Propagule in the context of "Spores"

Biological dispersal refers to both the movement of individuals (animals, plants, fungi, bacteria, etc.) from their birth site to their breeding site ('natal dispersal') and the movement from one breeding site to another ('breeding dispersal'). The term also encompasses the movement of propagules such as seeds and spores. Technically, dispersal is defined as any movement that has the potential to lead to gene flow. The act of dispersal involves three phases: departure, transfer, and settlement. Each phase is associated with distinct fitness costs and benefits. By simply moving from one habitat patch to another, an individual's dispersal can influence not only its own fitness but also broader processes such as population dynamics, population genetics, and species distribution. Understanding dispersal and its consequences, both for evolutionary strategies at a species level and for processes at an ecosystem level, requires understanding on the type of dispersal, the dispersal range of a given species, and the dispersal mechanisms involved. Biological dispersal can be correlated to population density. The range of variations of a species' location determines the expansion range.

Biological dispersal may be contrasted with geodispersal, which refers to the mixing of previously isolated populations (or entire biotas) following the erosion of geographic barriers to dispersal or gene flow.

Phytophthora ramorum is the oomycete known to cause the disease sudden oak death (SOD). The disease kills oak and other species of trees and has had devastating effects on the oak populations in California and Oregon, as well as being present in Europe. Symptoms include bleeding cankers on the tree's trunk and dieback of the foliage, in many cases leading to the death of the tree.

P. ramorum also infects a great number of other plant species, significantly woody ornamentals such as Rhododendron, Viburnum, and Pieris, causing foliar symptoms known as ramorum dieback or ramorum blight. Such plants can act as a source of inoculum for new infections, with the pathogen producing spores that can be transmitted by rainsplash and rainwater.

A plantlet is a young or small plant, produced on the leaf margins or the aerial stems of another plant.

Some plants, such as spider plants, grow stolons with plantlets on the ends as a form of asexual reproduction. Vegetative propagules or clippings of mature plants may form plantlets.Examples of plantlets budding from leaf or stem tissue may be found in several species known as mother of thousands. Kalanchoe daigremontiana forms somatic embryos on its leaf margins that germinate into deciduous juvenile plants before falling from the parent and growing independently.

Soredia are common reproductive structures of lichens. Lichens reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria or green algae. These can be either scattered diffusely across the surface of the lichen's thallus, or produced in localized structures called soralia. Fungal hyphae make up the basic body structure of a lichen. The soredia are released through openings in the upper cortex of the lichen structure. After their release, the soredia disperse to establish the lichen in a new location.

Cryptococcosis is a potentially fatal fungal infection of mainly the lungs, presenting as a pneumonia, and in the brain, where it appears as a meningitis. Coughing, difficulty breathing, chest pain and fever are seen when the lungs are infected. When the brain is infected, symptoms include headache, fever, neck pain, nausea and vomiting, light sensitivity and confusion or changes in behavior. It can also affect other parts of the body including skin, where it may appear as several fluid-filled nodules with dead tissue.

It is caused by the fungi Cryptococcus neoformans or less commonly Cryptococcus gattii, and is acquired by breathing in the spores from the air. These fungi are found globally in soil, decaying wood, pigeon droppings, and in the hollows of some species of trees. Whereas C. neoformans generally infects people with HIV/AIDS and those on immunosuppressant drugs and does not usually affect fit and healthy people, C. gattii (found in some parts of Canada and the US) does. Once breathed in, the dried yeast cells colonize the lungs, where they are either cleared by immune cells, lie dormant, or cause infection and spread.