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Reproductive Success
Reproductive success is an individual's production of offspring per breeding event or lifetime. This is not limited by the number of offspring produced by one individual, but also the reproductive success of these offspring themselves. Reproductive success is different from fitness in that individual success is not necessarily a determinant for adaptive strength of a genotype since the effects of chance and the environment have no influence on those specific genes. Reproductive success turns into a part of fitness when the offspring are actually recruited into the breeding population. If offspring quantity is not correlated with quality this holds up, but if not then reproductive success must be adjusted by traits that predict juvenile survival in order to be measured effectively. Quality and quantity is about finding the right balance between reproduction and maintenance. The disposable soma theory of aging tells us that a longer lifespan will come at the cost of reproduction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter T
Peter may refer to: People * List of people named Peter, a list of people and fictional characters with the given name * Peter (given name) ** Saint Peter (died 60s), apostle of Jesus, leader of the early Christian Church * Peter (surname), a surname (including a list of people with the name) Culture * Peter (actor) (born 1952), stage name Shinnosuke Ikehata, a Japanese dancer and actor * ''Peter'' (1934 film), a film directed by Henry Koster * ''Peter'' (2021 film), a Marathi language film * "Peter" (''Fringe'' episode), an episode of the television series ''Fringe'' * ''Peter'' (novel), a 1908 book by Francis Hopkinson Smith * "Peter" (short story), an 1892 short story by Willa Cather * ''Peter'' (album), a 1972 album by Peter Yarrow * ''Peter'', a 1993 EP by Canadian band Eric's Trip * "Peter", 2024 song by Taylor Swift from '' The Tortured Poets Department: The Anthology'' Animals * Peter (Lord's cat), cat at Lord's Cricket Ground in London * Peter (chief mouse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Developmental Biology
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism. Perspectives The main processes involved in the embryogenesis, embryonic development of animals are: tissue patterning (via regional specification and patterned cellular differentiation, cell differentiation); tissue growth; and tissue morphogenesis. * Regional specification refers to the processes that create the spatial patterns in a ball or sheet of initially similar cells. This generally involves the action of cytoplasmic determinants, located within parts of the fertilized egg, and of inductive signals emitted from signaling centers in the embryo. The early stages of regional specification do not generate functional differentiated cells, but cell populations committed to developing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleiotropy
Pleiotropy () is a condition in which a single gene or genetic variant influences multiple phenotypic traits. A gene that has such multiple effects is referred to as a ''pleiotropic gene''. Mutations in pleiotropic genes can impact several traits simultaneously, often because the gene product is used in various cell (biology), cells and affects different biological targets through shared signaling pathways. Pleiotropy can result from several distinct but potentially overlapping mechanisms, including gene pleiotropy, developmental biology, developmental pleiotropy, and selectional pleiotropy. Gene pleiotropy occurs when a gene product interacts with multiple proteins or catalyzes different reactions. Developmental pleiotropy refers to mutations that produce several phenotype, phenotypic effects during development. Selectional pleiotropy occurs when a single phenotype influences evolutionary fitness (biology), fitness in multiple ways (depending on factors such as age and sex). T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the Heredity, heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which is intentional, whereas natural selection is not. Genetic diversity, Variation of traits, both Genotype, genotypic and phenotypic, exists within all populations of organisms. However, some traits are more likely to facilitate survival and reproductive success. Thus, these traits are passed the next generation. These traits can also become more Allele frequency, common within a population if the environment that favours these traits remains fixed. If new traits become more favoured due to changes in a specific Ecological niche, niche, microevolution occurs. If new traits become more favoured due to changes in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraging
Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavior of animals in response to the environment where the animal lives. Behavioral ecologists use economic models and categories to understand foraging; many of these models are a type of optimal model. Thus foraging theory is discussed in terms of optimizing a payoff from a foraging decision. The payoff for many of these models is the amount of energy an animal receives per unit time, more specifically, the highest ratio of energetic gain to cost while foraging. Foraging theory predicts that the decisions that maximize energy per unit time and thus deliver the highest payoff will be selected for and persist. Key words used to describe foraging behavior include ''resources'', the elements necessary for survival and reproduction which have a l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperm Motility
Sperm motility describes the ability of sperm to move properly through the female reproductive tract (internal fertilization) or through water ( external fertilization) to reach the egg. Sperm motility can also be thought of as the ''quality'', which is a factor in successful conception; sperm that do not "swim" properly will not reach the egg in order to fertilize it. Sperm motility in mammals also facilitates the passage of the sperm through the cumulus oophorus (a layer of cells) and the zona pellucida (a layer of extracellular matrix), which surround the mammalian oocyte. In the wood mouse ''Apodemus sylvaticus'', sperms aggregate in 'trains' that are better able to fertilize eggs because they are more capable of navigating the viscous environment of the female reproductive tract. The trains move in a sinusoidal motion. Sperm motility is also affected by certain factors released by eggs. Sperm movement is activated by changes in intracellular ion concentration. The changes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Damage (naturally Occurring)
Natural DNA damage is an alteration in the chemical structure of DNA, such as a break in a strand of DNA, a nucleobase missing from the backbone of DNA, or a chemically changed base such as 8-OHdG. DNA damage can occur naturally or via environmental factors, but is distinctly different from mutation, although both are types of error in DNA. DNA damage is an abnormal chemical structure in DNA, while a mutation is a change in the sequence of base pairs. DNA damages cause changes in the structure of the genetic material and prevents the replication mechanism from functioning and performing properly. The DNA damage response (DDR) is a complex signal transduction pathway which recognizes when DNA is damaged and initiates the cellular response to the damage. DNA damage and mutation have different biological consequences. While most DNA damages can undergo DNA repair, such repair is not 100% efficient. Un-repaired DNA damages accumulate in non-replicating cells, such as cells in the brai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Male Infertility
Male infertility refers to a sexually mature male's inability to impregnate a fertile female. Male infertility can wholly or partially account for 40% of infertility among couples who are trying to have children. "A problem with the male is the sole cause, or a contributing cause, of infertility in about 40 percent of infertile couples. It affects approximately 7% of all men. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity. More recently, advance sperm analyses that examine intracellular sperm components are being developed. Age considerations Sperm motility increases from puberty through one's mid-thirties. Research shows that from the age of 36 onwards, sperm motility decreases from 40% Grade A & B to 31% in one's 50s. The effects of aging on semen quality is summarized below based on a study of 1,219 subjects: 90% of seminiferous tubules in men in their 20s and 30s contain spermatids, whereas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life History Theory
Life history theory (LHT) is an analytical frameworkVitzthum, V. (2008). Evolutionary models of women's reproductive functioning. ''Annual Review of Anthropology'', ''37'', 53-73 designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles.Flatt, T., & Heyland, A. (Eds.). (2011). Mechanisms of Life History Evolution : The Genetics and Physiology of Life History Traits and Trade-Offs. Oxford, GB: OUP Oxford. It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan (length of time alive)—have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns" and timing of events that make up an organism's life, such as birth, weaning, matu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological properties, and its behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code (its genotype) and the influence of environmental factors. Both factors may interact, further affecting the phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and again in his 1982 book '' The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as caddisfly larva cases and beaver dams ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menarche
Menarche ( ; ) is the first menstrual cycle, or first menstruation, menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility. Girls experience menarche at different ages, but the most common age is 12. Having menarche occur between the ages of 9–14 in the West is considered normal.US National Health Statistics Report September 2020 The timing of menarche is influenced by female biology, as well as Genetics, genetic, environmental factors, and nutritional factors. The mean age of menarche has declined over the last century, but the magnitude of the decline and the factors responsible remain subjects of contention. The worldwide average age of menarche is very difficult to estimate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
