scispace - formally typeset
Search or ask a question
Topic

Genus

About: Genus is a research topic. Over the lifetime, 68921 publications have been published within this topic receiving 590966 citations. The topic is also known as: monospecies genus & genus (zoology).


Papers
More filters
Journal ArticleDOI
TL;DR: Range expansion appears to be fundamentally coupled with speciation, producing the skewed distribution of species among genera, both globally and regionally, whereas clade longevity is achieved through extinction—resistance conferred by broad geographical ranges.
Abstract: The distribution of marine bivalve species among genera and higher taxa takes the form of the classic hollow curve, wherein few lineages are species rich and many are species poor. The distribution of species among genera (S/G ratio) varies with latitude, with temperate S/G9s falling within the null expectation, and tropical and polar S/G9s exceeding it. Here, we test several hypotheses for this polar overdominance in the species richness of small numbers of genera. We find a significant positive correlation between the latitudinal range of a genus and its species richness, both globally and within regions. Genus age and species richness are also positively related, but this relationship breaks down when the analysis is limited to genera endemic to climate zones or with narrow latitudinal ranges. The data suggest a link between speciation and range-expansion, with genera expanding out of the tropical latitudinal bins tending to speciate more prolifically, both globally and regionally. These genera contain more species within climate zones than taxa endemic to that zone. Range expansion thus appears to be fundamentally coupled with speciation, producing the skewed distribution of species among genera, both globally and regionally, whereas clade longevity is achieved through extinction—resistance conferred by broad geographical ranges.

76 citations

Journal ArticleDOI
TL;DR: There is now compelling evidence that the genus Lepidostrobus represents a heterogeneous group of monosporangiates and bisporangiate cone species and that it should be divided.

76 citations

Journal ArticleDOI
TL;DR: The range of soine species has been extended by man, for exan~ple, several agronomically interesting species of European origin are now well established in North Africa, New Zealand, Australia and on the American continent as forage crops.
Abstract: Introduction The genus Lotz~s of the tribe Loteae contains a heterogeneous assemblagc of annual and perennial species numbering close to 200 (Larsen, 1958). There are two principle geographic centers of origin of the species, namely, the Mediterranean region (Hertzsch, 1959) and Western North America (Nlunz and Keclt, 1959). A few endemic species are found in Australia, Japan, and North Africa (Brand, 1898). The range of soine species has been gfeatly extended by man, for exan~ple, several agronomically interesting species of European origin (of which L. conzicz~latz~s L. and L. 71zajor Scop. (syn. L. ~~ligi~zosz~s Schltuhr) are most widely cultivated) are now well established in North Africa, New Zealand, Australia and on the American continent as forage crops (I Hertzsch, 1959). Chron~oson~e numbers determined for different species (2n = 12, 14, 24, 28) indicate that a polyploid series with two basic chron~osome nuinbers (i.e., x = 6 and 7) exists within the genus (Darlington and Wylie, 1955; unpublished observations).

76 citations

Journal ArticleDOI
TL;DR: Phylogenetic results indicate that in both Namalycastis and Namanereis there is a preference for freshwater habitats among species with apomorphic traits (corollary being that marine habitats are favoured by the plesiomorphic members).
Abstract: A cladistic analysis and taxonomic revision of the Namanereidinae (Nereididae: Polychaeta) is presented. The cladistic analysis utilising 39 morphological characters (76 apomorphic states) yielded 10,000 minimal-length trees and a highly unresolved Strict Consensus tree. However, monophyly of the Namanereidinae is supported and two clades are identified: Namalycastis containing 18 species and Namanereis containing 15 species. The monospecific genus Lycastoides, represented by L. alticola Johnson, is too poorly known to be included in the analysis. Classification of the subfamily is modified to reflect the phylogeny. Thus, Namalycastis includes large-bodied species having four pairs of tentacular cirri; autapomorphies include the presence of short, subconical antennae and enlarged, flattened and leaf-like posterior cirrophores. Namanereis includes smaller-bodied species having three or four pairs of tentacular cirri; autapomorphies include the absence of dorsal cirrophores, absence of notosetae and a tripartite pygidium. Cryptonereis Gibbs, Lycastella Feuerborn, Lycastilla Solis-Weiss & Espinasa and Lycastopsis Augener become junior synonyms of Namanereis. Thirty-six species are described, including seven new species of Namalycastis (N. arista n.sp., N. borealis n.sp., N. elobeyensis n.sp., N. intermedia n.sp., N. macroplatis n.sp., N. multiseta n.sp., N. nicoleae n.sp.), four new species of Namanereis (N. minuta n.sp., N. serratis n.sp., N. stocki n.sp., N. sublittoralis n.sp.), and three widespread species groups ( Namalycastis abiuma, Namanereis littoralis, N. quadraticeps). Fourteen species are newly placed into synonymy, Lycastis maxillo-falciformis Harms, L. maxillo-ovata Harms, L. maxillo-robusta Harms, Lycastis meraukensis Horst, L. nipae Pflugfelder, L. ouanaryensis Gravier, L. ranauensis Feuerborn, L. vivax Pflugfelder, Lycastopsis augeneri Okuda, L. tecolutlensis Rioja, Namalycastis rigida Pillai, N. tachinensis Rosenfeldt, N. vuwaensis Ryan, and Namanereis littoralis Hutchings & Turvey. A neotype is designated for Namalycastis hawaiiensis (Johnson), and lectotypes are designated for Namalycastis geayi (Gravier), N. senegalensis (Saint-Joseph), N. terrestris (Pflugfelder), Namanereis amboinensis (Pflugfelder) and N. littoralis (Grube). Keys to genera and species are given. Namanereidinae are generally confined to the tropics and subtropics. Maximum species-diversity occurs in the Caribbean and Indo-Pacific, in particular in coastal areas subjected to recent uplifting, where both littoral-zone and freshwater (riparian and subterranean) forms occur. Phylogenetic results indicate that in both Namalycastis and Namanereis there is a preference for freshwater habitats among species with apomorphic traits (corollary being that marine habitats are favoured by the plesiomorphic members). This suggests that the ancestor of the Namanereidinae was a euryhaline coastal species.

75 citations


Network Information
Related Topics (5)
Systematics
7.8K papers, 211.9K citations
91% related
Monophyly
11.4K papers, 465.5K citations
90% related
Endemism
7.8K papers, 201.5K citations
89% related
Sister group
4.4K papers, 210.2K citations
88% related
Molecular phylogenetics
6.5K papers, 262.4K citations
88% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20232,790
20226,199
20212,431
20202,299
20192,015
20182,000