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Timema Californica
''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; 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 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 tarsi have three segments rather than five. For stick insects, they have relatively sm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timema Genevievae
''Timema genevievae'', or Genevieve's timema, is a species of walkingstick A walking stick or walking cane is a device used primarily to aid walking, provide postural stability or support, or assist in maintaining a good posture. Some designs also serve as a fashion accessory, or are used for self-defense. Walking sti ... 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 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 by animals or plants. Overview There is a strong evolutionary pressure for animals to blend into their environment or conceal their shape, for prey animals to avoid predators and for predators to be able to avoid detection by prey. Exceptions include large herbivores without natural enemies, brilliantly colored birds that rely on flight to escape predators, and venomous or otherwise powerfully armed animals with warning coloration. Cryptic animals include the tawny frogmouth (feather pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanja Schwander
Tanja Schwander is a Swiss evolutionary biologist and professor at the University of Lausanne. She is known for her work on the Evolution of sexual reproduction. Education and career Tanja Schwander 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. Work Tanja Schwander's work has focused on understanding the consequences of asexuality using '' Timema'' stick insects as a model system. Her work has contributed to the current understanding of the Evolution of sexual reproduction, the Paradox of Sex, and Sexual conflict. Awards * 2009. ''John Maynard Smith Prize'' of the European Societ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ant Mimicry
Ant mimicry or myrmecomorphy is mimicry of ants by other organisms. 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. Spiders are the most common ant mimics. Additionally, some arthropods mimic ants to escape predation (protective mimicry), while others mimic ants anatomically and behaviourally to hunt ants 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. Indeed one of the earliest, ''Burmomyrma'', was initially classified as an ant. In Wasmannian mimicry, mimic and model live commensally together; in the case of ants, the model is an inquiline in the ants' nest. Wasmannian mimics may also be Batesian or aggressive mimics. To simulate ants' powerful defences, mimics may imitate ants chemically w ... [...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 phasmoidea an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reproductive Isolation
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and 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 genetically controlled and can appear in species whose ... [...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. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments of speciation, laboratory experiments. Whether genetic drift is a minor or major contributor to speciation is the subject of much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecotype
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, or race within a species, which is genotypically adapted to specific environmental conditions. Typically, though ecotypes exhibit phenotypic differences (such as in 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, Townsend, Harper, Blackwell Publishing 4th ed. (2006), p.5,6,7,8''Environmental Encyclopedia'' by Bortman, Brimblecombe, Mary Ann Cunningham, William P. Cunningham, Freedman - 3rd ed., p.435, "Ecotype" Definition An ecotype is a variant in which the phenotypic differences are too few or too subtle to warrant being classified as a subspecies. These different variants ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceanothus
''Ceanothus'' is a genus of about 50–60 species of Actinorhizal plant, 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 grc, κεάνωθος (''keanōthos''), 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., ''Ceanothus americanus, C. americanus'') are restricted to the eastern United States and southeast Canada, and others (e.g., ''Ceanothus caeruleus, C. caeruleus'') extend as far south as Guatemala. Most are shrubs tall, but ''Ceanothus arboreus, C. arboreus'' and ''Ceanothus thyrsiflorus, C. thyrsiflorus'', both native to California, can be small multi-trunked trees up to tall. Taxonomy and etymology There are two subgenera within this genus: ''Ceanothus' ... [...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 North ... [...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 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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