Facultative

An example of facultative heterochromatin is X chromosome inactivation in female mammals: one X chromosome is packaged as facultative heterochromatin and silenced, while the other X chromosome is packaged as euchromatin and expressed.

Mutualistic relationships may be either obligate for both species, obligate for one but facultative for the other, or facultative for both.

Obligate and facultative adaptations A question that may be asked about an adaptation is whether it is generally obligate (relatively robust in the face of typical environmental variation) or facultative (sensitive to typical environmental variation).

Diving deeper into this, Associate Prof. Yasuyuki Choh from Chiba University, Japan, and Arne Janssen from the University of Amsterdam and the Federal University of Viçosa shed more light on factors that drive facultative brood parasitism.

A facultative anaerobe can tolerate anaerobic and aerobic conditions; however, an obligate anaerobe would die in the presence of even trace levels of oxygen.

Agkistrodon contortrix (copperhead snake) and Agkistrodon piscivorus (cotton mouth snake) can reproduce by facultative parthenogenesis.

An alternative to contrasting nature and nurture focuses on "obligate vs. facultative" adaptations.

An example of a facultative physiological adaptation is tanning of skin on exposure to sunlight (to prevent skin damage).

Animals that depend solely on animal flesh for their nutrient requirements are called obligate carnivores while those that also consume non-animal food are called facultative carnivores.

Diapause may be obligatory (required for the insect to survive) or facultative (the insect is able to undergo change before the initiating event arrives).

Evolutionary psychologists respond that EP works within a nature-nurture interactionist framework that acknowledges that many psychological adaptations are facultative (sensitive to environmental variations during individual development).

However, the Colombian Rainbow boa, Epicrates maurus can also reproduce by facultative parthenogenesis resulting in production of WW female progeny. citation The WW females are likely produced by terminal automixis.

In addition, adaptations are expected to manifest as proximate mechanisms that interact with the environment in either a generally obligate or facultative fashion (see above).

In many areas facultative varieties can be grown either as winter or as a spring, depending on time of sowing.

It is common for neck biting to occur while the snakes are entwined. citation Facultative parthenogenesis Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization.

Obligate vs. facultative adaptations Traits may be considered to be adaptations (such as the umbilical cord), byproducts of adaptations (the belly button) or due to random variation (convex or concave belly button shape).

Omnivores also consume both animal and non-animal food, and apart from the more general definition, there is no clearly defined ratio of plant to animal material that would distinguish a facultative carnivore from an omnivore.

The haploid fission yeast Schizosaccharomyces pombe is a facultative sexual microorganism that can undergo mating when nutrients are limiting.

The least common were infections caused exclusively by anaerobes and facultative organisms.

The obligate and facultative ant mutualists found in some Piper species have a strong influence on their biology, making them ideal systems for research on the evolution of symbioses and the effect of mutualisms on biotic communities.