Rates of Evolution

1999 ◽  
Vol 9 ◽  
pp. 319-328
Author(s):  
Steven M. Stanley
Keyword(s):  
New Species ◽  
The Other ◽  
Appreciable Change ◽  
Rate Of Evolution ◽  
Geologic Time ◽  
Other Hand ◽  
Rates Of Evolution ◽  
Or Groups

Any two biologic groups — populations, species, or groups of species — that are separated in time but connected by evolution provide us with the opportunity to measure a rate of evolution.Rates are interesting because they vary greatly. Some species have survived for millions of years without appreciable change. On the other hand, some species have arisen from other, quite different species within just a few thousands or tens of thousands of years: very brief intervals of time. Similarly, some groups of organisms have diversified rapidly, producing many new species during brief intervals of geologic time, whereas others have added new species very slowly.

Did Ground Cover Change Over Geologic Time?

2000 ◽  
Vol 6 ◽  
pp. 171-182 ◽  
Author(s):  
Ben A. LePage ◽  
Hermann W. Pfefferkorn
Keyword(s):  
Fossil Record ◽  
Ground Cover ◽  
The Other ◽  
Detailed Account ◽  
Geologic Time ◽  
The Past ◽  
Other Hand ◽  
Plant Fossil

When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

IV.—On some Freshwater Mollusca from the Pliocene Deposits of East Anglia

1911 ◽  
Vol 8 (9) ◽  
pp. 401-403 ◽  
Author(s):  
A. S. Kennard ◽  
B. B. Woodward
Keyword(s):  
New Species ◽  
Recent Work ◽  
The Other ◽  
East Anglia ◽  
Other Hand ◽  
Differences Of Opinion ◽  
Correct Determination

Non-marine Mollusca are extremely rare in the Pliocene deposits of this country, which fact must always be a matter of regret to the Palæontologist, since they are of the utmost importance in connexion with the origin of our present fauna. Unfortunately, in addition to their rarity, they are often decorticated or fragmentary, whence no doubt the differences in opinion as to their correct determination. A re-examination of all the available material has convinced us that there is still much to be done before it will be possible to reach finality. In these matters so much depends on one's standpoint. If one starts with the preconceived idea that the Pliocene shells must be identical with the recent forms, it is easy enough to identify them, even if one has to go to Japan or Greenland to find its present habitat. If, on the other hand, one considers it better to study carefully the results of recent work on other branches of the fauna, it is obvious that different results will be arrived at. Hence we are quite prepared for any differences of opinion as to the correctness of our views or the wisdom of creating four new species, as we now venture to do.

Rates of Evolution

2002 ◽  
Vol 11 ◽  
pp. 257-264
Author(s):  
Steven M. Stanley
Keyword(s):  
Rate Of Evolution ◽  
Rates Of Evolution ◽  
Or Groups

Any two biologic groups—populations, species, or groups of species—that are separated in time but connected by evolution provide us with the opportunity to measure a rate of evolution.

Braconidae : Notes and new Species

1931 ◽  
Vol 22 (1) ◽  
pp. 75-82 ◽  
Author(s):  
D. S. Wilkinson
Keyword(s):  
New Species ◽  
Posterior Margin ◽  
The Other ◽  
Lateral Carina ◽  
Median Carina ◽  
Other Hand ◽  
Basal Half ◽  
Apical Half

Rhaconotus mahensis, sp. n.♀♂. Black ; scape and all legs red testaceous ; ovipositor bright red ; flagellum red-brown, possibly rather darker at apex ; wings hyaline, the setae with a distinctly fulvous tinge, and the stigma hyaline (at least not darkened).♀♂. The integument is not coriaceous throughout, and is only sparsely clothed with setae (except on the flagellum and possibly the legs). Head smooth and highly shining, not coriaceous, impunctate, the vertex and occiput almost entirely devoid of setae ; antennae longer than head, thorax, and abdomen together ; flagellar joints in ♀ 29–33, in ♂ 26–28. Thorax : mesonotum dully shining, coriaceous ; the notauli well marked, joining slightly before reaching the posterior margin of the mesonotum ; propodeon with five longitudinal carinae, one in the middle and two on each side, these latter rather more closely placed to each other than to the median carina ; this median carina is discernible as such only in the basal half of the propodeon, thereafter becoming lost amongst the reticulate wrinkles with which the apical half of the propodeon abounds ; the lateral carinae, on the other hand, are discernible more or less throughout their length, particularly the inner pair which can generally be traced to the median apex of the propodeon where they join each other ; the integument of the basal half of the propodeon coriaceous on each side of the median carina as far as the first lateral carina, thereafter wrinkled as in the apical half.

The distribution and redistribution of heat-producing elements in the continents

1978 ◽  
Vol 288 (1355) ◽  
pp. 393-400 ◽  
Keyword(s):  
The Other ◽  
Element Content ◽  
Radioactive Element ◽  
Geological Data ◽  
Sialic Crust ◽  
Geologic Time ◽  
Other Hand ◽  
Early Formation ◽  
Constant Rate

Many geological data indicate that most sialic crust is of Archaean (> 2.5 Ga) age. Evidence also seems to agree for an early formation of a ‘protocrust’ concentrating the heat-producing elements. On the other hand if present day production of oceanic tholeiites can be assumed to have been constant through geologic time, and if their radioactive element content is gradually added to the continents, one could argue that the formation of continents has taken place at a reasonably constant rate. After presenting the relevant data the author discusses how the two apparently opposed views may be reconciled, and how secondary processes regulate the distribution of heat-producing elements in the continents.

Encyonema appalachianum (Bacillariophyta, Cymbellaceae), a new species from Western Pennsylvania, USA

Phytotaxa ◽  
2014 ◽  
Vol 184 (2) ◽  
pp. 115 ◽  
Author(s):  
Marina Potapova
Keyword(s):  
New Species ◽  
The Other ◽  
Other Hand ◽  
Type Population ◽  
Western Pennsylvania ◽  
A New Species ◽  
Rivers And Reservoirs

A new species of Encyonema was found in several rivers and reservoirs in Western Pennsylvania, USA, in 2013. The new species, E. appalachianum, has only very slightly dorsiventral valves, which is one of the characters separating the genus Encyonopsis from Encyonema. On the other hand, the long, sharply bent terminal raphe fissures and lateral raphe indicate that it should be placed in Encyonema. Some valves with occasionally biseriate striae have been observed in the type population of the new species. The finding of this species that apparently combines features of both Encyonema and Encyonopsis highlights the problem of poorly defined boundaries between some genera of cymbelloid diatoms.

scholarly journals Notes on the Genus Rhipicephalus, with the Description of New Species, and the Consideration of some Species hitherto described

Parasitology ◽  
1912 ◽  
Vol 5 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Cecil Warburton
Keyword(s):  
New Species ◽  
General Type ◽  
The Other ◽  
Single Individual ◽  
Other Hand ◽  
Identification Of Species ◽  
The One ◽  
Range Of Variation ◽  
A New Species

The identification of species of Rhipicephalus is likely to give more trouble than is the case with any other genus of Ixodidae, for while, on the one hand, there are few species which depart greatly from the general type, on the other hand the range of variation within the species is extremely great. In no genus is it so dangerous to describe a new species from a single individual, especially if the specimen be a female.

Unexplored richness: discovery of 31 new species of Giant Pill-Millipedes endemic to Madagascar, with a special emphasis on microendemism (Diplopoda, Sphaerotheriida)

Zootaxa ◽  
2009 ◽  
Vol 2097 (1) ◽  
pp. 1-134 ◽  
Author(s):  
THOMAS WESENER
Keyword(s):  
New Species ◽  
Dry Forest ◽  
The Other ◽  
Forest Species ◽  
Other Hand ◽  
Littoral Forest ◽  
Species Groups ◽  
Established Species ◽  
One New Species ◽  
Montane Rainforest

Thirty-one new species of giant pill-millipedes (order Sphaerotheriida) endemic to Madagascar are described: Zoosphaerium haackeri n. sp., Z. album n. sp., Z. discolor n. sp., Z. mitoho n. sp., Z. pulchellum n. sp., Z. endemicum n. sp., Z. xerophilum n. sp., Z. aureum n. sp., Z. pseudopriapus n. sp., Z. pseudoplatylabum n. sp., Z. solitarium n. sp., Z. tsingy n. sp., Z. corystoides n. sp., Z. broelemanni n. sp., Z. amabile n. sp., Z. trichordum n. sp., Z. smaragdinum n. sp., Z. ambrense n. sp., Z. isalo n. sp., Z. bilobum n. sp., Z. tampolo n. sp., Z. ignotum n. sp., Z. tainkintana n. sp., Z. viridissimum n. sp., Z. denticulatum n. sp., Z. pseudoblandum n. sp., Z. micropiligerum n. sp., Z. pseudopiligerum n. sp., Z. analavelona n. sp. and Z. fisheri n. sp., and Microsphaerotherium anjozorobe n. sp.. Twenty-eight of the Zoosphaerium species already fit into established species-groups. A key to all 55 recognizable Malagasy Sphaerotheriida species is given. Forty-two of the 55 giant pill-millipede species are ecosystem endemics, while 26 are geographically microendemic. The number of microendemic species is disproportionately distributed among Malagasy ecosystems. All 13 species restricted to the montane rainforest as well as all five species restricted to the Eastern littoral forest are microendemic. On the other hand, only two out of seven dry forest species, one out of seven rainforest species and one out of five spiny forest species are microendemics. A special emphasis is placed on two species endemic to the unique Western rainforest site of Analavelona, which is currently not protected.

Two new species of Clusia sect. Cordylandra (Clusiaceae) from the brejo de altitude vegetation, plateau of Ibiapaba, Ceará, Brazil

Phytotaxa ◽  
2020 ◽  
Vol 460 (4) ◽  
pp. 259-268
Author(s):  
ANA CLÁUDIA ALENCAR ◽  
JOSÉ ELVINO DO NASCIMENTO-JR ◽  
VOLKER BITTRICH ◽  
ANTÔNIO SÉRGIO FARIAS-CASTRO ◽  
MARIA DO CARMO ESTANISLAU DO AMARAL
Keyword(s):  
New Species ◽  
Male Flower ◽  
The Other ◽  
Northeastern Brazil ◽  
Other Hand ◽  
Two New Species ◽  
Shrubby Species

Two new shrubby species of Clusia sect. Cordylandra are described and illustrated. The male flower of Clusia nogueirae presents an androecium forming a conical volcano-like synandrium around a well-developed pistillode covered with resin. The male flower of Clusia ibiapabensis, on the other hand, presents an androecium of free claviform stamens, forming a broad torus-like structure around a well-developed pistillode. The two species occur in regions of brejos de altitude in the plateou of Ibiapaba, Ceará state, northeastern Brazil.

Two new species of Cosmos section Discopoda (Coreopsideae: Asteraceae) from Jalisco, Mexico

Phytotaxa ◽  
2013 ◽  
Vol 146 (2) ◽  
pp. 35 ◽  
Author(s):  
Arturo Castro Castro ◽  
Georgina Vargas-Amado ◽  
Mollie Harker ◽  
Aarón Rodríguez-Contreras
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
Taxonomic Revision ◽  
The Other ◽  
Fruiting Phenology ◽  
Western Mexico ◽  
Other Hand ◽  
Two New Species

Recent botanical explorations in western Mexico, as part of a taxonomic revision and a phylogenetic analysis of the genus Cosmos, have resulted in the discovery of two new species. The novelties belong to Cosmos section Discopoda and are described and illustrated. Morphologically, Cosmos pseudoperfoliatus resembles C. jaliscensis, C. peucedanifolius, C. palmeri and C. scabiosoides, but differs from them in having 4–7 leaf pairs on the stem, leaves tomentose on both faces, trullate external phyllaries, yellow disk florets with 4–5 lobes, and corky-tuberculate achenes. On the other hand, Cosmos ramirezianus is morphologically similar to C. montanus, but differs by its coriaceous and pinnatisect leaves, yellow internal phyllaries, yellow disk florets with light purple lobes, and by the persistence of paleae during fruiting. Phenology, distribution and habitat are provided as well as a key for the identification of the species in Cosmos section Discopoda. Recent botanical explorations in western Mexico, as part of a taxonomic revision and a phylogenetic analysis of the genus Cosmos, have resulted in the discovery of two new species. The novelties belong to Cosmos section Discopoda and are described and illustrated. Morphologically, Cosmos pseudoperfoliatus resembles C. jaliscensis, C. peucedanifolius, C. palmeri and C. scabiosoides, but differs from them in having 4–7 leaf pairs on the stem, leaves tomentose on both faces, trullate external phyllaries, yellow disk florets with 4–5 lobes, and corky-tuberculate achenes. On the other hand, Cosmos ramirezianus is morphologically similar to C. montanus, but differs by its coriaceous and pinnatisect leaves, yellow internal phyllaries, yellow disk florets with light purple lobes, and by the persistence of paleae during fruiting. Phenology, distribution and habitat are provided as well as a key for the identification of the species in Cosmos section Discopoda.

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