Parthenogenesis: A unisexual reproduction without the fusion of a male and a female gamete (FERTILIZATION). In parthenogenesis, an individual is formed from an unfertilized OVUM that did not complete MEIOSIS. Parthenogenesis occurs in nature and can be artificially induced.Taraxacum: A plant genus of the family ASTERACEAE. Members contain chicoric and chlorogenic acids and germacrane- and eudesmane-type SESQUITERPENES.Boidae: A family of snakes comprising the boas, anacondas, and pythons. They occupy a variety of habitats through the tropics and subtropics and are arboreal, aquatic or fossorial (burrowing). Some are oviparous, others ovoviviparous. Contrary to popular opinion, they do not crush the bones of their victims: their coils exert enough pressure to stop a prey's breathing, thus suffocating it. There are five subfamilies: Boinae, Bolyerinae, Erycinae, Pythoninae, and Tropidophiinae. (Goin, Goin, and Zug, Introduction to Herpetology, 3d ed, p315-320)Wolbachia: A genus of bacteria comprised of a heterogenous group of gram-negative small rods and coccoid forms associated with arthropods. (From Bergey's Manual of Systematic Bacteriology, vol 1, 1984)Daphnia: A diverse genus of minute freshwater CRUSTACEA, of the suborder CLADOCERA. They are a major food source for both young and adult freshwater fish.Apomixis: Asexual reproduction resulting in the formation of viable seeds from FLOWERS without fertlization (i.e. use of POLLEN). Progeny plants produced from apomictic seeds are perfect clones of the parent.Ants: Insects of the family Formicidae, very common and widespread, probably the most successful of all the insect groups. All ants are social insects, and most colonies contain three castes, queens, males, and workers. Their habits are often very elaborate and a great many studies have been made of ant behavior. Ants produce a number of secretions that function in offense, defense, and communication. (From Borror, et al., An Introduction to the Study of Insects, 4th ed, p676)Reproduction: The total process by which organisms produce offspring. (Stedman, 25th ed)Ranunculaceae: The buttercup plant family of the order Ranunculales, subclass Magnoliidae, class Magnoliopsida. The leaves are usually alternate and stalkless. The flowers usually have two to five free sepals and may be radially symmetrical or irregular.Diploidy: The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X.Reproduction, Asexual: Reproduction without fusion of two types of cells, mostly found in ALGAE; FUNGI; and PLANTS. Asexual reproduction occurs in several ways, such as budding, fission, or splitting from "parent" cells. Only few groups of ANIMALS reproduce asexually or unisexually (PARTHENOGENESIS).Rotifera: A class of minute animals of the phylum Aschelminthes.Wasps: Any of numerous winged hymenopterous insects of social as well as solitary habits and having formidable stings.Microsatellite Repeats: A variety of simple repeat sequences that are distributed throughout the GENOME. They are characterized by a short repeat unit of 2-8 basepairs that is repeated up to 100 times. They are also known as short tandem repeats (STRs).Aphids: A family (Aphididae) of small insects, in the suborder Sternorrhyncha, that suck the juices of plants. Important genera include Schizaphis and Myzus. The latter is known to carry more than 100 virus diseases between plants.Meiosis: A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.Ranunculus: A plant genus of the family RANUNCULACEAE that contains protoanemonin, anemonin, and ranunculin.Ovum: A mature haploid female germ cell extruded from the OVARY at OVULATION.Insects: The class Insecta, in the phylum ARTHROPODA, whose members are characterized by division into three parts: head, thorax, and abdomen. They are the dominant group of animals on earth; several hundred thousand different kinds having been described. Three orders, HEMIPTERA; DIPTERA; and SIPHONAPTERA; are of medical interest in that they cause disease in humans and animals. (From Borror et al., An Introduction to the Study of Insects, 4th ed, p1)Sex Determination Analysis: Validation of the SEX of an individual by inspection of the GONADS and/or by genetic tests.Rickettsiaceae: A family of small, gram-negative organisms, often parasitic in humans and other animals, causing diseases that may be transmitted by invertebrate vectors.Symbiosis: The relationship between two different species of organisms that are interdependent; each gains benefits from the other or a relationship between different species where both of the organisms in question benefit from the presence of the other.Oocytes: Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).Fertilization: The fusion of a spermatozoon (SPERMATOZOA) with an OVUM thus resulting in the formation of a ZYGOTE.Nuclear Transfer Techniques: Methods of implanting a CELL NUCLEUS from a donor cell into an enucleated acceptor cell.Sex Determination Processes: The mechanisms by which the SEX of an individual's GONADS are fixed.Sex Ratio: The number of males per 100 females.Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Polyploidy: The chromosomal constitution of a cell containing multiples of the normal number of CHROMOSOMES; includes triploidy (symbol: 3N), tetraploidy (symbol: 4N), etc.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Ploidies: The degree of replication of the chromosome set in the karyotype.Heterozygote: An individual having different alleles at one or more loci regarding a specific character.Chromosomes: In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Homozygote: An individual in which both alleles at a given locus are identical.Sexual Behavior, Animal: Sexual activities of animals.Blastocyst: A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.Genetic Variation: Genotypic differences observed among individuals in a population.Spermatozoa: Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.