Arctic-alpine disjunct
Range of cold-adapted species comprising northern arctic populations and separated southern alpine populations.

Amphiberingian
Range on either side of the Bering Strait, i.e. in both northwestern North America and northeastern Eurasia.

Amphicontinental
Range on both sides of the continent, with a gap between.

Arthropod
An animal with a segmented body, exoskeleton and jointed appendages, belonging to the phylum Arthropoda. (Insects, spiders, scorpions, millipedes, crayfish, crabs, trilobites, and many other groups are all arthropods). A terrestrial arthropod also breathes air at some stage in its life cycle.

Beringia (or Beringian refugium)
Area of northwestern North America and northeastern Asia, including the Bering Strait, that was unglaciated during the ice age.

Biome
Major ecological zone or community of plants and animals generally corresponding to a climatic zone or region.

Cordillera
Great mountain region of western North America, between the central lowlands and the Pacific Ocean.

Cryoprotectants
Substances manufactured by overwintering insects that protect tissues in various ways from the potentially injurious effects of low temperatures.

Diapause
Suppression of development that is programmed in advance by internal or external signals.

Ectoparasite
Parasite that feeds on the outside of its host, such as a flea on a mammal.

Ecotone
Transition zone betweeen major biomes or habitats.

Endemics (or Endemic species)
Species that are native to a particular and usually restricted area or region.

Endopterygotes
Insects with complete metamorphosis, changing markedly between the immature stages and the adult (e.g. caterpillar to butterfly).

Exopterygotes
Insects with incomplete metamorphosis, changing form only gradually from the immature stages to the adult (e.g. grasshopper nymph to adult).

Genotype
Genetic constitution of an organism (as opposed to its observable characteristics, which is the phenotype)

Holarctic
Biogeographic region that includes the Old World (Palaearctic, Eurasia) and the New World (Nearctic, North America).

Nucleators
Substances that assist the onset of freezing by acting as nuclei for the freezing process. [Most freezing-tolerant insects have such substances, which ensure that freezing takes place before the temperature gets so low that ice formation, once initiated, would be very rapid and so potentially injurious.]

Parasitoid
Insect such as a parasitic wasp that lives on or in its host and eventually kills it.

Parthenogenesis
Reproduction without fertilization.

Phytophagous species (or Phytophages)
Species that feed on plants.

Refugia (singular: Refugium)
Areas that were unglaciated during the ice age, and thus served as refuges in which organisms could survive.

Saprophagous species (or Saprophages)
Species that feed on decaying materials.

Suture zones
Zones where populations that were separated during the ice age have subsequently come into contact, typically marked by complex hybridization and other patterns of variation.

Xerophilous
Species that favour dry conditions or habitats.

Xerophytic plants
Plants that have very low water requirements and so can grow in dry places.