be based on sexual variation or juvenile characters ) have been reclassified a number of times, and several sub-genera have in the 1970s been erected by Halsey Wilkinson Miller to hold them in various combinations, further confusing the taxonomy ( subgenera include Longicepia, Occidentalia, and Geosternbergia ).

It is often incorrectly assumed that he insisted that the rate of change must be constant, or nearly so, but even the first edition of On the Origin of Species states that " Species of different genera and classes have not changed at the same rate, or in the same degree.

In the fourth edition ( 1866 ) of On the Origin of Species Darwin wrote that " the periods during which species have undergone modification, though long as measured in years, have probably been short in comparison with the periods during which they retain the same form.

However, these conclusions have been disputed, and Mammal Species of the World currently lists them both as subspecies of the gray wolf.

Stephen Hawking and Christopher Langan argue that the egg came before the chicken, though the real importance of the question has faded since Darwin's On the Origin of Species and the accompanying Theory of Evolution, under which the egg must have come first, assuming the question intended the egg to mean an egg in general or an egg that hatches into a chicken.

Species of Velociraptor, have also been reported from the slightly younger Barun Goyot Formation of Mongolia, though these are indeterminate and may belong to a related genus instead.

Species of note in the open enclosures include two subspecies of giraffe, rhinos ( the park has the world's most successful breeding program for Southern white rhinos and is the only New World zoo to have Northern white rhinos ), gaur, vultures, markhor, and many species of antelope, gazelle, and deer.

In On the Origin of Species ( 1859 ), Charles Darwin wrote " Although I do not know of any thoroughly well-authenticated cases of perfectly fertile hybrid animals, I have some reason to believe that the hybrids from Cervulus vaginalis and Reevesii [...] are perfectly fertile.

Species often have different mating or courtship patterns or behaviors, the breeding seasons may be distinct and even if mating does occur antigenic reactions to the sperm of other species prevent fertilization or embryo development.

:* Species cumulonimbus capillatus ( Cb cap ): Thunderclouds with very high tops that have become fibrous due to the presence of ice crystals ( C < sub > L </ sub > 9 ).

Species listed under this status by the International Union for Conservation of Nature ( IUCN ) are not known to have any living specimens in the wild, and are maintained only in zoos or other artificial environments.

Species in the genera Allium, Hippeastrum, Narcissus, and Tulipa all have tunicate bulbs.

Species in the Geranium genus have a distinctive mechanism for seed dispersal.

Species of this suborder have antennae but they cannot readily be seen because they lie in grooves in the side of the head.

Species of both genera are native to the area where Greek language and culture originated, though as the word " kedros " does not seem to be derived from any of the languages of the Middle East, it has been suggested the word may originally have applied to Greek species of juniper and was later adopted for species now classified in the genus Cedrus because of the similarity of their aromatic woods.

( 2000 ) Species boundaries in carp gudgeons ( Eleotrididae: Hypseleotris ) from the River Murray, South Australia: evidence for multiple species and extensive hybridization.

Species may be split-listed meaning that some populations of a species are on one Appendix, while some are on another.

Species in the Appendices may be proposed for addition, change of Appendix, or de-listing ( i. e., deletion ) by any Party, whether or not it is a range State and changes may be made despite objections by range States if there is sufficient ( 2 / 3 majority ) support for the listing.

Species close to the last common ancestor of gorillas, chimpanzees and humans may be represented by Nakalipithecus fossils found in Kenya and Ouranopithecus found in Greece.

Species of yeast found in the tea can vary, and may include: Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii and Zygosaccharomyces bailii.

Species in this genus may be part of the heath complex in oak-heath forests in eastern North America.

Species of sea cucumbers with specialized care for their offspring may also nurse the young in body cavities or on their surfaces.

Species that grow into a shrubby habit may be either deciduous or evergreen.

Species may be succulent or not.

Species which may be caught in freshwater include barramundi, tarpon, catfish and tarpin.

Species that move short distances, however, may not need such a timing mechanism, and may move in response to local weather conditions.

Species may also be partly migratory, with northern populations being migratory but more temperate populations being resident ( like the Meadow Pipit in Europe ).

Species may interact once in a generation ( e. g. pollination ) or live completely within another ( e. g. endosymbiosis ).

Species in the Crithagra clade could conceivably be split further into several more ( sub ) genera and may well be once relationships within the clade are better resolved.

Darwin also noted, in On the Origin of Species, that a vestigial structure could be useless for its primary function, but still retain secondary anatomical roles: " An organ serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose, and remain perfectly efficient for the other .... n organ may become rudimentary for its proper purpose, and be used for a distinct object.

All but five species of monitor lizard are classified by CITES ( the Convention on International Trade in Endangered Species of Wild Fauna and Flora ) under Appendix II, which is loosely defined as species that are not necessarily threatened with extinction, but may become so unless trade in such species is subject to strict regulation in order to avoid utilization incompatible with the survival of the species in the wild.

The Barbados Golden Warbler ( D. p. petechia ) is listed as " Endangered Foreign Wildlife " by the United States ' Endangered Species Act ( ESA ) since 1970 ; other than for scientific, educational or conservation purposes ( for which a permit may be available ) importing it into the USA is illegal.

The goal of the recovery program is to conserve and recover the species to the extent that it may be down-listed from endangered to threatened in the near future, and ultimately, that the population be healthy enough to no longer require federal protection under the Endangered Species Act.

Species that nest in marshes must construct a nesting platform in order to keep the nest dry, particularly in species that nest in tidal marshes.

Species used as nest trees vary with region and subspecies.