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PHENOTYPIC OPTIONS. "The mere fact that organisms are subject to natural selection, so that we only expect to observe organisms with maximal (or nearly maximal) relative fitness, implies that we’ll see trade-offs." https://lnkd.in/dGaAzSA View in LinkedIn

CONSTRAINTS ON PHENOTYPE. "The common theme of all of the above is constraints on phenotypes. Allocation, antagonistic pleiotropy, mutational decay, and the laws of physics are all reasons why organisms can’t build (or can’t maintain, over evolutionary time) certain phenotypes. Trade-offs reflect constraints on the range of phenotypic options that are open to organisms.” https://lnkd.in/dGaAzSA View in LinkedIn

REASONS FOR TRADE-OFFS. "Allocation is a big one: a unit of energy, materials, or time that an organism uses to do one thing (say, build a defensive structure) cannot be used to do something else (say, reproduce). Antagonistic pleiotropy is another big one: a mutation that improves one biological function often degrades another (although this is presumably not an ultimate explanation for trade offs, since one can ask why we expect antagonistic pleiotropy). Mutational decay is a third: a mutation that degrades an unused function (think cave fish eyes) will be selectively neutral." https://lnkd.in/dGaAzSA View in LinkedIn

DEVELOPMENTAL TEST. "When sections are cut from a Drosophila imaginal disc, adjoining cells divide to produce a normal-sized trait, even when the injured disc is placed outside of the environment of the developing larva." http://www.pnas.org/content/95/7/3685.full View in LinkedIn

"THE PRINCIPLE OF ALLOCATION is a basic concept in ecology. The principle of allocation also underlies some aspects of the concept of tradeoffs and typically is considered in terms of energy. As a result, organisms tend to be unable to be simultaneously exceptionally durable, such as in terms of maintaining homeostasis, and at the same time exceptionally fecund, at least in terms of a limited resource budget." https://lnkd.in/dSYMHu9 View in LinkedIn

VIRALLY-DERIVED DNA AND SELECTION. "Here we discuss the pervasiveness and power of Selfish Genetic Elements as an agent of sexual selection and show they can have remarkably wide-ranging impacts on male and female reproduction and therefore in shaping mating systems, even when present at low frequencies." https://lnkd.in/dN4U_8N View in LinkedIn

SEXUAL SELECTION AND SELFISH GENES. "One aspect of sexual selection that Darwin was completely unaware of was the role of Selfish Genetic Elements (SGEs). SGEs are genes, organelles or microorganisms present within the genome or cell of an organism that spread through populations by subverting normal patterns of inheritance in ways that increase their representation in the next generation." https://lnkd.in/dN4U_8N View in LinkedIn

SELFISH GENES. "Retrotransposons appear to have greater significance than other transposons in their potential for deleterious effects on host fitness. Functional retrotransposon inserts produce transcripts that are silenced by genome defense proteins. So far, it has been documented that the genome may be protected against overpopulation of selfish elements in several ways." https://lnkd.in/dgGPYYe View in LinkedIn

RETROTRANSPOSONS. "It has been hypothesized that asexual organisms lack mechanisms sufficient to keep retrotransposons proliferation under control, explaining why retrotransposons are missing from ancient (i.e., evolutionarily stable) asexuals." https://lnkd.in/deZ8DED View in LinkedIn

MIXED MODES. "Most of these models found that there was an advantage for a low frequency of sexual reproduction over complete asexuality. Very few models exist explaining the evolution and maintenance of obligate sexuality in comparison with facultative sex. In fact, according to most models, organisms that engage in sexual reproduction only part of the time seem to have the best of both worlds." https://lnkd.in/es2qrc5 View in LinkedIn