Glossary

Adaptation: in evolutionary biology the term indicates a character established by natural selection which increases the reproductive capacity of those who possess it. It is sometimes used to denote not a character, but the process by which a population or species is modified (by natural selection) to better adapt to the environment.

Biodiversity hotspots: regions of the planet characterized by particularly high levels of biological diversity and threatened by habitat loss and extensive species loss. Two of the requirements needed to consider a region as biodiversity hotspot are: it must have at least 1,500 vascular plants as endemics and it must have lost 70% or more of its primary vegetation.

CITES: Convention on International Trade of Endangered Species signed in Washington in 1973.

Consanguinity: it is the condition of close kinship between individuals. It is a relevant concept for conservation because the mating of consanguineous individuals (inbreeding), which is inevitable in small populations, can cause various unfavorable conditions in the offspring (inbreeding depression). They involve reduction of genetic variability, expression of recessive mutations (those that are not disadvantageous if transmitted by a single parent) and their possible spread in the population.

Conservation genomics: it is a new field of science that study whole genomes (or large fractions of the genome) to address questions in conservation biology. Rapidly advancing molecular and genomics technologies are revolutionizing the study of biodiversity, taxonomy, hybridization, diets, demographics, resistance to disease and epidemics, and local adaptation of wildlife.

Deleterious mutation: it is a genetic alteration that increases the susceptibility or predisposition of an individual to a certain disease or disorder, and in general reduces the fitness.

Endemic species: wild species living in a specific place and whose presence has not been found anywhere else in the world.

Fitness: it measures the relative ability of an individual to survive and reproduce, compared to other individuals in the same population. It therefore determines to what extent a genotype is favored by natural selection (the genotype is a particular and unique set of genes that characterize an individual over others).

Genetic drift: it is one of the components of the evolution of a species (together with mutation, selection and migration) and induces a random change in the allelic frequency of a population (alleles are alternative forms of the same gene). It is important to emphasize that, when populations become small (few individuals), genetic drift takes on an increasingly important role (over selection) determining the trend of allele frequencies. This reduces the ability to adapt and can increase the risk of extinction.

Genetic load: it is related to the reduction of fitness in an individual, or in a population, due to the presence of disadvantageous mutations in the genome. A low genetic load confers, in the same environment, a greater probability of generating offspring than a high genetic load. For this reason, a high genetic load increases the probability of extinction of a population.

Genetic rescue: strategy to restore genetic diversity and reduce the risk of extinction of small, isolated populations affected by high degrees of inbreeding. Genetic rescue is usually achieved by introducing individuals from a large and healthy population. The possible disadvantages of a strategy of this type mainly concern the loss of the genetic features typical of the population to be “saved”. For this reason, genetic rescue initiatives require detailed knowledge of the genetic features of both populations.

Genetic variability: it is the existence of multiple versions of the same gene mainly due to mutations and recombination processes. This is a measurable factor in a population or in a species, and is believed to be fundamental to avoid extinction, allowing adaptation, in a changing environment.

Genome: the entire genetic heritage (DNA) of an organism.

Genomic susceptibility to extinction: itrefers to the situation of an isolated population or species drastically reduced in number. This generates a significant loss of genetic variability, the fixation of deleterious mutations and inbreeding depression, which can compromise survival.

Inbreeding: mating between closely related (consanguineous) individuals

In silico: Latin phrase that indicates phenomena of biological nature reproduced in a mathematical simulation on a computer, rather than in a test tube or in an organism.

In vitro: Latin phrase used to indicate biological phenomena reproduced in a test tube and not in an organism or on a computer.

In vivo: Latin phrase used to indicate biological phenomena reproduced in an organism and not in a test tube or computer.

Invasive species: non-native (allochthonous) species that spread rapidly from the area where it was introduced, directly or indirectly by man, and has a negative impact on colonized ecosystems, for example by competing with native species or by spreading new diseases.

IUCN Red List: International Union for Conservation of Nature (IUCN) is the global authority that establishes the status of biodiversity and necessary measures to preserve it. The IUCN Red List is the most comprehensive inventory of endangered species globally and nationally.

Model species: animal models (mouse, rat, fruit fly, zebrafish, etc.) are species that are intensively studied to understand biological mechanisms or processes that occur in other organisms. For example, the animal model can make possible to study the evolution of diseases that also occur in humans.

Mutation: in genetics it means any stable and heritable change in the nucleotide sequence of a genome or more generally in the genetic material (both DNA and RNA) due to external agents or chance.

Natural selection: mechanism by which the individuals with higher fitness have more descendants than individuals with lower fitness, producing an increase of the favorable features in a certain number of generations. Charles Darwin was the first to discover that this process can explain both evolution and adaptation. Although natural selection is fundamental for the theory of evolution and to understand and interpret the diversity of species. we also know that it cannot explain every character of an organism and that other mechanisms and constraints intervene in the evolution of species.

Next Generation Sequencing: it is a DNA sequencing approach that can process millions of fragments in a short time (hours) and low cost (for example, the human genome can currently be sequenced for only 500-1000 US dollars).

Reference genome: it is aDNA sequence that represents the complete genome of an organism and works as a reference to align (the process determining the most likely location of origin of a sequence within a genome) short DNA sequences of an individual of the same species (or genetically very close species).

Segregation: the principle of segregation describes how gene variants (called alleles) are separated in reproductive cells. Segregation of alleles, and their corresponding morphological features, was first observed by Gregor Mendel in 1865. We now know that gene segregation occurs during meiosis in eukaryotes, a process that produces reproductive cells (gametes).

Subspecies: term belonging to the hierarchy of living organisms (taxonomy) placed one step lower than the species. It is used to describe individuals of the same species but with some significant genetic differences which, however, are not sufficient to consider them as two different species. As for the species, and to a greater extent, the identification of a subspecies is useful but often ambiguous and subject to revision.

Tetraploid: a species that has four copies of each chromosome, on the contrary of diploid species (including humans) that possess only two.

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