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Timema Morongense
''Timema'' is a genus of relatively short-bodied, stout and wingless stick insects native to the far western United States, and the sole extant member of the family Timematidae. The genus was first described in 1895 by Samuel Hubbard Scudder, based on observations of the species ''Timema californicum''. Compared to other stick insects (order Phasmatodea), the genus ''Timema'' is considered Basal (phylogenetics), basal; that is, the earliest "branch" to diverge from the phylogenetic tree that includes all Phasmatodea. To emphasize this outgroup status, all stick insects not included in ''Timema'' are sometimes described as "Euphasmatodea." Five of the twenty-one species of ''Timema'' are parthenogenesis, parthenogenetic, including two species that have not engaged in sexual reproduction for one million years, the longest known asexual period for any insect. Description ''Timema'' spp. differ from other Phasmatodea in that their arthropod leg, tarsi have three segments rather t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timema Genevievae
''Timema genevievae'', or Genevieve's timema, is a species of asexual reproduction, asexual walking stick, walking-stick-like animal in the family Timematidae. It is found in North America. References Phasmatodea Articles created by Qbugbot Insects described in 1978 {{Phasmatodea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crypsis
In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be part of a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and mimicry. Crypsis can involve visual, olfactory (with pheromones) or auditory concealment. When it is visual, the term cryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many different methods of camouflage are employed in nature. Overview There is a strong evolutionary pressure for prey animals to avoid predators through camouflage, and for predators to be able to detect camouflaged prey. There can be a self-perpetuating coevolution, in the shape of an evolutionary arms race, between the perceptive abilities of animals attempting to detect the cryptic animal and the cryptic characteristics of the hiding species. Methods Methods of crypsis include (visual) camouflage, nocturnality, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanja Schwander
Tanja Schwander (born 1978) is a Swiss evolutionary biologist and professor at the University of Lausanne. She is known for her work on the evolution of sexual reproduction. She was awarded the John Maynard Smith Prize by the European Society for Evolutionary Biology in 2009. She serves on the Swiss National Academy of Sciences Board of the Platform Biology, and is the secretary of the Swiss Zoological Society. Education and career Tanja Schwander was born in 1978 in Brugg in Switzerland. She obtained her PhD in 2007 from the University of Lausanne on 'Evolution, maintenance and ecological consequences of genetic caste determination in Pogonomyrmex harvester ants'. Tanja Schwander then took a postdoctoral position at Simon Fraser University in Prof. Bernard J. Crespi's lab, before being hired as an independent researcher at the University of Groningen. In 2013, she moved back to University of Lausanne to begin her own research group. She is an elected member of the Swiss Nationa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ant Mimicry
Ant mimicry or myrmecomorphy is mimicry of ants by other organisms; it has evolved over 70 times. Ants are abundant all over the world, and potential predators that rely on vision to identify their prey, such as birds and wasps, normally avoid them, because they are either unpalatable or aggressive. Some arthropods mimic ants to escape predation ( Batesian mimicry), while some predators of ants, especially spiders, mimic them anatomically and behaviourally in aggressive mimicry. Ant mimicry has existed almost as long as ants themselves; the earliest ant mimics in the fossil record appear in the mid-Cretaceous alongside the earliest ants. In myrmecophily, mimic and model live commensally together; in the case of ants, the mimic is an inquiline in the ants' nest. Such mimics may in addition be Batesian or aggressive mimics. To overcome ants' powerful defences, mimics may imitate ants chemically with ant-like pheromones, visually, or by imitating an ant's surface microstructure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operculum (animal)
An operculum is an anatomical feature, a stiff structure resembling a lid or a small door that opens and closes, and thus controls contact between the outside world and an internal part of an animal. Examples include: * An operculum (gastropod), a single lid that (in its most complete form) closes the aperture of the shell when the animal is retracted, and thus protects the internal soft parts of the animal that are not completely covered by the shell. The operculum lies on the top rear part of the foot. When the foot is retracted, the operculum is rotated 180° and closes the shell. * An operculum (fish), a flap that covers the gills in bony fishes and chimaeras. * The cover that rapidly opens a cnida of a cnidarian such as a jellyfish or a sea anemone. The lid may be a single hinged flap or three hinged flaps arranged like slices of pie. * In insects, the operculum is the name for one or more lids covering the tympanal cavity. A subgenital operculum is exhibited in stick ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reproductive Isolation
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, ethology, behaviors and physiology, physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.Strickberger, M. 1978. ''Genética''. Omega, Barcelona, España, p.: 874–879. .Futuyma, D. 1998. ''Evolutionary biology'' (3ª edición). Sinauer, Sunderland. The mechanisms of reproductive isolation have been classified in a number of ways. Zoologist Ernst Mayr classified the mechanisms of reproductive isolation in two broad categories: pre-zygotic for those that act before fertilization (or before mating in the case of animals) and post-zygotic for those that act after it.Mayr, E. 1963. ''Animal species and evolution''. Harvard University Press, Cambridge. The mechanisms are genetics, genetically controlle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speciation
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book ''On the Origin of Species''. He also identified sexual selection as a likely mechanism, but found it problematic. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric speciation, allopatric, peripatric speciation, peripatric, parapatric speciation, parapatric, and sympatric speciation, sympatric. Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion. Rapid sympatric speciation can take place through polyploidy, such as by doubling of chromosome number; the result is progeny wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecotype
Ecotypes are organisms which belong to the same species but possess different phenotypical features as a result of environmental factors such as elevation, climate and predation. Ecotypes can be seen in wide geographical distributions and may eventually lead to speciation. Definition In evolutionary ecology, an ecotype,Greek: ''οίκος'' = home and ''τύπος'' = type, coined by Göte Turesson in 1922 sometimes called ecospecies, describes a genetically distinct geographic variety, Population biology, population, or Race (biology), race within a species, which is genotypically Adaptation, adapted to specific environmental conditions. Typically, though ecotypes exhibit Phenotype, phenotypic differences (such as in Morphology (biology), morphology or physiology) stemming from environmental heterogeneity, they are capable of interbreeding with other geographically adjacent ecotypes without loss of fertility or vigor.''Ecology: From individuals to ecosystems'' by Begon, Townsen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceanothus
''Ceanothus'' is a genus of about 50–60 species of nitrogen-fixing shrubs and small trees in the buckthorn family (Rhamnaceae). Common names for members of this genus are buckbrush, California lilac, soap bush, or just ceanothus. ''"Ceanothus"'' comes from (''keánōthos''), which was applied by Theophrastus (371–287 BC) to an Old World plant believed to be '' Cirsium arvense''. The genus is native to North America with the highest diversity on the western coast. Some species (e.g., '' C. americanus'') are restricted to the eastern United States and southeast Canada, and others (e.g., '' C. caeruleus'') extend as far south as Guatemala. Most are shrubs tall, but '' C. arboreus'' and '' C. thyrsiflorus'', both native to California, can be small multi-trunked trees up to tall. Taxonomy There are two subgenera within this genus: ''Ceanothus'' and ''Cerastes''. The former clade is less drought-resistant, having bigger leaves. The evolution of these two clades likely started w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenostoma
''Adenostoma'' is a genus of shrubs in the rose family (Rosaceae) containing only two species, chamise (''Adenostoma fasciculatum'') and redshanks ('' Adenostoma sparsifolium''). Both are native to the Californias. Description Characteristics The plants grow in a habit of shrubs to small trees, and the stem is more or less resinous. Both species in this genus feature stiff, linear leaves arranged alternately or in clusters along stems with shredding bark. Flowers form on a panicle, are cream to white and, as in all members of the rose family, have hypanthia. The fruit is an achene. Chromosome number is 2n = 18. Distribution and habitat Both species are native to coastal California and Baja California. ''Adenostoma fasciculatum'' is also native to California in the Sierra Nevada. They are found in plant communities and sub-ecoregions of the California chaparral and woodlands ecoregion. Taxonomy File:Chamise resprout Mag Road III.jpg, ''Adenostoma fasciculatum'' Hook. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Generalist And Specialist Species
A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet. Most organisms do not all fit neatly into either group, however. Some species are highly specialized (the most extreme case being monophagous, eating one specific type of food), others less so, and some can tolerate many different environments. In other words, there is a continuum from highly specialized to broadly generalist species. Description Omnivores are usually generalists. Herbivores are often specialists, but those that eat a variety of plants may be considered generalists. A well-known example of a specialist animal is the monophagous koala, which subsists almost entirely on eucalyptus leaves. The raccoon is a generalist, because it has a natural range that includes most of Nor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (biology)
In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative '' phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating). Ford E.B. 1965. ''Genetic polymorphism''. Faber & Faber, London. Put simply, polymorphism is when there are two or more possibilities of a trait on a gene. For example, there is more than one possible trait in terms of a jaguar's skin colouring; they can be light morph or dark morph. Due to having more than one possible variation for this gene, it is termed 'polymorphism'. However, if the jaguar has only one possible trait for that gene, it would be termed "monomorphic". For example, if there was only one possible skin colour that a jaguar could have, it would be termed monomorphic. The term polyphenism can be used to clarify that the different forms arise from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
