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Timema Cristinae
''Timema cristinae'', or Cristina's ''Timema'', is a species of walking stick in the family Timematidae. This species is named in recognition of the person who first found and collected itCristina Sandoval It is found in North America, in a small region of southern California, US. ''T. cristinae'' is one of the smallest species of stick insects. They are flightless, and feed on the shrubs on which they live. Description ''T. cristinae'' is among the smallest species of stick insects, with adults only reaching 2-3cm in length. They have rounded bodies, an elongated abdomen, and are wingless. This species also displays sexual dimorphism. The males are smaller (~2cm long) and thinner than females (~3cm long), and can also be distinguished by their red legs. Males and females also differ in their mandible shape and size, with female mandibles being much longer than those of their male counterparts. ''T. cristinae'' has a great sense of smell. This is known because it was found tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phasmatodea
The Phasmatodea (also known as Phasmida, Phasmatoptera or Spectra) are an order of insects whose members are variously known as stick insects, stick-bugs, walking sticks, stick animals, or bug sticks. They are also occasionally referred to as Devil's darning needles, although this name is shared by both dragonflies and crane flies. They can be generally referred to as phasmatodeans, phasmids, or ghost insects, with phasmids in the family Phylliidae called leaf insects, leaf-bugs, walking leaves, or bug leaves. The group's name is derived from the Ancient Greek ', meaning an apparition or phantom, referring to their resemblance to vegetation while in fact being animals. Their natural camouflage makes them difficult for predators to detect; still, many species have one of several secondary lines of defense in the form of startle displays, spines or toxic secretions. Stick insects from the genera '' Phryganistria'', '' Ctenomorpha'', and '' Phobaeticus'' include the world's l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyandry In Nature
In behavioral ecology, polyandry is a class of mating system where one female mates with several males in a breeding season. Polyandry is often compared to the polygyny system based on the cost and benefits incurred by members of each sex. Polygyny is where one male mates with several females in a breeding season (e.g., lions, deer, some primates, and many systems where there is an alpha male). A common example of polyandrous mating can be found in the field cricket ('' Gryllus bimaculatus'') of the invertebrate order Orthoptera (containing crickets, grasshoppers, and groundhoppers). Polyandrous behavior is also prominent in many other insect species, including the red flour beetle and the species of spider '' Stegodyphus lineatus''. Polyandry also occurs in some primates such as marmosets, mammal groups, the marsupial genus' ''Antechinus'' and bandicoots, around 1% of all bird species, such as jacanas and dunnocks, insects such as honeybees, and fish such as pipefish. Predict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parapatric Speciation
In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes. This mode of speciation has three distinguishing characteristics: 1) mating occurs non-randomly, 2) gene flow occurs unequally, and 3) populations exist in either continuous or discontinuous geographic ranges. This distribution pattern may be the result of unequal dispersal, incomplete geographical barriers, or divergent expressions of behavior, among other things. Parapatric speciation predicts that hybrid zones will often exist at the junction between the two populations. In biogeography, the terms parapatric and parapatry are often used to describe the relationship between organisms whose ranges do not significantly overlap but are immediately adjacent to each other; they do not occur together except in a narrow contact zone. Parapatry is a geographical distribution opposed to sympatry (same area) and allopatry or peripatry (two simi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population
Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a census, a process of collecting, analysing, compiling, and publishing data regarding a population. Perspectives of various disciplines Social sciences In sociology and population geography, population refers to a group of human beings with some predefined criterion in common, such as location, race, ethnicity, nationality, or religion. Demography is a social science Social science is one of the branches of science, devoted to the study of societies and the relationships among individuals within those societies. The term was formerly used to refer to the field of sociology, the original "science of soc ... which entails the statistical study of populations. Ecology In ecology, a population is a group of organisms of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allopatric Speciation
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers. Human activity such as agriculture or developments can also change the distribution of species populations. These factors can substantially alter a region's geography, resulting in the separation of a species population into isolated subpopulations. The vicariant populations then undergo genetic changes as they become subjected to different selective pressures, experience genetic drift, and accumulate different mutations in the separated populations' gene pools. The barriers prevent the exchange of genetic information between th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as g ... [...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, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments. 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 numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Ecology
Evolutionary ecology lies at the intersection of ecology and evolutionary biology. It approaches the study of ecology in a way that explicitly considers the evolutionary histories of species and the interactions between them. Conversely, it can be seen as an approach to the study of evolution that incorporates an understanding of the interactions between the species under consideration. The main subfields of evolutionary ecology are life history evolution, sociobiology (the evolution of social behavior), the evolution of interspecific interactions (e.g. cooperation, predator–prey interactions, parasitism, mutualism) and the evolution of biodiversity and of ecological communities. Evolutionary ecology mostly considers two things: how interactions (both among species and between species and their physical environment) shape species through selection and adaptation, and the consequences of the resulting evolutionary change. Evolutionary models A large part of evolutionary ec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Death
Apparent death, colloquially known as playing dead, feigning death, or playing possum, is a behavior in which animals take on the appearance of being dead. It is an immobile state most often triggered by a predatory attack and can be found in a wide range of animals from insects and crustaceans to mammals, birds, reptiles, amphibians, and fish. Apparent death is also referred to as thanatosis, animal hypnosis, immobilization catatonia, or tonic immobility, the latter of which is preferred in the scientific literature on the subject. Apparent death is separate from the freezing behavior seen in some animals. Apparent death is a form of animal deception considered to be an anti-predator strategy, but it can also be used as a form of aggressive mimicry. When induced by humans, the state is sometimes colloquially known as animal hypnosis. The earliest written record of "animal hypnosis" dates back to the year 1646 in a report by Athanasius Kircher, in which he subdued chickens. De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diapause
In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It is a physiological state with very specific initiating and inhibiting conditions. The mechanism is a means of surviving predictable, unfavorable environmental conditions, such as temperature extremes, drought, or reduced food availability. Diapause is observed in all the life stages of arthropods, especially insects. Embryonic diapause, a somewhat similar phenomenon, occurs in over 130 species of mammals, possibly even in humans, and in the embryos of many of the oviparous species of fish in the order Cyprinodontiformes. Activity levels of diapausing stages can vary considerably among species. Diapause may occur in a completely immobile stage, such as the pupae and eggs, or it may occur in very active stages that undergo extensive migrati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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